I know how to draw a square, but how could I make it so that it only draws when I click on a "Draw Square" button? Also, I know to make a button (<p><button onclick="rect();">Rectangle</button></p>), but how do you link it to the javascript? Any help at all would be much appreciated...
HTML5:
<canvas id="canvas" width="500" height="500"></canvas>
JAVASCRIPT:
<script type="text/javascript">
var canvas = document.getElementById('canvas'),
ctx = canvas.getContext('2d'),
rect = {},
drag = false;
function init() {
canvas.addEventListener('mousedown', mouseDown, false);
canvas.addEventListener('mouseup', mouseUp, false);
canvas.addEventListener('mousemove', mouseMove, false);
}
function mouseDown(e) {
rect.startX = e.pageX - this.offsetLeft;
rect.startY = e.pageY - this.offsetTop;
drag = true;
}
function mouseUp() {
drag = false;
}
function mouseMove(e) {
if (drag) {
rect.w = (e.pageX - this.offsetLeft) - rect.startX;
rect.h = (e.pageY - this.offsetTop) - rect.startY ;
ctx.clearRect(0,0,canvas.width,canvas.height);
draw();
}
}
function draw() {
ctx.fillRect(rect.startX, rect.startY, rect.w, rect.h);
}
init();
</script>
Well, you have actually already linked your button to a javascript function by specifying its 'onclick' attribute.
Now you just need to add a rect() function to your js that will draw a rectangle.
Related
i got this code looking around this forum but, I'm not being able to make it work on mobile devices with touchscreen. Problem is I need it to work as simple as this, not calling any library, because it's not for an app but for a simple Wordpress that's using an html widget. Is this even posible?
Thank you all!
<!DOCTYPE html>
<html>
<body>
<canvas id="myCanvas" width="400" height="200" style="background: #ffffff; margin-left: 0px;">Your browser does not support the HTML5 canvas tag.</canvas>
<script>
const c = document.getElementById("myCanvas");
// c.addEventListener("click", penTool); // fires after mouse left btn is released
c.addEventListener("mousedown", setLastCoords); // fires before mouse left btn is released
c.addEventListener("mousemove", freeForm);
const ctx = c.getContext("2d");
function setLastCoords(e) {
const {x, y} = c.getBoundingClientRect();
lastX = e.clientX - x;
lastY = e.clientY - y;
}
function freeForm(e) {
if (e.buttons !== 1) return; // left button is not pushed yet
penTool(e);
}
function penTool(e) {
const {x, y} = c.getBoundingClientRect();
const newX = e.clientX - x;
const newY = e.clientY - y;
ctx.beginPath();
ctx.lineWidth = 5;
ctx.moveTo(lastX, lastY);
ctx.lineTo(newX, newY);
ctx.strokeStyle = 'black';
ctx.stroke();
ctx.closePath();
lastX = newX;
lastY = newY;
}
let lastX = 0;
let lastY = 0;
</script>
</body>
</html>
Came up with this for mobile version only, still not working :(
<!DOCTYPE html>
<html>
<body>
<canvas id="myCanvas" width="400" height="200" style="background: #ffffff; margin-left: 0px;">Your browser does not support the HTML5 canvas tag.</canvas>
<script>
const c = document.getElementById("myCanvas");
// c.addEventListener("click", penTool); // fires after mouse left btn is released
c.addEventListener("touchstart", setLastCoords); // fires before mouse left btn is released
c.addEventListener("touchmove", freeForm);
const ctx = c.getContext("2d");
function setLastCoords(e) {
const {x, y} = c.getBoundingClientRect();
lastX = e.touches[0].clientX - x;
lastY = e.touches[0].clientY - y;
}
function freeForm(e) {
if (e.touches !== 1) return; // left button is not pushed yet
penTool(e);
}
function penTool(e) {
const {x, y} = c.getBoundingClientRect();
const newX = e.touches[0].clientX;
const newY = e.touches[0].clientY;
ctx.beginPath();
ctx.lineWidth = 5;
ctx.moveTo(lastX, lastY);
ctx.lineTo(newX, newY);
ctx.strokeStyle = 'black';
ctx.stroke();
ctx.closePath();
lastX = newX;
lastY = newY;
}
let lastX = 0;
let lastY = 0;
</script>
