Graphics internal formats
The graphics library stores pixels in a small set of internal formats and then
converts to the platform backend as needed. Backend code should treat the
internal format as a contract, not as a suggestion, because SCREEN modes,
SCREENSET, image buffers, palette handling, and driver updates all depend on it.
What to watch
If a backend needs a native surface format that differs from the FreeBASIC
format, do the conversion at the backend boundary. Do not let backend-specific
pixel assumptions leak back into shared graphics code.
The graphics library stores pixels in a small set of internal formats and then
converts to the platform backend as needed. Backend code should treat the
internal format as a contract, not as a suggestion, because SCREEN modes,
SCREENSET, image buffers, palette handling, and driver updates all depend on it.
What to watch
Preserve byte order and pitch calculations.
Keep palette modes separate from true-color modes.
Avoid assuming that the visible window size equals the framebuffer size.
Test mode changes, SCREENSET pages, fullscreen/maximized/windowed cases, and
mouse coordinate scaling on the backend being changed.
Backend ruleKeep palette modes separate from true-color modes.
Avoid assuming that the visible window size equals the framebuffer size.
Test mode changes, SCREENSET pages, fullscreen/maximized/windowed cases, and
mouse coordinate scaling on the backend being changed.
If a backend needs a native surface format that differs from the FreeBASIC
format, do the conversion at the backend boundary. Do not let backend-specific
pixel assumptions leak back into shared graphics code.