iphone - EAGLView到UIImage的颜色转换问题

我有一个EAGLView(摘自Apple的示例)，可以使用以下代码成功将其转换为UIImage:

- (UIImage *)glToUIImage:(CGSize)size {

NSInteger backingWidth = size.width;
NSInteger backingHeight = size.height;

NSInteger myDataLength = backingWidth * backingHeight * 4;

// allocate array and read pixels into it.
GLuint *buffer = (GLuint *) malloc(myDataLength);
glReadPixels(0, 0, backingWidth, backingHeight, GL_RGBA, GL_UNSIGNED_BYTE, buffer);

// gl renders “upside down” so swap top to bottom into new array.
for(int y = 0; y < backingHeight / 2; y++) {
    for(int x = 0; x < backingWidth; x++) {
        //Swap top and bottom bytes
        GLuint top = buffer[y * backingWidth + x];
        GLuint bottom = buffer[(backingHeight - 1 - y) * backingWidth + x];
        buffer[(backingHeight - 1 - y) * backingWidth + x] = top;
        buffer[y * backingWidth + x] = bottom;
    }
}

// make data provider with data.
CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, buffer, myDataLength, releaseScreenshotData);

// prep the ingredients
const int bitsPerComponent = 8;
const int bitsPerPixel = 4 * bitsPerComponent;
const int bytesPerRow = 4 * backingWidth;
CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault;
CGColorRenderingIntent renderingIntent = kCGRenderingIntentDefault;

// make the cgimage
CGImageRef imageRef = CGImageCreate(backingWidth, backingHeight, bitsPerComponent, bitsPerPixel, bytesPerRow, colorSpaceRef, bitmapInfo, provider, NULL, YES, renderingIntent);
CGColorSpaceRelease(colorSpaceRef);
CGDataProviderRelease(provider);

// then make the UIImage from that
UIImage *myImage = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);

return myImage;

}

void releaseScreenshotData(void *info, const void *data, size_t size) {
free((void *)data);
};

这是我使用此方法转换为UIImage的代码:

EAGLView *newView = [[EAGLView alloc] initWithImage:photo.originalImage];

[newView reshapeFramebuffer];
[newView drawView:theSlider.tag value:theSlider.value];
//the two lines above are how EAGLViews in Apple's examples are modified


photoItem *newPhoto = [[photoItem alloc] initWithImage:[self glToUIImage:photo.originalImage.size]];

我遇到的问题是，有时转换后的UIImage不会与EAGLView具有相同的颜色。如果将高饱和度应用于EAGLView，高亮度或低对比度等情况，就会发生这种情况。例如，如果我将高饱和度应用于EAGLView，然后转换为UIImage，则图像的某些部分将比其预期的要明亮。

因此，我发现问题是变相的EAGLView计时问题，类似于我在此之前的问题(EAGLView to UIImage timing question)。

最佳答案

对于仍在乎的人，请参阅以下我的评论:

汤米，我终于破解了自己的解决方案。这是另一个EAGLView计时问题(实际上仅在饱和状态下才出现)，我可以使用performSelector:afterDelay:0.0方法解决此问题。谢谢

另外，我建议任何为iOS 5.0进行编码的人都可以研究Core Image和GLKView。它们基本上使您调整图像属性(如我在此处所做的工作)和将EAGLView转换为UIImage的工作变得简单得多。