examples(canvas): add canvas drawing examples

examples/widgets/canvas/index.rst

@@ -11,3 +11,37 @@ Transparent Canvas with chroma keying
 .. lv_example:: widgets/canvas/lv_example_canvas_2
   :language: c
 
+
+Draw a rectangle to the canvas
+""""""""""""""""""""""""""""""""""""""
+
+.. lv_example:: widgets/canvas/lv_example_canvas_3
+  :language: c
+
+
+Draw a label to the canvas
+""""""""""""""""""""""""""""""""""""""
+
+.. lv_example:: widgets/canvas/lv_example_canvas_4
+  :language: c
+
+
+Draw an arc to the canvas
+""""""""""""""""""""""""""""""""""""""
+
+.. lv_example:: widgets/canvas/lv_example_canvas_5
+  :language: c
+
+
+Draw an image to the canvas
+""""""""""""""""""""""""""""""""""""""
+
+.. lv_example:: widgets/canvas/lv_example_canvas_6
+  :language: c
+
+
+Draw a line to the canvas
+""""""""""""""""""""""""""""""""""""""
+
+.. lv_example:: widgets/canvas/lv_example_canvas_7
+  :language: c

examples/widgets/canvas/lv_example_canvas_3.c

@@ -0,0 +1,36 @@
+#include "../../lv_examples.h"
+#if LV_USE_CANVAS && LV_BUILD_EXAMPLES
+
+#define CANVAS_WIDTH  50
+#define CANVAS_HEIGHT  50
+
+/**
+ * Draw a rectangle to the canvas
+ */
+void lv_example_canvas_3(void)
+{
+    /*Create a buffer for the canvas*/
+    static uint8_t cbuf[LV_CANVAS_BUF_SIZE_TRUE_COLOR(CANVAS_WIDTH, CANVAS_HEIGHT)];
+
+    /*Create a canvas and initialize its palette*/
+    lv_obj_t * canvas = lv_canvas_create(lv_scr_act());
+    lv_canvas_set_buffer(canvas, cbuf, CANVAS_WIDTH, CANVAS_HEIGHT, LV_IMG_CF_TRUE_COLOR);
+    lv_canvas_fill_bg(canvas, lv_color_hex3(0xccc), LV_OPA_COVER);
+    lv_obj_center(canvas);
+
+    lv_draw_rect_dsc_t dsc;
+    lv_draw_rect_dsc_init(&dsc);
+    dsc.bg_color = lv_palette_main(LV_PALETTE_RED);
+    dsc.border_color = lv_palette_main(LV_PALETTE_BLUE);
+    dsc.border_width = 3;
+    dsc.outline_color = lv_palette_main(LV_PALETTE_GREEN);
+    dsc.outline_width = 2;
+    dsc.outline_pad = 2;
+    dsc.outline_opa = LV_OPA_50;
+    dsc.radius = 5;
+    dsc.border_width = 3;
+    lv_canvas_draw_rect(canvas, 10, 10, 30, 20, &dsc);
+
+
+}
+#endif

examples/widgets/canvas/lv_example_canvas_4.c

@@ -0,0 +1,29 @@
+#include "../../lv_examples.h"
+#if LV_USE_CANVAS && LV_FONT_MONTSERRAT_18 && LV_BUILD_EXAMPLES
+
+#define CANVAS_WIDTH  50
+#define CANVAS_HEIGHT  50
+
+/**
+ * Draw a text to the canvas
+ */
+void lv_example_canvas_4(void)
+{
+    /*Create a buffer for the canvas*/
+    static uint8_t cbuf[LV_CANVAS_BUF_SIZE_TRUE_COLOR(CANVAS_WIDTH, CANVAS_HEIGHT)];
+
+    /*Create a canvas and initialize its palette*/
+    lv_obj_t * canvas = lv_canvas_create(lv_scr_act());
+    lv_canvas_set_buffer(canvas, cbuf, CANVAS_WIDTH, CANVAS_HEIGHT, LV_IMG_CF_TRUE_COLOR);
+    lv_canvas_fill_bg(canvas, lv_color_hex3(0xccc), LV_OPA_COVER);
+    lv_obj_center(canvas);
+
+    lv_draw_label_dsc_t dsc;
+    lv_draw_label_dsc_init(&dsc);
+    dsc.color = lv_palette_main(LV_PALETTE_RED);
+    dsc.font = &lv_font_montserrat_18;
+    dsc.decor = LV_TEXT_DECOR_UNDERLINE;
+
+    lv_canvas_draw_text(canvas, 10, 10, 30, &dsc, "Hello");
+}
+#endif

