Please take a look at this little example. The clickhandler only works if you click in the middle of the line. It seems that the method isPointInPath does not consider the width of the line. Is there a way to solve this problem?
Yes, you are correct.
The new isPointInPath() works only on the centerline of a "fat" line--not the full width of the line.
It's more user friendly on closed shapes that are more than 1 pixel wide ;)
A Workaround for your exact question: Instead of drawing a fat line, draw a 20px wide rectangle.
Here is code and a Fiddle: http://jsfiddle.net/m1erickson/QyWDY/
This code uses basic trigonometry to create a rectangle around a line. In the mousedown event handler, it redraws the rectangle transparently and then tests isPointInPath().
If you need to test a poly-line, you can use these same principles to make rectangle-lines for each segment of your poly-line.
<!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; }
canvas{border:1px solid red;}
</style>
<script>
$(function(){
var canvas=document.getElementById("canvas");
var ctx=canvas.getContext("2d");
// get canvas's relative position
var canvasOffset=$("#canvas").offset();
var offsetX=canvasOffset.left;
var offsetY=canvasOffset.top;
// line specifications
var x1=50;
var y1=50;
var x2=300;
var y2=100;
// draw the lineRectangle
var lineRect=defineLineAsRect(x1,y1,x2,y2,20);
drawLineAsRect(lineRect,"black");
// overlay the line (just as visual proof)
drawLine(x1,y1,x2,y2,3,"red");
function drawLine(x1,y1,x2,y2,lineWidth,color){
ctx.fillStyle=color;
ctx.strokeStyle=color;
ctx.lineWidth=lineWidth;
ctx.save();
ctx.beginPath();
ctx.moveTo(x1,y1);
ctx.lineTo(x2,y2);
ctx.stroke();
ctx.restore();
}
function drawLineAsRect(lineAsRect,color){
var r=lineAsRect;
ctx.save();
ctx.beginPath();
ctx.translate(r.translateX,r.translateY);
ctx.rotate(r.rotation);
ctx.rect(r.rectX,r.rectY,r.rectWidth,r.rectHeight);
ctx.translate(-r.translateX,-r.translateY);
ctx.rotate(-r.rotation);
ctx.fillStyle=color;
ctx.strokeStyle=color;
ctx.fill();
ctx.stroke();
ctx.restore();
}
function defineLineAsRect(x1,y1,x2,y2,lineWidth){
var dx=x2-x1; // deltaX used in length and angle calculations
var dy=y2-y1; // deltaY used in length and angle calculations
var lineLength= Math.sqrt(dx*dx+dy*dy);
var lineRadianAngle=Math.atan2(dy,dx);
return({
translateX:x1,
translateY:y1,
rotation:lineRadianAngle,
rectX:0,
rectY:-lineWidth/2,
rectWidth:lineLength,
rectHeight:lineWidth
});
}
function handleMouseDown(e){
mouseX=parseInt(e.clientX-offsetX);
mouseY=parseInt(e.clientY-offsetY);
// draw our lineRect
drawLineAsRect(lineRect,"transparent");
// test if hit in the lineRect
if(ctx.isPointInPath(mouseX,mouseY)){
alert('Yes');
}
}
canvas.addEventListener("mousedown", handleMouseDown, false);
}); // end $(function(){});
</script>
</head>
<body>
<canvas id="canvas" width=310 height=115></canvas>
</body>
</html>
Related
I need something like the picture shown in the link below, I have no idea how to do it, the most important think is that the calendar is generated dynamically.... this calendar 'll display in a web page.
Interesting project!
You can use canvas transforms to radiate your calendar around a centerpoint.
A Demo: http://jsfiddle.net/m1erickson/Q7S9L/
The idea is to draw a line of your calendar vertically into a column:
And then rotate that column using canvas transforms.
