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ndg/lib/lvgl/examples/widgets/canvas/lv_example_canvas_2.py

44 lines
1.2 KiB
Python

CANVAS_WIDTH = 50
CANVAS_HEIGHT = 50
LV_COLOR_CHROMA_KEY = lv.color_hex(0x00ff00)
def LV_IMG_BUF_SIZE_ALPHA_1BIT(w, h):
return int(((w / 8) + 1) * h)
def LV_IMG_BUF_SIZE_INDEXED_1BIT(w, h):
return LV_IMG_BUF_SIZE_ALPHA_1BIT(w, h) + 4 * 2
def LV_CANVAS_BUF_SIZE_INDEXED_1BIT(w, h):
return LV_IMG_BUF_SIZE_INDEXED_1BIT(w, h)
#
# Create a transparent canvas with Chroma keying and indexed color format (palette).
#
# Create a button to better see the transparency
btn=lv.btn(lv.scr_act())
# Create a buffer for the canvas
cbuf= bytearray(LV_CANVAS_BUF_SIZE_INDEXED_1BIT(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.INDEXED_1BIT)
canvas.set_palette(0, LV_COLOR_CHROMA_KEY)
canvas.set_palette(1, lv.palette_main(lv.PALETTE.RED))
# Create colors with the indices of the palette
c0 = lv.color_t()
c1 = lv.color_t()
c0.full = 0
c1.full = 1
# Red background (There is no dedicated alpha channel in indexed images so LV_OPA_COVER is ignored)
canvas.fill_bg(c1, lv.OPA.COVER)
# Create hole on the canvas
for y in range(10,30):
for x in range(5,20):
canvas.set_px(x, y, c0)