ListWidget: Dragging before/after an item

It's useful to make a distinction whether a drag ended before or after an item, even if it's still referring to the same boundary between items.

This allows bookmarks to be reordered inside a folder so that an item is moved to the bottom of a folder, or out of the folder following it in order.

2 files changed, 39 insertions, 23 deletions

diff --git a/src/ui/listwidget.c b/src/ui/listwidget.c
index 652393ff..6bb53f2b 100644
--- a/src/ui/listwidget.c
+++ b/src/ui/listwidget.c
@@ -321,7 +321,14 @@ static void updateHover_ListWidget_(iListWidget *d, const iInt2 mouse) {
     setHoverItem_ListWidget(d, hover);
 }
 
-static size_t resolveDragDestination_ListWidget_(const iListWidget *d, iInt2 dstPos, iBool *isOnto) {
+enum iDragDestination {
+    before_DragDestination,
+    on_DragDestination,
+    after_DragDestination
+};
+
+static size_t resolveDragDestination_ListWidget_(const iListWidget *d, iInt2 dstPos,
+                                                 enum iDragDestination *dstKind) {
     size_t           index = itemIndex_ListWidget(d, dstPos);
     const iListItem *item  = constItem_ListWidget(d, index);
     if (!item) {
@@ -333,15 +340,17 @@ static size_t resolveDragDestination_ListWidget_(const iListWidget *d, iInt2 dst
     if (item->isDropTarget) {
         const int pad = size_Range(&span) / 4;
         if (dstPos.y >= span.start + pad && dstPos.y < span.end - pad) {
-            *isOnto = iTrue;
+            *dstKind = on_DragDestination;
             return index;
         }
     }
+    int delta = dstPos.y - top_Rect(rect);
     if (dstPos.y - span.start > span.end - dstPos.y) {
         index++;
+        delta -= d->itemHeight;
     }
     index = iMin(index, numItems_ListWidget(d));
-    *isOnto = iFalse;
+    *dstKind = delta < 0 && index > 0 ? after_DragDestination : before_DragDestination;
     return index;
 }
 
@@ -350,14 +359,16 @@ static iBool endDrag_ListWidget_(iListWidget *d, iInt2 endPos) {
         return iFalse;
     }
     stop_Anim(&d->scrollY.pos);
-    iBool isOnto;
-    const size_t index = resolveDragDestination_ListWidget_(d, endPos, &isOnto);
+    enum iDragDestination dstKind;
+    const size_t index = resolveDragDestination_ListWidget_(d, endPos, &dstKind);
     if (index != d->dragItem) {
-        if (isOnto) {
+        if (dstKind == on_DragDestination) {
             postCommand_Widget(d, "list.dragged arg:%zu onto:%zu", d->dragItem, index);
         }
         else {
-            postCommand_Widget(d, "list.dragged arg:%zu before:%zu", d->dragItem, index);
+            postCommand_Widget(d, "list.dragged arg:%zu %s:%zu", d->dragItem, 
+                               dstKind == after_DragDestination ? "after" : "before",
+                               dstKind == after_DragDestination ? index - 1 : index);
         }
     }
     invalidateItem_ListWidget(d, d->dragItem);
@@ -571,19 +582,19 @@ static void draw_ListWidget_(const iListWidget *d) {
         const iRect itemRect = { init_I2(left_Rect(bounds), pos.y),
                                  init_I2(d->visBuf->texSize.x, d->itemHeight) };
         SDL_SetRenderDrawBlendMode(renderer_Window(get_Window()), SDL_BLENDMODE_BLEND);
-        iBool dstOnto;
-        const size_t dstIndex = resolveDragDestination_ListWidget_(d, mousePos, &dstOnto);
+        enum iDragDestination dstKind;
+        const size_t dstIndex = resolveDragDestination_ListWidget_(d, mousePos, &dstKind);
         if (dstIndex != d->dragItem) {
             const iRect dstRect = itemRect_ListWidget(d, dstIndex);
             p.alpha = 0xff;
-            if (dstOnto) {
+            if (dstKind == on_DragDestination) {
                 drawRectThickness_Paint(&p, dstRect, gap_UI / 2, uiTextAction_ColorId);
             }
             else if (dstIndex != d->dragItem + 1) {
                 fillRect_Paint(&p, (iRect){ addY_I2(dstRect.pos, -gap_UI / 4),
                                             init_I2(width_Rect(dstRect), gap_UI / 2) },
                                uiTextAction_ColorId);
-            }
+            }                        
         }
         p.alpha = 0x80;
         setOpacity_Text(0.5f);
diff --git a/src/ui/sidebarwidget.c b/src/ui/sidebarwidget.c
index aaa6e9e9..4d229c59 100644
--- a/src/ui/sidebarwidget.c
+++ b/src/ui/sidebarwidget.c
@@ -1095,21 +1095,24 @@ static iBool handleSidebarCommand_SidebarWidget_(iSidebarWidget *d, const char *
     return iFalse;
 }
 
