Improve arrow key navigation for right-to-left languages

While using right-to-left languages most of Dolphin is mirrored.
However, the logic of what happens when the arrow keys are pressed to
move between items in the main view was never adapted to account for
that. Basically nothing works as expected because of this. It's more
like dealing with a psychopath who misinterprets every command you give:
Left is right, right is left, up is most of the time right but sometimes
not, down is most the time left but sometimes not.

This commit fixes and adapts the logic if a right-to-left layout is used.
This fully fixes icon view mode and improves compact view mode, though
compact view mode still has more issues which aren't addressed here.

This work for the benefit of the minority that use right-to-left
languages both in Europe and the world is sponsored by NLnet and the
European Commission which I think is beautfiul.

BUG: 453933

1 files changed, 28 insertions, 4 deletions

diff --git a/src/kitemviews/kitemlistcontroller.cpp b/src/kitemviews/kitemlistcontroller.cpp
index 60f23c1db..b4d28047e 100644
--- a/src/kitemviews/kitemlistcontroller.cpp
+++ b/src/kitemviews/kitemlistcontroller.cpp
@@ -295,6 +295,20 @@ bool KItemListController::keyPressEvent(QKeyEvent *event)
         }
     }
 
+    // For right to left languages, exchange right and left arrow keys.
+    if (m_view->layoutDirection() == Qt::RightToLeft) {
+        switch (key) {
+        case Qt::Key_Left:
+            key = Qt::Key_Right;
+            break;
+        case Qt::Key_Right:
+            key = Qt::Key_Left;
+            break;
+        default:
+            break;
+        }
+    }
+
     const bool selectSingleItem = m_selectionBehavior != NoSelection && itemCount == 1 && navigationPressed;
 
     if (selectSingleItem) {
@@ -1470,9 +1484,12 @@ int KItemListController::nextRowIndex(int index) const
         return index;
     }
 
+    const bool leftToRight = m_view->layoutDirection() != Qt::RightToLeft;
+
     // Calculate the index of the last column inside the row of the current index
     int lastColumnIndex = index;
-    while (keyboardAnchorPos(lastColumnIndex + 1) > keyboardAnchorPos(lastColumnIndex)) {
+    while ((leftToRight && keyboardAnchorPos(lastColumnIndex + 1) > keyboardAnchorPos(lastColumnIndex))
+           || (!leftToRight && keyboardAnchorPos(lastColumnIndex + 1) < keyboardAnchorPos(lastColumnIndex))) {
         ++lastColumnIndex;
         if (lastColumnIndex >= maxIndex) {
             return index;
@@ -1484,7 +1501,9 @@ int KItemListController::nextRowIndex(int index) const
     int nextRowIndex = lastColumnIndex + 1;
     int searchIndex = nextRowIndex;
     qreal minDiff = qAbs(m_keyboardAnchorPos - keyboardAnchorPos(nextRowIndex));
-    while (searchIndex < maxIndex && keyboardAnchorPos(searchIndex + 1) > keyboardAnchorPos(searchIndex)) {
+    while (searchIndex < maxIndex
+           && ((leftToRight && keyboardAnchorPos(searchIndex + 1) > keyboardAnchorPos(searchIndex))
+               || (!leftToRight && keyboardAnchorPos(searchIndex + 1) < keyboardAnchorPos(searchIndex)))) {
         ++searchIndex;
         const qreal searchDiff = qAbs(m_keyboardAnchorPos - keyboardAnchorPos(searchIndex));
         if (searchDiff < minDiff) {
@@ -1502,9 +1521,12 @@ int KItemListController::previousRowIndex(int index) const
         return index;
     }
 
+    const bool leftToRight = m_view->layoutDirection() != Qt::RightToLeft;
+
     // Calculate the index of the first column inside the row of the current index
     int firstColumnIndex = index;
-    while (keyboardAnchorPos(firstColumnIndex - 1) < keyboardAnchorPos(firstColumnIndex)) {
+    while ((leftToRight && keyboardAnchorPos(firstColumnIndex - 1) < keyboardAnchorPos(firstColumnIndex))
+           || (!leftToRight && keyboardAnchorPos(firstColumnIndex - 1) > keyboardAnchorPos(firstColumnIndex))) {
         --firstColumnIndex;
         if (firstColumnIndex <= 0) {
             return index;
@@ -1516,7 +1538,9 @@ int KItemListController::previousRowIndex(int index) const
     int previousRowIndex = firstColumnIndex - 1;
     int searchIndex = previousRowIndex;
     qreal minDiff = qAbs(m_keyboardAnchorPos - keyboardAnchorPos(previousRowIndex));
-    while (searchIndex > 0 && keyboardAnchorPos(searchIndex - 1) < keyboardAnchorPos(searchIndex)) {
+    while (searchIndex > 0
+           && ((leftToRight && keyboardAnchorPos(searchIndex - 1) < keyboardAnchorPos(searchIndex))
+               || (!leftToRight && keyboardAnchorPos(searchIndex - 1) > keyboardAnchorPos(searchIndex)))) {
         --searchIndex;
         const qreal searchDiff = qAbs(m_keyboardAnchorPos - keyboardAnchorPos(searchIndex));
         if (searchDiff < minDiff) {