QwtRasterData and values

[Uwe]

The map is somewhere allocated in your application code. It's up to the application code to take care of its lifetime. Also check the indices before accessing your map and double arrays - without setting the bounding rect you can be sure to see requests for positions you don't have.

Note, that SpectrogramData::value() is called very often ( for each pixel of your plot canvas: width * height ). So better don't use a QMap. Returning a rasterHint should be useful as well.

Uwe

[jcox23]

The map is somewhere allocated in your application code. It's up to the application code to take care of its lifetime.

Yes it is created outside the code, I cant afford copying it around, it can be big, and there's several of them...RAM usage could quickly explode...

Also check the indices before accessing your map and double arrays - without setting the bounding rect you can be sure to see requests for positions you don't have.

Yes turns out it was just that, a position request was outside the boundaries of my map...

Note, that SpectrogramData::value() is called very often ( for each pixel of your plot canvas: width * height ). So better don't use a QMap. Returning a rasterHint should be useful as well.
Uwe

I know, but QMap is just very convenient in my case, i have series of vectors (double) keyed by integers that are not linearly increasing....
QHash would be probably a bit faster, is that what you were thinking about or even going further than that by using a more low level container... like a long flatten array for example?