Improve avatar resampling of non-animated canvas

feature/8296-invite_api
Eugen Rochko 6 years ago
parent 57159804b8
commit 02cd2e42b2
  1. 94
      app/assets/javascripts/components/components/avatar.jsx

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

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