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How to save and restore the HTML5 Canvas states?

HTML5 canvas provides two important methods to save and restore the canvas states.

Canvas states are stored on a stack every time the save method is called, and the last saved state is returned from the stack every time the restore method is called.

Sr.No.
Method and Description
1
save()
This method pushes the current state onto the stack..
2
restore()
This method pops the top state on the stack, restoring the context to that state.                                                              

Example

You can try to run the following code to save and restore HTML5 Canvas −

<!DOCTYPE HTML>
<html>
   <head>
      <style>
         #test {
            width: 100px;
            height:100px;
            margin: 0px auto;
         }
      </style>
      <script>
         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 a rectangle with default settings
               ctx.fillRect(0,0,150,150);
               
               // Save the default state
               ctx.save();
               
               // Make changes to the settings
               ctx.fillStyle = '#66FFFF'
               ctx.fillRect( 15,15,120,120);
               
               // Save the current state
               ctx.save();
               
               // Make the new changes to the settings
               ctx.fillStyle = '#993333'
               ctx.globalAlpha = 0.5;
               ctx.fillRect(30,30,90,90);
               
                // Restore previous state
               ctx.restore();
               
               // Draw a rectangle with restored settings
               ctx.fillRect(45,45,60,60);
               
               // Restore original state
               ctx.restore();
               
               // Draw a rectangle with restored settings
               ctx.fillRect(40,40,90,90);
            } else {
               alert('You need Safari or Firefox 1.5+ to see this demo.');
            }
         }
      </script>
   </head>
   <body id = "test" onload = "drawShape();">
      <canvas id = "mycanvas"></canvas>
   </body>
</html>
Updated on 25-Jun-2020 07:37:05

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