UIWebView使用elementFromPoint()获取图像网址

Question

我正在尝试使用UILongPressGestureRecognizer获取UIWebView中的图像的url.

我有点工作,但我不确定坐标是否关闭,或者它只是没有在DOM中找到img标签,因为它并不总是有效.

我正在使用此代码:

int displayWidth = [[self.webView stringByEvaluatingJavaScriptFromString:@"window.outerWidth"] intValue];
CGFloat scale = self.webView.frame.size.width / displayWidth;
CGPoint pt = [gesture locationInView:self.webView];
pt.x /= scale;
pt.y /= scale;
NSString *imgURL = [NSString stringWithFormat:@"document.elementFromPoint(%f, %f).parentElement.getElementsByTagName(\"img\")[0].src", pt.x, pt.y];
NSString *urlToSave = [self.webView stringByEvaluatingJavaScriptFromString:imgURL];

如果我使用一个开始缩小的网站并在网格中放置图像,然后我放大然后选择一个图像,我会在页面的左上角给出图像而不是点击的图像.不确定是缩放问题,偏移问题还是DOM问题？

编辑------------

首先,坐标肯定是关闭的!如果我在UIWebView中单击网页上的某个点,我会得到以下结果:ScrollY:0单击pointY:89 Y*= scale + = scrollY = 86.8293

现在,如果我向上滚动页面,那么我点击的点与顶部一致(大约在y = 0)我得到这些结果:ScrollY:144点击pointY:1 Y*= scale + = scrollY = 144.976

现在在计算之前,滚动似乎已关闭.该点为89,但滚动到该点时,滚动条为144.为什么会这样？

我从window.pageYOffset获取滚动

Answer 1

将此2 javascript函数放在名为JSTools.js的文件中

function getHTMLElementsAtPoint(x,y) {
var tags = "";
var e;
var offset = 0;
while ((tags.search(",(A|IMG),") < 0) && (offset < 20)) {
    tags = ",";
    e = document.elementFromPoint(x,y+offset);
    while (e) {
        if (e.tagName) {
            tags += e.tagName + ',';
        }
        e = e.parentNode;
    }
    if (tags.search(",(A|IMG),") < 0) {
        e = document.elementFromPoint(x,y-offset);
        while (e) {
            if (e.tagName) {
                tags += e.tagName + ',';
            }
            e = e.parentNode;
        }
    }

    offset++;
}
return tags;}

function getLinkSRCAtPoint(x,y) {
var tags = "";
var e = "";
var offset = 0;
while ((tags.length == 0) && (offset < 20)) {
    e = document.elementFromPoint(x,y+offset);
    while (e) {
        if (e.src) {
            tags += e.src;
            break;
        }
        e = e.parentNode;
    }
    if (tags.length == 0) {
        e = document.elementFromPoint(x,y-offset);
        while (e) {
            if (e.src) {
                tags += e.src;
                break;
            }
            e = e.parentNode;
        }
    }
    offset++;
}
return tags;}

然后在你的控制器中

- (void)longPressRecognized:(UILongPressGestureRecognizer *)gestureRecognizer {
if (gestureRecognizer.state == UIGestureRecognizerStateBegan) {
    CGPoint point = [gestureRecognizer locationInView:webView];
    longpressTouchedPoint = point;
    // convert point from view to HTML coordinate system
    CGSize viewSize = [webView frame].size;
    CGSize windowSize = [webView windowSize];

    CGFloat f = windowSize.width / viewSize.width;
    if ([[[UIDevice currentDevice] systemVersion] doubleValue] >= 5.) {
        point.x = point.x * f;
        point.y = point.y * f;
    } else {
        // On iOS 4 and previous, document.elementFromPoint is not taking
        // offset into account, we have to handle it
        CGPoint offset = [webView scrollOffset];
        point.x = point.x * f + offset.x;
        point.y = point.y * f + offset.y;
    }

    // Load the JavaScript code from the Resources and inject it into the web page
    NSString *path = [[NSBundle mainBundle] pathForResource:@"JSTools" ofType:@"js"];
    NSString *jsCode = [NSString stringWithContentsOfFile:path encoding:NSUTF8StringEncoding error:nil];
    [webView stringByEvaluatingJavaScriptFromString: jsCode];


    // call js functions
    NSString *tags = [webView stringByEvaluatingJavaScriptFromString:
                      [NSString stringWithFormat:@"getHTMLElementsAtPoint(%i,%i);",(NSInteger)point.x,(NSInteger)point.y]];
    NSString *tagsSRC = [webView stringByEvaluatingJavaScriptFromString:
                         [NSString stringWithFormat:@"getLinkSRCAtPoint(%i,%i);",(NSInteger)point.x,(NSInteger)point.y]];

    NSLog(@"src : %@",tags);
    NSLog(@"src : %@",tagsSRC);

    NSString *url = nil;
    if ([tags rangeOfString:@",IMG,"].location != NSNotFound) {
        url = tagsSRC;    // Here is the image url!
    }

从几个来源混合,信用到网络社区!

编辑

您还必须使用以下两个函数在uiwebview上创建一个类别:

- (CGSize)windowSize {
CGSize size;
size.width = [[self stringByEvaluatingJavaScriptFromString:@"window.innerWidth"] integerValue];
size.height = [[self stringByEvaluatingJavaScriptFromString:@"window.innerHeight"] integerValue];
return size;}

- (CGPoint)scrollOffset {
CGPoint pt;
pt.x = [[self stringByEvaluatingJavaScriptFromString:@"window.pageXOffset"] integerValue];
pt.y = [[self stringByEvaluatingJavaScriptFromString:@"window.pageYOffset"] integerValue];
return pt;}