3

我正在为客户开发增强现实应用程序。OpenGL 和 EAGL 部分已在 Unity 3D 中完成，并在我的应用程序中实现为视图。

我现在需要的是一个按钮，它可以捕捉 OpenGL 内容的屏幕截图，这是最后面的视图。

我尝试自己编写它，但是当我单击分配了 IBAction 的按钮时，它只保存了屏幕的 1/4（左下角）——尽管它确实将它保存到了相机胶卷中。

所以基本上，我怎样才能让它保存整个屏幕尺寸，而不是四分之一？

这是我的方法代码：

-(IBAction)tagBillede:(id)sender
{
    UIImage *outputImage = nil;

    CGRect s = CGRectMake(0, 0, 320, 480);            
    uint8_t *buffer = (uint8_t *) malloc(s.size.width * s.size.height * 4);

    if (!buffer) goto error;

    glReadPixels(0, 0, s.size.width, s.size.height, GL_RGBA, GL_UNSIGNED_BYTE, buffer);    

    CGDataProviderRef ref = CGDataProviderCreateWithData(NULL, buffer, s.size.width * s.size.height * 4, NULL);

    if (!ref) goto error;

    CGImageRef iref = CGImageCreate(s.size.width, s.size.height, 8, 32, s.size.width * 4, CGColorSpaceCreateDeviceRGB(), kCGBitmapByteOrderDefault, ref, NULL, true, kCGRenderingIntentDefault);

    if (!iref) goto error;        

    size_t width = CGImageGetWidth(iref);    
    size_t height = CGImageGetHeight(iref);    
    size_t length = width * height * 4;            
    uint32_t *pixels = (uint32_t *)malloc(length);

    if (!pixels) goto error;

    CGContextRef context = CGBitmapContextCreate(pixels, width, height, 8, width * 4,    
        CGImageGetColorSpace(iref), kCGImageAlphaNoneSkipFirst | kCGBitmapByteOrder32Big);

    if (!context) goto error;            

    CGAffineTransform transform = CGAffineTransformIdentity;    
    transform = CGAffineTransformMakeTranslation(0.0f, height);    
    transform = CGAffineTransformScale(transform, 1.0, -1.0);    
    CGContextConcatCTM(context, transform);            
    CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, width, height), iref);         
    CGImageRef outputRef = CGBitmapContextCreateImage(context);

    if (!outputRef) goto error;

    outputImage = [UIImage imageWithCGImage: outputRef]; 

    if (!outputImage) goto error;    

    CGDataProviderRelease(ref);   
    CGImageRelease(iref);    
    CGContextRelease(context);    
    CGImageRelease(outputRef);
    free(pixels);
    free(buffer);

    UIImageWriteToSavedPhotosAlbum(outputImage, self, @selector(image: didFinishSavingWithError: contextInfo:), nil);
}
4

3 回答 3

2

我怀疑您使用的是带有 Retina 显示屏的设备，即 640x960。您需要考虑屏幕比例；在非 Retina 显示器上为 1.0，在 Retina 显示器上为 2.0。尝试s像这样初始化：

CGFloat scale = UIScreen.mainScreen.scale;
CGRect s = CGRectMake(0, 0, 320 * scale, 480 * scale);
于 2012-02-06T04:22:28.177 回答
2

如果设备是视网膜设备，您需要自己缩放 opengl 的东西。您实际上是通过仅捕获一半宽度和一半高度来指定您想要左下角。

您需要将视网膜屏幕的宽度和高度都加倍，但实际上，您应该将其乘以屏幕的比例：

CGFloat scale = [[UIScreen mainScreen] scale];
CGRect s = CGRectMake(0, 0, 320.0f * scale, 480.0f * scale);
于 2012-02-06T04:24:53.203 回答
0

以为我会响起，同时，表达一些感激之情:)

我现在让它像魅力一样工作，这是清理后的代码：

UIImage *outputImage = nil;

CGFloat scale = [[UIScreen mainScreen] scale];
CGRect s = CGRectMake(0, 0, 320.0f * scale, 480.0f * scale);            
uint8_t *buffer = (uint8_t *) malloc(s.size.width * s.size.height * 4);

glReadPixels(0, 0, s.size.width, s.size.height, GL_RGBA, GL_UNSIGNED_BYTE, buffer);    

CGDataProviderRef ref = CGDataProviderCreateWithData(NULL, buffer, s.size.width * s.size.height * 4, NULL);

CGImageRef iref = CGImageCreate(s.size.width, s.size.height, 8, 32, s.size.width * 4, CGColorSpaceCreateDeviceRGB(), kCGBitmapByteOrderDefault, ref, NULL, true, kCGRenderingIntentDefault);

size_t width = CGImageGetWidth(iref);    
size_t height = CGImageGetHeight(iref);    
size_t length = width * height * 4;            
uint32_t *pixels = (uint32_t *)malloc(length);

CGContextRef context = CGBitmapContextCreate(pixels, width, height, 8, width * 4,    
                                             CGImageGetColorSpace(iref), kCGImageAlphaNoneSkipFirst | kCGBitmapByteOrder32Big);           

CGAffineTransform transform = CGAffineTransformIdentity;    
transform = CGAffineTransformMakeTranslation(0.0f, height);    
transform = CGAffineTransformScale(transform, 1.0, -1.0);    
CGContextConcatCTM(context, transform);            
CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, width, height), iref);         
CGImageRef outputRef = CGBitmapContextCreateImage(context);

outputImage = [UIImage imageWithCGImage: outputRef]; 

CGDataProviderRelease(ref);   
CGImageRelease(iref);    
CGContextRelease(context);    
CGImageRelease(outputRef);
free(pixels);
free(buffer);

UIImageWriteToSavedPhotosAlbum(outputImage, nil, nil, nil);
于 2012-02-09T13:48:19.413 回答