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Canvas Class

Package: GHIElectronics.Endpoint.Drawing
Module: GHIElectronics.Endpoint.Drawing

A pixel buffer plus the primitives to draw into it. Pick the size and PixelFormat at Create time; when done, hand Buffer to whichever device accepts bytes.

class Canvas: ...

Example​

canvas = Canvas.Create(240, 320, PixelFormat.Rgb565)
canvas.Clear(Color.Black)
canvas.DrawLine(10, 10, 230, 310, Color.Red, 2)
canvas.FillCircle(120, 160, 40, Color.Blue)
canvas.DrawText("Hello Endpoint", font, 10, 30, 20, Color.White)
spi.Write(canvas.Buffer)

Properties​

Buffer​

Buffer: bytearray  # @property

Raw pixel bytes. Length and layout match Width, Height, and PixelFormat.

Width​

Width: int

Height​

Height: int

PixelFormat​

PixelFormat: int

Methods​

Create(width, height, pixel_format)​

@staticmethod
def Create(width: int, height: int, pixel_format: int) -> Canvas:

Allocate a new Canvas of the given size and pixel format.

Clear(color)​

def Clear(self, color: Color) -> None:

Fill the whole buffer with a single color.

SetPixel(x, y, color)​

def SetPixel(self, x: int, y: int, color: Color) -> None:

Set a single pixel. No-op if (x, y) is outside the canvas.

DrawLine(x0, y0, x1, y1, color, thickness=1)​

def DrawLine(self, x0: int, y0: int, x1: int, y1: int, color: Color, thickness: int = 1) -> None:

Bresenham line.

DrawRectangle(x, y, width, height, color, thickness=1)​

def DrawRectangle(self, x: int, y: int, width: int, height: int, color: Color, thickness: int = 1) -> None:

Stroke a rectangle outline.

FillRectangle(x, y, width, height, color)​

def FillRectangle(self, x: int, y: int, width: int, height: int, color: Color) -> None:

Fill a rectangle.

DrawCircle(cx, cy, radius, color, thickness=1)​

def DrawCircle(self, cx: int, cy: int, radius: int, color: Color, thickness: int = 1) -> None:

Midpoint-algorithm circle outline.

FillCircle(cx, cy, radius, color)​

def FillCircle(self, cx: int, cy: int, radius: int, color: Color) -> None:

Filled circle.

DrawText(text, font, x, y, size_px, color)​

def DrawText(self, text: str, font: Font, x: int, y: int, size_px: int, color: Color) -> None:

Rasterize text with font at size_px, with the top-left of the text box at (x, y). Alpha-blends against whatever is already in the canvas. Rgb565 and Monochrome targets only.

DrawImage(source, x, y, width=None, height=None, pixel_format=None)​

def DrawImage(self, source, x: int, y: int,
              width: int = None, height: int = None, pixel_format: int = None) -> None:

Blit an image into this canvas at (x, y). Overloads:

  • source is an Image: use its cached decoded pixels (fast path).
  • source is bytes-like and the other args are None: treat as encoded file bytes (JPG / PNG / BMP / GIF / TGA), decode once and blit.
  • source is bytes-like and width/height/pixel_format are given: treat as a raw pixel buffer of that size and format.

Dispose()​

def Dispose(self) -> None:

Release the pixel buffer.