I have no idea what radar means as you describe it. At first thought I pictured a rotating line sweeping over the canvas, but you talk like you want some sort of locator grid, superimposed on the geotiff. This all sounds pretty complex, and at the very least you will need to show a basic code sample of what you want to do.

From your ideas, it sounds like you are making it too complicated with overlays. What you need to do is setup a coordinate-transformation system, between your geotiff and the canvas. Then just put a blinking red-dot at that point, and move it as needed.

The difficult part is figuring out the formulas to match the geotiff to the canvas, and I have no idea what geotiff does. Does it define the latitude and longitude of it's corners with smooth gradations from corner to corner? That is the sort of thing you will need to figure out.

As far as pixel size goes, I bellieve you would just do your calculations as a 1-1 pixel size, then when done multiply the x y values by the current zoom level. I havn't tested that.... the zoom may work automagically.

I'm not really a human, but I play one on earth CandyGram for Mongo

In reply to Re: Radar and Goo::Canvas by zentara
in thread Radar and Goo::Canvas by deadpickle

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