</body>
</html>
I also tried this script (credits to Zipso, great article on that)
<head>
<title>Sketchpad</title>
<script type="text/javascript">
// Variables for referencing the canvas and 2dcanvas context
var canvas,ctx;
// Variables to keep track of the mouse position and left-button status
var mouseX,mouseY,mouseDown=0;
// Variables to keep track of the touch position
var touchX,touchY;
// Keep track of the old/last position when drawing a line
// We set it to -1 at the start to indicate that we don't have a good value for it yet
var lastX,lastY=-1;
// Draws a line between the specified position on the supplied canvas name
// Parameters are: A canvas context, the x position, the y position, the size of the dot
function drawLine(ctx,x,y,size) {
// If lastX is not set, set lastX and lastY to the current position
if (lastX==-1) {
lastX=x;
lastY=y;
}
// Let's use black by setting RGB values to 0, and 255 alpha (completely opaque)
r=0; g=0; b=0; a=255;
// Select a fill style
ctx.strokeStyle = "rgba("+r+","+g+","+b+","+(a/255)+")";
// Set the line "cap" style to round, so lines at different angles can join into each other
ctx.lineCap = "round";
//ctx.lineJoin = "round";
// Draw a filled line
ctx.beginPath();
// First, move to the old (previous) position
ctx.moveTo(lastX,lastY);
// Now draw a line to the current touch/pointer position
ctx.lineTo(x,y);
// Set the line thickness and draw the line
ctx.lineWidth = size;
ctx.stroke();
ctx.closePath();
// Update the last position to reference the current position
lastX=x;
lastY=y;
}
// Clear the canvas context using the canvas width and height
function clearCanvas(canvas,ctx) {
ctx.clearRect(0, 0, canvas.width, canvas.height);
}
// Keep track of the mouse button being pressed and draw a dot at current location
function sketchpad_mouseDown() {
mouseDown=1;
drawLine(ctx,mouseX,mouseY,12);
}
// Keep track of the mouse button being released
function sketchpad_mouseUp() {
mouseDown=0;
// Reset lastX and lastY to -1 to indicate that they are now invalid, since we have lifted the "pen"
lastX=-1;
lastY=-1;
}
// Keep track of the mouse position and draw a dot if mouse button is currently pressed
function sketchpad_mouseMove(e) {
// Update the mouse co-ordinates when moved
getMousePos(e);
// Draw a dot if the mouse button is currently being pressed
if (mouseDown==1) {
drawLine(ctx,mouseX,mouseY,12);
}
}
// Get the current mouse position relative to the top-left of the canvas
function getMousePos(e) {
if (!e)
var e = event;
if (e.offsetX) {
mouseX = e.offsetX;
mouseY = e.offsetY;
}
else if (e.layerX) {
mouseX = e.layerX;
mouseY = e.layerY;
}
}
// Draw something when a touch start is detected
function sketchpad_touchStart() {
// Update the touch co-ordinates
getTouchPos();
drawLine(ctx,touchX,touchY,12);
// Prevents an additional mousedown event being triggered
event.preventDefault();
}
function sketchpad_touchEnd() {
// Reset lastX and lastY to -1 to indicate that they are now invalid, since we have lifted the "pen"
lastX=-1;
lastY=-1;
}
// Draw something and prevent the default scrolling when touch movement is detected
function sketchpad_touchMove(e) {
// Update the touch co-ordinates
getTouchPos(e);
// During a touchmove event, unlike a mousemove event, we don't need to check if the touch is engaged, since there will always be contact with the screen by definition.
drawLine(ctx,touchX,touchY,12);
// Prevent a scrolling action as a result of this touchmove triggering.
event.preventDefault();
}
// Get the touch position relative to the top-left of the canvas
// When we get the raw values of pageX and pageY below, they take into account the scrolling on the page
// but not the position relative to our target div. We'll adjust them using "target.offsetLeft" and
// "target.offsetTop" to get the correct values in relation to the top left of the canvas.
