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我正在使用此代码将大小更改为图像，然后创建一个具有新尺寸的新文件。一切正常，但它改变了图像 dpi 分辨率，我不希望这样......初始图像 dpi res 为 328，调整大小后变为 72......如何保持原始 dpi 分辨率？这是我的代码：

- (void)scaleIcons:(NSString *)outputPath :(NSURL *)nomeImmagine
 {

 NSImage *image = [[NSImage alloc] initWithContentsOfFile:[nomeImmagine path]];
if (!image)
    image = [[NSWorkspace sharedWorkspace] iconForFile:[nomeImmagine path]];

NSSize outputSize = NSMakeSize(512.0f,512.0f);
NSImage *anImage  = [self scaleImage:image toSize:outputSize];

NSString *finalPath = [outputPath stringByAppendingString:@"/icon_512x512.png"];
NSData *imageData = [anImage TIFFRepresentation];
NSBitmapImageRep *rep = [NSBitmapImageRep imageRepWithData:imageData];
NSData *dataToWrite = [rep representationUsingType:NSPNGFileType properties:nil];
[dataToWrite writeToFile:finalPath atomically:NO];
}



- (NSImage *)scaleImage:(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;

        if (widthFactor < heightFactor)
        {
            thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
        }

        else if (widthFactor > heightFactor)
        {
            thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
        }

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

        [newImage lockFocus];

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

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

        [newImage unlockFocus];
    }


 }

return newImage;
}

任何帮助将不胜感激！谢谢... 马西

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1 回答 1

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最后，我已经能够更改资源...使用 trojanfoe 指向的帖子所采用的代码...我在编写文件之前将此添加到我的代码中：

NSSize pointsSize = rep.size;
NSSize pixelSize = NSMakeSize(rep.pixelsWide, rep.pixelsHigh);

CGFloat currentDPI = ceilf((72.0f * pixelSize.width)/pointsSize.width);
NSLog(@"current DPI %f", currentDPI);

NSSize updatedPointsSize = pointsSize;

updatedPointsSize.width = ceilf((72.0f * pixelSize.width)/328);
updatedPointsSize.height = ceilf((72.0f * pixelSize.height)/328);

[rep setSize:updatedPointsSize];

现在唯一的问题是最终分辨率是 321,894 而不是 328……但它已经是东西了！

于 2013-10-30T16:13:44.173 回答