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JavaScript

Posted by Nick Ruiz
Nick Ruiz
18,492 Points

Simple Drawing App for mobile devices

Hey guys I finished the Making a Simple drawing App using JQuery and it works great on desktop devices but the canvas does not recognize touch input on say a mobile device.

The action handlers they use in the app are mousedown, mouseup, mousemove etc events but on a mobile device they do nothing. I did some research and I saw a touch() method in the api but my initial attempt of swapping the mouse() methods with touch() methods was unsuccessful. Anyone tried this before?

Here is the code for app.js

 var color = $(".selected").css("background-color"); var $canvas = $("canvas"); var context = $canvas[0].getContext("2d"); var lastEvent; var mouseDown = false;

//when clicking on control list items $(".controls").on("click", "li", function(){ //deselect sibling items $(this).siblings().removeClass("selected"); //select clicked element $(this).addClass("selected"); //cache current color color = $(this).css("background-color"); });

//when "new color" is pressed $("#revealColorSelect").click(function(){ //show color select or hide the color select changeColor(); $("#colorSelect").toggle(); });

//update the new color span function changeColor() { var r = $("#red").val(); var g = $("#green").val(); var b = $("#blue").val();

$("#newColor").css("background-color", "rgb(" + r + "," + g + "," + b + ")"); }

//when color sliders change $("input[type=range]").change(changeColor);

//when "add color" is pressed $("#addNewColor").click(function(){ //append the color to the controls ul var $newColor = $("<li></li>"); $newColor.css("background-color", $("#newColor").css("background-color")); $(".controls ul").append($newColor); // select the new color $newColor.click(); });

//On mouse events on the canvas $canvas.mousedown(function(e){ lastEvent = e; mouseDown = true; }).mousemove(function(e){ //draw lines if (mouseDown){
context.beginPath(); context.moveTo(lastEvent.offsetX, lastEvent.offsetY); context.lineTo(e.offsetX, e.offsetY); context.strokeStyle = color; context.stroke(); lastEvent = e; } }).mouseup(function(){ mouseDown = false; }).mouseleave(function(){ $canvas.mouseup(); });