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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. |
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> |
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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