「App:Library:LVGL:docs:Overview:Images」の版間の差分
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__NOTOC__ | __NOTOC__ | ||
= Images = | = Images = | ||
+ | {| class="wikitable" | ||
+ | !英文 | ||
+ | !自動翻訳 | ||
+ | |- | ||
+ | | | ||
An image can be a file or a variable which stores the bitmap itself and some metadata. | An image can be a file or a variable which stores the bitmap itself and some metadata. | ||
+ | | | ||
+ | |} | ||
+ | :[[App:Library:LVGL:docs:Overview|戻る : Previous]] | ||
+ | |||
== Store images == | == Store images == | ||
+ | {| class="wikitable" | ||
+ | !英文 | ||
+ | !自動翻訳 | ||
+ | |- | ||
+ | | | ||
You can store images in two places | You can store images in two places | ||
* as a variable in internal memory (RAM or ROM) | * as a variable in internal memory (RAM or ROM) | ||
* as a file | * as a file | ||
+ | | | ||
+ | |} | ||
+ | :[[App:Library:LVGL:docs:Overview|戻る : Previous]] | ||
+ | |||
=== Variables === | === Variables === | ||
− | Images stored internally in a variable are composed mainly of an <code>lv_img_dsc_t</code> structure with the following fields: | + | {| class="wikitable" |
+ | !英文 | ||
+ | !自動翻訳 | ||
+ | |- | ||
+ | | | ||
+ | Images stored internally in a variable are composed mainly of an <code style="color: #bb0000;">lv_img_dsc_t</code> structure with the following fields: | ||
* header | * header | ||
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** ''reserved'' reserved for future use | ** ''reserved'' reserved for future use | ||
* data pointer to an array where the image itself is stored | * data pointer to an array where the image itself is stored | ||
− | * data_size length of <code>data</code> in bytes | + | * data_size length of <code style="color: #bb0000;">data</code> in bytes |
These are usually stored within a project as C files. They are linked into the resulting executable like any other constant data. | These are usually stored within a project as C files. They are linked into the resulting executable like any other constant data. | ||
+ | | | ||
+ | |} | ||
+ | :[[App:Library:LVGL:docs:Overview|戻る : Previous]] | ||
+ | |||
=== Files === | === Files === | ||
+ | {| class="wikitable" | ||
+ | !英文 | ||
+ | !自動翻訳 | ||
+ | |- | ||
+ | | | ||
To deal with files you need to add a storage ''Drive'' to LVGL. In short, a ''Drive'' is a collection of functions (''open'', ''read'', ''close'', etc.) registered in LVGL to make file operations. You can add an interface to a standard file system (FAT32 on SD card) or you create your simple file system to read data from an SPI Flash memory. In every case, a ''Drive'' is just an abstraction to read and/or write data to memory. See the File system section to learn more. | To deal with files you need to add a storage ''Drive'' to LVGL. In short, a ''Drive'' is a collection of functions (''open'', ''read'', ''close'', etc.) registered in LVGL to make file operations. You can add an interface to a standard file system (FAT32 on SD card) or you create your simple file system to read data from an SPI Flash memory. In every case, a ''Drive'' is just an abstraction to read and/or write data to memory. See the File system section to learn more. | ||
Images stored as files are not linked into the resulting executable, and must be read into RAM before being drawn. As a result, they are not as resource-friendly as images linked at compile time. However, they are easier to replace without needing to rebuild the main program. | Images stored as files are not linked into the resulting executable, and must be read into RAM before being drawn. As a result, they are not as resource-friendly as images linked at compile time. However, they are easier to replace without needing to rebuild the main program. | ||
+ | | | ||
+ | |} | ||
+ | :[[App:Library:LVGL:docs:Overview|戻る : Previous]] | ||
+ | |||
== Color formats == | == Color formats == | ||
+ | {| class="wikitable" | ||
+ | !英文 | ||
+ | !自動翻訳 | ||
+ | |- | ||
+ | | | ||
Various built-in color formats are supported: | Various built-in color formats are supported: | ||
* LV_IMG_CF_TRUE_COLOR Simply stores the RGB colors (in whatever color depth LVGL is configured for). | * LV_IMG_CF_TRUE_COLOR Simply stores the RGB colors (in whatever color depth LVGL is configured for). | ||
− | * LV_IMG_CF_TRUE_COLOR_ALPHA Like <code>LV_IMG_CF_TRUE_COLOR</code> but it also adds an alpha (transparency) byte for every pixel. | + | * LV_IMG_CF_TRUE_COLOR_ALPHA Like <code style="color: #bb0000;">LV_IMG_CF_TRUE_COLOR</code> but it also adds an alpha (transparency) byte for every pixel. |
− | * LV_IMG_CF_TRUE_COLOR_CHROMA_KEYED Like <code>LV_IMG_CF_TRUE_COLOR</code> but if a pixel has the <code>LV_COLOR_TRANSP</code> color (set in ''lv_conf.h'') it will be transparent. | + | * LV_IMG_CF_TRUE_COLOR_CHROMA_KEYED Like <code style="color: #bb0000;">LV_IMG_CF_TRUE_COLOR</code> but if a pixel has the <code style="color: #bb0000;">LV_COLOR_TRANSP</code> color (set in ''lv_conf.h'') it will be transparent. |
* LV_IMG_CF_INDEXED_1/2/4/8BIT Uses a palette with 2, 4, 16 or 256 colors and stores each pixel in 1, 2, 4 or 8 bits. | * LV_IMG_CF_INDEXED_1/2/4/8BIT Uses a palette with 2, 4, 16 or 256 colors and stores each pixel in 1, 2, 4 or 8 bits. | ||
− | * LV_IMG_CF_ALPHA_1/2/4/8BIT Only stores the Alpha value with 1, 2, 4 or 8 bits. The pixels take the color of <code>style.img_recolor</code> and the set opacity. The source image has to be an alpha channel. This is ideal for bitmaps similar to fonts where the whole image is one color that can be altered. | + | * LV_IMG_CF_ALPHA_1/2/4/8BIT Only stores the Alpha value with 1, 2, 4 or 8 bits. The pixels take the color of <code style="color: #bb0000;">style.img_recolor</code> and the set opacity. The source image has to be an alpha channel. This is ideal for bitmaps similar to fonts where the whole image is one color that can be altered. |
− | The bytes of <code>LV_IMG_CF_TRUE_COLOR</code> images are stored in the following order. | + | The bytes of <code style="color: #bb0000;">LV_IMG_CF_TRUE_COLOR</code> images are stored in the following order. |
For 32-bit color depth: | For 32-bit color depth: | ||
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* LV_IMG_CF_RAW Indicates a basic raw image (e.g. a PNG or JPG image). | * LV_IMG_CF_RAW Indicates a basic raw image (e.g. a PNG or JPG image). | ||
* LV_IMG_CF_RAW_ALPHA Indicates that an image has alpha and an alpha byte is added for every pixel. | * LV_IMG_CF_RAW_ALPHA Indicates that an image has alpha and an alpha byte is added for every pixel. | ||
− | * LV_IMG_CF_RAW_CHROMA_KEYED Indicates that an image is chroma-keyed as described in <code>LV_IMG_CF_TRUE_COLOR_CHROMA_KEYED</code> above. | + | * LV_IMG_CF_RAW_CHROMA_KEYED Indicates that an image is chroma-keyed as described in <code style="color: #bb0000;">LV_IMG_CF_TRUE_COLOR_CHROMA_KEYED</code> above. |
+ | | | ||
+ | |} | ||
+ | :[[App:Library:LVGL:docs:Overview|戻る : Previous]] | ||
+ | |||
== Add and use images == | == Add and use images == | ||
+ | {| class="wikitable" | ||
+ | !英文 | ||
+ | !自動翻訳 | ||
+ | |- | ||
+ | | | ||
You can add images to LVGL in two ways: | You can add images to LVGL in two ways: | ||
* using the online converter | * using the online converter | ||
