How to Copy Contents of One Canvas to Another Canvas Locally

Digging deeper into drawImage

The drawImage method used here can accept a HTMLCanvasElement as its image source. This essentially eliminates the need for multiple transition steps, resulting in cutting-edge efficiency.

Do note that drawImage isn't just exclusive for canvases. It's pretty versatile, handling both HTMLImageElement and HTMLVideoElement like a charm.

The need for speed

Canvas operations can feel like participating in a 100 m Olympic sprint. drawImage takes the gold here, leaving ImageData objects far behind. Trade in pixel-by-pixel operations with this one-shot method for a performance boost.

If you're in a memory tight situation or chasing performance, consider drawImage as your go-to choice. This method is proudly brought to you by drawImage, the unofficial memory consumption management committee 🏋️‍♂️.

Copying canvas content via toDataURL and Image

When you need to transport your canvas between different execution contexts (like an overworked web worker to a well-rested main thread), turn to toDataURL - your canvas postman!

Here's a sneak peek:

let dataURL = sourceCanvas.toDataURL();
let image = new Image();
image.onload = function() {
    destinationCanvas.getContext('2d').drawImage(image, 0, 0); // Delivering canvas mail 📨
};
image.src = dataURL;
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Wait for the image to be fully loaded with onload before you start drawing. toDataURL gives you a "image/png" format, carrying the transparent package intact.

Mixing it up with alternative methods

drawImage and toDataURL are rockstars in the canvas cloning concert. But, if you fancy some resizing or transforming during the copy, drawImage can include that in its performance:

destCtx.drawImage(sourceCanvas, 0, 0, width, height); // Resize and roll 🎳


Try out different sizes or aspect ratios for a more tailored display.

Look to resources and benchmarks

When it comes to speed, jsPerf is the Usain Bolt of performance benchmarks: jsperf.com/copying-a-canvas-element. Compare and contrast different methods confidently.

Also, remember the nifty context.canvas retrieves the original canvas element from a context, like finding your misplaced keys in your own pocket 👖.