#577 BITLOAD cannot load top-down bitmap images

[David Costanzo]

A BMP file (Windows device independent bitmap) can be stored top-down so that the top line of the image is at the beginning. Internally, the is specified by giving a negative height. When FMSLogo tries to load such an image, it does nothing. This is true for both BITLOAD and the Bitmap -> Load... menu item. Furthermore BITLOADSIZE returns a negative height instead of a positive height.

I found this when writing regression tests using the bmptestsuite. No one has ever reported this, so I expect that top-down images are uncommon.

How Reproducible:
Every Time

Steps to Reproduce:

1. Download the attached file.
2. Start FMSLogo
3. SHOW BITLOADSIZE "32bpp-towdown-320x240.bmp
4. BITLOAD "32bpp-towdown-320x240.bmp
5. Bitmap -> Load... and load the file.

What Happens:
In Step 3, the size is output as [320 -240].
In Step 4 and 5, no image is drawn in FMSLogo.

Expected Result:
In Step 3, the size is output as [320 240].
In Step 4 and 5, an image with three color bands is drawn at the turtle's location. The words "TOP LEFT" appear in the top left corner of the image.

[David Costanzo]

I have reproduced this on MSWLogo 6.5b, so it's not a regression in FMSLogo.

[David Costanzo]

I have fixed this by updating the bitmap reading logic to use wxImage to load the bitmap. This will be available in FMSLogo 8.3.0.