* manually create images | * manually create images | ||
+ | | | ||
+ | |} | ||
+ | :[[App:Library:LVGL:docs:Overview|戻る : Previous]] | ||
+ | |||
=== Online converter === | === Online converter === | ||
+ | {| class="wikitable" | ||
+ | !英文 | ||
+ | !自動翻訳 | ||
+ | |- | ||
+ | | | ||
The online Image converter is available here: <nowiki>https://lvgl.io/tools/imageconverter</nowiki> | The online Image converter is available here: <nowiki>https://lvgl.io/tools/imageconverter</nowiki> | ||
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# Give the image a name that will be used within LVGL. | # Give the image a name that will be used within LVGL. | ||
# Select the Color format. | # Select the Color format. | ||
− | # Select the type of image you want. Choosing a binary will generate a <code>.bin</code> file that must be stored separately and read using the file support. Choosing a variable will generate a standard C file that can be linked into your project. | + | # Select the type of image you want. Choosing a binary will generate a <code style="color: #bb0000;">.bin</code> file that must be stored separately and read using the file support. Choosing a variable will generate a standard C file that can be linked into your project. |
# Hit the ''Convert'' button. Once the conversion is finished, your browser will automatically download the resulting file. | # Hit the ''Convert'' button. Once the conversion is finished, your browser will automatically download the resulting file. | ||
− | In the generated C arrays (variables), bitmaps for all the color depths (1, 8, 16 or 32) are included in the C file, but only the color depth that matches <code>LV_COLOR_DEPTH</code> in ''lv_conf.h'' will actually be linked into the resulting executable. | + | In the generated C arrays (variables), bitmaps for all the color depths (1, 8, 16 or 32) are included in the C file, but only the color depth that matches <code style="color: #bb0000;">LV_COLOR_DEPTH</code> in ''lv_conf.h'' will actually be linked into the resulting executable. |
In the case of binary files, you need to specify the color format you want: | In the case of binary files, you need to specify the color format you want: | ||
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* RGB565 Swap for 16-bit color depth (two bytes are swapped) | * RGB565 Swap for 16-bit color depth (two bytes are swapped) | ||
* RGB888 for 32-bit color depth | * RGB888 for 32-bit color depth | ||
+ | | | ||
+ | |} | ||
+ | :[[App:Library:LVGL:docs:Overview|戻る : Previous]] | ||
+ | |||
=== Manually create an image === | === Manually create an image === | ||
+ | {| class="wikitable" | ||
+ | !英文 | ||
+ | !自動翻訳 | ||
+ | |- | ||
+ | | | ||
If you are generating an image at run-time, you can craft an image variable to display it using LVGL. For example: | If you are generating an image at run-time, you can craft an image variable to display it using LVGL. For example: | ||
uint8_t my_img_data[] = {0x00, 0x01, 0x02, ...}; | uint8_t my_img_data[] = {0x00, 0x01, 0x02, ...}; | ||
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.data = my_img_data, | .data = my_img_data, | ||
}; | }; | ||
− | If the color format is <code>LV_IMG_CF_TRUE_COLOR_ALPHA</code> you can set <code>data_size</code> like <code>80 * 60 * LV_IMG_PX_SIZE_ALPHA_BYTE</code>. | + | If the color format is <code style="color: #bb0000;">LV_IMG_CF_TRUE_COLOR_ALPHA</code> you can set <code style="color: #bb0000;">data_size</code> like <code style="color: #bb0000;">80 * 60 * LV_IMG_PX_SIZE_ALPHA_BYTE</code>. |
Another (possibly simpler) option to create and display an image at run-time is to use the Canvas object. | Another (possibly simpler) option to create and display an image at run-time is to use the Canvas object. | ||
+ | | | ||
+ | |} | ||
+ | :[[App:Library:LVGL:docs:Overview|戻る : Previous]] | ||
+ | |||
=== Use images === | === Use images === | ||
+ | {| class="wikitable" | ||
+ | !英文 | ||
+ | !自動翻訳 | ||
+ | |- | ||
+ | | | ||
The simplest way to use an image in LVGL is to display it with an lv_img object: | The simplest way to use an image in LVGL is to display it with an lv_img object: | ||
lv_obj_t * icon = lv_img_create(lv_scr_act(), NULL); | lv_obj_t * icon = lv_img_create(lv_scr_act(), NULL); | ||
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/*From file*/ | /*From file*/ | ||
lv_img_set_src(icon, "S:my_icon.bin"); | lv_img_set_src(icon, "S:my_icon.bin"); | ||
− | If the image was converted with the online converter, you should use <code>LV_IMG_DECLARE(my_icon_dsc)</code> to declare the image in the file where you want to use it. | + | If the image was converted with the online converter, you should use <code style="color: #bb0000;">LV_IMG_DECLARE(my_icon_dsc)</code> to declare the image in the file where you want to use it. |
+ | | | ||
+ | |} | ||
+ | :[[App:Library:LVGL:docs:Overview|戻る : Previous]] | ||
+ | |||
== Image decoder == | == Image decoder == | ||
− | + | {| class="wikitable" | |
+ | !英文 | ||
+ | !自動翻訳 | ||
+ | |- | ||
+ | | | ||
As you can see in the Color formats section, LVGL supports several built-in image formats. In many cases, these will be all you need. LVGL doesn't directly support, however, generic image formats like PNG or JPG. | As you can see in the Color formats section, LVGL supports several built-in image formats. In many cases, these will be all you need. LVGL doesn't directly support, however, generic image formats like PNG or JPG. | ||
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* info get some basic info about the image (width, height and color format). | * info get some basic info about the image (width, height and color format). | ||
− | * open open an image: either store a decoded image or set it to <code>NULL</code> to indicate the image can be read line-by-line. | + | * open open an image: either store a decoded image or set it to <code style="color: #bb0000;">NULL</code> to indicate the image can be read line-by-line. |
* read if ''open'' didn't fully open an image this function should give some decoded data (max 1 line) from a given position. | * read if ''open'' didn't fully open an image this function should give some decoded data (max 1 line) from a given position. | ||
* close close an opened image, free the allocated resources. | * close close an opened image, free the allocated resources. | ||
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You can add any number of image decoders. When an image needs to be drawn, the library will try all the registered image decoders until it finds one which can open the image, i.e. one which knows that format. | You can add any number of image decoders. When an image needs to be drawn, the library will try all the registered image decoders until it finds one which can open the image, i.e. one which knows that format. | ||
− | The <code>LV_IMG_CF_TRUE_COLOR_...</code>, <code>LV_IMG_INDEXED_...</code> and <code>LV_IMG_ALPHA_...</code> formats (essentially, all non-<code>RAW</code> formats) are understood by the built-in decoder. | + | The <code style="color: #bb0000;">LV_IMG_CF_TRUE_COLOR_...</code>, <code style="color: #bb0000;">LV_IMG_INDEXED_...</code> and <code style="color: #bb0000;">LV_IMG_ALPHA_...</code> formats (essentially, all non-<code style="color: #bb0000;">RAW</code> formats) are understood by the built-in decoder. |