function getTouchPos(e) {
if (!e)
var e = event;
if(e.touches) {
if (e.touches.length == 1) { // Only deal with one finger
var touch = e.touches[0]; // Get the information for finger #1
touchX=touch.pageX-touch.target.offsetLeft;
touchY=touch.pageY-touch.target.offsetTop;
}
}
}
// Set-up the canvas and add our event handlers after the page has loaded
function init() {
// Get the specific canvas element from the HTML document
canvas = document.getElementById('sketchpad');
// If the browser supports the canvas tag, get the 2d drawing context for this canvas
if (canvas.getContext)
ctx = canvas.getContext('2d');
// Check that we have a valid context to draw on/with before adding event handlers
if (ctx) {
// React to mouse events on the canvas, and mouseup on the entire document
canvas.addEventListener('mousedown', sketchpad_mouseDown, false);
canvas.addEventListener('mousemove', sketchpad_mouseMove, false);
window.addEventListener('mouseup', sketchpad_mouseUp, false);
// React to touch events on the canvas
canvas.addEventListener('touchstart', sketchpad_touchStart, false);
canvas.addEventListener('touchend', sketchpad_touchEnd, false);
canvas.addEventListener('touchmove', sketchpad_touchMove, false);
}
}
</script>
<style>
/* Some CSS styling */
#sketchpadapp {
/* Prevent nearby text being highlighted when accidentally dragging mouse outside confines of the canvas */
-webkit-touch-callout: none;
-webkit-user-select: none;
-khtml-user-select: none;
-moz-user-select: none;
-ms-user-select: none;
user-select: none;
}
.leftside {
float:left;
width:220px;
height:285px;
background-color:#def;
padding:10px;
border-radius:4px;
}
.rightside {
float:left;
margin-left:10px;
}
#sketchpad {
float:left;
height:300px;
width:400px;
border:2px solid #888;
border-radius:4px;
position:relative; /* Necessary for correct mouse co-ords in Firefox */
}
#clearbutton {
font-size: 15px;
padding: 10px;
-webkit-appearance: none;
background: #eee;
border: 1px solid #888;
}
</style>
</head>
<body onload="init()">
<div id="sketchpadapp">
<div class="leftside">
Touchscreen and mouse support HTML5 canvas sketchpad.<br/><br/>
Draw something by tapping or dragging.<br/><br/>
Works on iOS, Android and desktop/laptop touchscreens using Chrome/Firefox/Safari.<br/><br/>
<input type="submit" value="Clear Sketchpad" id="clearbutton" onclick="clearCanvas(canvas,ctx);">
</div>
<div class="rightside">
<canvas id="sketchpad" height="300" width="400">
</canvas>
</div>
</div>
</body>
</html>
But I can't manage to make it work on my mobile, as it only draws the first dot when touching!
I am using HexagonTools to draw hexagon using canvas.
I need to add an href link to elements of canvas.
I have tried this code:
function drawHexGrid()
{
var linkText="http://stackoverflow.com";
var linkX=5;
var linkY=15;
var linkHeight=10;
var linkWidth;
var inLink = false;
var grid = new HT.Grid(800, 600);
var canvas = document.getElementById("hexCanvas");
var ctx = canvas.getContext('2d');
ctx.clearRect(0, 0, 800, 600);
for(var h in grid.Hexes)
{
grid.Hexes[h].draw(ctx);
linkWidth=ctx.measureText(linkText).width;
canvas.addEventListener("mousemove", on_mousemove, false);
canvas.addEventListener("click", on_click, false);
}
}
But this is not working, I need a simple example on how to develop this, I have already looked at this SOF Question
But I couldn't develop it
You can test which hexagon you mouse clicked using context.isPointInPath.
Listen for mousedown events
In mousedown, fetch the mouseX, mouseY
Recreate each of your hex paths (no need to actually stroke/fill them).
For each hex, use .isPointInPath(mouseX,mouseY) to see if the mouse clicked in this hex.
If you find a clicked hex, use window.open(theUrl, '_blank') to navigate to its associated url.
In Hexagon Tools, each hex has a points property which you can use to receate each of your hex paths.
