http://eli.thegreenplace.net/2010/02/13/finding-out-the-mouse-click-position-on-a-canvas-with-javascript/ Eli Bendersky's personal website Wed, 01 Sep 2010 06:13:51 +0000 http://wordpress.org/?v=2.9.2 hourly 1 http://eli.thegreenplace.net/2010/02/13/finding-out-the-mouse-click-position-on-a-canvas-with-javascript/comment-page-1/#comment-274626 SaturnPolly Sun, 07 Mar 2010 22:36:03 +0000 http://eli.thegreenplace.net/?p=2082#comment-274626 A short note on offsetLeft/offsetTop: Unless the canvas itself is moved (which should rarely be the case) the offsets of the canvas should be cached, because reading the offsets of an element causes the browser to do a reflow (http://www.phpied.com/rendering-repaint-reflowrelayout-restyle/). It's not a big problem in combination with click-events, but sooner or later somebody will come along, c&p this and then use it in combination with 'mousemove'. ;) A short note on offsetLeft/offsetTop: Unless the canvas itself is moved (which should rarely be the case) the offsets of the canvas should be cached, because reading the offsets of an element causes the browser to do a reflow (http://www.phpied.com/rendering-repaint-reflowrelayout-restyle/). It’s not a big problem in combination with click-events, but sooner or later somebody will come along, c&p this and then use it in combination with ‘mousemove’.

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