What would be the best way?

[David Laplante]

I want to make a geographical statistics application that would show a map and draw some colors on it depending on the density of each section of the map.

What I supose I would do is divide that map in smaller sectors (40 Squares X 40 Squares for example) and for each entry of a statistic, a coordinate would be assigned to it. Then when I would draw it, I would set the transparency of ,let's say, red to represent the density of the statistic for that coordinate on the map.

I know that I could use BitBlt or DDraw (maybe something else, let me know)... But I have no idea if this is in fact possible and how I could alter an image.

Any suggestions or exemples?

[PaulLewis]

If the distribution of statistics is such that you are not likely to get two hot spots very close to each other, then I would recommend you start simple as follows:

Use a PictureBox for your bitmap. You may need scrollbars on it if it is bigger than the form you want to use. Search the forum for many solutions to that question...

Use simple non directx/non API methods to draw directly onto the bitmap. (Make sure the picture box has the autoredraw property = true).

I would use the Circle method to represent the data. The radius could indicate density and the the colour could give some other information. Depending on the amount of data likely in hot spots, you could use a logarithmic scale for the circle radius otherwise a simple linear relationship to the area of the circle would be best.

It would help if you could advise what sort of data you have. Is it population, resource availability, ozone levels...and the ranges. I was thinking about writing a control for a project I am working on in which the customer wants a graph showing a map of the country, split into provinces, and the numbers of faults logged for each province.

Excel does this already I believe, but we need it in a VB app. (I'm too cheap to pay for any charting controls)

Anyhow, I hope it helps in some way.
Cheers