Here's example code and a Demo:
var canvas=document.getElementById("canvas");
var ctx=canvas.getContext("2d");
var cw=canvas.width;
var ch=canvas.height;
function reOffset(){
var BB=canvas.getBoundingClientRect();
offsetX=BB.left;
offsetY=BB.top;
}
var offsetX,offsetY;
reOffset();
window.onscroll=function(e){ reOffset(); }
window.onresize=function(e){ reOffset(); }
var isDown=false;
var startX,startY;
var hexes=[];
hexes.push({
points:[{x:57.5,y:63},{x:42.5,y:63},{x:35,y:50},{x:42.5,y:37},{x:57.5,y:37},{x:65,y:50}],
url:'http://stackoverflow.com',
});
draw();
$("#canvas").mousedown(function(e){handleMouseDown(e);});
function draw(){
for(var i=0;i<hexes.length;i++){
var h=hexes[i];
ctx.beginPath();
ctx.moveTo(h.points[0].x,h.points[0].y);
for(var j=1;j<h.points.length;j++){
ctx.lineTo(h.points[j].x,h.points[j].y);
}
ctx.closePath();
ctx.stroke();
}
}
function handleMouseDown(e){
// tell the browser we're handling this event
e.preventDefault();
e.stopPropagation();
mouseX=parseInt(e.clientX-offsetX);
mouseY=parseInt(e.clientY-offsetY);
for(var i=0;i<hexes.length;i++){
var h=hexes[i];
ctx.beginPath();
ctx.moveTo(h.points[0].x,h.points[0].y);
for(var j=1;j<h.points.length;j++){
ctx.lineTo(h.points[j].x,h.points[j].y);
}
ctx.closePath();
//if(ctx.isPointInPath(mouseX,mouseY)){ window.open(h.url, '_blank'); }
if(ctx.isPointInPath(mouseX,mouseY)){ alert('Navigate to: '+h.url); }
}
}
body{ background-color: ivory; }
#canvas{border:1px solid red; margin:0 auto; }
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<h4>Click in the hexagon to navigate to Stackoverflow.com</h4>
<canvas id="canvas" width=300 height=300></canvas>
When a user drags their cursor across the screen a square canvas is drawn. My issue is that the canvas is "ghosting". I think it is possible to fix this problem using redraw() or clearrect() but I'm not sure how to implement those functions in this case. Thanks.
drawSquare = true;
//DRAG TO CREATE RECTANGLE
if(drawSquare == true){
$(document).mousedown(function(e) {
dragShape = true;
posYdown = e.pageY;
posXdown = e.pageX;
});
$(document).mousemove(function(e) {
if(dragShape == true) {
var c=document.getElementById("canvas1");
var ctx=c.getContext("2d");
ctx.fillStyle = "black";
ctx.fillRect(posXdown ,posYdown ,e.pageX - posXdown ,e.pageY - posYdown);
}
});
$(document).mouseup(function() {
dragShape = false;
});
}
Yes, you need context.clearRect to remove previously drawn pixels or you will have ghost remnants.
Here's a refactored version of your code:
Hints:
Clear the canvas before drawing a new rectangle.
Just get references to your canvas and context once at the beginning of your app.
Adjust your mouse position by the offset X,Y of the canvas (in case you later reposition your canvas on the page).
Good luck with your learning!
var canvas=document.getElementById("canvas");
var ctx=canvas.getContext("2d");
var cw=canvas.width;
var ch=canvas.height;
var $canvas=$("#canvas");
var canvasOffset=$canvas.offset();
var offsetX=canvasOffset.left;
var offsetY=canvasOffset.top;
var dragShape=false;
var posXdown,posYdown;
function handleMouseDown(e){
e.preventDefault();
e.stopPropagation();
posXdown=parseInt(e.clientX-offsetX);
posYdown=parseInt(e.clientY-offsetY);
dragShape = true;
}
function handleMouseUp(e){
e.preventDefault();
e.stopPropagation();
dragShape = false;
}
function handleMouseMove(e){
if(!dragShape){return;}
e.preventDefault();
e.stopPropagation();
var mouseX=parseInt(e.clientX-offsetX);
var mouseY=parseInt(e.clientY-offsetY);
var width=mouseX-posXdown;
var height=mouseY-posYdown;
ctx.clearRect(0,0,canvas.width,canvas.height);
ctx.fillRect(posXdown,posYdown,width,height);
}
$("#canvas").mousedown(function(e){handleMouseDown(e);});
$("#canvas").mousemove(function(e){handleMouseMove(e);});
$("#canvas").mouseup(function(e){handleMouseUp(e);});
$("#canvas").mouseout(function(e){handleMouseUp(e);});
body{ background-color: ivory; }
#canvas{border:1px solid red;}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<canvas id="canvas" width=300 height=300></canvas>
How do I drag and drop multiple images from one canvas to another? My manager has given me this task, it's been 3 days and I am not able to do this as I'm new to HTML5. I've searched Google but only got it working for one image. Please help me in this matter.
