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/**
* Reusable SVG data uri prefix for generated SVGs.
*/
const SVG_DATA_URI_PREFIX = 'data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg"';
/**
* Reusable SVG data uri suffix for generated SVGs.
*/
const SVG_DATA_URI_SUFFIX = '><rect fill="brown" x="-2000" y="-2000" width="4000" height="4000"></rect><rect fill="green" height="50" width="50"></rect><rect fill="yellow" x="10" y="10" height="30" width="30"></rect></svg>';
/**
* Generates full data URI for an SVG document, with the given parameters
* on the SVG element.
*
* @param aWidth The width attribute, or null for no width.
* @param aHeight The height attribute, or null for no height.
* @param aViewbox The viewBox attribute, or null for no viewBox.
*/
function generateSVGDataURI(aWidth, aHeight, aViewBox) {
let datauri = SVG_DATA_URI_PREFIX;
if (aWidth) {
datauri += " width=\"" + aWidth + "\""
}
if (aHeight) {
datauri += " height=\"" + aHeight + "\"";
}
if (aViewBox) {
datauri += " viewBox=\"" + aViewBox + "\"";
}
datauri += SVG_DATA_URI_SUFFIX;
return datauri;
}
/**
* Generates a canvas, with the given width and height parameters, and uses
* CanvasRenderingContext2D.drawImage() to draw a SVG image with the given
* width and height attributes.
*
* @param aCanvasWidth The width attribute of the canvas.
* @param aCanvasHeight The height attribute of the canvas.
* @param aSVGWidth The width attribute of the svg, or null for no width.
* @param aSVGHeight The height attribute of the svg, or null for no height.
* @param aSVGViewBox The viewBox attribute sf the svg, or null for no viewBox.
*
* @returns A promise that resolves when the SVG image has been drawn to the
* created canvas
*/
async function generateCanvasDrawImageSVG(aCanvasWidth, aCanvasHeight, aSVGWidth,
aSVGHeight, aSVGViewBox) {
let canvas = document.createElement("canvas");
let ctx = canvas.getContext("2d");
document.body.appendChild(canvas);
canvas.setAttribute("width", aCanvasWidth);
canvas.setAttribute("height", aCanvasHeight);
let img = document.createElement("img");
let promise = new Promise(resolve => {
img.onload = () => {
ctx.drawImage(img, 0, 0);
resolve();
};
});
let uri = generateSVGDataURI(aSVGWidth, aSVGHeight, aSVGViewBox);
img.src = uri;
return promise;
}
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