=== Custom image formats === | === Custom image formats === | ||
− | The easiest way to create a custom image is to use the online image converter and select <code>Raw</code>, <code>Raw with alpha</code> or <code>Raw with chroma-keyed</code> format. It will just take every byte of the binary file you uploaded and write it as an image "bitmap". You then need to attach an image decoder that will parse that bitmap and generate the real, renderable bitmap. | + | The easiest way to create a custom image is to use the online image converter and select <code style="color: #bb0000;">Raw</code>, <code style="color: #bb0000;">Raw with alpha</code> or <code style="color: #bb0000;">Raw with chroma-keyed</code> format. It will just take every byte of the binary file you uploaded and write it as an image "bitmap". You then need to attach an image decoder that will parse that bitmap and generate the real, renderable bitmap. |
− | <code>header.cf</code> will be <code>LV_IMG_CF_RAW</code>, <code>LV_IMG_CF_RAW_ALPHA</code> or <code>LV_IMG_CF_RAW_CHROMA_KEYED</code> accordingly. You should choose the correct format according to your needs: a fully opaque image, using an alpha channel or using a chroma key. | + | <code style="color: #bb0000;">header.cf</code> will be <code style="color: #bb0000;">LV_IMG_CF_RAW</code>, <code style="color: #bb0000;">LV_IMG_CF_RAW_ALPHA</code> or <code style="color: #bb0000;">LV_IMG_CF_RAW_CHROMA_KEYED</code> accordingly. You should choose the correct format according to your needs: a fully opaque image, using an alpha channel or using a chroma key. |
After decoding, the ''raw'' formats are considered ''True color'' by the library. In other words, the image decoder must decode the ''Raw'' images to ''True color'' according to the format described in the Color formats section. | After decoding, the ''raw'' formats are considered ''True color'' by the library. In other words, the image decoder must decode the ''Raw'' images to ''True color'' according to the format described in the Color formats section. | ||
− | If you want to create a custom image, you should use <code>LV_IMG_CF_USER_ENCODED_0..7</code> color formats. However, the library can draw images only in ''True color'' format (or ''Raw'' but ultimately it will be in ''True color'' format). The <code>LV_IMG_CF_USER_ENCODED_...</code> formats are not known by the library and therefore they should be decoded to one of the known formats from the Color formats section. It's possible to decode an image to a non-true color format first (for example: <code>LV_IMG_INDEXED_4BITS</code>) and then call the built-in decoder functions to convert it to ''True color''. | + | If you want to create a custom image, you should use <code style="color: #bb0000;">LV_IMG_CF_USER_ENCODED_0..7</code> color formats. However, the library can draw images only in ''True color'' format (or ''Raw'' but ultimately it will be in ''True color'' format). The <code style="color: #bb0000;">LV_IMG_CF_USER_ENCODED_...</code> formats are not known by the library and therefore they should be decoded to one of the known formats from the Color formats section. It's possible to decode an image to a non-true color format first (for example: <code style="color: #bb0000;">LV_IMG_INDEXED_4BITS</code>) and then call the built-in decoder functions to convert it to ''True color''. |
+ | |||
+ | With ''User encoded'' formats, the color format in the open function (<code style="color: #bb0000;">dsc->header.cf</code>) should be changed according to the new format. | ||
+ | | | ||
+ | |} | ||
+ | :[[App:Library:LVGL:docs:Overview|戻る : Previous]] | ||
− | |||
=== Register an image decoder === | === Register an image decoder === | ||
+ | {| class="wikitable" | ||
+ | !英文 | ||
+ | !自動翻訳 | ||
+ | |- | ||
+ | | | ||
Here's an example of getting LVGL to work with PNG images. | Here's an example of getting LVGL to work with PNG images. | ||
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So in summary: | So in summary: | ||
− | * In <code>decoder_info</code>, you should collect some basic information about the image and store it in <code>header</code>. | + | * In <code style="color: #bb0000;">decoder_info</code>, you should collect some basic information about the image and store it in <code style="color: #bb0000;">header</code>. |
− | * In <code>decoder_open</code>, you should try to open the image source pointed by <code>dsc->src</code>. Its type is already in <code>dsc->src_type == LV_IMG_SRC_FILE/VARIABLE</code>. If this format/type is not supported by the decoder, return <code>LV_RES_INV</code>. However, if you can open the image, a pointer to the decoded ''True color'' image should be set in <code>dsc->img_data</code>. If the format is known, but you don't want to decode the entire image (e.g. no memory for it), set <code>dsc->img_data = NULL</code> and use <code>read_line</code> to get the pixel data. | + | * In <code style="color: #bb0000;">decoder_open</code>, you should try to open the image source pointed by <code style="color: #bb0000;">dsc->src</code>. Its type is already in <code style="color: #bb0000;">dsc->src_type == LV_IMG_SRC_FILE/VARIABLE</code>. If this format/type is not supported by the decoder, return <code style="color: #bb0000;">LV_RES_INV</code>. However, if you can open the image, a pointer to the decoded ''True color'' image should be set in <code style="color: #bb0000;">dsc->img_data</code>. If the format is known, but you don't want to decode the entire image (e.g. no memory for it), set <code style="color: #bb0000;">dsc->img_data = NULL</code> and use <code style="color: #bb0000;">read_line</code> to get the pixel data. |
− | * In <code>decoder_close</code> you should free all allocated resources. | + | * In <code style="color: #bb0000;">decoder_close</code> you should free all allocated resources. |
− | * <code>decoder_read</code> is optional. Decoding the whole image requires extra memory and some computational overhead. However, it can decode one line of the image without decoding the whole image, you can save memory and time. To indicate that the ''line read'' function should be used, set <code>dsc->img_data = NULL</code> in the open function. | + | * <code style="color: #bb0000;">decoder_read</code> is optional. Decoding the whole image requires extra memory and some computational overhead. However, it can decode one line of the image without decoding the whole image, you can save memory and time. To indicate that the ''line read'' function should be used, set <code style="color: #bb0000;">dsc->img_data = NULL</code> in the open function. |
+ | | | ||
+ | |} | ||
+ | :[[App:Library:LVGL:docs:Overview|戻る : Previous]] | ||
+ | |||
=== Manually use an image decoder === | === Manually use an image decoder === | ||
− | LVGL will use registered image decoders automatically if you try and draw a raw image (i.e. using the <code>lv_img</code> object) but you can use them manually too. Create an <code>lv_img_decoder_dsc_t</code> variable to describe the decoding session and call <code>lv_img_decoder_open()</code>. | + | {| class="wikitable" |
+ | !英文 | ||
+ | !自動翻訳 | ||
+ | |- | ||
+ | | | ||