This is what I got for one image:
<pre>
<script>
window.onload = function ()
{
var canvas1 = document.getElementById("cvs1");
var canvas2 = document.getElementById("cvs2");
var context1 = canvas1.getContext('2d');
var context2 = canvas2.getContext('2d');
var imageXY = {x: 5, y: 5};
/**
* This draws the image to the canvas
*/
function Draw ()
{
//Clear both canvas first
context1.clearRect(0,0,canvas1.width,canvas1.height);
context2.clearRect(0,0,canvas2.width,canvas2.height);
//Draw a red rectangle around the image
if (state && state.dragging) {
state.canvas.getContext('2d').strokeStyle = 'red';
state.canvas.getContext('2d').strokeRect(imageXY.x - 2.5,
imageXY.y - 2.5,
state.image.width + 5,
state.image.height + 5);
}
// Now draw the image
state.canvas.getContext('2d').drawImage(state.image, imageXY.x, imageXY.y);
}
canvas2.onclick =
canvas1.onclick = function (e)
{
if (state && state.dragging) {
state.dragging = false;
Draw();
return;
}
var mouseXY = RGraph.getMouseXY(e);
state.canvas = e.target;
if ( mouseXY[0] > imageXY.x
&& mouseXY[0] < (imageXY.x + state.image.width)
&& mouseXY[1] > imageXY.y
&& mouseXY[1] < (imageXY.y + state.image.height)) {
state.dragging = true;
state.originalMouseX = mouseXY[0];
state.originalMouseY = mouseXY[1];
state.offsetX = mouseXY[0] - imageXY.x;
state.offsetY = mouseXY[1] - imageXY.y;
}
}
canvas1.onmousemove =
canvas2.onmousemove = function (e)
{
if (state.dragging) {
state.canvas = e.target;
var mouseXY = RGraph.getMouseXY(e);
// Work how far the mouse has moved since the mousedon event was triggered
var diffX = mouseXY[0] - state.originalMouseX;
var diffY = mouseXY[1] - state.originalMouseY;
imageXY.x = state.originalMouseX + diffX - state.offsetX;
imageXY.y = state.originalMouseY + diffY - state.offsetY;
Draw();
e.stopPropagation();
}
}
/**
* Load the image on canvas1 initially and set the state up with some defaults
*/
state = {}
state.dragging = false;
state.canvas = document.getElementById("cvs1");
state.image = new Image();
state.image.src = 'images/logo.png';
state.offsetX = 0;
state.offsetY = 0;
state.image.onload = function ()
{
Draw();
}
}
</script>
<canvas id="cvs1" width="400" height="125" style="float: left">[No canvas support]</canvas>
<canvas id="cvs2" width="400" height="125" style="float: left; margin-left: 100px">[No canvas support]</canvas>
</pre>
Drag/Drop multiple items between 2 canvases
Here’s what the code does:
Click to select one or more images from the top source canvas
Click an image again to toggle its selection on/off
Once you have made all your selections, drag from the top canvas to the bottom canvas
Your selections will be moved to the bottom canvas
Some explanation about the code:
Each image is stored in an array called Images
An item-object for each image is stored in an array called items
The item-object contains an item’s description, image-url, an isSelected flag and an isDropped flag.
The mouseup event handler of the top source canvas checks for hits on images and toggles their isSelected flags.
The mouseup event handler responds to drops onto the bottom drop canvas. It checks for selected items and records them as dropped by setting their isDropped flags.
