init Files

libraries/lvgl/examples/widgets/canvas/lv_example_canvas_2.c

@@ -0,0 +1,47 @@
+#include "../../lv_examples.h"
+#if LV_USE_CANVAS && LV_BUILD_EXAMPLES
+
+#define CANVAS_WIDTH  80
+#define CANVAS_HEIGHT  40
+
+/**
+ * Create a transparent canvas with transparency
+ */
+void lv_example_canvas_2(void)
+{
+    lv_obj_set_style_bg_color(lv_screen_active(), lv_palette_lighten(LV_PALETTE_RED, 5), 0);
+
+    /*Create a buffer for the canvas*/
+    LV_DRAW_BUF_DEFINE_STATIC(draw_buf, CANVAS_WIDTH, CANVAS_HEIGHT, LV_COLOR_FORMAT_ARGB8888);
+    LV_DRAW_BUF_INIT_STATIC(draw_buf);
+
+    /*Create a canvas and initialize its palette*/
+    lv_obj_t * canvas = lv_canvas_create(lv_screen_active());
+    lv_canvas_set_draw_buf(canvas, &draw_buf);
+    lv_obj_center(canvas);
+
+    /*Red background (There is no dedicated alpha channel in indexed images so LV_OPA_COVER is ignored)*/
+    lv_canvas_fill_bg(canvas, lv_palette_main(LV_PALETTE_BLUE), LV_OPA_COVER);
+
+    /*Create hole on the canvas*/
+    uint32_t x;
+    uint32_t y;
+    for(y = 10; y < 20; y++) {
+        for(x = 5; x < 75; x++) {
+            lv_canvas_set_px(canvas, x, y, lv_palette_main(LV_PALETTE_BLUE), LV_OPA_50);
+        }
+    }
+
+    for(y = 20; y < 30; y++) {
+        for(x = 5; x < 75; x++) {
+            lv_canvas_set_px(canvas, x, y, lv_palette_main(LV_PALETTE_BLUE), LV_OPA_20);
+        }
+    }
+
+    for(y = 30; y < 40; y++) {
+        for(x = 5; x < 75; x++) {
+            lv_canvas_set_px(canvas, x, y, lv_palette_main(LV_PALETTE_BLUE), LV_OPA_0);
+        }
+    }
+}
+#endif