CODEWITHSUNDEEP
javascriptiphoneobjective-cipaduiwebview
adit
adit

Reputation: 33644

how to find the center/x,y coordinate of an image in UIWebView

So I have a UIWebView which I have added a touch gesture in it, and I would like to find the x,y origin coordinates of an image tapped in the web view or if possible the center of the image in x y coordinates in the web view. The code I have is:

- (CGPoint) topLeftPointsForImage:(UIGestureRecognizer *)sender
{
    CGPoint pt = [sender locationInView:self];
    NSString * offsetTop = [NSString stringWithFormat:@"document.elementFromPoint(%f, %f).offsetTop", pt.x, pt.y
                          ];

    NSString * offsetLeft = [NSString stringWithFormat:@"document.elementFromPoint(%f, %f).offsetLeft", pt.x, pt.y
                      ];

    NSString * scrollTop = [NSString stringWithFormat:@"document.elementFromPoint(%f, %f).parentNode.scrollTop", pt.x, pt.y
                              ];

    NSString * scrollLeft = [NSString stringWithFormat:@"document.elementFromPoint(%f, %f).parentNode.scrollLeft", pt.x, pt.y
                             ];


    float x = [[self stringByEvaluatingJavaScriptFromString:offsetTop] floatValue] - [[self stringByEvaluatingJavaScriptFromString:scrollTop] floatValue];
    float y = [[self stringByEvaluatingJavaScriptFromString:offsetLeft] floatValue] - [[self stringByEvaluatingJavaScriptFromString:scrollLeft] floatValue];
    NSLog(@"Coor height is %f with coor width is %f", x, y);

    CGPoint point = CGPointMake(x, y);
    return point;
}

However, this doesn't seem to give me a correct value. I am not a javascript master, so looking for some advice for this.

Upvotes: 0

Views: 1289

Answers (1)

Programer Joe
Programer Joe

Reputation: 11

If you use jQuery in your html page, then you may try to use : 

NSString * offsetTop = [NSString stringWithFormat:@"$(document).elementFromPoint(%f, %f).offsetTop;", pt.x, pt.y
                      ];

also note the semi-colon at the end of the statement. All Javascript statements must be valid and properly terminated, just like inside a html page.

If you are injecting a library, you have to properly put into a function class with namespaces, as follows:

"(function () {return "your data";}) ();"

Upvotes: 1

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