var canvas = document.getElementById('main');
var ctx = document.getElementById('main').getContext('2d');
var tile = new Image();
tile.src = document.getElementById('image').src;
tile.onload = function() {
draw(tile);
}
function draw(img) {
var buffer = document.createElement('canvas');
var bufferctx = buffer.getContext('2d');
bufferctx.drawImage(img, 0, 0);
var imageData = bufferctx.getImageData(0,0,buffer.width, buffer.height);
var data = imageData.data;
var removeBlack = function() {
for (var i = 0; i < data.length; i += 4) {
if(data[i]+ data[i + 1] + data[i + 2] < 10){
data[i + 3] = 0; // alpha
}
}
ctx.putImageData(imageData, 0, 0);
};
removeBlack();
}
如果您确定只使用 #000 黑色,那么您可以轻松地将这行代码 if(data[i]+ data[i + 1] + data[i + 2] < 10){
更改为 if(data[i]+ data[i+1] + data[i+2]==0){
。
getImageData
获取并将所有黑色像素变为透明是一个不错的开始。 :-) 可能在钻石形状内部有所需的黑色像素,因此您可以改进解决方案,仅影响钻石外部的黑色像素。例如:从左上角开始,行==0,列==0。向右移动并清除所有黑色像素,直到达到非黑色像素。从行==1,列==0重新开始。向右移动并清除所有黑色像素,直到达到非黑色像素...以此类推。从所有4个角开始重复此过程。 - markEglobalCompositeOperation
更改为 screen
,就可以得到该结果。以下是一个示例:
var canvas = document.getElementById("canvas");
var context = canvas.getContext("2d");
var image = new Image();
image.src = "https://images.blogthings.com/thecolorfulpatterntest/pattern-4.png";
image.onload = function() {
context.drawImage(image, 0, 0, canvas.width, canvas.height);
var blackImage = new Image();
blackImage.src="http://www.printmag.com/wp-content/uploads/Sillitoe-black-white.gif";
blackImage.onload = function(){
context.globalCompositeOperation = "screen";
context.drawImage(blackImage, 0, 0, canvas.width, canvas.height);
}
};
<canvas id="canvas" width="300" height="250"></canvas>
<hr/>
<h1>Images used:</h1>
<img src="https://images.blogthings.com/thecolorfulpatterntest/pattern-4.png"/>
<img src="http://www.printmag.com/wp-content/uploads/Sillitoe-black-white.gif"/>
将图片保存为 .svg 文件怎么样?从那里你可以更改所有的颜色和其他设置。
例如:
this.ctx1.putImageData(output, 0, 0); // without setting the context's globalCompositeOperation, this image is written over by the next putImage operation
this.ctx1.putImageData(output, 20, 0);
请点击此处查看混合选项。https://developer.mozilla.org/zh-CN/docs/Web/API/CanvasRenderingContext2D/globalCompositeOperation
convert withblack/x.png -transparent black transparent/x.png
- Amadanmogrify -transparent black *.png
,就大功告成了! - Sosa