Bugs in QwtMatrixRasterData?

[alex_sh]

Hello,

I encountered 3 bugs in (or related to) QwtMatrixRasterData (I'm using Qwt6 SVN). My emails always get lost on sourceforge so I'm writing this here.
I'm attaching a screenshot and a modified "rasterview" example to demonstrate.

1. There seems to be a bug with Bilinear interpolation. I get these mosaic-like pictures (nearest-neighbor looks ok). Seems to be dependent on intervals and number of matrix elements. See attached screenshot, segment 2 (top right).

2. There seems to be a bug when QwtMatrixRasterData's default pixelHint() implementation is used as it is. Randomly colored lines start to appear at interval borders (see picture segments 1 and 4). They're not always visible, but usually appear at the top and right sides, usually when zooming. Overriding pixelHint() in QwtMatrixRasterData's child class and returning QRectF() fixes this problem (see the commented block in the example), BUT introduces another one, which is probably a hidden bug because of QwtMatrixRasterData's default pixelHint():

3. If returning QRectF() from QwtMatrixRasterData's pixelHint(), a solid line (with a small corner to the right) appears to at top of the interval. I overrode QwtMatrixRasterData's value() function and did a range check before getting the data from QVector, and it seems to have helped. So I guess it's an out-of-bounds problem.

Thanks,
Alexander

qwt_matrix_bugs.jpg
rasterview_modified.tar.gz

[Uwe]

1 is fixed in SVN trunk, but I couldn't reproduce the bugs described in 2 and 3 ?

Uwe