Transforms include context.translate (which moves) and context.rotate (which rotates)
// save the context state
ctx.save();
// translate to the centerpoint around which we will rotate the column
ctx.translate(cx,cy);
// rotate the canvas (which will rotate the column)
ctx.rotate( desiredRadianAngle );
// now draw the column and it will be rotated to the desired angle
Here's example code:
<!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; }
canvas{border:1px solid red;}
</style>
<script>
$(function(){
var canvas=document.getElementById("canvas");
var ctx=canvas.getContext("2d");
var year=2014;
var PI2=Math.PI*2;
var cx=375;
var cy=375;
var radialIncrement=15;
var rotationIncrement=-Math.PI/31;
var months=['Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec'];
var days=[31,28,31,30,31,30,31,31,30,31,30,31];
var dayNames=['Su','M','Tu','W','Th','F','Sa','Su','M','Tu','W','Th','F','Sa','Su','M','Tu','W','Th','F','Sa','Su','M','Tu','W','Th','F','Sa','Su','M','Tu','W','Th','F','Sa','Su','M','Tu','W','Th','F','Sa'];
var monthsFirstWeekday=[]
for(var m=1;m<=12;m++){
monthsFirstWeekday.push(new Date(m+"/01/"+year).getDay());
}
for(var d=0;d<=38;d++){
ctx.save();
ctx.translate(cx,cy);
ctx.rotate(rotationIncrement*(31-d)+Math.PI/2);
var x=-3;
var y=-13*radialIncrement-150;
ctx.font="12px verdana";
ctx.fillStyle="blue";
ctx.fillText(dayNames[d],x,y);
ctx.restore();
}
for(var m=0;m<months.length;m++){
ctx.save();
ctx.translate(cx,cy+25);
ctx.rotate(Math.PI*3/2);
ctx.fillStyle="blue";
ctx.fillText(months[m],0,-(months.length-m)*radialIncrement-150);
ctx.restore();
}
for(var d=0;d<=38;d++){
ctx.save();
ctx.translate(cx,cy);
ctx.rotate(rotationIncrement*(31-d)+Math.PI/2);
for(var m=0;m<months.length;m++){
var x=0;
var y=-(months.length-m)*radialIncrement-150;
var dd=d-monthsFirstWeekday[m]+1;
if(dd>0 && dd<=days[m]){
ctx.fillStyle="black";
ctx.fillText(dd,x,y);
}else{
ctx.beginPath();
ctx.arc(x+3,y,1,0,Math.PI*2);
ctx.closePath();
ctx.fillStyle="red";
ctx.fill();
}
}
ctx.restore();
}
}); // end $(function(){});
</script>
</head>
<body>
<canvas id="canvas" width=775 height=650></canvas>
</body>
</html>
Good morning everyone.
I'm building a graph for the enterprise system where I work, but I came across a problem where I need to insert some kind of identification, that I may be rescued by JavaScript (name, id, label, ...).
Someone could tell me how I could do to identify each element of the graph separately? To be more exact, what I'm wondering identifies each element arc is created.
If someone wanted to see the code to understand it better, I'll put the link here:
- JS Bin
Nothing you draw on the canvas is automatically remembered or labeled with an id.
All canvas drawings become forgotten and inaccessible pixels. However there are ways of keeping track of your various drawings.
Instead of keeping your posX,posY and color info in separate parallel arrays, how about creating an object for each node.
Then you could add the id property to each node object:
var nodes=[];
nodes.push({id:"sun", x:100, y:100, color:"yellow"});
nodes.push({id:"earth", x:50, y:50, color:"blue"});
nodes.push({id:"moon", x:50, y:60, color:"gray"});
And, of course, pull the graphing info from each node...
You can draw your graph inside a function and apply a scaleFactor when needed.
function drawGraph(){
context.clearRect(0,0,canvas.width,canvas.height);
context.save();
context.scale(scaleFactor,scaleFactor);
for(var i=0; i<nodes.length;i++){
var node=nodes[i];
context.beginPath();
context.moveTo(centerCanvasX,centerCanvasY);
context.lineTo(node.x,node.y);
context.stroke();
context.beginPath();
context.arc(node.x,node.y,node.radius,0,Math.PI*2,false);
context.closePath();
context.stroke();
context.fillStyle=node.color;
context.fill();
}
context.restore();
}
For dragging/clicking/etc, You could hit test each node array element until you found a match.
function hit(x,y){
for(var i=0;i<nodes.length;i++){
var node=nodes[i];
var dx=node.x-x;
var dy=node.y-y;
var rr=node.radius;
if(dx*dx+dy*dy<rr*rr){
return(i);
}
}
return(-1);
}
The matching element would have the id you need.
