Question

您好我正在使用UIimage，我需要将图像裁剪为特定尺寸，假设我的特定尺寸宽度等于设备宽度，高度固定为200。我尝试了很多例子，但没有那些不适合我的人，我试过以下样本

reshape

以下是我的实际图片

裁剪后我会变得如下

我所有的例子都在拉伸图像但是我想要伸展需要缩放图像。我在哪里缺少？请帮助我。

Answer 1

您正在使用的代码将调整图像大小，我们将其用于图像压缩或图像大小调整。如果要裁剪图像，有两种方法。 1）允许用户在选择图像时进行编辑。您可以通过将allowEditing属性添加到选择器（

）来实现此目的

2016-12-23 22:23:38.060 Quiz App[9064:278885] -[Quiz_App.ViewController Btn3:]: unrecognized selector sent to instance 0x7ffce6507860
2016-12-23 22:23:38.084 Quiz App[9064:278885] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[Quiz_App.ViewController Btn3:]: unrecognized selector sent to instance 0x7ffce6507860'
*** First throw call stack:
(
    0   CoreFoundation                      0x0000000109600d4b __exceptionPreprocess + 171
    1   libobjc.A.dylib                     0x000000010691321e objc_exception_throw + 48
    2   CoreFoundation                      0x0000000109670f04 -[NSObject(NSObject) doesNotRecognizeSelector:] + 132
    3   CoreFoundation                      0x0000000109586005 ___forwarding___ + 1013
    4   CoreFoundation                      0x0000000109585b88 _CF_forwarding_prep_0 + 120
    5   UIKit                               0x0000000106de48bc -[UIApplication sendAction:to:from:forEvent:] + 83
    6   UIKit                               0x0000000106f6ac38 -[UIControl sendAction:to:forEvent:] + 67
    7   UIKit                               0x0000000106f6af51 -[UIControl _sendActionsForEvents:withEvent:] + 444
    8   UIKit                               0x0000000106f69e4d -[UIControl touchesEnded:withEvent:] + 668
    9   UIKit                               0x0000000106e52545 -[UIWindow _sendTouchesForEvent:] + 2747
    10  UIKit                               0x0000000106e53c33 -[UIWindow sendEvent:] + 4011
    11  UIKit                               0x0000000106e009ab -[UIApplication sendEvent:] + 371
    12  UIKit                               0x00000001075ed72d __dispatchPreprocessedEventFromEventQueue + 3248
    13  UIKit                               0x00000001075e6463 __handleEventQueue + 4879
    14  CoreFoundation                      0x00000001095a5761 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
    15  CoreFoundation                      0x000000010958a98c __CFRunLoopDoSources0 + 556
    16  CoreFoundation                      0x0000000109589e76 __CFRunLoopRun + 918
    17  CoreFoundation                      0x0000000109589884 CFRunLoopRunSpecific + 420
    18  GraphicsServices                    0x000000010b540a6f GSEventRunModal + 161
    19  UIKit                               0x0000000106de2c68 UIApplicationMain + 159
    20  Quiz App                            0x000000010633040f main + 111
    21  libdyld.dylib                       0x000000010a5b068d start + 1
    22  ???                                 0x0000000000000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)

这将为您提供矩形裁剪图像，您可以从选择器视图的 didFinish 方法中检索已编辑的图像

2）通过编程

要以编程方式裁剪图像，您需要传递裁剪框。

这是我正在使用的功能

pickerView.allowEditing = true

以上代码将返回裁剪后的图像。

Answer 2

这些会将您的图像裁剪成您需要的尺寸。

- (CGImageRef)newTransformedImage:(CGAffineTransform)transform
                      sourceImage:(CGImageRef)sourceImage
                       sourceSize:(CGSize)sourceSize
                sourceOrientation:(UIImageOrientation)sourceOrientation
                      outputWidth:(CGFloat)outputWidth
                         cropSize:(CGSize)cropSize
                    imageViewSize:(CGSize)imageViewSize
{
    CGImageRef source = [self newScaledImage:sourceImage
                             withOrientation:sourceOrientation
                                      toSize:sourceSize
                                 withQuality:kCGInterpolationNone];

