App:Library:LVGL:docs:Overview:Animations

https://docs.lvgl.io/8.2/overview/animation.html

Animations

英文

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You can automatically change the value of a variable between a start and an end value using animations. Animation will happen by periodically calling an "animator" function with the corresponding value parameter. The animator functions have the following prototype: void func(void * var, lv_anim_var_t value); This prototype is compatible with the majority of the property set functions in LVGL. For example lv_obj_set_x(obj, value) or lv_obj_set_width(obj, value)

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Create an animation

英文

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To create an animation an lv_anim_t variable has to be initialized and configured with lv_anim_set_...() functions. /* INITIALIZE AN ANIMATION *-----------------------*/ lv_anim_t a; lv_anim_init(&a); /* MANDATORY SETTINGS *------------------*/ /*Set the "animator" function*/ lv_anim_set_exec_cb(&a, (lv_anim_exec_xcb_t) lv_obj_set_x); /*Set target of the animation*/ lv_anim_set_var(&a, obj); /*Length of the animation [ms]*/ lv_anim_set_time(&a, duration); /*Set start and end values. E.g. 0, 150*/ lv_anim_set_values(&a, start, end); /* OPTIONAL SETTINGS *------------------*/ /*Time to wait before starting the animation [ms]*/ lv_anim_set_delay(&a, delay); /*Set path (curve). Default is linear*/ lv_anim_set_path(&a, lv_anim_path_ease_in); /*Set a callback to indicate when the animation is ready (idle).*/ lv_anim_set_ready_cb(&a, ready_cb); /*Set a callback to indicate when the animation is started (after delay).*/ lv_anim_set_start_cb(&a, start_cb); /*When ready, play the animation backward with this duration. Default is 0 (disabled) [ms]*/ lv_anim_set_playback_time(&a, time); /*Delay before playback. Default is 0 (disabled) [ms]*/ lv_anim_set_playback_delay(&a, delay); /*Number of repetitions. Default is 1. LV_ANIM_REPEAT_INFINITE for infinite repetition*/ lv_anim_set_repeat_count(&a, cnt); /*Delay before repeat. Default is 0 (disabled) [ms]*/ lv_anim_set_repeat_delay(&a, delay); /*true (default): apply the start value immediately, false: apply start value after delay when the anim. really starts. */ lv_anim_set_early_apply(&a, true/false); /* START THE ANIMATION *------------------*/ lv_anim_start(&a); /*Start the animation*/ You can apply multiple different animations on the same variable at the same time. For example, animate the x and y coordinates with lv_obj_set_x and lv_obj_set_y. However, only one animation can exist with a given variable and function pair and lv_anim_start() will remove any existing animations for such a pair.

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Animation path

英文

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You can control the path of an animation. The most simple case is linear, meaning the current value between start and end is changed with fixed steps. A path is a function which calculates the next value to set based on the current state of the animation. Currently, there are the following built-in path functions: lv_anim_path_linear linear animation lv_anim_path_step change in one step at the end lv_anim_path_ease_in slow at the beginning lv_anim_path_ease_out slow at the end lv_anim_path_ease_in_out slow at the beginning and end lv_anim_path_overshoot overshoot the end value lv_anim_path_bounce bounce back a little from the end value (like hitting a wall)

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Speed vs time

英文

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By default, you set the animation time directly. But in some cases, setting the animation speed is more practical. The lv_anim_speed_to_time(speed, start, end) function calculates the required time in milliseconds to reach the end value from a start value with the given speed. The speed is interpreted in unit/sec dimension. For example, lv_anim_speed_to_time(20,0,100) will yield 5000 milliseconds. For example, in the case of lv_obj_set_x unit is pixels so 20 means 20 px/sec speed.

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Delete animations

英文	自動翻訳
You can delete an animation with lv_anim_del(var, func) if you provide the animated variable and its animator function.