The drawContainer function distributes items between the source and drop canvas based on their isDropped flags (isDropped==false are drawn in the top source canvas – isDropped==true are drawn in the bottom drop canvas)
Here is code and a Fiddle: http://jsfiddle.net/m1erickson/3KqgX/
<!doctype html>
<html>
<head>
<link rel="stylesheet" type="text/css" media="all" href="css/reset.css" /> <!-- reset css -->
<script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
<style>
body{ background-color: ivory; padding:10px; }
canvas{border:1px solid red;}
#canvas {
}
#canvas:active {
cursor: move;
}
</style>
<script>
$(function(){
var canvas=document.getElementById("canvas");
var ctx=canvas.getContext("2d");
var drop=document.getElementById("dropzone");
var dropCtx=drop.getContext("2d");
var canvasOffset=$("#canvas").offset();
var offsetX=canvasOffset.left;
var offsetY=canvasOffset.top;
var mouseIsDown=false;
var frameWidth=128;
var frameHeight=128;
// checkmark for selected
var checkmark=document.createElement("img");
checkmark.src="https://dl.dropboxusercontent.com/u/139992952/stackoverflow/smallCheckmark.png";
var images=[];
var items=[];
items.push({description:"House#1",url:"https://dl.dropboxusercontent.com/u/139992952/stackoverflow/house1.jpg",isSelected:false,isDropped:false,x:0,y:0});
items.push({description:"House#2",url:"https://dl.dropboxusercontent.com/u/139992952/stackoverflow/house2.jpg",isSelected:false,isDropped:false,x:0,y:0});
items.push({description:"House#3",url:"https://dl.dropboxusercontent.com/u/139992952/stackoverflow/house3.jpg",isSelected:false,isDropped:false,x:0,y:0});
var imgLoadCount=0;
for(var i=0;i<items.length;i++){
images[i]=document.createElement("img");
images[i].onload=function(){
if(++imgLoadCount>=items.length){ draw(); }
}
images[i].src=items[i].url;
}
function draw(){
ctx.clearRect(0,0,canvas.width,canvas.height);
dropCtx.clearRect(0,0,drop.width,drop.height);
var canvasX=0;
var dropX=0;
//
for(var i=0;i<items.length;i++){
if(items[i].isDropped){
x=dropX*160+10;
drawContainer(dropCtx,i,x,20);
dropX++;
items[i].x=x;
}else{
x=canvasX*160+10;
drawContainer(ctx,i,x,20);
canvasX++;
items[i].x=x;
}
}
}
// draw image container
function drawContainer(context,index,x,y){
context.beginPath();
context.rect(x,y+frameHeight,frameWidth,30);
context.fillStyle="black";
context.fill();
context.beginPath();
context.fillStyle="white";
context.font="10pt Verdana";
context.fillText(items[index].description,x+10,y+frameHeight+18);
// draw a thumbnail of the image
var img=images[index];
if(img.width>=img.height){
context.drawImage(img,0,0,img.width,img.height,
x,y,128,128*img.height/img.width);
}else{
context.drawImage(img,0,0,img.width,img.height,
x,y,128*img.width/img.height,128); // edited s/b [,128], not [/128]
}
// outer frame (green if selected)
context.beginPath();
context.rect(x-2,y-2,frameWidth+4,frameHeight+30+4);
context.lineWidth=3;
context.strokeStyle="lightgray";
if(items[index].isSelected){
context.strokeStyle="green";
context.drawImage(checkmark,x+frameWidth-30,y+frameHeight+3);
}
context.stroke();
}
function handleMouseDown(e){
mouseX=parseInt(e.clientX-offsetX);
mouseY=parseInt(e.clientY-offsetY);
// Put your mousedown stuff here
mouseIsDown=true;
}
function handleMouseUp(e){
mouseIsDown=false;
mouseX=parseInt(e.clientX-offsetX);
mouseY=parseInt(e.clientY-offsetY);
// Put your mouseup stuff here
for(var i=0;i<items.length;i++){
var item=items[i];
// have we clicked on something?
