transparent canvas with chroma keying for little vGL

本文主要是介绍transparent canvas with chroma keying for little vGL，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

定义画布尺寸

#define TRANSPARENT_CANVAS_WIDTH    50
#define TRANSPARENT_CANVAS_HIGHT    50

创建一个button
```
lv_btn_create(lv_scr_act(), NULL);
```

定义画布缓冲buffer，注意不能是局部的

static lv_color_t cbuf[LV_CANVAS_BUF_SIZE_INDEXED_1BIT(TRANSPARENT_CANVAS_WIDTH,TRANSPARENT_CANVAS_HIGHT)];

创建画布对象

 lv_obj_t* canvas = lv_canvas_create(lv_scr_act(), NULL);

设置关联画布缓冲buffer

 lv_canvas_set_buffer(canvas, cbuf, TRANSPARENT_CANVAS_WIDTH, TRANSPARENT_CANVAS_HIGHT, LV_IMG_CF_INDEXED_1BIT);

设置透明和红色2个调色盘

    lv_canvas_set_palette(canvas, 0, LV_COLOR_TRANSP);lv_canvas_set_palette(canvas, 1, LV_COLOR_RED);

定义颜色变量C0,C1

    lv_color_t c0;lv_color_t c1;c0.full = 0;c1.full = 1;

绘制C0,C1

    lv_canvas_fill_bg(canvas, c1);uint32_t x, y;for (y = 10; y < 30; y++){for (x = 5; x < 20; x++){lv_canvas_set_px(canvas, x, y, c0);}}

完整的实现

#define TRANSPARENT_CANVAS_WIDTH    50
#define TRANSPARENT_CANVAS_HIGHT    50
void transparent_canvas_demo(void) {lv_btn_create(lv_scr_act(), NULL);static lv_color_t cbuf[LV_CANVAS_BUF_SIZE_INDEXED_1BIT(TRANSPARENT_CANVAS_WIDTH,TRANSPARENT_CANVAS_HIGHT)];lv_obj_t* canvas = lv_canvas_create(lv_scr_act(), NULL);lv_canvas_set_buffer(canvas, cbuf, TRANSPARENT_CANVAS_WIDTH, TRANSPARENT_CANVAS_HIGHT, LV_IMG_CF_INDEXED_1BIT);lv_canvas_set_palette(canvas, 0, LV_COLOR_TRANSP);lv_canvas_set_palette(canvas, 1, LV_COLOR_RED);lv_color_t c0;lv_color_t c1;c0.full = 0;c1.full = 1;lv_canvas_fill_bg(canvas, c1);uint32_t x, y;for (y = 10; y < 30; y++) {for (x = 5; x < 20; x++) {lv_canvas_set_px(canvas, x, y, c0);}}
}