HTML5 Canvas - Using Images


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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 −

Sr.No. 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>

It will produce the following result −


html5_canvas.htm

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