Colour detection on click event.

In my project GWT Java, I need colour detection on click event. When user clicks any where in program window, I need to detect the colour of click point(x,y). How it is possible. Where as keeping in view 开发者_StackOverflow中文版that there may be no one image in the program window. Thanks.

My first thought was to take a screenshot, and then determine the color information of the pixel at that particular location in the captured image. A little Google-ing turned up this gem: html2canvas - Screenshots with JavaScript.

I haven't used it though, so I can't give you any more help than that, unfortunately.