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HTML5 Canvas - Drawing Lines
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Line Methods:
There are following methods required to draw lines on the canvas:
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 | lineTo(x, y) This method adds the given point to the current subpath, connected to the previous one by a straight line. |
Example:
Following is a simple example which makes use of above mentioned methods to draw a triangle.
<!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');
// Filled triangle
ctx.beginPath();
ctx.moveTo(25,25);
ctx.lineTo(105,25);
ctx.lineTo(25,105);
ctx.fill();
// Stroked triangle
ctx.beginPath();
ctx.moveTo(125,125);
ctx.lineTo(125,45);
ctx.lineTo(45,125);
ctx.closePath();
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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The above example would draw following shape:
To learn above concept - Do Online Practice using latest version of either Safari or Opera.
Line Properties:
There are several properties which allow us to style lines.
SN | Property and Description |
1 | lineWidth [ = value ] This property returns the current line width and can be set, to change the line width. |
2 | lineCap [ = value ] This property returns the current line cap style and can be set, to change the line cap style. The possible line cap styles are butt, round, and square |
3 | lineJoin [ = value ] This property returns the current line join style and can be set, to change the line join style. The possible line join styles are bevel, round, and miter. |
4 | miterLimit [ = value ] This property returns the current miter limit ratio and can be set, to change the miter limit ratio. |
Example:
Following is a simple example which makes use of lineWidth property to draw lines of different width.
<!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');
for (i=0;i<10;i++){
ctx.lineWidth = 1+i;
ctx.beginPath();
ctx.moveTo(5+i*14,5);
ctx.lineTo(5+i*14,140);
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>
|
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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