How to draw image in memory manually in pyglet?

Question

In pyglet, I want to create an image buffer in memory, then set the bytes manually, then draw it. I tried making a 3x3 red square like this in my draw() function:

imageData = pyglet.image.ImageData(3, 3, 'RGB', [1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0 ])
imageData.blit(10, 10)

...but at runtime, Python complains:

ctypes.ArgumentError: argument 9: <type 'exceptions.TypeError'>: wrong type

Is this the right approach? Am I missing a step? How can I fix this?

Answer 1

Yes, you can do this, but as the error tells you, you must use ctypes instead of Python types for it.

RGB values are unsigned byte triplets, which means c_ubyte in ctypes, also available in pyglet.gl as GL_ubyte. So you can do this:

pixels = [
    255, 0, 0,      0, 255, 0,      0, 0, 255,     # RGB values range from
    255, 0, 0,      255, 0, 0,      255, 0, 0,     # 0 to 255 for each color
    255, 0, 0,      255, 0, 0,      255, 0, 0,     # component.
]
rawData = (GLubyte * len(pixels))(*pixels)
imageData = pyglet.image.ImageData(3, 3, 'RGB', rawData)

The above is the recommended ctypes syntax, which generates an array of GLubyte with the right size and then populates it with your pixel data.