From 6b868a8d4d7b9f0ac1efbb19284dfd2cb91aba84 Mon Sep 17 00:00:00 2001
From: Ingo Weyrich <heckflosse67@gmx.de>
Date: Tue, 30 Jul 2019 13:22:15 +0200
Subject: [PATCH] Make thumbnail range-selection more similar to OS behaviour,
 fixes #5393

---
 rtgui/filebrowser.cc      |  1 +
 rtgui/thumbbrowserbase.cc | 26 +++++++++++++-------------
 rtgui/thumbbrowserbase.h  |  1 +
 3 files changed, 15 insertions(+), 13 deletions(-)

diff --git a/rtgui/filebrowser.cc b/rtgui/filebrowser.cc
index cc215e70a..b968a285e 100644
--- a/rtgui/filebrowser.cc
+++ b/rtgui/filebrowser.cc
@@ -667,6 +667,7 @@ void FileBrowser::close ()
         MYWRITERLOCK(l, entryRW);
 
         selected.clear ();
+        anchor = nullptr;
 
         MYWRITERLOCK_RELEASE(l); // notifySelectionListener will need read access!
 
diff --git a/rtgui/thumbbrowserbase.cc b/rtgui/thumbbrowserbase.cc
index 53b5828aa..71f9e4a04 100644
--- a/rtgui/thumbbrowserbase.cc
+++ b/rtgui/thumbbrowserbase.cc
@@ -28,7 +28,7 @@
 using namespace std;
 
 ThumbBrowserBase::ThumbBrowserBase ()
-    : location(THLOC_FILEBROWSER), inspector(nullptr), isInspectorActive(false), eventTime(0), lastClicked(nullptr), previewHeight(options.thumbSize), numOfCols(1), arrangement(TB_Horizontal)
+    : location(THLOC_FILEBROWSER), inspector(nullptr), isInspectorActive(false), eventTime(0), lastClicked(nullptr), anchor(nullptr), previewHeight(options.thumbSize), numOfCols(1), arrangement(TB_Horizontal)
 {
     inW = -1;
     inH = -1;
@@ -162,30 +162,29 @@ inline void removeFromSelection (const ThumbIterator& iterator, ThumbVector& sel
 
 void ThumbBrowserBase::selectSingle (ThumbBrowserEntryBase* clicked)
 {
-    clearSelection (selected);
+    clearSelection(selected);
+    anchor = clicked;
 
-    if (clicked)
-        addToSelection (clicked, selected);
+    if (clicked) {
+        addToSelection(clicked, selected);
+    }
 }
 
 void ThumbBrowserBase::selectRange (ThumbBrowserEntryBase* clicked, bool additional)
 {
-    if (selected.empty()) {
+    if (selected.empty() && !anchor) {
         addToSelection(clicked, selected);
+        anchor = clicked;
         return;
     }
 
     if (!additional || !lastClicked) {
         // Extend the current range w.r.t to first selected entry.
-        ThumbIterator front = std::find(fd.begin(), fd.end(), selected.front());
-        ThumbIterator back;
-        ThumbIterator current = std::find(fd.begin(), fd.end(), clicked);
+        ThumbIterator back = std::find(fd.begin(), fd.end(), clicked);
+        ThumbIterator front = std::find(fd.begin(), fd.end(), anchor);
 
-        if (front > current) {
-            front = current;
-            back = std::find(fd.begin(), fd.end(), selected.back());
-        } else {
-            back = current;
+        if (front > back) {
+            std::swap(front, back);
         }
 
         clearSelection(selected);
@@ -217,6 +216,7 @@ void ThumbBrowserBase::selectSet (ThumbBrowserEntryBase* clicked)
     } else {
         addToSelection (clicked, selected);
     }
+    anchor = clicked;
 }
 
 static void scrollToEntry (double& h, double& v, int iw, int ih, ThumbBrowserEntryBase* entry)
diff --git a/rtgui/thumbbrowserbase.h b/rtgui/thumbbrowserbase.h
index ae561db43..953ec44ec 100644
--- a/rtgui/thumbbrowserbase.h
+++ b/rtgui/thumbbrowserbase.h
@@ -171,6 +171,7 @@ protected:
     std::vector<ThumbBrowserEntryBase*> fd;
     std::vector<ThumbBrowserEntryBase*> selected;
     ThumbBrowserEntryBase* lastClicked;
+    ThumbBrowserEntryBase* anchor;
 
     int previewHeight;
     int numOfCols;