EffectLayer is a visual effect layer for Pebble Smartwatch. User places the layer over screen at set coordinates and special effects are applied to that area of the screen. Effects work both on Aplite/Classic Pebble and Basalt/Pebble time unless specified (e.g. Blur works only on Basalt)

To use the library place the source files in your SRC directory and add #include "effect_layer.h" to your source. EffectLayer library is implemented in efficient pay-to-play way so only effects that you actualy use get compiled into your binary.

Currently supported effects:

• Invert
• Vertical Mirror
• Horizontal Mirror
• Rotate 90 degrees (counter- or clock-wise)
• Blur
• Zoom
• Lens
• Mask
• FPS
• Shadow
• Outline

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Functions

EffectLayer* effect_layer_create(GRect frame) - creates effect layer and returns pointer to it. Parameter is GRect with coordinates and layer size, for example EffectLayer* effect_layer = effect_layer_create(GRect(0, 0, 144, 168)); will cover entire screen

void effect_layer_destroy(EffectLayer *effect_layer) - destroys effect layer and frees memory.

Layer* effect_layer_get_layer(EffectLayer *effect_layer) - gets underlying Layer of the effect layer for basic manipulations such as addin to Window root layer or layer's changing frame or bounds

void effect_layer_add_effect(EffectLayer effect_layer, effect_cb effect, void* param) - adds effect to the layer. Parameters are - effect layer that you created previously, name of the function to perform effect, optional data to pass to the effect. User can call this function multiple times on the same effect layer, adding multiple effects, so there's no need to create multiple layers. At this time library has following built in effect functions to represent the effects listed above:

• effect_invert
• effect_mirror_vertical
• effect_mirror_horizontal
• effect_rotate_90_degrees
• effect_blur
• effect_zoom
• effect_lens
• effect_mask
• effect_fps
• effect_shadow
• effect_outline

Usage

effect_layer_add_effect(my_effect_layer, effect_invert, NULL); - adds inverter effect

effect_layer_add_effect(my_effect_layer, effect_mirror_vertical, NULL); - adds vertical mirror effect

effect_layer_add_effect(my_effect_layer, effect_mirror_horizontal, NULL); - adds horizontal mirror effect

effect_layer_add_effect(my_effect_layer, effect_rotate_90_degrees, (void *)true); - rotates 90 degrees counterclockwise

effect_layer_add_effect(my_effect_layer, effect_rotate_90_degrees, (void *)false); - rotates 90 degrees clockwise

effect_layer_add_effect(my_effect_layer, effect_blur, (void *)my_radius); - Creates blur effect (on Basalt/Pebble Time only), where my_radius is uint_8t radius of the blur.

effect_layer_add_effect(my_effect_layer, effect_zoom, EL_ZOOM(x,y)); - Zooms screen area under layer by x and y

effect_layer_add_effect(my_effect_layer, effect_lens, EL_LENS(f,d)); - Applies Lens effect, where f & d are focal distance of the lens and distane to object respectfully.

effect_layer_add_effect(my_effect_layer, effect_mask, mask); - Applies Mask, achieving various transparency effects. See this article on usage examples.

effect_layer_add_effect(my_effect_layer, effect_fps, EffectFPS); - displays average FPS of the app

effect_layer_add_effect(my_effect_layer, effect_shadow, &shadow); - adds shadow of a given color to objects on screen of given color. shadow is a parameter of type EffectOffset:

typedef struct {
   GColor orig_color; //color of pixel being ofset
   GColor offset_color; //new color of pixel at offset coords
   int8_t offset_x; // horizontal ofset
   int8_t offset_y; // vertical offset
} EffectOffset;

For example if you want to give all red text under layer a yellow shadow 2 pixels long, you parameter would be:

EffectOffset shadow;
shadow.orig_color = GColorRed;
shadow.offset_color = GColorYellow;
shadow.offset_y = 2;  
shadow.offset_x = 2;

You can specify option in the parameter shadow.option = 1; to display long contiuous shadow (to use this on Aplite you also need to specify shadow.aplite_visited array to keep track of set pixels. See https://github.com/ygalanter/Color_Shadow/ watchface for example implementation.

effect_layer_add_effect(my_effect_layer, effect_outline, &shadow); - Similar to the Shadow effect, however the color is added in all directions.

Extentions

Library is user-extendable, if you define your function in format

void effect_my_own_cool_effect(GContext* ctx, GRect position, void* param) { /* cool effect code */ }

you can add it to EffectLayer in maner similar to above:

effect_layer_add_effect(my_effect_layer, effect_my_own_cool_effect, param);

Usage examples

Simple Striped watchface uses Mask effect to show background image thru transparent text
TV Time watchaface uses inverter effect for battery info and blur effect for antialiasing fonts