You can do some really impressive charting this way, which a lot of companies pay a lot of money for. Your canvas would then be more like a view-port. Plus, you can draw outside of your canvas, it just won't be visible. If a data point was a certain percentage of a way across a chart, it can be drawn at any size.

Instead, use the percentages for size (like I showed you) and use the values for left and top positioning as starting points in your drawing. Your page can get jumbled up and sloppy that way.

More importantly though, I do not suggest that you ever re-size and re-position your canvas on zoom. If you canvas was holding data points (like a chart) then I would suggest that you make your data points have percentage like (probably a word for that) positions along your chart, not pixel positions. If your canvas was holding an image, then that's simple, redraw that image at that size. Remember, any time that you re-size a canvas, you clear the canvas. Now that your canvas has been re-sized, you will need to redraw whatever was in it. = (evt.layerY - ) įor(iiDS = 0 iiDS < iiDS++) Now, I'm going to write a quick function to retrieve the zoom, then I'll explain it. Next, I set an event listener on my canvas to watch for mousewheel.

The zoom level will be adjusted by this amount every time that the zoom event occurs. I also retain the original left and top of the canvas for reference. I also retain the original size of the canvas for reference. First of all, I set a zoom level attribute on my canvas.

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