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Fix to prevent low-res image download when exporting #130

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Fix to prevent low-res image download when exporting #130

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41 changes: 30 additions & 11 deletions src/hooks/useDiagram.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -396,30 +396,49 @@ export function useDiagram(username: string, repo: string) {
const svgElement = document.querySelector(".mermaid svg");
if (!(svgElement instanceof SVGSVGElement)) return;

const svgElementCopy = svgElement.cloneNode(true) as SVGSVGElement; //Copy the SVG to avoid modifying the original

const removeZoomControls = svgElementCopy.querySelector(
"#svg-pan-zoom-controls",
);
removeZoomControls?.remove();

const svgZoomViewportGroup = svgElementCopy.querySelector(
".svg-pan-zoom_viewport",
);

if (svgZoomViewportGroup) {
svgZoomViewportGroup.removeAttribute("transform");
svgZoomViewportGroup.removeAttribute("style");
}

try {
const canvas = document.createElement("canvas");
const scale = 4;

const bbox = svgElement.getBBox();
const transform = svgElement.getScreenCTM();
if (!transform) return;
const rootElement = svgElement.querySelector("g.root");

if (!rootElement) {
console.error("Could not find root element");
return;
}

const originalBbox = (rootElement as SVGGElement).getBBox();
const width = originalBbox.width;
const height = originalBbox.height;

const width = Math.ceil(bbox.width * transform.a);
const height = Math.ceil(bbox.height * transform.d);
canvas.width = width * scale;
canvas.height = height * scale;
canvas.width = width;
canvas.height = height;

const ctx = canvas.getContext("2d");
if (!ctx) return;

const svgData = new XMLSerializer().serializeToString(svgElement);
const svgData = new XMLSerializer().serializeToString(svgElementCopy);
const img = new Image();

img.onload = () => {
ctx.fillStyle = "white";
ctx.fillRect(0, 0, canvas.width, canvas.height);

ctx.scale(scale, scale);
ctx.drawImage(img, 0, 0, width, height);

const a = document.createElement("a");
Expand All @@ -432,7 +451,7 @@ export function useDiagram(username: string, repo: string) {

img.src =
"data:image/svg+xml;base64," +
btoa(unescape(encodeURIComponent(svgData)));
btoa(decodeURIComponent(encodeURIComponent(svgData))); //removed deprecated unescape()
} catch (error) {
console.error("Error generating PNG:", error);
}
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