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47 lines
1.4 KiB
C
47 lines
1.4 KiB
C
#include "../../lv_examples.h"
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#if LV_USE_CANVAS && LV_BUILD_EXAMPLES
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#define CANVAS_WIDTH 80
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#define CANVAS_HEIGHT 40
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/**
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* Create a transparent canvas with transparency
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*/
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void lv_example_canvas_2(void)
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{
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lv_obj_set_style_bg_color(lv_screen_active(), lv_palette_lighten(LV_PALETTE_RED, 5), 0);
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/*Create a buffer for the canvas*/
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static uint8_t cbuf[CANVAS_WIDTH * CANVAS_HEIGHT * 4];
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/*Create a canvas and initialize its palette*/
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lv_obj_t * canvas = lv_canvas_create(lv_screen_active());
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lv_canvas_set_buffer(canvas, cbuf, CANVAS_WIDTH, CANVAS_HEIGHT, LV_COLOR_FORMAT_ARGB8888);
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lv_obj_center(canvas);
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/*Red background (There is no dedicated alpha channel in indexed images so LV_OPA_COVER is ignored)*/
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lv_canvas_fill_bg(canvas, lv_palette_main(LV_PALETTE_BLUE), LV_OPA_COVER);
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/*Create hole on the canvas*/
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uint32_t x;
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uint32_t y;
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for(y = 10; y < 20; y++) {
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for(x = 5; x < 75; x++) {
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lv_canvas_set_px(canvas, x, y, lv_palette_main(LV_PALETTE_BLUE), LV_OPA_50);
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}
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}
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for(y = 20; y < 30; y++) {
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for(x = 5; x < 75; x++) {
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lv_canvas_set_px(canvas, x, y, lv_palette_main(LV_PALETTE_BLUE), LV_OPA_20);
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}
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}
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for(y = 30; y < 40; y++) {
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for(x = 5; x < 75; x++) {
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lv_canvas_set_px(canvas, x, y, lv_palette_main(LV_PALETTE_BLUE), LV_OPA_0);
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}
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}
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}
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#endif
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