[multimedia/kdenlive/release/26.08] src/timeline2: Fix allowing 0 length composition causing crash

Git commit 3c360c62be755be4c74dcab0136aaea07a139137 by Jean-Baptiste Mardelle.
Committed on 22/07/2026 at 05:35.
Pushed by mardelle into branch 'release/26.08'.

Fix allowing 0 length composition causing crash
Related to #2218

M  +1    -3    src/timeline2/model/timelinemodel.cpp
M  +6    -2    src/timeline2/view/timelinecontroller.cpp

https://invent.kde.org/multimedia/kdenlive/-/commit/3c360c62be755be4c74dcab0136aaea07a139137

diff --git a/src/timeline2/model/timelinemodel.cpp b/src/timeline2/model/timelinemodel.cpp
index 3a8df7d359..547d83ba36 100644
--- a/src/timeline2/model/timelinemodel.cpp
+++ b/src/timeline2/model/timelinemodel.cpp
@@ -6239,6 +6239,7 @@ bool TimelineModel::requestCompositionInsertion(const QString &transitionId, int
     // TRACE(transitionId, trackId, position, length, transProps.get(), id, logUndo);
     Fun undo = []() { return true; };
     Fun redo = []() { return true; };
+    Q_ASSERT(length > 0);
     bool result = requestCompositionInsertion(transitionId, trackId, -1, position, length, std::move(transProps), id, undo, redo, logUndo);
     if (result && logUndo) {
         PUSH_UNDO(undo, redo, i18n("Insert Composition"));
@@ -6282,9 +6283,6 @@ bool TimelineModel::requestCompositionInsertion(const QString &transitionId, int
         return true;
     };
     bool res = requestCompositionMove(compositionId, trackId, compositionTrack, position, true, finalMove, local_undo, local_redo);
-    if (res) {
-        res = requestItemResize(compositionId, length, true, true, local_undo, local_redo, true);
-    }
     if (!res) {
         bool undone = local_undo();
         Q_ASSERT(undone);
diff --git a/src/timeline2/view/timelinecontroller.cpp b/src/timeline2/view/timelinecontroller.cpp
index 143d60f8ce..49e110df4a 100644
--- a/src/timeline2/view/timelinecontroller.cpp
+++ b/src/timeline2/view/timelinecontroller.cpp
@@ -637,16 +637,20 @@ int TimelineController::insertNewComposition(int tid, int clipId, int offset, QS
     bool isShortComposition = TransitionsRepository::get()->getType(transitionId) == AssetListType::AssetType::VideoShortComposition;
     if (duration < 0 || (isShortComposition && duration > 1.5 * defaultLength)) {
         duration = defaultLength;
-    } else if (duration <= 1) {
+    } else if (duration <= 1 && duration < clip_duration) {
         // if suggested composition duration is lower than 4 frames, use default
         duration = pCore->getDurationFromString(KdenliveSettings::transition_duration());
         if (minimumPos + clip_duration - position < 3) {
-            position = minimumPos + clip_duration - duration;
+            position = qMax(minimumPos, minimumPos + clip_duration - duration);
         }
     }
     QPair<int, int> finalPos = m_model->getTrackById_const(tid)->validateCompositionLength(position, offset, duration, endPos);
     position = finalPos.first;
     duration = finalPos.second;
+    if (duration == 0) {
+        pCore->displayMessage(i18n("Could not add composition at selected position"), ErrorMessage, 500);
+        return -1;
+    }
 
     std::unique_ptr<Mlt::Properties> props(nullptr);
     if (TransitionsRepository::get()->isLuma(transitionId)) {