+ | LVGL will use registered image decoders automatically if you try and draw a raw image (i.e. using the <code style="color: #bb0000;">lv_img</code> object) but you can use them manually too. Create an <code style="color: #bb0000;">lv_img_decoder_dsc_t</code> variable to describe the decoding session and call <code style="color: #bb0000;">lv_img_decoder_open()</code>. | ||
− | The <code>color</code> parameter is used only with <code>LV_IMG_CF_ALPHA_1/2/4/8BIT</code> images to tell color of the image. <code>frame_id</code> can be used if the image to open is an animation. | + | The <code style="color: #bb0000;">color</code> parameter is used only with <code style="color: #bb0000;">LV_IMG_CF_ALPHA_1/2/4/8BIT</code> images to tell color of the image. <code style="color: #bb0000;">frame_id</code> can be used if the image to open is an animation. |
lv_res_t res; | lv_res_t res; | ||
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lv_img_decoder_close(&dsc); | lv_img_decoder_close(&dsc); | ||
} | } | ||
+ | | | ||
+ | |} | ||
+ | :[[App:Library:LVGL:docs:Overview|戻る : Previous]] | ||
+ | |||
== Image caching == | == Image caching == | ||
+ | {| class="wikitable" | ||
+ | !英文 | ||
+ | !自動翻訳 | ||
+ | |- | ||
+ | | | ||
Sometimes it takes a lot of time to open an image. Continuously decoding a PNG image or loading images from a slow external memory would be inefficient and detrimental to the user experience. | Sometimes it takes a lot of time to open an image. Continuously decoding a PNG image or loading images from a slow external memory would be inefficient and detrimental to the user experience. | ||
− | Therefore, LVGL caches a given number of images. Caching means some images will be left open, hence LVGL can quickly access them from <code>dsc->img_data</code> instead of needing to decode them again. | + | Therefore, LVGL caches a given number of images. Caching means some images will be left open, hence LVGL can quickly access them from <code style="color: #bb0000;">dsc->img_data</code> instead of needing to decode them again. |
Of course, caching images is resource intensive as it uses more RAM to store the decoded image. LVGL tries to optimize the process as much as possible (see below), but you will still need to evaluate if this would be beneficial for your platform or not. Image caching may not be worth it if you have a deeply embedded target which decodes small images from a relatively fast storage medium. | Of course, caching images is resource intensive as it uses more RAM to store the decoded image. LVGL tries to optimize the process as much as possible (see below), but you will still need to evaluate if this would be beneficial for your platform or not. Image caching may not be worth it if you have a deeply embedded target which decodes small images from a relatively fast storage medium. | ||
+ | | | ||
+ | |} | ||
+ | :[[App:Library:LVGL:docs:Overview|戻る : Previous]] | ||
+ | |||
=== Cache size === | === Cache size === | ||
− | The number of cache entries can be defined with <code>LV_IMG_CACHE_DEF_SIZE</code> in ''lv_conf.h''. The default value is 1 so only the most recently used image will be left open. | + | {| class="wikitable" |
+ | !英文 | ||
+ | !自動翻訳 | ||
+ | |- | ||
+ | | | ||
+ | The number of cache entries can be defined with <code style="color: #bb0000;">LV_IMG_CACHE_DEF_SIZE</code> in ''lv_conf.h''. The default value is 1 so only the most recently used image will be left open. | ||
+ | |||
+ | The size of the cache can be changed at run-time with <code style="color: #bb0000;">lv_img_cache_set_size(entry_num)</code>. | ||
+ | | | ||
+ | |} | ||
+ | :[[App:Library:LVGL:docs:Overview|戻る : Previous]] | ||
− | |||
=== Value of images === | === Value of images === | ||
+ | {| class="wikitable" | ||
+ | !英文 | ||
+ | !自動翻訳 | ||
+ | |- | ||
+ | | | ||
When you use more images than cache entries, LVGL can't cache all the images. Instead, the library will close one of the cached images to free space. | When you use more images than cache entries, LVGL can't cache all the images. Instead, the library will close one of the cached images to free space. | ||
To decide which image to close, LVGL uses a measurement it previously made of how long it took to open the image. Cache entries that hold slower-to-open images are considered more valuable and are kept in the cache as long as possible. | To decide which image to close, LVGL uses a measurement it previously made of how long it took to open the image. Cache entries that hold slower-to-open images are considered more valuable and are kept in the cache as long as possible. | ||
− | If you want or need to override LVGL's measurement, you can manually set the ''time to open'' value in the decoder open function in <code>dsc->time_to_open = time_ms</code> to give a higher or lower value. (Leave it unchanged to let LVGL control it.) | + | If you want or need to override LVGL's measurement, you can manually set the ''time to open'' value in the decoder open function in <code style="color: #bb0000;">dsc->time_to_open = time_ms</code> to give a higher or lower value. (Leave it unchanged to let LVGL control it.) |
Every cache entry has a ''"life"'' value. Every time an image is opened through the cache, the ''life'' value of all entries is decreased to make them older. When a cached image is used, its ''life'' value is increased by the ''time to open'' value to make it more alive. | Every cache entry has a ''"life"'' value. Every time an image is opened through the cache, the ''life'' value of all entries is decreased to make them older. When a cached image is used, its ''life'' value is increased by the ''time to open'' value to make it more alive. | ||
If there is no more space in the cache, the entry with the lowest life value will be closed. | If there is no more space in the cache, the entry with the lowest life value will be closed. | ||
+ | | | ||
+ | |} | ||
+ | :[[App:Library:LVGL:docs:Overview|戻る : Previous]] | ||
+ | |||
=== Memory usage === | === Memory usage === | ||
+ | {| class="wikitable" | ||
+ | !英文 | ||
+ | !自動翻訳 | ||
+ | |- | ||
+ | | | ||
Note that a cached image might continuously consume memory. For example, if three PNG images are cached, they will consume memory while they are open. | Note that a cached image might continuously consume memory. For example, if three PNG images are cached, they will consume memory while they are open. | ||
Therefore, it's the user's responsibility to be sure there is enough RAM to cache even the largest images at the same time. | Therefore, it's the user's responsibility to be sure there is enough RAM to cache even the largest images at the same time. | ||
+ | | | ||
+ | |} | ||
+ | :[[App:Library:LVGL:docs:Overview|戻る : Previous]] | ||
+ | |||
=== Clean the cache === | === Clean the cache === | ||
− | Let's say you have loaded a PNG image into a <code>lv_img_dsc_t my_png</code> variable and use it in an <code>lv_img</code> object. If the image is already cached and you then change the underlying PNG file, you need to notify LVGL to cache the image again. Otherwise, there is no easy way of detecting that the underlying file changed and LVGL will still draw the old image from cache. | + | {| class="wikitable" |
+ | !英文 | ||
+ | !自動翻訳 | ||
+ | |- | ||
+ | | | ||
