iss-1881: Better handling for moving frames beyond the track cell area

[MrStevns]

This fixes #1881

Instead of moving keyframes back to where they were, the frames will now be shifted to the right until there's room for all selected frames.

[J5lx]

Ok so this fix seems to work just as described (except that it also affects frames being moved on top of other frames, but I assume that’s intended), however I’m a little confused why it requires so much work. To me it seems like the simplified diff below would essentially have the same effect, yet you must have had a reason to go with the more involved approach. Do you still remember what it is that necessitates the extra work?

diff --git a/core_lib/src/structure/layer.cpp b/core_lib/src/structure/layer.cpp
index c05ca919..09ad6bde 100644
--- a/core_lib/src/structure/layer.cpp
+++ b/core_lib/src/structure/layer.cpp
@@ -640,10 +640,11 @@ bool Layer::moveSelectedFrames(int offset)
         step = 1;
 
         // Check if we are not moving out of the timeline
-        if (mSelectedFrames_byPosition[0] + offset < 1) return false;
+        if (mSelectedFrames_byPosition[0] + offset < 1) offset = 1 - mSelectedFrames_byPosition[0];
     }
 
-    if (!canMoveSelectedFramesToOffset(offset)) { return false; }
+    while (!canMoveSelectedFramesToOffset(offset)) { offset += 1; }
+    if (offset == 0) { return false; }
 
     for (; indexInSelection > -1 && indexInSelection < mSelectedFrames_byPosition.count(); indexInSelection += step)
     {

[MrStevns]

Thanks for reviewing Jakob. If there was a reason for making it so elaborated, I cannot remember it anymore.

Your suggested diff does indeed work. I don't see a reason to complicate the logic further if we can avoid it. I'll revert my changes and apply yours instead.

[J5lx]

Well, alright then! Thanks for double checking.