examples/widgets/canvas/lv_example_canvas_5.c

@@ -0,0 +1,28 @@
+#include "../../lv_examples.h"
+#if LV_USE_CANVAS && LV_BUILD_EXAMPLES
+
+#define CANVAS_WIDTH  50
+#define CANVAS_HEIGHT  50
+
+/**
+ * Draw an arc to the canvas
+ */
+void lv_example_canvas_5(void)
+{
+    /*Create a buffer for the canvas*/
+    static uint8_t cbuf[LV_CANVAS_BUF_SIZE_TRUE_COLOR(CANVAS_WIDTH, CANVAS_HEIGHT)];
+
+    /*Create a canvas and initialize its palette*/
+    lv_obj_t * canvas = lv_canvas_create(lv_scr_act());
+    lv_canvas_set_buffer(canvas, cbuf, CANVAS_WIDTH, CANVAS_HEIGHT, LV_IMG_CF_TRUE_COLOR);
+    lv_canvas_fill_bg(canvas, lv_color_hex3(0xccc), LV_OPA_COVER);
+    lv_obj_center(canvas);
+
+    lv_draw_arc_dsc_t dsc;
+    lv_draw_arc_dsc_init(&dsc);
+    dsc.color = lv_palette_main(LV_PALETTE_RED);
+    dsc.width = 5;
+
+    lv_canvas_draw_arc(canvas, 25, 25, 15, 0, 220, &dsc);
+}
+#endif

examples/widgets/canvas/lv_example_canvas_6.c

@@ -0,0 +1,27 @@
+#include "../../lv_examples.h"
+#if LV_USE_CANVAS && LV_BUILD_EXAMPLES
+
+#define CANVAS_WIDTH  50
+#define CANVAS_HEIGHT  50
+
+/**
+ * Draw an image to the canvas
+ */
+void lv_example_canvas_6(void)
+{
+    /*Create a buffer for the canvas*/
+    static uint8_t cbuf[LV_CANVAS_BUF_SIZE_TRUE_COLOR(CANVAS_WIDTH, CANVAS_HEIGHT)];
+
+    /*Create a canvas and initialize its palette*/
+    lv_obj_t * canvas = lv_canvas_create(lv_scr_act());
+    lv_canvas_set_buffer(canvas, cbuf, CANVAS_WIDTH, CANVAS_HEIGHT, LV_IMG_CF_TRUE_COLOR);
+    lv_canvas_fill_bg(canvas, lv_color_hex3(0xccc), LV_OPA_COVER);
+    lv_obj_center(canvas);
+
+    lv_draw_img_dsc_t dsc;
+    lv_draw_img_dsc_init(&dsc);
+
+    LV_IMG_DECLARE(img_star);
+    lv_canvas_draw_img(canvas, 5, 5, &img_star, &dsc);
+}
+#endif

examples/widgets/canvas/lv_example_canvas_7.c

@@ -0,0 +1,35 @@
+#include "../../lv_examples.h"
+#if LV_USE_CANVAS&& LV_BUILD_EXAMPLES
+
+#define CANVAS_WIDTH  50
+#define CANVAS_HEIGHT  50
+
+/**
+ * Draw a line to the canvas
+ */
+void lv_example_canvas_7(void)
+{
+
+    /*Create a button to better see the transparency*/
+    lv_btn_create(lv_scr_act());
+
+    /*Create a buffer for the canvas*/
+    static uint8_t cbuf[LV_CANVAS_BUF_SIZE_TRUE_COLOR(CANVAS_WIDTH, CANVAS_HEIGHT)];
+
+    /*Create a canvas and initialize its palette*/
+    lv_obj_t * canvas = lv_canvas_create(lv_scr_act());
+    lv_canvas_set_buffer(canvas, cbuf, CANVAS_WIDTH, CANVAS_HEIGHT, LV_IMG_CF_TRUE_COLOR);
+    lv_canvas_fill_bg(canvas, lv_color_hex3(0xccc), LV_OPA_COVER);
+    lv_obj_center(canvas);
+
+    lv_draw_line_dsc_t dsc;
+    lv_draw_line_dsc_init(&dsc);
+    dsc.color = lv_palette_main(LV_PALETTE_RED);
+    dsc.width = 4;
+    dsc.round_end = 1;
+    dsc.round_start = 1;
+
+    lv_point_t p[] = {{15, 15}, {35, 10}, {10, 40}};
+    lv_canvas_draw_line(canvas, p, 3, &dsc);
+}
+#endif

examples/widgets/lv_example_widgets.h

@@ -49,6 +49,11 @@ void lv_example_calendar_1(void);
 
 void lv_example_canvas_1(void);
 void lv_example_canvas_2(void);
+void lv_example_canvas_3(void);
+void lv_example_canvas_4(void);
+void lv_example_canvas_5(void);
+void lv_example_canvas_6(void);
+void lv_example_canvas_7(void);
 
 void lv_example_chart_1(void);
 void lv_example_chart_2(void);