+ | Let's say you have loaded a PNG image into a <code style="color: #bb0000;">lv_img_dsc_t my_png</code> variable and use it in an <code style="color: #bb0000;">lv_img</code> object. If the image is already cached and you then change the underlying PNG file, you need to notify LVGL to cache the image again. Otherwise, there is no easy way of detecting that the underlying file changed and LVGL will still draw the old image from cache. | ||
+ | |||
+ | To do this, use <code style="color: #bb0000;">lv_img_cache_invalidate_src(&my_png)</code>. If <code style="color: #bb0000;">NULL</code> is passed as a parameter, the whole cache will be cleaned. | ||
+ | | | ||
+ | |} | ||
+ | :[[App:Library:LVGL:docs:Overview|戻る : Previous]] | ||
− | |||
== API == | == API == | ||
− | |||
=== Image buffer === | === Image buffer === | ||
+ | {| class="wikitable" | ||
+ | !英文 | ||
+ | !自動翻訳 | ||
+ | |- | ||
+ | | | ||
Typedefs | Typedefs | ||
− | + | <span style="background-color:#e7f2fa;color:#2980b9;">typedef uint8_t lv_img_cf_t </span> | |
: | : | ||
Enums | Enums | ||
− | + | <span style="background-color:#e7f2fa;color:#2980b9;">enum [anonymous] </span> | |
: ''Values:'' | : ''Values:'' | ||
− | : | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_UNKNOWN </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_RAW </span> |
− | :: | + | :: Contains the file as it is. Needs custom decoder function |
− | : | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_RAW_ALPHA </span> |
− | :: | + | :: Contains the file as it is. The image has alpha. Needs custom decoder function |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_RAW_CHROMA_KEYED </span> | |
− | :: | + | :: Contains the file as it is. The image is chroma keyed. Needs custom decoder function |
− | : | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_TRUE_COLOR </span> |
− | :: | + | :: Color format and depth should match with LV_COLOR settings |
− | : | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_TRUE_COLOR_ALPHA </span> |
− | :: | + | :: Same as <code style="color: #bb0000;">LV_IMG_CF_TRUE_COLOR</code> but every pixel has an alpha byte |
− | : | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_TRUE_COLOR_CHROMA_KEYED </span> |
− | :: | + | :: Same as <code style="color: #bb0000;">LV_IMG_CF_TRUE_COLOR</code> but LV_COLOR_TRANSP pixels will be transparent |
− | : | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_INDEXED_1BIT </span> |
− | :: | + | :: Can have 2 different colors in a palette (always chroma keyed) |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_INDEXED_2BIT </span> | |
− | + | :: Can have 4 different colors in a palette (always chroma keyed) | |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_INDEXED_4BIT </span> | |
− | + | :: Can have 16 different colors in a palette (always chroma keyed) | |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_INDEXED_8BIT </span> | |
− | + | :: Can have 256 different colors in a palette (always chroma keyed) | |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_ALPHA_1BIT </span> | |
− | + | :: Can have one color and it can be drawn or not | |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_ALPHA_2BIT </span> | |
− | + | :: Can have one color but 4 different alpha value | |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_ALPHA_4BIT </span> | |
− | + | :: Can have one color but 16 different alpha value | |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_ALPHA_8BIT </span> | |
− | + | :: Can have one color but 256 different alpha value | |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_RESERVED_15 </span> | |
− | + | :: Reserved for further use. | |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_RESERVED_16 </span> | |
− | + | :: Reserved for further use. | |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_RESERVED_17 </span> | |
− | + | :: Reserved for further use. | |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_RESERVED_18 </span> | |
− | + | :: Reserved for further use. | |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_RESERVED_19 </span> | |
− | + | :: Reserved for further use. | |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_RESERVED_20 </span> | |
− | + | :: Reserved for further use. | |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_RESERVED_21 </span> | |
− | + | :: Reserved for further use. | |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_RESERVED_22 </span> | |
− | + | :: Reserved for further use. | |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_RESERVED_23 </span> | |
− | + | :: Reserved for further use. | |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_USER_ENCODED_0 </span> | |
− | + | :: User holder encoding format. | |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_USER_ENCODED_1 </span> | |
− | + | :: User holder encoding format. | |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_USER_ENCODED_2 </span> | |
− | + | :: User holder encoding format. | |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_USER_ENCODED_3 </span> | |
− | + | :: User holder encoding format. | |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_USER_ENCODED_4 </span> | |
− | + | :: User holder encoding format. | |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_USER_ENCODED_5 </span> | |
− | + | :: User holder encoding format. | |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_USER_ENCODED_6 </span> | |
− | + | :: User holder encoding format. | |
− | + | : <span style="background-color: #eeeeee;">enumerator LV_IMG_CF_USER_ENCODED_7 </span> | |
− | :: User holder encoding format. | + | :: User holder encoding format. |
Functions | Functions | ||
− | + | <span style="background-color:#e7f2fa;color:#2980b9;">lv_img_dsc_t *lv_img_buf_alloc(lv_coord_t w, lv_coord_t h, lv_img_cf_t cf) </span> | |
: Allocate an image buffer in RAM | : Allocate an image buffer in RAM | ||
− | : | + | : Parameters |
− | ::* w -- width of image | + | ::* w -- width of image |
::* h -- height of image | ::* h -- height of image | ||
− | ::* cf -- a color format (<code>LV_IMG_CF_...</code>) | + | ::* cf -- a color format (<code style="color: #bb0000;">LV_IMG_CF_...</code>) |
− | : | + | : Returns |
:: an allocated image, or NULL on failure | :: an allocated image, or NULL on failure | ||
− | + | <span style="background-color:#e7f2fa;color:#2980b9;">lv_color_t lv_img_buf_get_px_color(lv_img_dsc_t *dsc, lv_coord_t x, lv_coord_t y, lv_color_t color) </span> | |
: Get the color of an image's pixel | : Get the color of an image's pixel | ||
− | : | + | : Parameters |
::* dsc -- an image descriptor | ::* dsc -- an image descriptor | ||
− | ::* x -- x | + | ::* x -- x coordinate of the point to get |
::* y -- x coordinate of the point to get | ::* y -- x coordinate of the point to get | ||
− | ::* color -- the color of the image. In case of <code>LV_IMG_CF_ALPHA_1/2/4/8</code> this color is used. Not used in other cases. | + | ::* color -- the color of the image. In case of <code style="color: #bb0000;">LV_IMG_CF_ALPHA_1/2/4/8</code> this color is used. Not used in other cases. |
::* safe -- true: check out of bounds | ::* safe -- true: check out of bounds | ||
− | : | + | : Returns |
:: color of the point | :: color of the point | ||
