在Iphone中调整图像大小

我试图调整图像大小，但它不能正常工作。我有一个图像的宽度320和高度480我想调整它的宽度1024和高度1024。我正在使用此代码调整图像大小

- (UIImage *)resizeImageToSize:(CGSize)targetSize
{
    UIImage *sourceImage = [self saveImage:0];

    UIImage *newImage = nil;

    CGSize imageSize = sourceImage.size;
    CGFloat width = imageSize.width;
    CGFloat height = imageSize.height;

    CGFloat targetWidth = targetSize.width;
    CGFloat targetHeight = targetSize.height;

    CGFloat scaleFactor = 0.0;
    CGFloat scaledWidth = targetWidth;
    CGFloat scaledHeight = targetHeight;

    CGPoint thumbnailPoint = CGPointMake(0.0,0.0);

    if (CGSizeEqualToSize(imageSize, targetSize) == NO) {

        CGFloat widthFactor = targetWidth / width;
        CGFloat heightFactor = targetHeight / height;

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

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

        // make image center aligned
        if (widthFactor < heightFactor)
        {
            thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
        }
        else if (widthFactor > heightFactor)
        {
            thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
        }
    }

    UIGraphicsBeginImageContext(targetSize);
    CGRect thumbnailRect = CGRectZero;
    thumbnailRect.origin = thumbnailPoint;
    thumbnailRect.size.width  = scaledWidth;
    thumbnailRect.size.height = scaledHeight;

    [sourceImage drawInRect:thumbnailRect];
    newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    if(newImage == nil)
        NSLog(@"could not scale image");

    return newImage ;
}

-（UIImage*）resizeImageToSize:（CGSize）targetSize
{
UIImage*sourceImage=[self-saveImage:0]；
UIImage*newImage=nil；
CGSize imageSize=sourceImage.size；
CGFloat width=imageSize.width；
CGFloat height=图像大小.height；
CGFloat targetWidth=targetSize.width；
CGFloat targetHeight=targetSize.height；
CGFloat scaleFactor=0.0；
CGFloat scaledWidth=targetWidth；
CGFloat缩放高度=目标高度；
CGPoint thumbnailPoint=CGPointMake（0.0,0.0）；
if（CGSizeEqualToSize（imageSize，targetSize）==否）{
CGFloat宽度系数=目标宽度/宽度；
CGFloat高度系数=目标高度/高度；
if（宽度系数<高度系数）
scaleFactor=宽度因子；
其他的
比例因子=高度因子；
scaledWidth=宽度*缩放因子；
缩放高度=高度*缩放因子；
//使图像中心对齐
if（宽度系数<高度系数）
{
thumbnailPoint.y=（targetLight-缩放高度）*0.5；
}
否则如果（宽度因子>高度因子）
{
thumbnailPoint.x=（targetWidth-缩放宽度）*0.5；
}
}
UIGraphicsBeginImageContext（targetSize）；
CGRect thumbnailRect=CGRectZero；
thumbnailRect.origin=thumbnailPoint；
thumbnailRect.size.width=缩放宽度；
thumbnailRect.size.height=缩放高度；
[sourceImage drawInRect:thumbnailRect]；
newImage=UIGraphicsGetImageFromCurrentImageContext（）；
UIGraphicsSendImageContext（）；
if（newImage==nil）
NSLog（@“无法缩放图像”）；
返回新图像；
}

我没有得到我想要的图像大小

这是我从320x480调整图像大小到1280x1024时得到的结果

---

图像大小正在增加，但图像没有增加。我想让那辆车在白色背景上伸展。

你想调整尺寸并保持纵横比试试这个。。。。与上述方法非常相似：

- (UIImage*)imageWithImage:(UIImage*)sourceImage scaledToSizeWithSameAspectRatio:(CGSize)targetSize;
{  
    CGSize imageSize = sourceImage.size;
    CGFloat width = imageSize.width;
    CGFloat height = imageSize.height;
    CGFloat targetWidth = targetSize.width;
    CGFloat targetHeight = targetSize.height;
    CGFloat scaleFactor = 0.0;
    CGFloat scaledWidth = targetWidth;
    CGFloat scaledHeight = targetHeight;
    CGPoint thumbnailPoint = CGPointMake(0.0,0.0);

    if (CGSizeEqualToSize(imageSize, targetSize) == NO) {
        CGFloat widthFactor = targetWidth / width;
        CGFloat heightFactor = targetHeight / height;

        if (widthFactor > heightFactor) {
            scaleFactor = widthFactor; // scale to fit height
        }
        else {
            scaleFactor = heightFactor; // scale to fit width
        }

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

        // center the image
        if (widthFactor > heightFactor) {
            thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5; 
        }
        else if (widthFactor < heightFactor) {
            thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
        }
    }     

    CGImageRef imageRef = [sourceImage CGImage];
    CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef);
    CGColorSpaceRef colorSpaceInfo = CGImageGetColorSpace(imageRef);

    if (bitmapInfo == kCGImageAlphaNone) {
        bitmapInfo = kCGImageAlphaNoneSkipLast;
    }

    CGContextRef bitmap;

    if (sourceImage.imageOrientation == UIImageOrientationUp || sourceImage.imageOrientation == UIImageOrientationDown) {
        bitmap = CGBitmapContextCreate(NULL, targetWidth, targetHeight, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);

    } else {
        bitmap = CGBitmapContextCreate(NULL, targetHeight, targetWidth, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);

    }   

    // In the right or left cases, we need to switch scaledWidth and scaledHeight,
    // and also the thumbnail point
    if (sourceImage.imageOrientation == UIImageOrientationLeft) {
        thumbnailPoint = CGPointMake(thumbnailPoint.y, thumbnailPoint.x);
        CGFloat oldScaledWidth = scaledWidth;
        scaledWidth = scaledHeight;
        scaledHeight = oldScaledWidth;

        CGContextRotateCTM (bitmap, M_PI_2); // + 90 degrees
        CGContextTranslateCTM (bitmap, 0, -targetHeight);

    } else if (sourceImage.imageOrientation == UIImageOrientationRight) {
        thumbnailPoint = CGPointMake(thumbnailPoint.y, thumbnailPoint.x);
        CGFloat oldScaledWidth = scaledWidth;
        scaledWidth = scaledHeight;
        scaledHeight = oldScaledWidth;

        CGContextRotateCTM (bitmap, -M_PI_2); // - 90 degrees
        CGContextTranslateCTM (bitmap, -targetWidth, 0);

    } else if (sourceImage.imageOrientation == UIImageOrientationUp) {
        // NOTHING
    } else if (sourceImage.imageOrientation == UIImageOrientationDown) {
        CGContextTranslateCTM (bitmap, targetWidth, targetHeight);
        CGContextRotateCTM (bitmap, -M_PI); // - 180 degrees
    }

    CGContextDrawImage(bitmap, CGRectMake(thumbnailPoint.x, thumbnailPoint.y, scaledWidth, scaledHeight), imageRef);
    CGImageRef ref = CGBitmapContextCreateImage(bitmap);
    UIImage* newImage = [UIImage imageWithCGImage:ref];

    CGContextRelease(bitmap);
    CGImageRelease(ref);

    return newImage; 
}

要将其保存到磁盘（例如保存到documents目录中）：

---

您想调整大小并保持纵横比，请尝试此。。。。与上述方法非常相似：

- (UIImage*)imageWithImage:(UIImage*)sourceImage scaledToSizeWithSameAspectRatio:(CGSize)targetSize;
{  
    CGSize imageSize = sourceImage.size;
    CGFloat width = imageSize.width;
    CGFloat height = imageSize.height;
    CGFloat targetWidth = targetSize.width;
    CGFloat targetHeight = targetSize.height;
    CGFloat scaleFactor = 0.0;
    CGFloat scaledWidth = targetWidth;
    CGFloat scaledHeight = targetHeight;
    CGPoint thumbnailPoint = CGPointMake(0.0,0.0);

    if (CGSizeEqualToSize(imageSize, targetSize) == NO) {
        CGFloat widthFactor = targetWidth / width;
        CGFloat heightFactor = targetHeight / height;

        if (widthFactor > heightFactor) {
            scaleFactor = widthFactor; // scale to fit height
        }
        else {
            scaleFactor = heightFactor; // scale to fit width
        }

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

        // center the image
        if (widthFactor > heightFactor) {
            thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5; 
        }
        else if (widthFactor < heightFactor) {
            thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
        }
    }     

    CGImageRef imageRef = [sourceImage CGImage];
    CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef);
    CGColorSpaceRef colorSpaceInfo = CGImageGetColorSpace(imageRef);

    if (bitmapInfo == kCGImageAlphaNone) {
        bitmapInfo = kCGImageAlphaNoneSkipLast;
    }

    CGContextRef bitmap;

    if (sourceImage.imageOrientation == UIImageOrientationUp || sourceImage.imageOrientation == UIImageOrientationDown) {
        bitmap = CGBitmapContextCreate(NULL, targetWidth, targetHeight, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);

    } else {
        bitmap = CGBitmapContextCreate(NULL, targetHeight, targetWidth, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);

    }   

    // In the right or left cases, we need to switch scaledWidth and scaledHeight,
    // and also the thumbnail point
    if (sourceImage.imageOrientation == UIImageOrientationLeft) {
        thumbnailPoint = CGPointMake(thumbnailPoint.y, thumbnailPoint.x);
        CGFloat oldScaledWidth = scaledWidth;
        scaledWidth = scaledHeight;
        scaledHeight = oldScaledWidth;

        CGContextRotateCTM (bitmap, M_PI_2); // + 90 degrees
        CGContextTranslateCTM (bitmap, 0, -targetHeight);

    } else if (sourceImage.imageOrientation == UIImageOrientationRight) {
        thumbnailPoint = CGPointMake(thumbnailPoint.y, thumbnailPoint.x);
        CGFloat oldScaledWidth = scaledWidth;
        scaledWidth = scaledHeight;
        scaledHeight = oldScaledWidth;

        CGContextRotateCTM (bitmap, -M_PI_2); // - 90 degrees
        CGContextTranslateCTM (bitmap, -targetWidth, 0);

    } else if (sourceImage.imageOrientation == UIImageOrientationUp) {
        // NOTHING
    } else if (sourceImage.imageOrientation == UIImageOrientationDown) {
        CGContextTranslateCTM (bitmap, targetWidth, targetHeight);
        CGContextRotateCTM (bitmap, -M_PI); // - 180 degrees
    }

    CGContextDrawImage(bitmap, CGRectMake(thumbnailPoint.x, thumbnailPoint.y, scaledWidth, scaledHeight), imageRef);
    CGImageRef ref = CGBitmapContextCreateImage(bitmap);
    UIImage* newImage = [UIImage imageWithCGImage:ref];

    CGContextRelease(bitmap);
    CGImageRelease(ref);

    return newImage; 
}

要将其保存到磁盘（例如保存到documents目录中）：

这很简单

- (void)viewDidLoad{
    self.testImageView = [[UIImageView alloc]initWithImage:[UIImage imageNamed:@"youImage.png"]];
    self.testImageView.frame = CGRectMake(100, 100, 320, 480);
    [self.view addSubview:self.testImageView];
}

-(void)resizeImageToSize:(CGSize)targetSize
{
    self.testImageView.fram = targetSize;
}

这很简单

- (void)viewDidLoad{
    self.testImageView = [[UIImageView alloc]initWithImage:[UIImage imageNamed:@"youImage.png"]];
    self.testImageView.frame = CGRectMake(100, 100, 320, 480);
    [self.view addSubview:self.testImageView];
}

-(void)resizeImageToSize:(CGSize)targetSize
{
    self.testImageView.fram = targetSize;
}

这对你来说够了吗

---

这对您来说够了吗？

当我返回图像并保存它时。这不是储蓄。和日志显示宽度0高度0。当我返回图像并保存它时，请查看新图像。这不是储蓄。和日志显示宽度0高度0。对于该新图像，我希望调整图像大小，而不是图像视图。所以图像没有边框属性。我想调整图像大小，而不是图像视图。所以图像没有帧属性。

if(image)
    {
        UIGraphicsBeginImageContext(CGSizeMake(newWidth, newHeight));
        [image drawInRect:CGRectMake(0, 0, newWidth, newHeight)];
         imageAfterResize = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
        ;
    }