extmod/modframebuf: Add polygon drawing methods.
Add method for drawing polygons. For non-filled polygons, uses the existing line-drawing code to render arbitrary polygons using the given coords list, at the given x,y position, in the given colour. For filled polygons, arbitrary closed polygons are rendered using a fast point-in-polygon algorithm to determine where the edges of the polygon lie on each pixel row. Tests and documentation updates are also included. Signed-off-by: Mat Booth <mat.booth@gmail.com>
This commit is contained in:
Mat Booth
222
tests/extmod/framebuf_polygon.py
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222
tests/extmod/framebuf_polygon.py
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import sys
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try:
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import framebuf
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from array import array
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except ImportError:
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print("SKIP")
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raise SystemExit
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# TODO: poly needs functions that aren't in dynruntime.h yet.
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if not hasattr(framebuf.FrameBuffer, "poly"):
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print("SKIP")
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raise SystemExit
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def print_buffer(buffer, width, height):
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for row in range(height):
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for col in range(width):
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val = buffer[(row * width) + col]
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sys.stdout.write(" {:02x}".format(val) if val else " ··")
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sys.stdout.write("\n")
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buf = bytearray(70 * 70)
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w = 30
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h = 25
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fbuf = framebuf.FrameBuffer(buf, w, h, framebuf.GS8)
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col = 0xFF
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col_fill = 0x99
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# This describes a arbitrary polygon (this happens to be a concave polygon in
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# the shape of an upper-case letter 'M').
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poly = array(
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"h",
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(
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0,
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20,
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3,
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20,
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3,
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10,
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6,
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17,
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9,
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10,
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9,
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20,
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12,
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20,
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12,
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3,
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9,
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3,
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6,
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10,
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3,
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3,
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0,
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3,
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),
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)
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# This describes the same polygon, but the points are in reverse order
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# (it shouldn't matter if the polygon has clockwise or anti-clockwise
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# winding). Also defined as a bytes instead of array.
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poly_reversed = bytes(
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(
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0,
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3,
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3,
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3,
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6,
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10,
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9,
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3,
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12,
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3,
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12,
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20,
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9,
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20,
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9,
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10,
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6,
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17,
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3,
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10,
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3,
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20,
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0,
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20,
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)
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)
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# Draw the line polygon (at the origin) and the reversed-order polygon (offset).
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fbuf.fill(0)
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fbuf.poly(0, 0, poly, col)
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fbuf.poly(15, -2, poly_reversed, col)
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print_buffer(buf, w, h)
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print()
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# Same but filled.
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fbuf.fill(0)
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fbuf.poly(0, 0, poly, col_fill, True)
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fbuf.poly(15, -2, poly_reversed, col_fill, True)
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print_buffer(buf, w, h)
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print()
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# Draw the fill then the outline to ensure that no fill goes outside the outline.
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fbuf.fill(0)
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fbuf.poly(0, 0, poly, col_fill, True)
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fbuf.poly(0, 0, poly, col)
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fbuf.poly(15, -2, poly, col_fill, True)
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fbuf.poly(15, -2, poly, col)
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print_buffer(buf, w, h)
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print()
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# Draw the outline then the fill to ensure the fill completely covers the outline.
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fbuf.fill(0)
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fbuf.poly(0, 0, poly, col)
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fbuf.poly(0, 0, poly, col_fill, True)
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fbuf.poly(15, -2, poly, col)
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fbuf.poly(15, -2, poly, col_fill, True)
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print_buffer(buf, w, h)
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print()
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# Draw polygons that will go out of bounds at each of the edges.
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for x, y in (
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(
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-8,
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-8,
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),
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(
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24,
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-6,
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),
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(
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20,
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12,
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),
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(
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-2,
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10,
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),
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):
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fbuf.fill(0)
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fbuf.poly(x, y, poly, col)
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print_buffer(buf, w, h)
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print()
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fbuf.fill(0)
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fbuf.poly(x, y, poly_reversed, col, True)
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print_buffer(buf, w, h)
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print()
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# Edge cases: These two lists describe self-intersecting polygons
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poly_hourglass = array("h", (0, 0, 9, 0, 0, 19, 9, 19))
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poly_star = array("h", (7, 0, 3, 18, 14, 5, 0, 5, 11, 18))
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# As before, fill then outline.
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fbuf.fill(0)
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fbuf.poly(0, 2, poly_hourglass, col_fill, True)
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fbuf.poly(0, 2, poly_hourglass, col)
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fbuf.poly(12, 2, poly_star, col_fill, True)
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fbuf.poly(12, 2, poly_star, col)
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print_buffer(buf, w, h)
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print()
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# Outline then fill.
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fbuf.fill(0)
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fbuf.poly(0, 2, poly_hourglass, col)
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fbuf.poly(0, 2, poly_hourglass, col_fill, True)
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fbuf.poly(12, 2, poly_star, col)
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fbuf.poly(12, 2, poly_star, col_fill, True)
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print_buffer(buf, w, h)
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print()
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# Edge cases: These are "degenerate" polygons.
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poly_empty = array("h") # Will draw nothing at all.
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poly_one = array("h", (20, 20)) # Will draw a single point.
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poly_two = array("h", (10, 10, 5, 5)) # Will draw a single line.
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poly_wrong_length = array("h", (2, 2, 4)) # Will round down to one point.
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fbuf.fill(0)
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fbuf.poly(0, 0, poly_empty, col)
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fbuf.poly(0, 0, poly_one, col)
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fbuf.poly(0, 0, poly_two, col)
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fbuf.poly(0, 0, poly_wrong_length, col)
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print_buffer(buf, w, h)
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print()
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# A shape with a horizontal overhang.
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poly_overhang = array("h", (0, 0, 0, 5, 5, 5, 5, 10, 10, 10, 10, 0))
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fbuf.fill(0)
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fbuf.poly(0, 0, poly_overhang, col)
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fbuf.poly(0, 0, poly_overhang, col_fill, True)
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print_buffer(buf, w, h)
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print()
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fbuf.fill(0)
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fbuf.poly(0, 0, poly_overhang, col_fill, True)
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fbuf.poly(0, 0, poly_overhang, col)
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print_buffer(buf, w, h)
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print()
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# Triangles
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w = 70
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h = 70
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fbuf = framebuf.FrameBuffer(buf, w, h, framebuf.GS8)
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t1 = array("h", [40, 0, 20, 68, 62, 40])
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t2 = array("h", [40, 0, 0, 16, 20, 68])
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fbuf.fill(0)
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fbuf.poly(0, 0, t1, 0xFF, False)
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fbuf.poly(0, 0, t2, 0xFF, False)
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print_buffer(buf, w, h)
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fbuf.fill(0)
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fbuf.poly(0, 0, t1, 0xFF, True)
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fbuf.poly(0, 0, t2, 0xFF, True)
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print_buffer(buf, w, h)
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