FMSLogo Code

Add bilinear interpolation when drawing rotated sprites. This is very slow, but otherwise the sprites look terrible when rotated at oblique angles.

Add special cases when drawing sprints of rotations of 90, 180, and 270 degrees to make sure that the sine and cosine are exactly as they should be, and not slightly off due to the imprecision of the trig functions in Borland's libc. This was done to get crisp-looking bitmaps at those angles.

Add support for rotating bitmapped turtles, called "sprites". The implementation is a bit slow, clumsy, and doesn't quite solve everything it was supposed to solve. This will remain an undocumented and unsupported feature until these problems are taken care of.

Refactoring: Centralize the logic for computing the turtle's bounding box in ibmturt(), now that I better understand what it is doing and why.

Simplify ibmturt() a bit by keeping the bounding box in screen coordinates, rather than mapping it to world coordinates, then mapping it back. This has a small gain in performance (measured by benchmark.lgo), but the main motivation was to make it easier to later centralize the way bounding boxes are computed in turtlepaste() and ibmturt().

Update to include latest translation from Theodoros, particularly for Redo.

Fix bug #1602855; Scolling the main window when zoomed now tracks the scrollbar's position (the screen slides as you scroll the tracker).

This was fixed by removing some special logic that inhibited tracking while scrolled. I don't know why George intentionally disabled this. The only thing I can think of is performance, but I tested this on a 90 MHz Pentium running Windows 95 and the performance was fine.

Anyway, I may later learn that I regressed something by fixing this bug.

Fix bug #2813670; OK and Cancel buttons for SELECTBOX no longer have access keys. This was unnecessary because they have shortcuts (Enter and Esc).

Fix a typo.

Fix bug #1327775; FMSLogo now cleans up the "turtle traces" (when parts of the turtle are drawn outside the turtle's drawable area). The fix is to blank out any part of the update region that is outside the drawable area in the WM_PAINT handler.