The save function

• What is saved by the save function?
• An example

The save function saves the state of the canvas. It is most commonly used when using the clip function - so that you can save the state of the canvas, clip it, do some drawing whilst the canvas is clipped and then restore the canvas to as it was before the canvas was clipped, allowing you to draw freely again.

An example of the save function can be found in the page explaining the clip function .

What is saved by the save function?

The following settings are saved by the save function (and also are subsequently restored when you call restore):

• The current transformation matrix (ie the translation, rotation and scale settings)
• The clipping region
• The following settings: strokeStyle, fillStyle, globalAlpha, lineWidth, lineCap, lineJoin, miterLimit, shadowOffsetX, shadowOffsetY, shadowBlur, shadowColor, globalCompositeOperation, font, textAlign, textBaseline, imageSmoothingEnabled (imageSmoothingEnabled is a recent addition so may not be supported).

An example

Here the canvas is first saved, then clipped to a small rectangle (but not stroked or filled). Then a bigger rectangle is drawn - though because the canvas is clipped the only thing that is seen is the clipped area. Then, using the restore function, the canvas is returned to the state it was in before it was clipped.

This demonstrates how the canvas state can be saved and then subsequently restored.

<script>
    window.onload = function ()
    {
        var canvas  = document.getElementById("cvs");
        var context = canvas.getContext('2d');
    
        context.save();
            
            context.beginPath();
            context.rect(50,50,50,50);
            context.clip();
    
            context.fillRect(0,0,600,250);
    
        context.restore();
    }
</script>