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HTML5 Canvas - Pattern and Shadow
Create Pattern:
There is following method required to create a pattern on the canvas:
SN | Method and Description |
1 | createPattern(image, repetition) This method will use image to create the pattern. The second argument could be a string with one of the following values: repeat, repeat-x, repeat-y, and no-repeat. If the empty string or null is specified, repeat will. be assumed |
Example:
Following is a simple example which makes use of above mentioned method to create a nice pattern.
<!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');
// create new image object to use as pattern
var img = new Image();
img.src = 'images/pattern.jpg';
img.onload = function(){
// create pattern
var ptrn = ctx.createPattern(img,'repeat');
ctx.fillStyle = ptrn;
ctx.fillRect(0,0,150,150);
}
} 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 pattern images/pattern.jpg.
The above example would draw following result:
To learn above concept - Do Online Practice using latest version of either Safari or Opera.
Create Shadows:
HTML5 canvas provides capabilities to create nice shadows around the drawings. All drawing operations are affected by the four global shadow attributes
SN | Property and Description |
1 | shadowColor [ = value ] This property returns the current shadow color and can be set, to change the shadow color. |
2 | shadowOffsetX [ = value ] This property returns the current shadow offset X and can be set, to change the shadow offset X. |
3 | shadowOffsetY [ = value ] This property returns the current shadow offset Y and can be set, change the shadow offset Y. |
4 | shadowBlur [ = value ] This property returns the current level of blur applied to shadows and can be set, to change the blur level. |
Example:
Following is a simple example which makes use of above mentioned attributes to draw a shadow.
<!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');
ctx.shadowOffsetX = 2;
ctx.shadowOffsetY = 2;
ctx.shadowBlur = 2;
ctx.shadowColor = "rgba(0, 0, 0, 0.5)";
ctx.font = "20px Times New Roman";
ctx.fillStyle = "Black";
ctx.fillText("This is shadow test", 5, 30);
} 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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The above example would produce following result:
To learn above concept - Do Online Practice using latest version of either Safari or Opera.
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