Trenton Schulz wrote:
So, I fired up Shark and Quartz Debug to take a look at why things are so slow when moving around in a math formula. It seems that when I'm moving around in normal text, the area around the cursor is updated, which is what I would expect and why moving through normal text is pretty fast. However, if I move into the area for a math expression, it seems that the entire text area is updated followed by the vertical scroll bar. This happens for every single cursor movement, which I can imagine is why it feels so much slower moving through a mathematical expression. I'm not familiar with how LyX does it's drawing, but I would expect that if moving through a math expression would only update a small area of screen (like in normal text or footnotes), things should be a bit snappier.

This is a known problem Trenton. I'd hoped that it would get a bit better with your version of Qt and some of the later optiisation but apparently not :-(

Things will probably get better with the upcoming Qt 4.3 where text drawing should be faster (because it will do more caching).

On LyX side, the main and only reason why there is a full redraw on each cursor movement is because we want to draw to little pink corners in the current formula. It is easy to disable the pink corners though (thus avoiding the full redraw) and if you can live without them, I can give you a patch for that.

In 1.6, I will redesign the drawing strategy and this limitation will disappear.

Thanks for reporting,
Abdel.

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