xcode UIWebView 到 UIImage

UIWebView to UIImage

提问by Vad

I tried to capture image from UIWebView using this method but the image contains only visible area of the screen. How do I capture full content of UIWebView including invisible areas, i.e. the entire web page into one single image?

我尝试使用此方法从 UIWebView 捕获图像，但图像仅包含屏幕的可见区域。如何捕获 UIWebView 的全部内容，包括不可见区域，即将整个网页合并为一个图像？

-(UIImage*)captureScreen:(UIView*) viewToCapture{
  UIGraphicsBeginImageContext(viewToCapture.bounds.size);
  [viewToCapture.layer renderInContext:UIGraphicsGetCurrentContext()];
  UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();
  return viewImage;
}

采纳答案by dasblinkenlight

EDIT(from a comment by Vad)

编辑（来自Vad的评论）

Solution was to call

解决方案是调用

webView.scalesPageToFit = YES;

in the initialization, and

在初始化中，和

[webView sizeToFit]

when the page did finish loading.

当页面完成加载时。

You are currently capturing only the visible part because you are limiting the image context to what's visible. You should limit it to what's available.

您当前仅捕获可见部分，因为您将图像上下文限制为可见部分。您应该将其限制在可用的范围内。

UIViewhas a scrollViewproperty that has contentSize, telling you what is the size of the web view inside the scroll view. You can use that size to set your image context like this:

UIView有一个scrollView属性 has contentSize，告诉你滚动视图中 web 视图的大小是多少。您可以使用该大小来设置图像上下文，如下所示：

-(UIImage*)captureScreen:(UIView*) viewToCapture{
    CGSize overallSize = overallSize;
    UIGraphicsBeginImageContext(viewToCapture.scrollView.contentSize);
    // Save the current bounds
    CGRect tmp = viewToCapture.bounds;
    viewToCapture.bounds = CGRectMake(0, 0, overallSize.width, overallSize.height);
    // Wait for the view to finish loading.
    // This is not very nice, but it should work. A better approach would be
    // to use a delegate, and run the capturing on the did finish load event.
    while (viewToCapture.loading) {
         [NSThread sleepForTimeInterval:0.1];
    }
    [viewToCapture.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    // Restore the bounds
    viewToCapture.bounds = tmp;
    return viewImage;
}

回答by MQoder

Check this out Rendering a UIWebView into an ImageContext

查看将 UIWebView 渲染到 ImageContext 中

or just use this :) :

或者只是使用这个:)：

    (UIImage*) imageFromWebview:(UIWebView*) webview{

//store the original framesize to put it back after the snapshot
CGRect originalFrame = webview.frame;

//get the width and height of webpage using js (you might need to use another call, this doesn't work always)
int webViewHeight = [[webview stringByEvaluatingJavaScriptFromString:@"document.body.scrollHeight;"] integerValue];
int webViewWidth = [[webview stringByEvaluatingJavaScriptFromString:@"document.body.scrollWidth;"] integerValue];

//set the webview's frames to match the size of the page
[webview setFrame:CGRectMake(0, 0, webViewWidth, webViewHeight)];

//make the snapshot
UIGraphicsBeginImageContextWithOptions(webview.frame.size, false, 0.0);
[webview.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

//set the webview's frame to the original size
[webview setFrame:originalFrame];

//and VOILA :)
return image;
}

回答by Paresh Navadiya

EDIT: New answer from me with tested code.

编辑：我用经过测试的代码提供的新答案。

Add below methodto captureUIWebViewinto UIImage. It will also capture unvisible areaas well.

下面添加method到captureUIWebView成UIImage。它也将捕获unvisible area。

- (UIImage*)webviewToImage:(UIWebView*)webView
{
  int currentWebViewHeight = webView.scrollView.contentSize.height;
  int scrollByY = webView.frame.size.height;

  [webView.scrollView setContentOffset:CGPointMake(0, 0)];

  NSMutableArray* images = [[NSMutableArray alloc] init];

  CGRect screenRect = webView.frame;

  int pages = currentWebViewHeight/scrollByY;
  if (currentWebViewHeight%scrollByY > 0) {
      pages ++;
  } 

  for (int i = 0; i< pages; i++)
  {
    if (i == pages-1) {
        if (pages>1)
            screenRect.size.height = currentWebViewHeight - scrollByY;
    }

    if (IS_RETINA)
        UIGraphicsBeginImageContextWithOptions(screenRect.size, NO, 0);
    else
        UIGraphicsBeginImageContext( screenRect.size );
    if ([webView.layer respondsToSelector:@selector(setContentsScale:)]) {
        webView.layer.contentsScale = [[UIScreen mainScreen] scale];
    }
    //UIGraphicsBeginImageContext(screenRect.size);
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    [[UIColor blackColor] set];
    CGContextFillRect(ctx, screenRect);

    [webView.layer renderInContext:ctx];

    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    if (i == 0)
    {
        scrollByY = webView.frame.size.height;
    }
    else
    {
        scrollByY += webView.frame.size.height;
    }
    [webView.scrollView setContentOffset:CGPointMake(0, scrollByY)];
    [images addObject:newImage];
  }

  [webView.scrollView setContentOffset:CGPointMake(0, 0)];

  UIImage *resultImage;

  if(images.count > 1) {
    //join all images together..
    CGSize size;
    for(int i=0;i<images.count;i++) {

        size.width = MAX(size.width, ((UIImage*)[images objectAtIndex:i]).size.width );
        size.height += ((UIImage*)[images objectAtIndex:i]).size.height;
    }

    if (IS_RETINA)
        UIGraphicsBeginImageContextWithOptions(size, NO, 0);
    else
        UIGraphicsBeginImageContext(size);
    if ([webView.layer respondsToSelector:@selector(setContentsScale:)]) {
        webView.layer.contentsScale = [[UIScreen mainScreen] scale];
    }
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    [[UIColor blackColor] set];
    CGContextFillRect(ctx, screenRect);

    int y=0;
    for(int i=0;i<images.count;i++) {

        UIImage* img = [images objectAtIndex:i];
        [img drawAtPoint:CGPointMake(0,y)];
        y += img.size.height;
    }

    resultImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
  } else {

    resultImage = [images objectAtIndex:0];
  }
  [images removeAllObjects];
  return resultImage;
}

Also add these macrofor checking if iOSis retinadisplay

还添加这些macro如果检查iOS是retina显示

#define IS_RETINA ([[UIScreen mainScreen] respondsToSelector:@selector(displayLinkWithTarget:selector:)] && ([UIScreen mainScreen].scale == 2.0))