Question

there’s an example, which loads 2 images:

    canvas = document.getElementById("canvas");
    ctx = canvas.getContext("2d");

    var img1 = new Image();
    img.src = "/path/to/image/img1.png";
    img.onload = function() {
      ctx.drawImage(img, 0, 0);
    };

    var img2 = new Image();
    img2.src = "/path/to/image/img2.png";
    img2.onload = function() {
      ctx.drawImage(img2, 100, 100);
    };

I need to remove(replace) img2 from canvas. What is the best way to do it?

Answer 1

It’s not clear what you want the canvas to show when the image is gone. If you want it to be transparent, you could get the image data and fill it with transparent pixels:

var img = ctx.createImageData(w, h);
for (var i = img.data.length; --i >= 0; )
  img.data[i] = 0;
ctx.putImageData(img, 100, 100);

where “w” and “h” would be the width and height of your original image.

edit — if you just want another image there, why not just put one there? It will overwrite whatever pixels are there on the canvas.