在Cocoa中，如何在没有透明度的情况下缩放NSImage

我用这段代码缩放一幅图像，一切正常，但生成的图像在其属性中有透明度，我只需要一幅没有透明度和alpha通道的图像。。。有人知道我如何修改代码以获得没有透明胶片的图像吗？ 这是我的代码：

- (void)scalePreviews:(NSString *)outputPath :(NSURL *)nomeImmagine :(CGFloat)size1   :(CGFloat)size2 :(NSString *)nomeIcona
{
NSImage *image = [[NSImage alloc] initWithContentsOfFile:[nomeImmagine path]];
if (!image)
    image = [[NSWorkspace sharedWorkspace] iconForFile:[nomeImmagine path]];


NSSize outputSize = NSMakeSize(size1,size2);
NSImage *anImage  = [self scaleImagePreviews:image toSize:outputSize];


NSString *finalPath = [outputPath stringByAppendingString:[NSString stringWithFormat:@"/image-previews/%@",nomeIcona]];

//questo serve a creare la directory delle icone se gia' non esiste
NSFileManager *fileManager= [NSFileManager defaultManager];
if(![fileManager fileExistsAtPath:[outputPath stringByAppendingString:@"/image-previews"] isDirectory:nil])
    if(![fileManager createDirectoryAtPath:[outputPath stringByAppendingString:@"/image-previews"] withIntermediateDirectories:YES attributes:nil error:NULL])
        NSLog(@"Error: Create folder failed %@", [outputPath stringByAppendingString:@"/image-previews"]);

//  NSLog(@"finalPath: %@",finalPath);
NSData *imageData = [anImage TIFFRepresentation];

NSBitmapImageRep *rep = [NSBitmapImageRep imageRepWithData:imageData];

NSData *dataToWrite = [rep representationUsingType:NSPNGFileType properties:nil];

[dataToWrite writeToFile:finalPath atomically:NO];


}





- (NSImage *)scaleImagePreviews:(NSImage *)image toSize:(NSSize)targetSize
 {
       if ([image isValid])
        {

          NSSize imageSize = [image size];
         float width  = imageSize.width;
         float height = imageSize.height;
         float targetWidth  = targetSize.width;
        float targetHeight = targetSize.height;
        float scaleFactor  = 0.0;
        float scaledWidth  = targetWidth;
        float scaledHeight = targetHeight;

        NSPoint thumbnailPoint = NSZeroPoint;

        if (!NSEqualSizes(imageSize, targetSize))
        {
            float widthFactor  = targetWidth / width;
            float heightFactor = targetHeight / height;

            if (widthFactor < heightFactor)
            {
                scaleFactor = widthFactor;
            }
            else
            {
                scaleFactor = heightFactor;
            }

            scaledWidth  = width  * scaleFactor;
            scaledHeight = height * scaleFactor;

            newImage = [[NSImage alloc] initWithSize:targetSize];

            [newImage lockFocus];

            NSRect thumbnailRect;
            thumbnailRect.origin = thumbnailPoint;
            thumbnailRect.size.width = targetSize.width;  //scaledWidth;
            thumbnailRect.size.height = targetSize.height; //scaledHeight;

            [image drawInRect:thumbnailRect
                     fromRect:NSZeroRect
                    operation:NSCompositeSourceOver
                     fraction:1.0];

            [newImage unlockFocus];
        }

 }

 return newImage;

}

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我找到了一个解决办法。。。我用类型更改了表示。。。我使用了JPEG文件类型，所以图像根本没有透明胶片

以下是更改后的代码：

NSData*dataToWrite=[rep rep representationUsingType:NSJPEGFileType属性：nil]

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你所说的透明性是什么意思？您希望在原始图像透明的地方使用什么颜色？在绘制原始图像之前，您是否尝试过用该颜色填充矩形？e、 g.[NSColor whiteColor]集]；NSRectFillthumbnailRect；我试图使用你的代码，但我仍然有那个问题。。。对于其属性中的透明度，我的意思是，当我在一个只接受没有透明度和alpha通道的图像的站点中使用图像时，如果图像没有透明度，我会得到一个错误，说它找到了透明度。。。所以我猜它一定是在它的DNA里。。。我不知道怎么。。。我还注意到，如果我用Photoshop打开图像，并发出“展平图像”命令，问题就会消失。。。