− | + | <span style="background-color:#e7f2fa;color:#2980b9;">lv_opa_t lv_img_buf_get_px_alpha(lv_img_dsc_t *dsc, lv_coord_t x, lv_coord_t y) </span> | |
: Get the alpha value of an image's pixel | : Get the alpha value of an image's pixel | ||
− | : | + | : Parameters |
− | ::* dsc -- pointer | + | ::* dsc -- pointer to an image descriptor |
::* x -- x coordinate of the point to set | ::* x -- x coordinate of the point to set | ||
::* y -- x coordinate of the point to set | ::* y -- x coordinate of the point to set | ||
::* safe -- true: check out of bounds | ::* safe -- true: check out of bounds | ||
− | : | + | : Returns |
:: alpha value of the point | :: alpha value of the point | ||
− | + | <span style="background-color:#e7f2fa;color:#2980b9;">void lv_img_buf_set_px_color(lv_img_dsc_t *dsc, lv_coord_t x, lv_coord_t y, lv_color_t c) </span> | |
: Set the color of a pixel of an image. The alpha channel won't be affected. | : Set the color of a pixel of an image. The alpha channel won't be affected. | ||
− | : | + | : Parameters |
::* dsc -- pointer to an image descriptor | ::* dsc -- pointer to an image descriptor | ||
::* x -- x coordinate of the point to set | ::* x -- x coordinate of the point to set | ||
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::* safe -- true: check out of bounds | ::* safe -- true: check out of bounds | ||
− | + | <span style="background-color:#e7f2fa;color:#2980b9;">void lv_img_buf_set_px_alpha(lv_img_dsc_t *dsc, lv_coord_t x, lv_coord_t y, lv_opa_t opa) </span> | |
: Set the alpha value of a pixel of an image. The color won't be affected | : Set the alpha value of a pixel of an image. The color won't be affected | ||
− | : | + | : Parameters |
::* dsc -- pointer to an image descriptor | ::* dsc -- pointer to an image descriptor | ||
::* x -- x coordinate of the point to set | ::* x -- x coordinate of the point to set | ||
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::* safe -- true: check out of bounds | ::* safe -- true: check out of bounds | ||
− | + | <span style="background-color:#e7f2fa;color:#2980b9;">void lv_img_buf_set_palette(lv_img_dsc_t *dsc, uint8_t id, lv_color_t c) </span> | |
− | : Set the palette color of an indexed image. Valid only for <code>LV_IMG_CF_</code> | + | : Set the palette color of an indexed image. Valid only for <code style="color: #bb0000;">LV_IMG_CF_</code><code style="color: #bb0000;">INDEXED1/2/4/8</code> |
− | : | + | : Parameters |
::* dsc -- pointer to an image descriptor | ::* dsc -- pointer to an image descriptor | ||
::* id -- the palette color to set: | ::* id -- the palette color to set: | ||
− | ::** for <code>LV_IMG_CF_INDEXED1</code>: 0..1 | + | ::** for <code style="color: #bb0000;">LV_IMG_CF_INDEXED1</code>: 0..1 |
− | ::** for <code>LV_IMG_CF_INDEXED2</code>: 0..3 | + | ::** for <code style="color: #bb0000;">LV_IMG_CF_INDEXED2</code>: 0..3 |
− | ::** for <code>LV_IMG_CF_INDEXED4</code>: 0..15 | + | ::** for <code style="color: #bb0000;">LV_IMG_CF_INDEXED4</code>: 0..15 |
− | ::** for <code>LV_IMG_CF_INDEXED8</code>: 0..255 | + | ::** for <code style="color: #bb0000;">LV_IMG_CF_INDEXED8</code>: 0..255 |
::* c -- the color to set | ::* c -- the color to set | ||
− | + | <span style="background-color:#e7f2fa;color:#2980b9;">void lv_img_buf_free(lv_img_dsc_t *dsc) </span> | |
: Free an allocated image buffer | : Free an allocated image buffer | ||
− | : | + | : Parameters |
:: dsc -- image buffer to free | :: dsc -- image buffer to free | ||
− | + | <span style="background-color:#e7f2fa;color:#2980b9;">uint32_t lv_img_buf_get_img_size(lv_coord_t w, lv_coord_t h, lv_img_cf_t cf) </span> | |
− | : Get the memory consumption of a raw bitmap, given color format and | + | : Get the memory consumption of a raw bitmap, given color format and dimensions. |
− | : | + | : Parameters |
::* w -- width | ::* w -- width | ||
::* h -- height | ::* h -- height | ||
::* cf -- color format | ::* cf -- color format | ||
− | : | + | : Returns |
:: size in bytes | :: size in bytes | ||
− | + | <span style="background-color:#e7f2fa;color:#2980b9;">void _lv_img_buf_transform_init(lv_img_transform_dsc_t *dsc) </span> | |
: Initialize a descriptor to rotate an image | : Initialize a descriptor to rotate an image | ||
− | : | + | : Parameters |
− | :: dsc -- pointer to an <code>lv_img_transform_dsc_t</code> variable whose <code>cfg</code> field is initialized | + | :: dsc -- pointer to an <code style="color: #bb0000;">lv_img_transform_dsc_t</code> variable whose <code style="color: #bb0000;">cfg</code> field is initialized |
− | + | <span style="background-color:#e7f2fa;color:#2980b9;">bool _lv_img_buf_transform_anti_alias(lv_img_transform_dsc_t *dsc) </span> | |
: Continue transformation by taking the neighbors into account | : Continue transformation by taking the neighbors into account | ||
− | : | + | : |
− | : | + | : Parameters |
:: dsc -- pointer to the transformation descriptor | :: dsc -- pointer to the transformation descriptor | ||
− | + | <span style="background-color:#e7f2fa;color:#2980b9;">bool _lv_img_buf_transform(lv_img_transform_dsc_t *dsc, lv_coord_t x, lv_coord_t y) </span> | |
− | : Get which color and opa would come to a pixel if it were rotated Note the | + | : Get which color and opa would come to a pixel if it were rotated Note the result is written back to <code style="color: #bb0000;">dsc->res_color</code> and <code style="color: #bb0000;">dsc->res_opa</code> |
− | : | + | : Parameters |
− | ::* dsc -- a descriptor initialized by <code>lv_img_buf_rotate_init</code> | + | ::* dsc -- a descriptor initialized by <code style="color: #bb0000;">lv_img_buf_rotate_init</code> |
::* x -- the coordinate which color and opa should be get | ::* x -- the coordinate which color and opa should be get | ||
::* y -- the coordinate which color and opa should be get | ::* y -- the coordinate which color and opa should be get | ||
− | : | + | : Returns |
:: true: there is valid pixel on these x/y coordinates; false: the rotated pixel was out of the image | :: true: there is valid pixel on these x/y coordinates; false: the rotated pixel was out of the image | ||
− | + | <span style="background-color:#e7f2fa;color:#2980b9;">void _lv_img_buf_get_transformed_area(lv_area_t *res, lv_coord_t w, lv_coord_t h, int16_t angle, uint16_t zoom, const lv_point_t *pivot) </span> | |
: Get the area of a rectangle if its rotated and scaled | : Get the area of a rectangle if its rotated and scaled | ||
− | : | + | : Parameters |
::* res -- store the coordinates here | ::* res -- store the coordinates here | ||
− | ::* w -- width of the | + | ::* w -- width of the rectangle to transform |
::* h -- height of the rectangle to transform | ::* h -- height of the rectangle to transform | ||
::* angle -- angle of rotation | ::* angle -- angle of rotation | ||
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::* pivot -- x,y pivot coordinates of rotation | ::* pivot -- x,y pivot coordinates of rotation | ||
− | + | <span style="background-color:#e7f2fa;color:#2980b9;">struct lv_img_header_t </span> | |
− | : ''#include <lv_img_b'' | + | : ''#include <lv_img_b''''uf.h>'' The first 8 bit is very important to distinguish the different source types. For more info see <code style="color: #bb0000;">lv_img_get_src_type()</code> in lv_img.c On big endian systems the order is reversed so cf and always_zero must be at the end of the struct. Public Members |
