ios - 无法将图像加载到 ScrollView 中以进行缩放和滚动
<p><p>我正在尝试将图像加载到 ScrollView 中并将手势识别器添加到图像中，以便可以放大和滚动。但不知何故，我无法让这个工作。我已经使用 xib 文件构建了应用程序。起初我将 ScrollView 放在 xib 文件中的 View 顶部，但因为它没有成功(给我一个空白的黑屏)然后我尝试以编程方式将 ScrollView 放在 .m 文件上。但现在它给了我一个空白的白色屏幕。我正在使用 SDWebImage 下载图像。这是我的代码:</p>
<pre><code> #import "ZoomAndPanViewController.h"
#import "UIImageView+WebCache.h"
@interface ZoomAndPanViewController ()
@property (nonatomic, strong) UIImageView *imageView;
@property (nonatomic, strong) UIImage *image;
- (void)centerScrollViewContents;
- (void)scrollViewDoubleTapped:(UITapGestureRecognizer*)recognizer;
- (void)scrollViewTwoFingerTapped:(UITapGestureRecognizer*)recognizer;
@end
@implementation ZoomAndPanViewController
@synthesize scrollView = _scrollView;
@synthesize imageView = _imageView;
- (void)centerScrollViewContents {
CGSize boundsSize = self.scrollView.bounds.size;
CGRect contentsFrame = self.imageView.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.imageView.frame = contentsFrame;
}
- (void)scrollViewDoubleTapped:(UITapGestureRecognizer*)recognizer {
// Get the location within the image view where we tapped
CGPoint pointInView = ;
// Get a zoom scale that's zoomed in slightly, capped at the maximum zoom scale specified by the scroll view
CGFloat newZoomScale = self.scrollView.zoomScale * 1.5f;
newZoomScale = MIN(newZoomScale, self.scrollView.maximumZoomScale);
// Figure out the rect we want to zoom to, then zoom to it
CGSize scrollViewSize = self.scrollView.bounds.size;
CGFloat w = scrollViewSize.width / newZoomScale;
CGFloat h = scrollViewSize.height / newZoomScale;
CGFloat x = pointInView.x - (w / 2.0f);
CGFloat y = pointInView.y - (h / 2.0f);
CGRect rectToZoomTo = CGRectMake(x, y, w, h);
;
}
- (void)scrollViewTwoFingerTapped:(UITapGestureRecognizer*)recognizer {
// Zoom out slightly, capping at the minimum zoom scale specified by the scroll view
CGFloat newZoomScale = self.scrollView.zoomScale / 1.5f;
newZoomScale = MAX(newZoomScale, self.scrollView.minimumZoomScale);
;
}
- (void)viewDidLoad
{
;
// Do any additional setup after loading the view, typically from a nib.
CGRect scrollFrame = [applicationFrame];
self.scrollView = [initWithFrame:scrollFrame];
self.scrollView.delegate = self;
// Set a nice title
self.title = @"Image";
self.imageView = [ init];
self.image = [init];
__block UIActivityIndicatorView *activityIndicator;
placeholderImage:nil options:SDWebImageProgressiveDownload progress:^(NSUInteger receivedSize, long long expectedSize)
{
if (!activityIndicator)
{
NSLog(@"setting up the indicator");
];
activityIndicator.center = self.imageView.center;
;
NSLog(@"indicator start animating");
}
}
completed:^(UIImage *uiimage, NSError *error, SDImageCacheType cacheType)
{
NSLog(@"download image completed");
;
activityIndicator = nil;
self.image = uiimage;
;
NSLog(@"image vs uiimage : %f x %f vs %f vs %f", self.image.size.width, self.image.size.height, uiimage.size.width, uiimage.size.height);
}];
// Set up the image we want to scroll & zoom and add it to the scroll view
self.imageView.frame = (CGRect){.origin=CGPointMake(0.0f, 0.0f), .size=self.image.size};
;
// Tell the scroll view the size of the contents
self.scrollView.contentSize = self.image.size;
NSLog(@"scrollview contentsize %f x %f",self.image.size.width,self.scrollView.contentSize.height);
UITapGestureRecognizer *doubleTapRecognizer = [ initWithTarget:self action:@selector(scrollViewDoubleTapped:)];
doubleTapRecognizer.numberOfTapsRequired = 2;
doubleTapRecognizer.numberOfTouchesRequired = 1;
;
UITapGestureRecognizer *twoFingerTapRecognizer = [ initWithTarget:self action:@selector(scrollViewTwoFingerTapped:)];
twoFingerTapRecognizer.numberOfTapsRequired = 1;
twoFingerTapRecognizer.numberOfTouchesRequired = 2;
;
//;
;
SDWebImageManager.sharedManager.imageDownloader.queueMode = SDWebImageDownloaderLIFOQueueMode;
}
- (void)viewDidUnload
{
;
// Release any retained subviews of the main view.
