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Improve avatar resampling of non-animated canvas
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@ -1,5 +1,91 @@
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import PureRenderMixin from 'react-addons-pure-render-mixin';
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// From: http://stackoverflow.com/a/18320662
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const resample = (canvas, width, height, resize_canvas) => {
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let width_source = canvas.width;
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let height_source = canvas.height;
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width = Math.round(width);
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height = Math.round(height);
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let ratio_w = width_source / width;
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let ratio_h = height_source / height;
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let ratio_w_half = Math.ceil(ratio_w / 2);
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let ratio_h_half = Math.ceil(ratio_h / 2);
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let ctx = canvas.getContext("2d");
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let img = ctx.getImageData(0, 0, width_source, height_source);
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let img2 = ctx.createImageData(width, height);
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let data = img.data;
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let data2 = img2.data;
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for (let j = 0; j < height; j++) {
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for (let i = 0; i < width; i++) {
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let x2 = (i + j * width) * 4;
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let weight = 0;
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let weights = 0;
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let weights_alpha = 0;
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let gx_r = 0;
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let gx_g = 0;
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let gx_b = 0;
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let gx_a = 0;
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let center_y = (j + 0.5) * ratio_h;
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let yy_start = Math.floor(j * ratio_h);
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let yy_stop = Math.ceil((j + 1) * ratio_h);
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for (let yy = yy_start; yy < yy_stop; yy++) {
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let dy = Math.abs(center_y - (yy + 0.5)) / ratio_h_half;
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let center_x = (i + 0.5) * ratio_w;
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let w0 = dy * dy; //pre-calc part of w
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let xx_start = Math.floor(i * ratio_w);
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let xx_stop = Math.ceil((i + 1) * ratio_w);
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for (let xx = xx_start; xx < xx_stop; xx++) {
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let dx = Math.abs(center_x - (xx + 0.5)) / ratio_w_half;
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let w = Math.sqrt(w0 + dx * dx);
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if (w >= 1) {
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// pixel too far
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continue;
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}
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// hermite filter
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weight = 2 * w * w * w - 3 * w * w + 1;
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let pos_x = 4 * (xx + yy * width_source);
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// alpha
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gx_a += weight * data[pos_x + 3];
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weights_alpha += weight;
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// colors
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if (data[pos_x + 3] < 255)
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weight = weight * data[pos_x + 3] / 250;
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gx_r += weight * data[pos_x];
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gx_g += weight * data[pos_x + 1];
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gx_b += weight * data[pos_x + 2];
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weights += weight;
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}
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}
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data2[x2] = gx_r / weights;
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data2[x2 + 1] = gx_g / weights;
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data2[x2 + 2] = gx_b / weights;
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data2[x2 + 3] = gx_a / weights_alpha;
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}
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}
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// clear and resize canvas
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if (resize_canvas === true) {
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canvas.width = width;
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canvas.height = height;
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} else {
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ctx.clearRect(0, 0, width_source, height_source);
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}
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// draw
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ctx.putImageData(img2, 0, 0);
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};
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const Avatar = React.createClass({
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propTypes: {
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@ -25,7 +111,11 @@ const Avatar = React.createClass({
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},
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handleLoad () {
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this.canvas.getContext('2d').drawImage(this.image, 0, 0, this.props.size * window.devicePixelRatio, this.props.size * window.devicePixelRatio);
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this.canvas.width = this.image.naturalWidth;
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this.canvas.height = this.image.naturalHeight;
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this.canvas.getContext('2d').drawImage(this.image, 0, 0);
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resample(this.canvas, this.props.size * window.devicePixelRatio, this.props.size * window.devicePixelRatio, true);
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},
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setImageRef (c) {
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@ -42,7 +132,7 @@ const Avatar = React.createClass({
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return (
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<div onMouseEnter={this.handleMouseEnter} onMouseLeave={this.handleMouseLeave} style={{ ...this.props.style, width: `${this.props.size}px`, height: `${this.props.size}px`, position: 'relative' }}>
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<img ref={this.setImageRef} onLoad={this.handleLoad} src={this.props.src} width={this.props.size} height={this.props.size} alt='' style={{ position: 'absolute', top: '0', left: '0', visibility: hovering ? 'visible' : 'hidden', borderRadius: '4px' }} />
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<canvas ref={this.setCanvasRef} width={this.props.size * window.devicePixelRatio} height={this.props.size * window.devicePixelRatio} style={{ borderRadius: '4px', width: this.props.size, height: this.props.size }} />
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<canvas ref={this.setCanvasRef} style={{ borderRadius: '4px', width: this.props.size, height: this.props.size, visibility: hovering ? 'hidden' : 'visible' }} />
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</div>
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);
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}
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