AGS: Zniw Adventure issues and crash (segmentation fault)

[antoniou79]

This is tested on Windows 10 x64 21H2 (19044.1620) using ScummVM latest development build from master (2.6.0git)

I'm logging the issues I've experience in the game that also exist in the demo that is available on the IndieDB web site (​https://www.indiedb.com/games/zid-zniw-chronicles-zniw-adventure/downloads).

In short the issues are:

• A segmentation fault in the "Extras" in-game option.
• Fonts or glyphs looking different (bolder or more cleanly defined) than when running the game or demo without ScummVM.
• Main character's outline is also more bold and cleanly defined when running the game or demo without ScummVM
• There's a glitch happening in the in-game Credits, when moving to the next credit screen.

Steps to reproduce the *segmentation fault* issue:

• Launch the game, choose a language from the start screen
• Start the game proper (in the demo choose one of the "Forest Demo" or "Cave Demo).
• when you gain control of the main character, press Esc to bring the native in-game menu.
• Click on the "Extras" option. The segmentation fault may happen immediately at this point, but it may not and the Extras dialogue window will be displayed.
• If the Extras dialogue window is displayed, move or click randomly the cursor around within that window. The segmentation fault occurs always for me -- I'm not sure if it's an exact spot or area that triggers it.

Debugging the segmentation fault issue with Visual Studio points to putpixel() from engines\ags\lib\allegro\gfx.cpp, when its x, y argument values are outside the width, height limits. This putpixel() call is done by alfont_textout_ex() in engines\ags\lib\alfont\alfont.cpp.

Putting a CLIP in the two lines here:
​https://github.com/scummvm/scummvm/blob/d719e83783a530e6e272ddd0207edaf33fb37ed0/engines/ags/lib/alfont/alfont.cpp#L2177
fixes the segfault, but this may not be the right solution -- since it causes some new glitches in the credits (not shown in this ticket).

I am attaching screenshots from the rest of the issues (bad font rendering, bad character outline, credits glitch).

Note: The issue with in-game fonts black outline not being drawn below the glyph's "baseline" was fixed by one the commits by DreamMaster, a few weeks ago, in the process of synching the AGS engine with upstream code.