Integration with other Libraries — Pycairo documentation

# Integration with other Libraries

## NumPy & ImageSurface

Creating an ImageSurface from a NumPy array:

      import numpy
      import cairo

      width, height = 255, 255
      data = numpy.ndarray(shape=(height, width), dtype=numpy.uint32)
      surface = cairo.ImageSurface.create_for_data(
          data, cairo.FORMAT_ARGB32, width, height)

Creating a NumPy array from an ImageSurface:

      import numpy
      import cairo

      width, height = 255, 255
      surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, width, height)
      buf = surface.get_data()
      data = numpy.ndarray(shape=(height, width),
                           dtype=numpy.uint32,
                           buffer=buf)

## Pygame & ImageSurface

Creating a pygame.image from an ImageSurface:

      import pygame
      import cairo

      width, height = 255, 255
      surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, width, height)
      buf = surface.get_data()
      image = pygame.image.frombuffer(buf, (width, height), "ARGB")

## Pyglet & ImageSurface as Texture

Creating a pyglet.Texture from an ImageSurface:

      import ctypes
      import cairo

      from pyglet import app, clock, gl, image, window

      # create data shared by ImageSurface and Texture
      width, height = 400, 400

      surface_data = (ctypes.c_ubyte * (width * height * 4))()
      surface = cairo.ImageSurface.create_for_data (surface_data, cairo.FORMAT_ARGB32,
      width, height, width * 4);
      texture = image.Texture.create_for_size(gl.GL_TEXTURE_2D, width, height, gl.GL_RGBA)

Draw pyglet.Texture bound to ImageSurface

      window = window.Window(width=width, height=height)

      @window.event
      def on_draw():
          window.clear()

          # Draw texture backed by ImageSurface
          gl.glEnable(gl.GL_TEXTURE_2D)

          gl.glBindTexture(gl.GL_TEXTURE_2D, texture.id)
          gl.glTexImage2D(gl.GL_TEXTURE_2D, 0, gl.GL_RGBA, width, height, 0, gl.GL_BGRA,
          gl.GL_UNSIGNED_BYTE,
          surface_data)

          gl.glBegin(gl.GL_QUADS)
          gl.glTexCoord2f(0.0, 1.0)
          gl.glVertex2i(0, 0)
          gl.glTexCoord2f(1.0, 1.0)
          gl.glVertex2i(width, 0)
          gl.glTexCoord2f(1.0, 0.0)
          gl.glVertex2i(width, height)
          gl.glTexCoord2f(0.0, 0.0)
          gl.glVertex2i(0, height)
          gl.glEnd()

      # call clock.schedule_update here to update the ImageSurface every frame
      app.run()

## Pillow (PIL) & Cairo

Creating an ImageSurface from a PIL Image:

      import cairo
      import PIL.Image as Image

      def from_pil(im: Image, alpha: float=1.0, format: cairo.Format=cairo.FORMAT_ARGB32) -> cairo.ImageSurface:
          """
          :param im: Pillow Image
          :param alpha: 0..1 alpha to add to non-alpha images
          :param format: Pixel format for output surface
          """
          assert format in (cairo.FORMAT_RGB24, cairo.FORMAT_ARGB32), "Unsupported pixel format: %s" % format
          if 'A' not in im.getbands():
              im.putalpha(int(alpha * 256.))
          arr = bytearray(im.tobytes('raw', 'BGRa'))
          surface = cairo.ImageSurface.create_for_data(arr, format, im.width, im.height)
          return surface

      filename = 'test.jpeg'

      # Open image to an ARGB32 ImageSurface
      im = Image.open(filename)
      surface1 = from_pil(im)

      # Open image to an RGB24 ImageSurface
      im = Image.open(filename)
      surface2 = from_pil(im, format=cairo.FORMAT_RGB24)

      # Open image to an ARGB32 ImageSurface, 50% opacity
      im = Image.open(filename)
      surface3 = from_pil(im, alpha=0.5, format=cairo.FORMAT_ARGB32)

Converting an ImageSurface to a PIL Image:

      import cairo
      import PIL.Image as Image

      def to_pil(surface: cairo.ImageSurface) -> Image:
          format = surface.get_format()
          size = (surface.get_width(), surface.get_height())
          stride = surface.get_stride()

          with surface.get_data() as memory:
              if format == cairo.Format.RGB24:
                  return Image.frombuffer(
                      "RGB", size, memory.tobytes(),
                      'raw', "BGRX", stride)
              elif format == cairo.Format.ARGB32:
                  return Image.frombuffer(
                      "RGBA", size, memory.tobytes(),
                      'raw', "BGRa", stride)
              else:
                  raise NotImplementedError(repr(format))

      # Create an image surface from a PNG file (or any other source)
      surface = cairo.ImageSurface.create_from_png("test.png")

      # Convert to a PIL Image
      im = to_pil(surface)

      # Use Pillow to store it as a JPEG
      im.save("result.jpg")

## Freetype-py & Cairo

See https://github.com/rougier/freetype-py/tree/master/examples for examples. Most of the `*-cairo.py` examples illustrate conversion from FreeType bitmaps to Cairo surfaces; the two examples, `glyph-vector-cairo.py` and `glyph-vector-2-cairo.py`, illustrate conversion from FreeType glyph contours to Cairo paths.

## ModernGL & ImageSurface as Texture

Creating a moderngl.Texture from an ImageSurface:

      import moderngl
      import cairo
      ctx = moderngl.create_context(standalone=True)
      width, height = 400, 400
      surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, width, height)
      texture = ctx.texture((width, height), 4, data=surface.get_data())

An example can also be found in the ModernGL project: https://github.com/moderngl/moderngl/blob/master/examples/integration_pycairo.py