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/*
GoToSocial
Copyright (C) GoToSocial Authors admin@gotosocial.org
SPDX-License-Identifier: AGPL-3.0-or-later
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import React, { useEffect, useRef } from "react";
import { MediaAttachment } from "../lib/types/status";
import { decode } from "blurhash";
export default function BlurhashCanvas({ media }: { media: MediaAttachment }) {
const hash = media.blurhash;
const thumbHeight = media.meta.small.height;
const thumbWidth = media.meta.small.width;
const thumbAspect = media.meta.small.aspect;
/*
It's very expensive to draw big canvases
with blurhashes, so use tiny ones, keeping
aspect ratio of the original thumbnail.
*/
var useWidth = 32;
var useHeight = 32;
switch (true) {
case thumbWidth > thumbHeight:
useHeight = Math.round(useWidth / thumbAspect);
break;
case thumbHeight > thumbWidth:
useWidth = Math.round(useHeight * thumbAspect);
break;
}
const pixels = decode(
hash,
useWidth,
useHeight,
);
const canvasRef = useRef<HTMLCanvasElement>(null);
useEffect(() => {
const ctx = canvasRef.current?.getContext("2d");
if (!ctx) {
return;
}
const imageData = ctx.createImageData(
useWidth,
useHeight,
);
imageData.data.set(pixels);
ctx.putImageData(imageData, 0, 0);
}, [pixels, useHeight, useWidth]);
return (
<canvas
width={useWidth}
height={useHeight}
ref={canvasRef}
></canvas>
);
}
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