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Timeline

英文

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A timeline is a collection of multiple animations which makes it easy to create complex composite animations. Firstly, create an animation element but don’t call lv_anim_start(). Secondly, create an animation timeline object by calling lv_anim_timeline_create(). Thirdly, add animation elements to the animation timeline by calling lv_anim_timeline_add(at, start_time, &a). start_time is the start time of the animation on the timeline. Note that start_time will override the value of delay. Finally, call lv_anim_timeline_start(at) to start the animation timeline. It supports forward and backward playback of the entire animation group, using lv_anim_timeline_set_reverse(at, reverse). Call lv_anim_timeline_stop(at) to stop the animation timeline. Call lv_anim_timeline_set_progress(at, progress) function to set the state of the object corresponding to the progress of the timeline. Call lv_anim_timeline_get_playtime(at) function to get the total duration of the entire animation timeline. Call lv_anim_timeline_get_reverse(at) function to get whether to reverse the animation timeline. Call lv_anim_timeline_del(at) function to delete the animation timeline.

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Examples

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Start animation on an event
Playback animation
Animation timeline

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API

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Typedefs typedef int32_t (*lv_anim_path_cb_t)(const struct _lv_anim_t*) Get the current value during an animation typedef void (*lv_anim_exec_xcb_t)(void*, int32_t) Generic prototype of "animator" functions. First parameter is the variable to animate. Second parameter is the value to set. Compatible with lv_xxx_set_yyy(obj, value) functions The x in _xcb_t means it's not a fully generic prototype because it doesn't receive lv_anim_t * as its first argument typedef void (*lv_anim_custom_exec_cb_t)(struct _lv_anim_t*, int32_t) Same as lv_anim_exec_xcb_t but receives lv_anim_t * as the first parameter. It's more consistent but less convenient. Might be used by binding generator functions. typedef void (*lv_anim_ready_cb_t)(struct _lv_anim_t*) Callback to call when the animation is ready typedef void (*lv_anim_start_cb_t)(struct _lv_anim_t*) Callback to call when the animation really stars (considering delay) typedef int32_t (*lv_anim_get_value_cb_t)(struct _lv_anim_t*) Callback used when the animation values are relative to get the current value typedef struct _lv_anim_t lv_anim_t Describes an animation Enums enum lv_anim_enable_t Can be used to indicate if animations are enabled or disabled in a case Values: enumerator LV_ANIM_OFF enumerator LV_ANIM_ON
Functions LV_EXPORT_CONST_INT(LV_ANIM_REPEAT_INFINITE) LV_EXPORT_CONST_INT(LV_ANIM_PLAYTIME_INFINITE) void _lv_anim_core_init(void) Init. the animation module void lv_anim_init(lv_anim_t *a) Initialize an animation variable. E.g.: lv_anim_t a; lv_anim_init(&a); lv_anim_set_...(&a); lv_anim_start(&a); Parameters a -- pointer to an lv_anim_t variable to initialize static inline void lv_anim_set_var(lv_anim_t *a, void *var) Set a variable to animate Parameters a -- pointer to an initialized lv_anim_t variable var -- pointer to a variable to animate static inline void lv_anim_set_exec_cb(lv_anim_t *a, lv_anim_exec_xcb_t exec_cb) Set a function to animate var Parameters a -- pointer to an initialized lv_anim_t variable exec_cb -- a function to execute during animation LVGL's built-in functions can be used. E.g. lv_obj_set_x static inline void lv_anim_set_time(lv_anim_t *a, uint32_t duration) Set the duration of an animation Parameters a -- pointer to an initialized lv_anim_t variable duration -- duration of the animation in milliseconds static inline void lv_anim_set_delay(lv_anim_t *a, uint32_t delay) Set a delay before starting the animation Parameters a -- pointer to an initialized lv_anim_t variable delay -- delay before the animation in milliseconds static inline void lv_anim_set_values(lv_anim_t *a, int32_t start, int32_t end) Set the start and end values of an animation Parameters a -- pointer to an initialized lv_anim_t variable start -- the start value end -- the end value static inline void lv_anim_set_custom_exec_cb(lv_anim_t *a, lv_anim_custom_exec_cb_t exec_cb) Similar to lv_anim_set_exec_cb but lv_anim_custom_exec_cb_t receives lv_anim_t * as its first