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HTML5 Canvas - Using Images
This tutorial would show how to import and external image into a canvas and then how to draw on that image by using following methods:
SN | Method and Description |
1 | beginPath() This method resets the current path. |
2 | moveTo(x, y) This method creates a new subpath with the given point. |
3 | closePath() This method marks the current subpath as closed, and starts a new subpath with a point the same as the start and end of the newly closed subpath. |
4 | fill() This method fills the subpaths with the current fill style. |
5 | stroke() This method strokes the subpaths with the current stroke style. |
6 | drawImage(image, dx, dy) This method draws the given image onto the canvas. Here image is a reference to an image or canvas object. x and y form the coordinate on the target canvas where our image should be placed. |
Example:
Following is a simple example which makes use of above mentioned methods to import an draw on an image.
<!DOCTYPE HTML>
<html>
<head>
<script type="text/javascript">
function drawShape(){
// get the canvas element using the DOM
var canvas = document.getElementById('mycanvas');
// Make sure we don't execute when canvas isn't supported
if (canvas.getContext){
// use getContext to use the canvas for drawing
var ctx = canvas.getContext('2d');
// Draw shapes
var img = new Image();
img.src = '/images/backdrop.jpg';
img.onload = function(){
ctx.drawImage(img,0,0);
ctx.beginPath();
ctx.moveTo(30,96);
ctx.lineTo(70,66);
ctx.lineTo(103,76);
ctx.lineTo(170,15);
ctx.stroke();
}
} else {
alert('You need Safari or Firefox 1.5+ to see this demo.');
}
}
</script>
</head>
<body onload="drawShape();">
<canvas id="mycanvas"></canvas>
</body>
</html>
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Assuming we have following image to import images/backdrop.jpg.
The above example would draw following shape:
To learn above concept - Do Online Practice using latest version of either Safari or Opera.
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