Question

我已经从我身边做了很多努力。最后我需要帮助。感谢

目标： 1）我如何在ScrollView中使用imageView

2）如何在scrollView内部裁剪缩放图像。

我在Scroll View中有一个imageView。我希望缩放后的裁剪图像显示在scrollview边界内。我已经剪裁了图像，但它与我想要的完全相同。

这里我将backgroundColor Black设置为我的scrollView。当我在其中放置imageView时，它不合适。 enter image description here

滚动视图内的缩放图像后

enter image description here

和裁剪图像后

enter image description here

我的代码在这里：

- (void)viewDidLoad
{
    [super viewDidLoad];

    CGRect frame1 = CGRectMake(50,50,200,200);

    CGRect frame2 = CGRectMake(50,50,200,200);

    imageView1=[[UIImageView alloc]initWithFrame:frame1];

   imageView1.image= [UIImage imageNamed:@"back.jpeg"];

   imageView1.backgroundColor=[UIColor brownColor];

   imageView1.contentMode = UIViewContentModeScaleAspectFit;



   scroll=[[UIScrollView alloc]initWithFrame:frame2];

   scroll.backgroundColor=[UIColor blackColor];

  [scroll addSubview:imageView1];

  scroll.delegate=self;

 [self.view addSubview:scroll];

 [self setContentSizeForScrollView];

 self.imageView1.userInteractionEnabled = YES;

}

设置滚动视图contentSize

-(void)setContentSizeForScrollView
{
 // scroll.contentSize = CGSizeMake(imageView1.frame.size.width,imageView1.frame.size.height);

    scroll.contentSize = CGSizeMake(200, 200);
   scroll.minimumZoomScale = .50;
  scroll.maximumZoomScale = 1.5;
}

我的裁剪逻辑是

-(IBAction)cropButtonClicked
{
    //Calculate the required area from the scrollview

CGRect rect = CGRectMake(50, 50, 200,200);


UIImage *image = [self imageByCropping:imageView1.image toRect:rect];

imageView1.image=image;


imageView1.contentMode = UIViewContentModeScaleAspectFit;


 }

此方法裁剪图片：

- (UIImage*)imageByCropping:(UIImage *)myImage toRect:(CGRect)cropToArea{
    CGImageRef cropImageRef = CGImageCreateWithImageInRect(myImage.CGImage, cropToArea);
    UIImage* cropped = [UIImage imageWithCGImage:cropImageRef];

    CGImageRelease(cropImageRef);
    return cropped;
}

Answer 1

回答我自己的问题：经过多方努力，我找到了两个问题的答案。

它对我有用。我在这里分享，可能对某人有所帮助。：）

1）在Scroll View中调整图像视图。我用这个link

- (void)centerScrollViewContents {

CGSize boundsSize = scroll.bounds.size;
CGRect contentsFrame = self.imageView1.frame;

if (contentsFrame.size.width < boundsSize.width) {
contentsFrame.origin.x = (boundsSize.width - contentsFrame.size.width) / 2.0f;
} 
else {
contentsFrame.origin.x = 0.0f;
}

if (contentsFrame.size.height < boundsSize.height) {
    contentsFrame.origin.y = (boundsSize.height - contentsFrame.size.height) / 2.0f;
} 
else {
contentsFrame.origin.y = 0.0f;
}

self.imageView1.frame = contentsFrame;
}

2）在scrollView内部裁剪缩放的图像。我用这个link

    UIGraphicsBeginImageContext(CGSizeMake(200, 200));

    [scroll.layer renderInContext:UIGraphicsGetCurrentContext()];

    UIImage *fullScreenshot = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    imageView1.contentMode = UIViewContentModeScaleAspectFill;

    UIImageWriteToSavedPhotosAlbum(fullScreenshot, nil, nil, nil);

    return fullScreenshot;

Answer 2

我最近遇到了类似的问题，我使用相对的想法得到了解决方案（Xa，b = Xa，c - Xb，c）

-(IBAction)crop:(id)sender{

        // F = frame
        // i = image
        // iv = imageview
        // sv = self.view
        // of = offset

        //Frame Image in imageView coordinates
        CGRect Fi_iv = [self frameForImage:self.image inImageViewAspectFit:self.imageView];

        //Frame ImageView in self.view coordinates
        CGRect Fiv_sv = self.imageView.frame;

        //Frame Image in self.view coordinates
        CGRect Fi_sv = CGRectMake(Fi_iv.origin.x + Fiv_sv.origin.x
                                  ,Fi_iv.origin.y + Fiv_sv.origin.y,
                                  Fi_iv.size.width, Fi_iv.size.height);
        //ScrollView offset
        CGPoint offset = self.scrollView.contentOffset;

        //Frame Image in offset coordinates
        CGRect Fi_of = CGRectMake(Fi_sv.origin.x - offset.x,
                                        Fi_sv.origin.y - offset.y,
                                        Fi_sv.size.width,
                                        Fi_sv.size.height);

        CGFloat scale = self.imageView.image.size.width/Fi_of.size.width;

        //the crop frame in image offset coordinates
        CGRect Fcrop_iof = CGRectMake((self.cropView.frame.origin.x - Fi_of.origin.x)*scale,
                                      (self.cropView.frame.origin.y - Fi_of.origin.y)*scale,
                                      self.cropView.frame.size.width*scale,
                                      self.cropView.frame.size.height*scale);

        UIImage *image = [self image:self.imageView.image cropRect:Fcrop_iof];
        // Use this crop image...

您可以使用以下方式裁剪图像：

//Use this code to crop when you have the right frame
-(UIImage*)image:(UIImage *)image cropRect:(CGRect)frame
{
    // Create a new UIImage
    CGImageRef imageRef = CGImageCreateWithImageInRect(image.CGImage, frame);
    UIImage *croppedImage = [UIImage imageWithCGImage:imageRef];
    CGImageRelease(imageRef);

    return croppedImage;
}

由于您在Aspect Fit中使用ImageView，因此需要计算imageView

中的图像帧

-(CGRect)frameForImage:(UIImage*)image inImageViewAspectFit:(UIImageView*)imageView
{
    float imageRatio = image.size.width / image.size.height;

    float viewRatio = imageView.frame.size.width / imageView.frame.size.height;

    if(imageRatio < viewRatio)
    {
        float scale = imageView.frame.size.height / image.size.height;

        float width = scale * image.size.width;

        float topLeftX = (imageView.frame.size.width - width) * 0.5;

        return CGRectMake(topLeftX, 0, width, imageView.frame.size.height);
    }
    else
    {
        float scale = imageView.frame.size.width / image.size.width;

        float height = scale * image.size.height;

        float topLeftY = (imageView.frame.size.height - height) * 0.5;

        return CGRectMake(0, topLeftY, imageView.frame.size.width, height);
    }
}

我希望这段代码对我有用，因为它对我有用。

最佳，

圣拉斐尔。

在scrollView中的ImageView中裁剪缩放图像

2 个答案: