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There are following methods required to draw quadratic curve 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 | quadraticCurveTo(cpx, cpy, x, y) This method adds the given point to the current path, connected to the previous one by a quadratic Bezier curve with the given control point. |
The x and y parameters in quadraticCurveTo() method are the coordinates of the end point. cpx and cpy are the coordinates of the control point.
Following is a simple example which makes use of above mentioned methods to draw a Quadratic curves.
<!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 ctx.beginPath(); ctx.moveTo(75,25); ctx.quadraticCurveTo(25,25,25,62.5); ctx.quadraticCurveTo(25,100,50,100); ctx.quadraticCurveTo(50,120,30,125); ctx.quadraticCurveTo(60,120,65,100); ctx.quadraticCurveTo(125,100,125,62.5); ctx.quadraticCurveTo(125,25,75,25); 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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