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124 lines
3.0 KiB
JavaScript
124 lines
3.0 KiB
JavaScript
// Great resource from https://stackoverflow.com/a/40700068
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// Thank you ConnorFan
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var strokeWidth = 2;
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var bufferSize = 5;
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var svgElement = document.getElementById("svg-canvas");
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svgElement.setAttribute("viewBox", `0 0 ${window.innerWidth} ${window.innerHeight}`);
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svgElement.setAttribute("width", `${window.innerWidth}px`);
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svgElement.setAttribute("height", `${document.innerHeight}px`);
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var rect = svgElement.getBoundingClientRect();
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var path = document.createElementNS("http://www.w3.org/2000/svg", "path");
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path.setAttribute("fill", "none");
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path.setAttribute("stroke", "currentColor");
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path.setAttribute("stroke-width", strokeWidth);
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var strPath;
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var buffer = []; // Contains the last positions of the mouse cursor
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svgElement.addEventListener("mousedown", function (e) {
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path = document.createElementNS("http://www.w3.org/2000/svg", "path");
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path.setAttribute("fill", "none");
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path.setAttribute("stroke", "currentColor");
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path.setAttribute("stroke-width", strokeWidth);
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buffer = [];
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var pt = getMousePosition(e);
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appendToBuffer(pt);
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strPath = "M" + pt.x + " " + pt.y;
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path.setAttribute("d", strPath);
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svgElement.appendChild(path);
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});
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svgElement.addEventListener("mousemove", function (e) {
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// if (path) {
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appendToBuffer(getMousePosition(e));
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updateSvgPath();
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// }
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});
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svgElement.addEventListener("mouseup", function () {
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// if (path) {
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// path = null;
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// }
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});
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svgElement.addEventListener("mouseleave", function () {
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// if (path) {
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// path = null;
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// }
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});
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var getMousePosition = function (e) {
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return {
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x: e.pageX - rect.left,
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y: e.pageY - rect.top,
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};
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};
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var appendToBuffer = function (pt) {
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buffer.push(pt);
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while (buffer.length > bufferSize) {
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buffer.shift();
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}
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};
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// Calculate the average point, starting at offset in the buffer
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var getAveragePoint = function (offset) {
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var len = buffer.length;
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if (len % 2 === 1 || len >= bufferSize) {
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var totalX = 0;
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var totalY = 0;
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var pt, i;
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var count = 0;
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for (i = offset; i < len; i++) {
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count++;
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pt = buffer[i];
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totalX += pt.x;
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totalY += pt.y;
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}
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return {
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x: totalX / count,
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y: totalY / count,
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};
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}
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return null;
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};
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var updateSvgPath = function () {
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var pt = getAveragePoint(0);
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if (pt) {
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// Get the smoothed part of the path that will not change
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strPath += " L" + pt.x + " " + pt.y;
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// Get the last part of the path (close to the current mouse position)
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// This part will change if the mouse moves again
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var tmpPath = "";
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for (var offset = 2; offset < buffer.length; offset += 2) {
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pt = getAveragePoint(offset);
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tmpPath += " L" + pt.x + " " + pt.y;
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}
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// Set the complete current path coordinates
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path.setAttribute("d", strPath + tmpPath);
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}
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};
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const presets = document.querySelectorAll(".preset");
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for (const preset of presets) {
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if (preset.dataset.path) {
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let offset = preset.getBoundingClientRect();
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let drawing = preset.dataset.path.split(" ");
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let index = 1;
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preset.addEventListener("mousemove", (e) => {
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strPath += ` ${drawing[index]}`;
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index += 1;
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path.setAttribute("d", strPath);
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});
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}
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}
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