是否可以查询HTML画布对象以获取特定位置的颜色?
发布于 2009-03-20 17:06:53
W3C文档中有一节是关于pixel manipulation的。
这是an example on how to invert an image
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);
发布于 2009-03-20 17:11:21
尝试getImageData
方法:
var data = context.getImageData(x, y, 1, 1).data;
var rgb = [ data[0], data[1], data[2] ];
发布于 2015-04-17 21:44:40
function GetPixel(context, x, y)
{
var p = context.getImageData(x, y, 1, 1).data;
var hex = "#" + ("000000" + rgbToHex(p[0], p[1], p[2])).slice(-6);
return hex;
}
function rgbToHex(r, g, b) {
if (r > 255 || g > 255 || b > 255)
throw "Invalid color component";
return ((r << 16) | (g << 8) | b).toString(16);
}
https://stackoverflow.com/questions/667045
复制相似问题