Html5 画布覆盖

Question

有没有一个好的解决方案可以用画布绘制带有叠加颜色的位图？

我要做的是为所有不透明的像素绘制一个具有唯一颜色的位图。 我没有找到任何解决方案，它可能对我有用！

谢谢

Answer 1

Live Demo

一种方法是循环遍历每个像素并将 r/g/b 值更改为您想要的值。通过跳过 alpha 值，它只会将不透明像素更改为您想要的颜色。

var canvas = document.getElementById("canvas"),
    ctx = canvas.getContext("2d"),
    image = document.getElementById("testImage");

ctx.drawImage(image,0,0);

var imgd = ctx.getImageData(0, 0, 128, 128),
    pix = imgd.data,
    uniqueColor = [0,0,255]; // Blue for an example, can change this value to be anything.

// Loops through all of the pixels and modifies the components.
for (var i = 0, n = pix.length; i <n; i += 4) {
      pix[i] = uniqueColor[0];   // Red component
      pix[i+1] = uniqueColor[1]; // Green component
      pix[i+2] = uniqueColor[2]; // Blue component
      //pix[i+3] is the transparency.
}

ctx.putImageData(imgd, 0, 0);

// Just extra if you wanted to display within an img tag.
var savedImageData = document.getElementById("imageData");
savedImageData.src = canvas.toDataURL("image/png");