GLPaint save image

Question

I\'m trying to develop a complex painting application on the iPhone. I\'m currently drawing using Quartz (e.g. CGContext...). Unfortunately the Quartz overhead is

Answer 1

Same as @Quakeboy's answer, but passing in the view so that the size can be dynamically determined (I used this for my universal app):

- (UIImage *)saveImageFromGLView:(UIView *)glView {
    int width = glView.frame.size.width;
    int height = glView.frame.size.height;

    NSInteger myDataLength = width * height * 4;
    // allocate array and read pixels into it.
    GLubyte *buffer = (GLubyte *) malloc(myDataLength);
    glReadPixels(0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
    // gl renders "upside down" so swap top to bottom into new array.
    // there's gotta be a better way, but this works.
    GLubyte *buffer2 = (GLubyte *) malloc(myDataLength);
    for(int y = 0; y < height; y++)
    {
        for(int x = 0; x < width * 4; x++)
        {
            buffer2[((height - 1) - y) * width * 4 + x] = buffer[y * 4 * width + x];
        }
    }
    // make data provider with data.
    CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, buffer2, myDataLength, NULL);
    // prep the ingredients
    int bitsPerComponent = 8;
    int bitsPerPixel = 32;
    int bytesPerRow = 4 * width;
    CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
    CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault;
    CGColorRenderingIntent renderingIntent = kCGRenderingIntentDefault;
    // make the cgimage
    CGImageRef imageRef = CGImageCreate(width, height, bitsPerComponent, bitsPerPixel, bytesPerRow, colorSpaceRef, bitmapInfo, provider, NULL, NO, renderingIntent);
    // then make the uiimage from that
    UIImage *myImage = [UIImage imageWithCGImage:imageRef];
    return myImage;
}