}
- (void)viewWillAppear:(BOOL)animated {
;
// Set up the minimum & maximum zoom scales
CGRect scrollViewFrame = self.scrollView.frame;
CGFloat scaleWidth = scrollViewFrame.size.width / self.scrollView.contentSize.width;
CGFloat scaleHeight = scrollViewFrame.size.height / self.scrollView.contentSize.height;
CGFloat minScale = MIN(scaleWidth, scaleHeight);
self.scrollView.minimumZoomScale = minScale;
self.scrollView.maximumZoomScale = 1.0f;
self.scrollView.zoomScale = minScale;
;
}
- (void)didReceiveMemoryWarning
{
;
// Dispose of any resources that can be recreated.
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
}
- (UIView*)viewForZoomingInScrollView:(UIScrollView *)scrollView {
// Return the view that we want to zoom
return self.imageView;
}
- (void)scrollViewDidZoom:(UIScrollView *)scrollView {
// The scroll view has zoomed, so we need to re-center the contents
;
}
@end
</code></pre>
<p>任何关于我在代码中做错的线索以及任何帮助都将不胜感激。</p>
<p>谢谢!</p></p>
<br><hr><h1><strong>Best Answer-推荐答案</ strong></h1><br>
<p><p>只需创建 2 个名为 CustomScroll.h 和 .m 的类</p>
<p>在 CustomScroll.h 中写入</p>
<pre><code>@interface CustomScroll : UIScrollView
{
}
@property (nonatomic,strong) IBOutlet UIView *imageContainer;
</code></pre>
<p>在 .m 中编写以下代码:</p>
<pre><code>@synthesize imageContainer;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
//self = ;
if (self) {
// Custom initialization
}
return self;
}
// Override layoutSubviews to center content
- (void)layoutSubviews
{
;
// center the image as it becomes smaller than the size of the screen
CGSize boundsSize = self.bounds.size;
CGRect frameToCenter = imageContainer.frame;
// center horizontally
if (frameToCenter.size.width < boundsSize.width)
frameToCenter.origin.x = (boundsSize.width - frameToCenter.size.width) / 2;
else
frameToCenter.origin.x = 0;
// center vertically
if (frameToCenter.size.height < boundsSize.height)
frameToCenter.origin.y = (boundsSize.height - frameToCenter.size.height) / 2;
else
frameToCenter.origin.y = 0;
imageContainer.frame = frameToCenter;
NSLog(@"imageContainer.frame.height=== %f",imageContainer.frame.size.height);
}
-(BOOL)shouldAutorotateToInterfaceOrientation:UIInterfaceOrientation)interfaceOrientation
{
// Return YES for supported orientations
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
</code></pre>
<p>并且在你想在 .h 文件中滚动图像的类中，导入 CustomScroll.h 并制作像 </p> 的对象
<pre><code>CustomScroll *customScrl;
</code></pre>
<p>并在您的 View 中获取 ScrollView 并将 imageview 放入其中并将 ScrollView 与 customScrl 绑定(bind)(不要忘记绑定(bind)委托(delegate)并在 .h 文件中添加 UIScrollViewDelegate)并在自定义类选项卡中将 CustomScroll 写为类。</p>
<p>现在在 .m 文件中写入要显示图像或在 viewDidLoad 中:</p>
<pre><code>// Zoom image inside Scrol view //
// outputImage is my imageview inside Scrollview
self.customScrl.contentSize= CGSizeMake(outputImage.frame.size.width, outputImage.frame.size.height);
self.customScrl.maximumZoomScale=5.0;
self.customScrl.minimumZoomScale=1.0;
self.customScrl.clipsToBounds=YES;
self.customScrl.delegate=self;
;
self.customScrl.imageContainer=outputImage;
;
#pragma ImageZooming Function
-(UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
UIImageView *zoomImg = outputImage;
//NSLog(@"zoom img=== %@",zoomImg);
return zoomImg;
}
</code></pre>
<p>照着写的去做。它肯定也对你有用。 :)</p></p>
<p style="font-size: 20px;">关于ios - 无法将图像加载到 ScrollView 中以进行缩放和滚动，我们在Stack Overflow上找到一个类似的问题：
<a href="https://stackoverflow.com/questions/15239347/" rel="noreferrer noopener nofollow" style="color: red;">
https://stackoverflow.com/questions/15239347/
</a>
</p>
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