0

画像のサイズを変更しようとしていますが、正しく機能していません。幅320、高さ480の画像があります。幅1024、高さ1024にサイズ変更したいです。このコードを使用して画像のサイズを変更しています

- (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 ;
}

必要な画像サイズが得られません。

これは、画像のサイズを 320x480 から 1280x1024 に変更したときに得られるものです。画像サイズは増加していますが、画像は増加していません。私はその車を白い背景の上に引き延ばしたいここに画像の説明を入力.

4

3 に答える 3

2

サイズを変更してアスペクト比を維持したい場合は、これを試してください....上記の方法と非常に似ています：

- (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; 
}

それらを使用したい場合は、次のようにします。

UIImage* myThumbnail = ...; // Get some image
NSData* imageData = UIImagePNGRepresentation(myThumbnail);

それをディスクに保存するには（たとえば、ドキュメントディレクトリに）：

// Give a name to the file
NSString* imageName = @"MyImage.png";

// Now, we have to find the documents directory so we can save it
// Note that you might want to save it elsewhere, like the cache directory,
// or something similar.
NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString* documentsDirectory = [paths objectAtIndex:0];

// Now we get the full path to the file
NSString* fullPathToFile = [documentsDirectory stringByAppendingPathComponent:imageName];

// and then we write it out
[imageData writeToFile:fullPathToFile atomically:NO];
于 2013-03-27T08:13:04.677 に答える
1 
if(image)
    {
        UIGraphicsBeginImageContext(CGSizeMake(newWidth, newHeight));
        [image drawInRect:CGRectMake(0, 0, newWidth, newHeight)];
         imageAfterResize = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
        ;
    }

これで十分ですか？

于 2013-03-27T08:31:28.793 に答える
0

とてもシンプルです

- (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;
}
于 2013-03-27T08:21:40.033 に答える