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5.6.1-像素化.html

<!DOCTYPE html>
<html>

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <link rel="stylesheet" href="style.css">
</head>

<body>
    <canvas id="canvas" width="400" height="400"></canvas>
    <script src="initCanvas.js"></script>
    <script>
        var image = new Image()
        image.src = 'a.jpg'
        image.onload = function () {
            context.drawImage(image, 0, 0, 100, 100, 0, 0, 400, 400)

            var imagedata = context.getImageData(0, 0, canvas.width(), canvas.height())
            var pixels = imagedata.data

            context.clearRect(0, 0, canvas.width(), canvas.height())

            var tilsCols = 10
            var tilsRows = 10

            var tilsWidth = imagedata.width / tilsCols
            var tilsHeight = imagedata.height / tilsRows

            for (var row = 0; row < tilsRows; row++) {
                for (var col = 0; col < tilsCols; col++) {
                    //取每个马赛克的中心位置
                    var x = Math.floor(col * tilsWidth + tilsWidth / 2)
                    var y = Math.floor(row * tilsHeight + tilsHeight / 2)
                    //确定在数组中的位置
                    var pos = y * imagedata.height * 4 + x * 4

                    var r = pixels[pos]
                    var g = pixels[pos + 1]
                    var b = pixels[pos + 2]

                    context.fillStyle = 'rgb(' + r + ',' + g + ',' + b + ')'
                    // context.fillRect(x - tilsWidth / 2, y - tilsHeight / 2, tilsWidth, tilsHeight)
                    context.beginPath()
                    context.arc(x, y, tilsWidth / 2, 0, Math.PI * 2, false)
                    context.closePath()
                    context.fill()


                }
            }

        }
    </script>
</body>

</html>