if(!item.isDropped && mouseX>=item.x && mouseX<=item.x+frameWidth){
// if so, toggle its selection
items[i].isSelected=!(items[i].isSelected);
draw();
}
}
}
function handleMouseOut(e){
if(!mouseIsDown){return;}
mouseX=parseInt(e.clientX-offsetX);
mouseY=parseInt(e.clientY-offsetY);
// Put your mouseOut stuff here
}
function handleMouseMove(e){
mouseX=parseInt(e.clientX-offsetX);
mouseY=parseInt(e.clientY-offsetY);
// Put your mousemove stuff here
}
function handleDrop(e){
for(var i=0;i<items.length;i++){
if(items[i].isSelected){
items[i].isDropped=true;
items[i].isSelected=false;
console.log(i);
}
}
draw();
}
$("#canvas").mousedown(function(e){handleMouseDown(e);});
$("#canvas").mousemove(function(e){handleMouseMove(e);});
$("#canvas").mouseup(function(e){handleMouseUp(e);});
$("#canvas").mouseout(function(e){handleMouseOut(e);});
$("#dropzone").mouseup(function(e){handleDrop(e);});
}); // end $(function(){});
</script>
</head>
<body>
<p>Click an item to toggle it's selection</p>
<p>Drag from top to bottom canvas to drop selected items</p>
<canvas id="canvas" width=500 height=200></canvas><br>
<canvas id="dropzone" width=500 height=200></canvas>
</body>
</html>
[Addition: Alternate code to sort bottom canvas by order dropped]
function handleDrop(e){
for(var i=items.length-1;i>=0;i--){
if(items[i].isSelected){
items[i].isDropped=true;
items[i].isSelected=false;
// sort the bottom canvas by order dropped
var move=items[i];
items.splice(i,1);
items.push(move);
}
}
draw();
}
[ Edited to present a solution in KineticJS ]
Here is code and a Fiddle: http://jsfiddle.net/m1erickson/bSpBF/
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
<script src="http://d3lp1msu2r81bx.cloudfront.net/kjs/js/lib/kinetic-v4.5.1.min.js"></script>
<style>
body{ background-color: ivory; padding:10px;}
#container1,#container2{
border:solid 1px #ccc;
margin-top: 10px;
width:300px;
height:100px;
}
#container2{
height:300px;
}
</style>
<script>
$(function(){
var highlightWidth=8;
var stage = new Kinetic.Stage({
container: 'container1',
width: 300,
height: 100
});
var layer = new Kinetic.Layer();
stage.add(layer);
var dropzone = new Kinetic.Stage({
container: 'container2',
width: 300,
height: 300
});
var dropLayer = new Kinetic.Layer();
dropzone.add(dropLayer);
// these must go after the creation of stages & layers
addBackground(stage,layer,dropLayer);
layer.draw();
addBackground(dropzone,dropLayer,layer);
dropLayer.draw();
// get images & then trigger start()
var images={};
var URLs = {
house1: 'https://dl.dropboxusercontent.com/u/139992952/stackoverflow/house204-3.jpg',
house2: 'https://dl.dropboxusercontent.com/u/139992952/stackoverflow/house204-4.jpg',
house3: 'https://dl.dropboxusercontent.com/u/139992952/stackoverflow/house204-1.jpg'
};
loadImages(URLs,start);
function start(){
var house1=kImage(images.house1,10,10,50,50,layer);
var house2=kImage(images.house2,75,10,50,50,layer);
var house3=kImage(images.house3,140,10,50,50,layer);
layer.draw();
}
function swapStagesIfSelected(sourceLayer,destinationLayer,startX,startY){
// get all elements on the source layer
var elements=sourceLayer.get("Image");
// don't let dropped elements fall off the stage
var totalWidth=0;
var maxHeight=-999;
var layerWidth=destinationLayer.getStage().getWidth();
var layerHeight=destinationLayer.getStage().getHeight();
for(var i=0;i<elements.length;i++){
if(elements[i].isSelected){
totalWidth+=elements[i].getWidth();
maxHeight=Math.max(elements[i].getHeight(),maxHeight);
}
}
if(startX+totalWidth>layerWidth){
startX=layerWidth-totalWidth-15;
}
if(startY+maxHeight>layerHeight){
startY=layerHeight-maxHeight-15;
}
// move all selected images
// to the clicked x/y of the destination layer
for(var i=0;i<elements.length;i++){
var element=elements[i];
if(element.isSelected){
var img=element.getImage();
kImage(img,startX,startY,element.getWidth(),element.getHeight(),destinationLayer);
startX+=element.getWidth()+10;
element.remove();
}
}
sourceLayer.draw();
destinationLayer.draw();
}
// build the specified KineticJS Image and add it to the specified layer
function kImage(image,x,y,width,height,theLayer){
var image=new Kinetic.Image({
image:image,
x:x,
y:y,
width:width,
height:height,
strokeWidth:0.1,
stroke:"green",
draggable:true
});
image.myLayer=theLayer;