If your graph is scaled and you're using mouse coordinates to drag, you must adjust the coordinates that the browser gives you by the current scaleFactor of your graph:
mouseX=parseInt(event.clientX-offsetX)/scaleFactor;
mouseY=parseInt(event.clientY-offsetY)/scaleFactor;
Here is code and a Fiddle: http://jsfiddle.net/m1erickson/c4hsW/
<!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:20px; }
#canvas{border:1px solid red;}
</style>
<script>
$(function(){
var canvas=document.getElementById("canvas");
var context=canvas.getContext("2d");
var canvasOffset=$("#canvas").offset();
var offsetX=canvasOffset.left;
var offsetY=canvasOffset.top;
var centerCanvasX=canvas.width/2;
var centerCanvasY=canvas.height/2;
var startX;
var startY;
var isDown=false;
var nodes=[];
var dragNode;
var scaleFactor=1.00;
nodes.push({id:"sun", x:centerCanvasX, y:centerCanvasY, radius:20, color:"yellow"});
nodes.push({id:"earth", x:50, y:50, radius:5, color:"blue"});
nodes.push({id:"moon", x:50, y:65, radius:3, color:"gray"});
drawGraph();
function drawGraph(){
context.clearRect(0,0,canvas.width,canvas.height);
context.save();
context.scale(scaleFactor,scaleFactor);
for(var i=0; i<nodes.length;i++){
var node=nodes[i];
context.beginPath();
context.moveTo(centerCanvasX,centerCanvasY);
context.lineTo(node.x,node.y);
context.stroke();
context.beginPath();
context.arc(node.x,node.y,node.radius,0,Math.PI*2,false);
context.closePath();
context.stroke();
context.fillStyle=node.color;
context.fill();
}
context.restore();
}
function hit(x,y){
for(var i=0;i<nodes.length;i++){
var node=nodes[i];
var dx=node.x-x;
var dy=node.y-y;
var rr=node.radius;
if(dx*dx+dy*dy<rr*rr){
return(i);
}
}
return(-1);
}
function handleMouseDown(e){
mouseX=parseInt(e.clientX-offsetX)/scaleFactor;
mouseY=parseInt(e.clientY-offsetY)/scaleFactor;
var i=hit(mouseX,mouseY);
if(i>=0){
startX=mouseX;
startY=mouseY;
isDown=true;
dragNode=nodes[i];
}
}
function handleMouseUp(e){
isDown=false;
}
function handleMouseOut(e){
isDown=false;
}
function handleMouseMove(e){
if(!isDown){return;}
// get the current mouse position
mouseX=parseInt(e.clientX-offsetX)/scaleFactor;
mouseY=parseInt(e.clientY-offsetY)/scaleFactor;
// reposition the dragged node
dragNode.x+=(mouseX-startX);
dragNode.y+=(mouseY-startY);
startX=mouseX;
startY=mouseY;
// redraw the graph
drawGraph();
}
$("#canvas").mousedown(function(e){handleMouseDown(e);});
$("#canvas").mousemove(function(e){handleMouseMove(e);});
$("#canvas").mouseup(function(e){handleMouseUp(e);});
$("#canvas").mouseout(function(e){handleMouseOut(e);});
$("#bigger").click(function(){
scaleFactor+=0.20;
drawGraph();
});
$("#smaller").click(function(){
scaleFactor-=0.20;
drawGraph();
});
}); // end $(function(){});
</script>
</head>
<body>
<button id="bigger">Scale Up</button>
<button id="smaller">Scale Down</button><br>
<canvas id="canvas" width=300 height=300></canvas>
</body>
</html>
I need to connect two canvas with a line to create a dynamic workflow.
I'll generate the canvas rectangle dynamic (amount of steps I have at DB) but I need to connect the steps with lines.
Anybody have some ideas?
Here’s how to automatically connect 2 draggable canvas rectangles with a line
First, define some boxes and connectors:
// define any boxes that will be drawn
var boxes=[];
boxes.push({x:50,y:25,w:75,h:50}); // x,y,width,height
boxes.push({x:200,y:100,w:50,h:50});
// define any connectors between any boxes
var connectors=[];
connectors.push({box1:0,box2:1});
Draw the boxes and automatically draw their connectors:
function draw(){
// clear the canvas
ctx.clearRect(0,0,canvas.width,canvas.height);
for(var i=0;i<boxes.length;i++){
var box=boxes[i];
ctx.fillRect(box.x,box.y,box.w,box.h);
}
for(var i=0;i<connectors.length;i++){
var connector=connectors[i];
var box1=boxes[connector.box1];
var box2=boxes[connector.box2];
ctx.beginPath();
ctx.moveTo(box1.x+box1.w/2,box1.y+box1.h/2);
ctx.lineTo(box2.x+box2.w/2,box2.y+box2.h/2);
ctx.stroke();
}
}
The code below allows any box to be dragged and remain connected.
