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我正在尝试获取 NinevehGL 对象的屏幕截图，该对象是基于 OpenGL 构建的 3D 库。所以我认为OpenGL命令也可以在这里工作。

问题是屏幕截图在 iOS 5 或更早版本中可以正常工作，但在 iOS6 中不行。它在 iOS6 模拟器中也可以正常工作，但在 iOS 6 设备上则不行。它给了我黑色背景。我读过很多帖子，其中大多数建议放

 CAEAGLLayer *eaglLayer = (CAEAGLLayer *) [self theNGLView].layer;
[eaglLayer setDrawableProperties:@{
kEAGLDrawablePropertyRetainedBacking: [NSNumber numberWithBool:YES],
kEAGLDrawablePropertyColorFormat: kEAGLColorFormatRGBA8
 }];

在初始化方法中。我做到了，但没有运气。

我正在使用下面的方法来获取屏幕截图。

 -(UIImage *)getImage{

GLint width;
GLint height;

glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_WIDTH, &width);

glGetRenderbufferParameteriv(GL_RENDERBUFFER, GL_RENDERBUFFER_HEIGHT, &height);

NSLog(@"%d %d",width,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];
CGImageRelease(imageRef);
CGDataProviderRelease(provider);
CGColorSpaceRelease(colorSpaceRef);
free(buffer);
free(buffer2);
return myImage;
}
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