parameter instead of void *. This function might be used when LVGL is bound to other languages because it's more consistent to have lv_anim_t * as first parameter. The variable to animate can be stored in the animation's user_data Parameters a -- pointer to an initialized lv_anim_t variable exec_cb -- a function to execute. static inline void lv_anim_set_path_cb(lv_anim_t *a, lv_anim_path_cb_t path_cb) Set the path (curve) of the animation. Parameters a -- pointer to an initialized lv_anim_t variable path_cb -- a function to set the current value of the animation. static inline void lv_anim_set_start_cb(lv_anim_t *a, lv_anim_start_cb_t start_cb) Set a function call when the animation really starts (considering delay) Parameters a -- pointer to an initialized lv_anim_t variable start_cb -- a function call when the animation starts static inline void lv_anim_set_get_value_cb(lv_anim_t *a, lv_anim_get_value_cb_t get_value_cb) Set a function to use the current value of the variable and make start and end value relative to the returned current value. Parameters a -- pointer to an initialized lv_anim_t variable get_value_cb -- a function call when the animation starts static inline void lv_anim_set_ready_cb(lv_anim_t *a, lv_anim_ready_cb_t ready_cb) Set a function call when the animation is ready Parameters a -- pointer to an initialized lv_anim_t variable ready_cb -- a function call when the animation is ready static inline void lv_anim_set_playback_time(lv_anim_t *a, uint32_t time) Make the animation to play back to when the forward direction is ready Parameters a -- pointer to an initialized lv_anim_t variable time -- the duration of the playback animation in milliseconds. 0: disable playback static inline void lv_anim_set_playback_delay(lv_anim_t *a, uint32_t delay) Make the animation to play back to when the forward direction is ready Parameters a -- pointer to an initialized lv_anim_t variable delay -- delay in milliseconds before starting the playback animation. static inline void lv_anim_set_repeat_count(lv_anim_t *a, uint16_t cnt) Make the animation repeat itself. Parameters a -- pointer to an initialized lv_anim_t variable cnt -- repeat count or LV_ANIM_REPEAT_INFINITE for infinite repetition. 0: to disable repetition. static inline void lv_anim_set_repeat_delay(lv_anim_t *a, uint32_t delay) Set a delay before repeating the animation. Parameters a -- pointer to an initialized lv_anim_t variable delay -- delay in milliseconds before repeating the animation. static inline void lv_anim_set_early_apply(lv_anim_t *a, bool en) Set a whether the animation's should be applied immediately or only when the delay expired. Parameters a -- pointer to an initialized lv_anim_t variable en -- true: apply the start value immediately in lv_anim_start; false: apply the start value only when delay ms is elapsed and the animations really starts static inline void lv_anim_set_user_data(lv_anim_t *a, void *user_data) Set the custom user data field of the animation. Parameters a -- pointer to an initialized lv_anim_t variable user_data -- pointer to the new user_data. lv_anim_t *lv_anim_start(const lv_anim_t *a) Create an animation Parameters a -- an initialized 'anim_t' variable. Not required after call. Returns pointer to the created animation (different from the a parameter) static inline uint32_t lv_anim_get_delay(lv_anim_t *a) Get a delay before starting the animation Parameters a -- pointer to an initialized lv_anim_t variable Returns delay before the animation in milliseconds uint32_t lv_anim_get_playtime(lv_anim_t *a) Get the time used to play the animation. Parameters a -- pointer to an animation. Returns the play time in milliseconds. static inline void *lv_anim_get_user_data(lv_anim_t *a) Get the user_data field of the animation Parameters a -- pointer to an initialized lv_anim_t variable Returns the pointer to the custom user_data of the animation bool lv_anim_del(void *var, lv_anim_exec_xcb_t exec_cb) Delete an animation of a variable with a given animator function Parameters var -- pointer to variable exec_cb -- a function pointer which is animating 'var', or NULL to ignore it and delete all the animations of 'var Returns true: at least 1 animation is deleted, false: no animation is deleted void lv_anim_del_all(void) Delete all the animations lv_anim_t *lv_anim_get(void *var, lv_anim_exec_xcb_t exec_cb) Get the animation of a variable and its exec_cb. Parameters var -- pointer to variable exec_cb -- a function pointer which is animating 'var', or NULL to return first matching 