是否可以查询HTML Canvas对象以获取特定位置的颜色?
W3C文档中有关于像素操纵的部分。
这是有关如何反转图像的示例:
var context = document.getElementById('myCanvas').getContext('2d'); // Get the CanvasPixelArray from the given coordinates and dimensions. var imgd = context.getImageData(x, y, width, height); var pix = imgd.data; // Loop over each pixel and invert the color. for (var i = 0, n = pix.length; i < n; i += 4) { pix[i ] = 255 - pix[i ]; // red pix[i+1] = 255 - pix[i+1]; // green pix[i+2] = 255 - pix[i+2]; // blue // i+3 is alpha (the fourth element) } // Draw the ImageData at the given (x,y) coordinates. context.putImageData(imgd, x, y);