The user wanted the image content to be readable (not X-flipped).
The X-swap arrangement (canvasX = -perp + ...) already places east
tiles on the right side of the screen, so the X arrangement
reads naturally left to right without needing the image to be
flipped.
The image is now drawn with positive width and height, so
place names, street names, and the coordinates labels (x=NNN,
y=NNN) are all readable. The X-swap arrangement positions the
tiles so that:
- west tiles (low x) drawn at canvas left
- east tiles (high x) drawn at canvas right
So the X coordinates increase left to right when reading the
corridor from screen left to screen right.
Richard Zink
97e37e065a