− | : | + | : <span style="background-color: #eeeeee;">uint32_t h </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">uint32_t w </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">uint32_t reserved </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">uint32_t always_zero </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">uint32_t cf </span> |
:: | :: | ||
− | + | <span style="background-color:#e7f2fa;color:#2980b9;">struct lv_img_header_t </span> | |
− | : ''#include <lv_img_buf.h>'' The first 8 bit is very important to distinguish the different source types. For more info see <code>lv_img_get_src_type()</code> in lv_img.c On big endian systems the order is reversed so cf and always_zero must be at the end of the struct. Public Members | + | : ''#include <lv_img_buf.h>'' The first 8 bit is very important to distinguish the different source types. For more info see <code style="color: #bb0000;">lv_img_get_src_type()</code> in lv_img.c On big endian systems the order is reversed so cf and always_zero must be at the end of the struct. Public Members |
− | : | + | : <span style="background-color: #eeeeee;">uint32_t h </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">uint32_t w </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">uint32_t reserved </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">uint32_t always_zero </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">uint32_t cf </span> |
:: | :: | ||
− | + | <span style="background-color:#e7f2fa;color:#2980b9;">struct lv_img_dsc_t </span> | |
− | : ''#include <lv_im'' | + | : ''#include <lv_im''''g_buf.h>'' Image header it is compatible with the result from image converter utility Public Members |
− | : | + | : <span style="background-color: #eeeeee;">lv_img_header_t header </span> |
− | :: A header | + | :: A header describing the basics of the image |
− | : | + | : <span style="background-color: #eeeeee;">uint32_t data_size </span> |
− | :: Size of the | + | :: Size of the image in bytes |
− | : | + | : <span style="background-color: #eeeeee;">const uint8_t *data </span> |
− | :: Pointer to the | + | :: Pointer to the data of the image |
− | + | <span style="background-color:#e7f2fa;color:#2980b9;">struct lv_img_transform_dsc_t </span> | |
: Public Members | : Public Members | ||
− | : | + | : <span style="background-color: #eeeeee;">const void *src </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">lv_coord_t src_w </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">lv_coord_t src_h </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">lv_coord_t pivot_x </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">lv_coord_t pivot_y </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">int16_t angle </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">uint16_t zoom </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">lv_color_t color </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">lv_img_cf_t cf </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">bool antialias </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">stru<nowiki>ct lv_img_transform_dsc_t::[anonymous] cfg</nowiki> </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">lv_opa_t opa </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">struct lv_im<nowiki>g_transform_dsc_t::[anonymous] res</nowiki> </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">lv_img_dsc_t img_dsc </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">int32_t pivot_x_256 </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">int32_t pivot_y_256 </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">int32_t sinma </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">int32_t cosma </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">uint8_t chroma_keyed </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">uint8_t has_alpha </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">uint8_t native_color </span> |
:: | :: | ||
− | : | + | : <span style="background-color: #eeeeee;">uint32_t zoom_inv </span> |
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− | : | + | : <span style="background-color: #eeeeee;">lv_coord_t xs </span> |
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− | : | + | : <span style="background-color: #eeeeee;">lv_coord_t ys </span> |
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− | : | + | : <span style="background-color: #eeeeee;">uint32_t pxi </span> |
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− | : | + | : <span style="background-color: #eeeeee;">uint8_t px_size </span> |
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− | : | + | : <span style="background-color: #eeeeee;">struc<nowiki>t lv_img_transform_dsc_t::[anonymous] tmp</nowiki></span> |
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:[[App:Library:LVGL#Overview|戻る : Previous]] | :[[App:Library:LVGL#Overview|戻る : Previous]] |
2022年7月2日 (土) 08:59時点における版
https://docs.lvgl.io/8.2/overview/image.html
Images
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An image can be a file or a variable which stores the bitmap itself and some metadata. |
Store images
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You can store images in two places
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Variables
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Images stored internally in a variable are composed mainly of an
These are usually stored within a project as C files. They are linked into the resulting executable like any other constant data. |
Files
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To deal with files you need to add a storage Drive to LVGL. In short, a Drive is a collection of functions (open, read, close, etc.) registered in LVGL to make file operations. You can add an interface to a standard file system (FAT32 on SD card) or you create your simple file system to read data from an SPI Flash memory. In every case, a Drive is just an abstraction to read and/or write data to memory. See the File system section to learn more. Images stored as files are not linked into the resulting executable, and must be read into RAM before being drawn. As a result, they are not as resource-friendly as images linked at compile time. However, they are easier to replace without needing to rebuild the main program. |
Color formats
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Various built-in color formats are supported:
The bytes of For 32-bit color depth:
For 16-bit color depth:
For 8-bit color depth:
You can store images in a Raw format to indicate that it's not encoded with one of the built-in color formats and an external Image decoder needs to be used to decode the image.
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Add and use images
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You can add images to LVGL in two ways:
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Online converter
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The online Image converter is available here: https://lvgl.io/tools/imageconverter Adding an image to LVGL via the online converter is easy.