image.isSelected=false;
image.on("click",function(){
highlight(this);
this.myLayer.draw();
});
image.myLayer.add(image);
return(image);
}
// build a background image and add it to the specified stage
function addBackground(theStage,theLayer,otherLayer){
var background = new Kinetic.Rect({
x: 0,
y: 0,
width: theStage.getWidth(),
height: theStage.getHeight(),
fill: "white",
stroke: "green",
strokeWidth: 1
});
background.on("click",function(){
var pos=theStage.getMousePosition();
var mouseX=parseInt(pos.x);
var mouseY=parseInt(pos.y);
swapStagesIfSelected(otherLayer,theLayer,mouseX,mouseY);
});
theLayer.add(background);
}
///////////// Image loader
function loadImages(URLs, callback) {
var loaded = 0;
var needed = 0;
for(var url in URLs) { needed++; console.log(url); }
for(var url in URLs) {
images[url] = new Image();
images[url].onload = function() {
if(++loaded >= needed) {
callback(images);
}
};
images[url].src = URLs[url];
}
}
///////////// Toggle Highlighting
function highlight(element,setStrokeWidth){
if(setStrokeWidth){
element.setStrokeWidth(setStrokeWidth);
}else{
if(element.getStrokeWidth()>5){
element.setStrokeWidth(0.1);
element.isSelected=false;
}else{
element.setStrokeWidth(highlightWidth);
element.isSelected=true;
}
}
}
}); // end $(function(){});
</script>
</head>
<body>
<p>Click on image(s) to toggle selection</p>
<p>Then click in the other canvas to drop</p>
<div id="container1"></div>
<div id="container2"></div>
<button id="clear">Clear Hightlights</button>
<button id="swap">Swap Selected</button>
</body>
</html>
<script type="text/javascript">
var canvas, context, tool, e;
var varblurup=0;
var varsizeup=1;
var swtchclr;
// Keep everything in anonymous function, called on window load.
if(window.addEventListener) {
window.addEventListener('load', function () {
//check tool is pen or line or shape
var chktool="pen";
function init () {
alert("Line3");
// Find the canvas element.
canvas = document.getElementById('canvas');
context = canvas.getContext('2d');
//varblurup=10;
context.shadowColor = 'colour';
context.shadowBlur = 0;
context.lineWidth=1;
context.lineJoin = 'miter';
context.miterLimit = 4;
this.context.save();
// Pencil tool instance.
//tool = new tool_pencil();
//alert("Pen");
if(chktool=="pen")
{ tool = new tool_pencil();
alert("Pen");
}else if (chktool=="line")
{
tool2 = new tool_line();
alert("Line");
}
// Attach the mousedown, mousemove and mouseup event listeners.
canvas.addEventListener('mousedown', ev_canvas, false);
canvas.addEventListener('mousemove', ev_canvas, false);
canvas.addEventListener('mouseup', ev_canvas, false);
}
// This painting tool works like a drawing pencil which tracks the mouse
// movements.
function tool_pencil () {
var tool = this;
this.started = false;
// This is called when you start holding down the mouse button.
// This starts the pencil drawing.
this.mousedown = function (ev) {
context.beginPath();
context.moveTo(ev._x, ev._y);
tool.started = true;
};
// This function is called every time you move the mouse. Obviously, it only
// draws if the tool.started state is set to true (when you are holding down
// the mouse button).
this.mousemove = function (ev) {
if (tool.started) {
context.lineTo(ev._x, ev._y);
//this.style('stroke-opacity').value
context.stroke();
}
};
// This is called when you release the mouse button.
this.mouseup = function (ev) {
if (tool.started) {
tool.mousemove(ev);
tool.started = false;
}
};
}
// The general-purpose event handler. This function just determines the mouse
// position relative to the canvas element.
function ev_canvas (ev) {
if (ev.layerX || ev.layerX == 0) { // Firefox
ev._x = ev.layerX;
ev._y = ev.layerY;
} else if (ev.offsetX || ev.offsetX == 0) { // Opera
ev._x = ev.offsetX;
ev._y = ev.offsetY;
}
// Call the event handler of the tool.
var func = tool[ev.type];
if (func) {
func(ev);
}
}
init();
}, false); }
I found the Mozilla canvas tutorial to be a helpful guide. It covers most areas including shape drawing:
https://developer.mozilla.org/en/Canvas_tutorial
https://developer.mozilla.org/en/Canvas_tutorial/Drawing_shapes
It is quite an extended question so here are a couple of links about it..
HTML5 Canvas: Shape Drawing
A Quick Introduction to the HTML 5 Canvas
A Quick Introduction to the HTML 5 Canvas – Part Two