example(canvas): add MicroPython draw examples (#3823)

examples/widgets/canvas/lv_example_canvas_3.py

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+CANVAS_WIDTH  = 50
+CANVAS_HEIGHT =  50
+
+LV_COLOR_SIZE = 32
+# 
+# Draw a rectangle to the canvas
+# 
+# Create a buffer for the canvas
+cbuf = bytearray((LV_COLOR_SIZE // 8) * CANVAS_WIDTH * CANVAS_HEIGHT)
+
+# Create a canvas and initialize its palette*/
+canvas = lv.canvas(lv.scr_act())
+canvas.set_buffer(cbuf, CANVAS_WIDTH, CANVAS_HEIGHT, lv.img.CF.TRUE_COLOR)
+
+canvas.fill_bg(lv.color_hex3(0xccc), lv.OPA.COVER)
+canvas.center()
+
+dsc = lv.draw_rect_dsc_t()
+dsc.init()
+
+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
+canvas.draw_rect(10, 10, 30, 20, dsc)
+

examples/widgets/canvas/lv_example_canvas_4.py

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+import fs_driver
+
+CANVAS_WIDTH  = 50
+CANVAS_HEIGHT = 50
+
+LV_COLOR_SIZE = 32
+
+#
+# Draw a text to the canvas
+#
+
+# Create a buffer for the canvas
+cbuf = bytearray((LV_COLOR_SIZE // 8) * CANVAS_WIDTH * CANVAS_HEIGHT)
+
+# Create a canvas and initialize its palette
+canvas = lv.canvas(lv.scr_act())
+canvas.set_buffer(cbuf, CANVAS_WIDTH, CANVAS_HEIGHT, lv.img.CF.TRUE_COLOR)
+canvas.fill_bg(lv.color_hex3(0xccc), lv.OPA.COVER)
+canvas.center()
+
+dsc = lv.draw_label_dsc_t()
+dsc.init()
+
+dsc.color = lv.palette_main(lv.PALETTE.RED)
+
+try:
+    dsc.font = lv_font_montserrat_18
+except:
+    # needed for dynamic font loading
+    fs_drv = lv.fs_drv_t()
+    fs_driver.fs_register(fs_drv, 'S')
+
+    print("Loading font montserrat_18")
+    font_montserrat_18 = lv.font_load("S:../../assets/font/montserrat-18.fnt")
+    if not font_montserrat_18:
+        print("Font loading failed")
+    else:
+        dsc.font = font_montserrat_18
+
+dsc.decor = lv.TEXT_DECOR.UNDERLINE
+print('Printing "Hello"')
+canvas.draw_text(10, 10, 30, dsc, "Hello")
+
+

examples/widgets/canvas/lv_example_canvas_5.py

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+#!/opt/bin/lv_micropython -i
+# Initialize 
+
+import lvgl as lv
+import display_driver
+import fs_driver
+
+CANVAS_WIDTH  = 50
+CANVAS_HEIGHT = 50
+
+LV_COLOR_SIZE = 32
+
+#
+# Draw an arc to the canvas
+#
+
+# Create a buffer for the canvas
+cbuf = bytearray((LV_COLOR_SIZE // 8) * CANVAS_WIDTH * CANVAS_HEIGHT)
+
+# Create a canvas and initialize its palette
+canvas = lv.canvas(lv.scr_act())
+canvas.set_buffer(cbuf, CANVAS_WIDTH, CANVAS_HEIGHT, lv.img.CF.TRUE_COLOR)
+canvas.fill_bg(lv.color_hex3(0xccc), lv.OPA.COVER)
+canvas.center()
+
+dsc = lv.draw_arc_dsc_t()
+dsc.init()
+dsc.color = lv.palette_main(lv.PALETTE.RED)
+dsc.width = 5
+
+canvas.draw_arc(25, 25, 15, 0, 220, dsc)
+

examples/widgets/canvas/lv_example_canvas_6.py

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+CANVAS_WIDTH  = 50
+CANVAS_HEIGHT = 50
+
+LV_COLOR_SIZE = 32
+
+# Create an image from the png file
+try:
+    with open('../../assets/img_star.png','rb') as f:
+        png_data = f.read()
+except:
+    print("Could not find star.png")
+    sys.exit()
+
+img_star_argb = lv.img_dsc_t({
+  'data_size': len(png_data),
+  'data': png_data
+})
+
+#
+# Draw an image to the canvas
+#
+
+# Create a buffer for the canvas
+cbuf = bytearray((LV_COLOR_SIZE // 8) * CANVAS_WIDTH * CANVAS_HEIGHT)
+
+# Create a canvas and initialize its palette
+canvas = lv.canvas(lv.scr_act())
+canvas.set_buffer(cbuf, CANVAS_WIDTH, CANVAS_HEIGHT, lv.img.CF.TRUE_COLOR)
+canvas.fill_bg(lv.color_hex3(0xccc), lv.OPA.COVER)
+canvas.center()
+
+dsc = lv.draw_img_dsc_t()
+dsc.init()
+
+canvas.draw_img(5, 5, img_star_argb, dsc)
+

examples/widgets/canvas/lv_example_canvas_7.py

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+CANVAS_WIDTH  = 50
+CANVAS_HEIGHT = 50
+
+LV_COLOR_SIZE = 32
+
+#
+# Draw a line to the canvas
+#
+
+# Create a buffer for the canvas
+cbuf = bytearray((LV_COLOR_SIZE // 8) * CANVAS_WIDTH * CANVAS_HEIGHT)
+
+# Create a canvas and initialize its palette
+canvas = lv.canvas(lv.scr_act())
+canvas.set_buffer(cbuf, CANVAS_WIDTH, CANVAS_HEIGHT, lv.img.CF.TRUE_COLOR)
+canvas.fill_bg(lv.color_hex3(0xccc), lv.OPA.COVER)
+canvas.center()
+
+dsc = lv.draw_line_dsc_t()
+dsc.init()
+
+dsc.color = lv.palette_main(lv.PALETTE.RED)
+dsc.width = 4
+dsc.round_end = 1
+dsc.round_start = 1
+
+p = [ {"x":15,"y":15},
+      {"x":35,"y":10},
+      {"x":10,"y":40} ]
+      
+canvas.draw_line(p, 3, dsc)
+
+