In the generated C arrays (variables), bitmaps for all the color depths (1, 8, 16 or 32) are included in the C file, but only the color depth that matches In the case of binary files, you need to specify the color format you want:
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Manually create an image
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If you are generating an image at run-time, you can craft an image variable to display it using LVGL. For example: uint8_t my_img_data[] = {0x00, 0x01, 0x02, ...}; static lv_img_dsc_t my_img_dsc = { .header.always_zero = 0, .header.w = 80, .header.h = 60, .data_size = 80 * 60 * LV_COLOR_DEPTH / 8, .header.cf = LV_IMG_CF_TRUE_COLOR, /*Set the color format*/ .data = my_img_data, }; If the color format is Another (possibly simpler) option to create and display an image at run-time is to use the Canvas object. |
Use images
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The simplest way to use an image in LVGL is to display it with an lv_img object: lv_obj_t * icon = lv_img_create(lv_scr_act(), NULL); /*From variable*/ lv_img_set_src(icon, &my_icon_dsc); /*From file*/ lv_img_set_src(icon, "S:my_icon.bin"); If the image was converted with the online converter, you should use |
Image decoder
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As you can see in the Color formats section, LVGL supports several built-in image formats. In many cases, these will be all you need. LVGL doesn't directly support, however, generic image formats like PNG or JPG. To handle non-built-in image formats, you need to use external libraries and attach them to LVGL via the Image decoder interface. An image decoder consists of 4 callbacks:
You can add any number of image decoders. When an image needs to be drawn, the library will try all the registered image decoders until it finds one which can open the image, i.e. one which knows that format. The Custom image formatsThe easiest way to create a custom image is to use the online image converter and select
After decoding, the raw formats are considered True color by the library. In other words, the image decoder must decode the Raw images to True color according to the format described in the Color formats section. If you want to create a custom image, you should use With User encoded formats, the color format in the open function ( |
Register an image decoder
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Here's an example of getting LVGL to work with PNG images. First, you need to create a new image decoder and set some functions to open/close the PNG files. It should look like this: /*Create a new decoder and register functions */ lv_img_decoder_t * dec = lv_img_decoder_create(); lv_img_decoder_set_info_cb(dec, decoder_info); lv_img_decoder_set_open_cb(dec, decoder_open); lv_img_decoder_set_close_cb(dec, decoder_close); /** * Get info about a PNG image * @param decoder pointer to the decoder where this function belongs * @param src can be file name or pointer to a C array * @param header store the info here * @return LV_RES_OK: no error; LV_RES_INV: can't get the info */ static lv_res_t decoder_info(lv_img_decoder_t * decoder, const void * src, lv_img_header_t * header) { /*Check whether the type `src` is known by the decoder*/ if(is_png(src) == false) return LV_RES_INV; /* Read the PNG header and find `width` and `height` */ ... header->cf = LV_IMG_CF_RAW_ALPHA; header->w = width; header->h = height; } /** * Open a PNG image and return the decided image * @param decoder pointer to the decoder where this function belongs * @param dsc pointer to a descriptor which describes this decoding session * @return LV_RES_OK: no error; LV_RES_INV: can't get the info */ static lv_res_t decoder_open(lv_img_decoder_t * decoder, lv_img_decoder_dsc_t * dsc) { /*Check whether the type `src` is known by the decoder*/ if(is_png(src) == false) return LV_RES_INV; /*Decode and store the image. If `dsc->img_data` is `NULL`, the `read_line` function will be called to get the image data line-by-line*/ dsc->img_data = my_png_decoder(src); /*Change the color format if required. For PNG usually 'Raw' is fine*/ dsc->header.cf = LV_IMG_CF_... /*Call a built in decoder function if required. It's not required if`my_png_decoder` opened the image in true color format.*/ lv_res_t res = lv_img_decoder_built_in_open(decoder, dsc); return res; } /** * Decode `len` pixels starting from the given `x`, `y` coordinates and store them in `buf`. * Required only if the "open" function can't open the whole decoded pixel array. (dsc->img_data == NULL) * @param decoder pointer to the decoder the function associated with * @param dsc pointer to decoder descriptor * @param x start x coordinate * @param y start y coordinate * @param len number of pixels to decode * @param buf a buffer to store the decoded pixels * @return LV_RES_OK: ok; LV_RES_INV: failed */ lv_res_t decoder_built_in_read_line(lv_img_decoder_t * decoder, lv_img_decoder_dsc_t * dsc, lv_coord_t x, lv_coord_t y, lv_coord_t len, uint8_t * buf) { /*With PNG it's usually not required*/ /*Copy `len` pixels from `x` and `y` coordinates in True color format to `buf` */ } /** * Free the allocated resources * @param decoder pointer to the decoder where this function belongs * @param dsc pointer to a descriptor which describes this decoding session */ static void decoder_close(lv_img_decoder_t * decoder, lv_img_decoder_dsc_t * dsc) { /*Free all allocated data*/ /*Call the built-in close function if the built-in open/read_line was used*/ lv_img_decoder_built_in_close(decoder, dsc); } So in summary:
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Manually use an image decoder
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LVGL will use registered image decoders automatically if you try and draw a raw image (i.e. using the The lv_res_t res; lv_img_decoder_dsc_t dsc; res = lv_img_decoder_open(&dsc, &my_img_dsc, color, frame_id); if(res == LV_RES_OK) { /*Do something with `dsc->img_data`*/ lv_img_decoder_close(&dsc); } |
Image caching
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Sometimes it takes a lot of time to open an image. Continuously decoding a PNG image or loading images from a slow external memory would be inefficient and detrimental to the user experience. Therefore, LVGL caches a given number of images. Caching means some images will be left open, hence LVGL can quickly access them from Of course, caching images is resource intensive as it uses more RAM to store the decoded image. LVGL tries to optimize the process as much as possible (see below), but you will still need to evaluate if this would be beneficial for your platform or not. Image caching may not be worth it if you have a deeply embedded target which decodes small images from a relatively fast storage medium. |
Cache size
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The number of cache entries can be defined with The size of the cache can be changed at run-time with |
Value of images
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When you use more images than cache entries, LVGL can't cache all the images. Instead, the library will close one of the cached images to free space. To decide which image to close, LVGL uses a measurement it previously made of how long it took to open the image. Cache entries that hold slower-to-open images are considered more valuable and are kept in the cache as long as possible. If you want or need to override LVGL's measurement, you can manually set the time to open value in the decoder open function in Every cache entry has a "life" value. Every time an image is opened through the cache, the life value of all entries is decreased to make them older. When a cached image is used, its life value is increased by the time to open value to make it more alive. If there is no more space in the cache, the entry with the lowest life value will be closed. |
Memory usage
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Note that a cached image might continuously consume memory. For example, if three PNG images are cached, they will consume memory while they are open. Therefore, it's the user's responsibility to be sure there is enough RAM to cache even the largest images at the same time. |
Clean the cache
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Let's say you have loaded a PNG image into a To do this, use |
API
Image buffer
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Typedefs typedef uint8_t lv_img_cf_t Enums enum [anonymous]
Functions lv_img_dsc_t *lv_img_buf_alloc(lv_coord_t w, lv_coord_t h, lv_img_cf_t cf)
lv_color_t lv_img_buf_get_px_color(lv_img_dsc_t *dsc, lv_coord_t x, lv_coord_t y, lv_color_t color)
lv_opa_t lv_img_buf_get_px_alpha(lv_img_dsc_t *dsc, lv_coord_t x, lv_coord_t y)
void lv_img_buf_set_px_color(lv_img_dsc_t *dsc, lv_coord_t x, lv_coord_t y, lv_color_t c)
void lv_img_buf_set_px_alpha(lv_img_dsc_t *dsc, lv_coord_t x, lv_coord_t y, lv_opa_t opa)
void lv_img_buf_set_palette(lv_img_dsc_t *dsc, uint8_t id, lv_color_t c)
void lv_img_buf_free(lv_img_dsc_t *dsc)
uint32_t lv_img_buf_get_img_size(lv_coord_t w, lv_coord_t h, lv_img_cf_t cf)
void _lv_img_buf_transform_init(lv_img_transform_dsc_t *dsc)
bool _lv_img_buf_transform_anti_alias(lv_img_transform_dsc_t *dsc)
bool _lv_img_buf_transform(lv_img_transform_dsc_t *dsc, lv_coord_t x, lv_coord_t y)
void _lv_img_buf_get_transformed_area(lv_area_t *res, lv_coord_t w, lv_coord_t h, int16_t angle, uint16_t zoom, const lv_point_t *pivot)
struct lv_img_header_t
struct lv_img_header_t
struct lv_img_dsc_t
struct lv_img_transform_dsc_t
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