[webkit-dev] the absolute coordinates in the webkit
simon.fraser at apple.com
Thu Jan 8 08:37:02 PST 2009
On Jan 8, 2009, at 2:17 AM, Ariya Hidayat wrote:
>> Now I want to obtain the absolute coordinates of <img> in the
>> Through code how to achieve
> Hint: have a look at RenderImage::paintReplaced() function. If you
> get the
> render object for that <img>, which is a RenderImage instance, then
> you are
HTMLImageElement already has x() and y() methods that return the
absolute coordinates of the image. However, these methods don't take
CSS transforms into account.
Node::getRect() will also give you back an absolute rect for a node,
but again it's broken with transforms.
If you're in renderer code, the correct solution is to call
localToAbsolute() on the image's renderer, passing 'true' for the
In general, you should be wary of using absolute coordinates unless
you absolutely have to. I've been fixing many bugs caused by the use
of absolute coordinates for event handling and repainting that show up
when CSS transforms are being used. The general rule should be that
your coordinate math should be as "local" as possible.
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