'var' Returns pointer to the animation. static inline bool lv_anim_custom_del(lv_anim_t *a, lv_anim_custom_exec_cb_t exec_cb) Delete an animation by getting the animated variable from a. Only animations with exec_cb will be deleted. This function exists because it's logical that all anim. functions receives an lv_anim_t as their first parameter. It's not practical in C but might make the API more consequent and makes easier to generate bindings. Parameters a -- pointer to an animation. exec_cb -- a function pointer which is animating 'var', or NULL to ignore it and delete all the animations of 'var Returns true: at least 1 animation is deleted, false: no animation is deleted static inline lv_anim_t *lv_anim_custom_get(lv_anim_t *a, lv_anim_custom_exec_cb_t exec_cb) Get the animation of a variable and its exec_cb. This function exists because it's logical that all anim. functions receives an lv_anim_t as their first parameter. It's not practical in C but might make the API more consequent and makes easier to generate bindings. Parameters a -- pointer to an animation. exec_cb -- a function pointer which is animating 'var', or NULL to return first matching 'var' Returns pointer to the animation. uint16_t lv_anim_count_running(void) Get the number of currently running animations Returns the number of running animations uint32_t lv_anim_speed_to_time(uint32_t speed, int32_t start, int32_t end) Calculate the time of an animation with a given speed and the start and end values Parameters speed -- speed of animation in unit/sec start -- start value of the animation end -- end value of the animation Returns the required time [ms] for the animation with the given parameters void lv_anim_refr_now(void) Manually refresh the state of the animations. Useful to make the animations running in a blocking process where lv_timer_handler can't run for a while. Shouldn't be used directly because it is called in lv_refr_now(). int32_t lv_anim_path_linear(const lv_anim_t *a) Calculate the current value of an animation applying linear characteristic Parameters a -- pointer to an animation Returns the current value to set int32_t lv_anim_path_ease_in(const lv_anim_t *a) Calculate the current value of an animation slowing down the start phase Parameters a -- pointer to an animation Returns the current value to set int32_t lv_anim_path_ease_out(const lv_anim_t *a) Calculate the current value of an animation slowing down the end phase Parameters a -- pointer to an animation Returns the current value to set int32_t lv_anim_path_ease_in_out(const lv_anim_t *a) Calculate the current value of an animation applying an "S" characteristic (cosine) Parameters a -- pointer to an animation Returns the current value to set int32_t lv_anim_path_overshoot(const lv_anim_t *a) Calculate the current value of an animation with overshoot at the end Parameters a -- pointer to an animation Returns the current value to set int32_t lv_anim_path_bounce(const lv_anim_t *a) Calculate the current value of an animation with 3 bounces Parameters a -- pointer to an animation Returns the current value to set int32_t lv_anim_path_step(const lv_anim_t *a) Calculate the current value of an animation applying step characteristic. (Set end value on the end of the animation) Parameters a -- pointer to an animation Returns the current value to set struct _lv_anim_t #include <lv_'anim.h> Describes an animation Public Members void *var Variable to animate lv_anim_exec_xcb_t exec_cb Function to execute to animate lv_anim_start_cb_t start_cb Call it when the animation is starts (considering delay) lv_anim_ready_cb_t ready_cb Call it when the animation is ready lv_anim_get_value_cb_t get_value_cb Get the current value in relative mode void *user_data Custom user data lv_anim_path_cb_t path_cb Describe the path (curve) of animations int32_t start_value Start value int32_t current_value Current value int32_t end_value End value int32_t time Animation time in ms int32_t act_time Current time in animation. Set to negative to make delay. uint32_t playback_delay Wait before play back uint32_t playback_time Duration of playback animation uint32_t repeat_delay Wait before repeat uint16_t repeat_cnt Repeat count for the animation uint8_t early_apply 1: Apply start value immediately even is there is delay uint8_t playback_now Play back is in progress uint8_t run_round Indicates the animation has run in this round uint8_t start_cb_called Indicates that the start_cb was already called

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