-static void bookmarkMoved_SidebarWidget_(iSidebarWidget *d, size_t index, size_t beforeIndex) {
+static void bookmarkMoved_SidebarWidget_(iSidebarWidget *d, size_t index, size_t dstIndex,
+                                         iBool isBefore) {
     const iSidebarItem *movingItem = item_ListWidget(d->list, index);
-    const iBool         isLast     = (beforeIndex == numItems_ListWidget(d->list));
+    const iBool         isLast     = (dstIndex == numItems_ListWidget(d->list));
     const iSidebarItem *dstItem    = item_ListWidget(d->list,
                                                      isLast ? numItems_ListWidget(d->list) - 1
-                                                            : beforeIndex);
+                                                            : dstIndex);
+    if (isLast && isBefore) isBefore = iFalse;
     const iBookmark *dst = get_Bookmarks(bookmarks_App(), dstItem->id);
-    if (hasParent_Bookmark(dst, movingItem->id)) {
+    if (hasParent_Bookmark(dst, movingItem->id) || hasTag_Bookmark(dst, remote_BookmarkTag)) {
+        /* Can't move a folder inside itself, and remote bookmarks cannot be reordered. */
         return;
     }
-    reorder_Bookmarks(bookmarks_App(), movingItem->id, dst->order + (isLast ? 1 : 0));
+    reorder_Bookmarks(bookmarks_App(), movingItem->id, dst->order + (isBefore ? 0 : 1));
     get_Bookmarks(bookmarks_App(), movingItem->id)->parentId = dst->parentId;
     updateItems_SidebarWidget_(d);
     /* Don't confuse the user: keep the dragged item in hover state. */
-    setHoverItem_ListWidget(d->list, index < beforeIndex ? beforeIndex - 1 : beforeIndex);
+    setHoverItem_ListWidget(d->list, dstIndex + (isBefore ? 0 : 1) + (index < dstIndex ? -1 : 0));
     postCommandf_App("bookmarks.changed nosidebar:%p", d); /* skip this sidebar since we updated already */
 }
 
@@ -1243,17 +1246,19 @@ static iBool processEvent_SidebarWidget_(iSidebarWidget *d, const SDL_Event *ev)
         }
         else if (isCommand_Widget(w, ev, "list.dragged")) {
             iAssert(d->mode == bookmarks_SidebarMode);
-            if (hasLabel_Command(cmd, "before")) {
-                bookmarkMoved_SidebarWidget_(d,
-                                             argU32Label_Command(cmd, "arg"),
-                                             argU32Label_Command(cmd, "before"));
-            }
-            else {
+            if (hasLabel_Command(cmd, "onto")) {
                 /* Dragged onto a folder. */
                 bookmarkMovedOntoFolder_SidebarWidget_(d,
                                                        argU32Label_Command(cmd, "arg"),
                                                        argU32Label_Command(cmd, "onto"));
             }
+            else {
+                const iBool isBefore = hasLabel_Command(cmd, "before");
+                bookmarkMoved_SidebarWidget_(d,
+                                             argU32Label_Command(cmd, "arg"),
+                                             argU32Label_Command(cmd, isBefore ? "before" : "after"),
+                                             isBefore);
+            }
             return iTrue;
         }
         else if (isCommand_Widget(w, ev, "menu.closed")) {