    CGFloat aspect = cropSize.height/cropSize.width;
    CGSize outputSize = CGSizeMake(outputWidth, outputWidth*aspect);

    CGContextRef context = CGBitmapContextCreate(NULL,
                                                 outputSize.width,
                                                 outputSize.height,
                                                 CGImageGetBitsPerComponent(source),
                                                 0,
                                                 CGImageGetColorSpace(source),
                                                 CGImageGetBitmapInfo(source));
    CGContextSetFillColorWithColor(context, [[UIColor clearColor] CGColor]);
    CGContextFillRect(context, CGRectMake(0, 0, outputSize.width, outputSize.height));

    CGAffineTransform uiCoords = CGAffineTransformMakeScale(outputSize.width / cropSize.width,
                                                            outputSize.height / cropSize.height);
    uiCoords = CGAffineTransformTranslate(uiCoords, cropSize.width/2.0, cropSize.height / 2.0);
    uiCoords = CGAffineTransformScale(uiCoords, 1.0, -1.0);
    CGContextConcatCTM(context, uiCoords);

    CGContextConcatCTM(context, transform);
    CGContextScaleCTM(context, 1.0, -1.0);

    CGContextDrawImage(context, CGRectMake(-imageViewSize.width/2.0,
                                           -imageViewSize.height/2.0,
                                           imageViewSize.width,
                                           imageViewSize.height)
                       , source);

    CGImageRef resultRef = CGBitmapContextCreateImage(context);
    CGContextRelease(context);
    CGImageRelease(source);
    return resultRef;
}

- (CGImageRef)newScaledImage:(CGImageRef)source withOrientation:(UIImageOrientation)orientation toSize:(CGSize)size withQuality:(CGInterpolationQuality)quality
{
    CGSize srcSize = size;
    CGFloat rotation = 0.0;

    switch(orientation)
    {
        case UIImageOrientationUp: {
            rotation = 0;
        } break;
        case UIImageOrientationDown: {
            rotation = M_PI;
        } break;
        case UIImageOrientationLeft:{
            rotation = M_PI_2;
            srcSize = CGSizeMake(size.height, size.width);
        } break;
        case UIImageOrientationRight: {
            rotation = -M_PI_2;
            srcSize = CGSizeMake(size.height, size.width);
        } break;
        default:
            break;
    }

    CGContextRef context = CGBitmapContextCreate(NULL,
                                                 size.width,
                                                 size.height,
                                                 8,  //CGImageGetBitsPerComponent(source),
                                                 0,
                                                 CGImageGetColorSpace(source),
                                                 (CGBitmapInfo)kCGImageAlphaNoneSkipFirst  //CGImageGetBitmapInfo(source)
                                                 );

    CGContextSetInterpolationQuality(context, quality);
    CGContextTranslateCTM(context,  size.width/2,  size.height/2);
    CGContextRotateCTM(context,rotation);

    CGContextDrawImage(context, CGRectMake(-srcSize.width/2 ,
                                           -srcSize.height/2,
                                           srcSize.width,
                                           srcSize.height),
                       source);

    CGImageRef resultRef = CGBitmapContextCreateImage(context);
    CGContextRelease(context);

    return resultRef;
}

///你要裁剪的地方。

CGImageRef imageRef = [self newTransformedImage:transform
                                    sourceImage:self.image.CGImage
                                     sourceSize:self.image.size
                              sourceOrientation:self.image.imageOrientation
                                    outputWidth:self.image.size.width
                                       cropSize:self.photoView.cropView.frame.size
                                  imageViewSize:self.photoView.photoContentView.bounds.size];

UIImage *image = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);

谢谢。享受编码：）

如何将UiImage裁剪为特定尺寸？

2 个答案: