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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 = 8;
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var bufferSize;
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var svgElement = document.getElementById("svgElement");
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var rect = svgElement.getBoundingClientRect();
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var path = null;
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var strPath;
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var buffer = []; // Contains the last positions of the mouse cursor
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const startDrawing = (e) => {
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e.preventDefault();
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// console.log("start");
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bufferSize = 2;
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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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const draw = (e) => {
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e.preventDefault();
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if (path) {
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// console.log("draw");
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appendToBuffer(getMousePosition(e));
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updateSvgPath();
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}
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};
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const stopDrawing = () => {
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if (path) {
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// console.log("stop");
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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 || e?.changedTouches[0]?.pageX) - rect.left,
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y: (e.pageY || e?.changedTouches[0]?.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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svgElement.addEventListener("mousedown", (e) => startDrawing(e));
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svgElement.addEventListener("touchstart", (e) => startDrawing(e), { passive: false });
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svgElement.addEventListener("mousemove", (e) => draw(e));
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svgElement.addEventListener("touchmove", (e) => draw(e), { passive: false });
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svgElement.addEventListener("mouseup", () => stopDrawing());
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svgElement.addEventListener("mouseleave", () => stopDrawing());
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svgElement.addEventListener("touchend", () => stopDrawing());
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//
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//
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//
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// SAVE THE BRANCH
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const form = document.querySelector("form");
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form.addEventListener("submit", () => {
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let wrapper = document.createElement("div");
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wrapper.appendChild(svgElement);
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form["content"].value = wrapper.innerHTML;
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return true;
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});
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