Here is code and a Fiddle: http://jsfiddle.net/m1erickson/GX6HS/
<!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:20px;}
#canvas{border:1px solid red;}
</style>
<script>
$(function(){
var canvas=document.getElementById("canvas");
var ctx=canvas.getContext("2d");
var canvasOffset=$("#canvas").offset();
var offsetX=canvasOffset.left;
var offsetY=canvasOffset.top;
var startX;
var startY;
var isDown=false;
var dragTarget;
var boxes=[];
boxes.push({x:50,y:25,w:75,h:50}); // x,y,width,height
boxes.push({x:200,y:100,w:50,h:50});
var connectors=[];
connectors.push({box1:0,box2:1});
draw();
function draw(){
// clear the canvas
ctx.clearRect(0,0,canvas.width,canvas.height);
for(var i=0;i<boxes.length;i++){
var box=boxes[i];
ctx.fillRect(box.x,box.y,box.w,box.h);
}
for(var i=0;i<connectors.length;i++){
var connector=connectors[i];
var box1=boxes[connector.box1];
var box2=boxes[connector.box2];
ctx.beginPath();
ctx.moveTo(box1.x+box1.w/2,box1.y+box1.h/2);
ctx.lineTo(box2.x+box2.w/2,box2.y+box2.h/2);
ctx.stroke();
}
}
function hit(x,y){
for(var i=0;i<boxes.length;i++){
var box=boxes[i];
if(x>=box.x && x<=box.x+box.w && y>=box.y && y<=box.y+box.h){
dragTarget=box;
return(true);
}
}
return(false);
}
function handleMouseDown(e){
startX=parseInt(e.clientX-offsetX);
startY=parseInt(e.clientY-offsetY);
// Put your mousedown stuff here
isDown=hit(startX,startY);
}
function handleMouseUp(e){
// Put your mouseup stuff here
dragTarget=null;
isDown=false;
}
function handleMouseOut(e){
handleMouseUp(e);
}
function handleMouseMove(e){
if(!isDown){return;}
mouseX=parseInt(e.clientX-offsetX);
mouseY=parseInt(e.clientY-offsetY);
// Put your mousemove stuff here
var dx=mouseX-startX;
var dy=mouseY-startY;
startX=mouseX;
startY=mouseY;
dragTarget.x+=dx;
dragTarget.y+=dy;
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);});
}); // end $(function(){});
</script>
</head>
<body>
<p>Drag boxes--they remain connected</p>
<canvas id="canvas" width=300 height=300></canvas>
</body>
</html>
Could somebody advice how to transform image on canvas from rectangle to trapeze?
For example I have a image-rectangle 100x200 and canvas 300x300.
Then I want to transform my image and put corners in the following points:
100,0; 200,0;
0,300; 300,300
And transformation should re-size image to fit new figure.
I get it, you want to do a y-rotation (like the star wars scrolling intro).
Not possible with the current canvas 2d context transform matrix
The 2d transformation matrix looks like this with the last values fixed at 0,0,1:
M11, M21, dx
M12, M22, dy
0, 0, 1
You would need a y-rotation matrix that looks like this:
cosA, 0, sinA
0, 1, 0
-sinA, 0, cosA
But you can't set -sinA, 0, cosA
[Previous answer]
Here's how you change an rectangle-containing-image to a trapezoid-containing-image
You have to draw each leg of the trapeze individually. But you can draw 3 of the sides and then use closePath() to automatically draw the 4th side.
This code animates between the rectangle and the trapezoid and scales the clipped image. This code assumes you want the image presented in a way that keeps the scaling image as large as possible.
