Canvas: Difference between revisions
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The [[wikipedia:Canvas element|canvas]] tag was introduced by Apple and has been [http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html standardized to become part of HTML5]. | The [[wikipedia:Canvas element|canvas]] tag was introduced by Apple and has been [http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html standardized to become part of HTML5]. | ||
Get the canvas tag: | Get the canvas tag: | ||
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</canvas> | </canvas> | ||
== | == Links == | ||
* http://developer.mozilla.org/en-US/docs/Canvas_tutorial | * [http://developer.mozilla.org/en-US/docs/Canvas_tutorial Mozilla Tutorial] | ||
* http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html | * [http://www.whatwg.org/specs/web-apps/current-work/multipage/the-canvas-element.html The official specification] | ||
* [http://www.effectgames.com/demos/canvascycle/ An example for color cycling with the canvas element] | |||
Revision as of 16:50, 25 September 2012
The canvas tag was introduced by Apple and has been standardized to become part of HTML5.
Get the canvas tag:
c=document.getElementById("c")
Get the "context" (like a paper):
p=c.getContext("2d");
Draw something!
p.fillRect(0, 0, 100, 100);
Examples
Here is a complete HTML page with a working canvas:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<script>
function draw(){
c = document.getElementById("canvas")
//console.log("c is",c)
p = c.getContext("2d")
x = 10
while (x<300) {
p.strokeRect(x,100,20,40)
x+=60
}
}
</script>
</head>
<body onload="draw()">
<h1>Hello canvas</h1>
<canvas id="canvas" width="640" height="640" style="border: 3px dotted red"></canvas>
</body>
</html>
Here's the output:
<canvas id="c1"> function draw(){
c = document.getElementById("c1")
//console.log("c is",c)
p = c.getContext("2d")
x = 10
while (x<250) {
p.strokeRect(x,100,20,40)
x+=60
}
} </canvas>
Variation: When the loop reaches the end of page it breaks the line. It redefines the "x" value to the begin of the line and adds 40px to "y".
<canvas id="c2" width="300" height="300" showsrc="true"> function draw() {
c = document.getElementById("c2");
p = c.getContext("2d");
hands = 1;
x = 20;
y = 20;
while (hands < 100) {
//console.log(hands);
p.strokeRect(x,y,20,20);
x = x + 50;
hands++;
if (x > 600) {
x = 20;
y = y + 40;
}
}
} </canvas>