Here's code and a Fiddle: http://jsfiddle.net/m1erickson/7T2YQ/
<!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:20px;}
canvas{border:1px solid red;}
</style>
<script>
$(function(){
var canvas=document.getElementById("canvas");
var ctx=canvas.getContext("2d");
ctx.lineWidth=5;
window.requestAnimFrame = (function(callback) {
return window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame ||
function(callback) {
window.setTimeout(callback, 1000 / 60);
};
})();
var left=1.0;
var right=300;
var sizing=.25;
var img=new Image();
img.onload=function(){
animate();
}
img.src="http://dl.dropbox.com/u/139992952/stackoverflow/KoolAidMan.png";
function animate() {
// update scaling factors
left+=sizing;
right-=sizing;
if(left<0 || left>100){sizing = -sizing;}
console.log(left+"/"+right);
// clear and save the context
ctx.clearRect(0, 0, canvas.width, canvas.height);
ctx.save();
// draw the clipping trapezoid
defineTrapezoid(left,right);
ctx.clip();
// draw trapezoid border
defineTrapezoid(left,right);
ctx.stroke();
// draw image clipped in trapeze
var imgX=left/2;
var imgY=left;
var w=300-left;
ctx.drawImage(img,0,0,img.width,img.height,imgX,imgY,w,w);
ctx.restore();
// request new frame
requestAnimFrame(function() {
animate();
});
}
animate();
function defineTrapezoid(left,right){
ctx.beginPath();
ctx.moveTo(left,0);
ctx.lineTo(right,0);
ctx.lineTo(300,300);
ctx.lineTo(0,300);
ctx.closePath();
}
}); // end $(function(){});
</script>
</head>
<body>
<canvas id="canvas" width=300 height=300></canvas>
</body>
</html>
This code is diplaying a rotating wheel. What I want to achieve is to duplicate the wheel and re position the duplicate and move both wheels forwards. Just like the wheels of a car looks like. I´m very new with canvas. Thanks in advance
<html>
<head>
<script type="text/javascript">
addEventListener("load", windowLoaded, false);
function windowLoaded()
{
canvasApp();
}
function canvasApp()
{
var canvas = document.getElementById("canvas01");
var context = canvas.getContext("2d");
var wiel = new Image();
wiel.src = "wiel.png";
setInterval(draw, 25);
function draw(width)
{
context.clearRect(width, 0, 800, 600)
context.drawImage(wiel, 0, 0);
context.translate(176, 176);
context.rotate(1 * 0.1);
context.translate(-176, -176);
}
}
</script>
</head>
<body>
<canvas id="canvas01" width="800" height="600">
no support
</canvas>
</body>
</html>
Here is how you animate 2 rotating "wheels" across the canvas: http://jsfiddle.net/m1erickson/Yv62X/
The “window.requestAnimFrame” is there for cross-browser compatibility—thanks to Paul Irish for this useful feature.
Notice that RequestAnimFrame() is now preferred over setInterval() for concurrent animations, etc.
The animate() function goes through these steps:
Update: calculates the position & rotation required in this animation frame.
Clear: clears the canvas to make it ready for drawing
Draw: calls the draw() function which does the actual drawing
The draw() function: We draw both wheels using this same function—just changing the attributes. This follows an important programming concept of “DRY”—Don’t Repeat Yourself. Two wheels in a single function makes for easier debugging, more readable and more maintainable code.
<!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; }
canvas{border:1px solid red;}
</style>
<script>
$(function(){
var canvas=document.getElementById("canvas");
var ctx=canvas.getContext("2d");
window.requestAnimFrame = (function(callback) {
return window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame ||
function(callback) {
window.setTimeout(callback, 1000 / 60);
};
})();
var rotation=0;
var radius=50;
var x=50;
var y=100;
var direction=1;
function animate() {
// update
rotation+=10;
x+=1;
if(x-50>canvas.width){ x=0 }
// clear
ctx.clearRect(0, 0, canvas.width, canvas.height);
// draw stuff
draw(x,y,rotation,"red");
draw(x+150,y,rotation,"green");
// request new frame
requestAnimFrame(function() {
animate();
});
}
animate();
function draw(x,y,degrees,color){
var radians=degrees*(Math.PI/180);
ctx.save();
ctx.beginPath();
ctx.translate(x,y);
ctx.rotate(radians);
ctx.fillStyle="black";
ctx.strokeStyle="gray";
ctx.arc(0, 0, radius, 0 , 2 * Math.PI, false);
ctx.fill();
ctx.stroke();
ctx.beginPath();
ctx.strokeStyle=color;
ctx.lineWidth=5;
ctx.moveTo(-20,0);
ctx.lineTo(+20,0);
ctx.stroke();
ctx.restore();
}
}); // end $(function(){});
</script>
</head>
<body>
<canvas id="canvas" width=400 height=200></canvas>
</body>
</html>