From 9ec927f89b0e907c45143bb3de0548b97361b6b2 Mon Sep 17 00:00:00 2001
From: Vadim Zeitlin <vadim@wxwidgets.org>
Date: Mon, 4 Dec 2006 11:05:59 +0000
Subject: [PATCH] ensure that scroll position is always in scrolling range,
 otherwise we could have a window without scrollbars at all but with non zero
 scroll offset which was really strange

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@43795 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
---
 include/wx/gtk/scrolwin.h | 21 +++++++++++++++++++++
 src/gtk/scrolwin.cpp      | 35 ++++++++++++++++++-----------------
 2 files changed, 39 insertions(+), 17 deletions(-)

diff --git a/include/wx/gtk/scrolwin.h b/include/wx/gtk/scrolwin.h
index 246e8269f7..909b616097 100644
--- a/include/wx/gtk/scrolwin.h
+++ b/include/wx/gtk/scrolwin.h
@@ -35,9 +35,30 @@ protected:
                            int pixelsPerLine,
                            int winSize,
                            int virtSize,
+                           int *pos,
                            int *lines,
                            int *linesPerPage);
 
+    void DoAdjustHScrollbar(int winSize, int virtSize)
+    {
+        DoAdjustScrollbar
+        (
+            m_win->m_scrollBar[wxWindow::ScrollDir_Horz],
+            m_xScrollPixelsPerLine, winSize, virtSize,
+            &m_xScrollPosition, &m_xScrollLines, &m_xScrollLinesPerPage
+        );
+    }
+
+    void DoAdjustVScrollbar(int winSize, int virtSize)
+    {
+        DoAdjustScrollbar
+        (
+            m_win->m_scrollBar[wxWindow::ScrollDir_Vert],
+            m_yScrollPixelsPerLine, winSize, virtSize,
+            &m_yScrollPosition, &m_yScrollLines, &m_yScrollLinesPerPage
+        );
+    }
+
     // and this does the same for Scroll()
     void DoScroll(int orient,
                   int pos,
diff --git a/src/gtk/scrolwin.cpp b/src/gtk/scrolwin.cpp
index 72e831f69d..2f0bea636a 100644
--- a/src/gtk/scrolwin.cpp
+++ b/src/gtk/scrolwin.cpp
@@ -85,6 +85,7 @@ void wxScrollHelperNative::DoAdjustScrollbar(GtkRange* range,
                                              int pixelsPerLine,
                                              int winSize,
                                              int virtSize,
+                                             int *pos,
                                              int *lines,
                                              int *linesPerPage)
 {
@@ -106,6 +107,11 @@ void wxScrollHelperNative::DoAdjustScrollbar(GtkRange* range,
         *lines = 0;
         *linesPerPage = 0;
     }
+
+    // ensure that the scroll position is always in valid range
+    if ( *pos > *lines )
+        *pos = *lines;
+
     GtkAdjustment* adj = range->adjustment;
     adj->step_increment = 1;
     adj->page_increment =
@@ -115,26 +121,24 @@ void wxScrollHelperNative::DoAdjustScrollbar(GtkRange* range,
 
 void wxScrollHelperNative::AdjustScrollbars()
 {
-    int w, h;
-    int vw, vh;
-
     // this flag indicates which window has the scrollbars
-    m_win->m_hasScrolling = m_xScrollPixelsPerLine != 0 || m_yScrollPixelsPerLine != 0;
+    m_win->m_hasScrolling = m_xScrollPixelsPerLine != 0 ||
+                                m_yScrollPixelsPerLine != 0;
 
+    int vw, vh;
     m_targetWindow->GetVirtualSize( &vw, &vh );
 
+    int w;
     m_targetWindow->GetClientSize(&w, NULL);
-    DoAdjustScrollbar(
-        m_win->m_scrollBar[wxWindow::ScrollDir_Horz], m_xScrollPixelsPerLine,
-        w, vw, &m_xScrollLines, &m_xScrollLinesPerPage);
+    DoAdjustHScrollbar(w, vw);
+
+    int h;
     m_targetWindow->GetClientSize(NULL, &h);
-    DoAdjustScrollbar(
-        m_win->m_scrollBar[wxWindow::ScrollDir_Vert], m_yScrollPixelsPerLine,
-        h, vh, &m_yScrollLines, &m_yScrollLinesPerPage);
+    DoAdjustVScrollbar(h, vh);
 
     const int w_old = w;
     m_targetWindow->GetClientSize(&w, NULL);
-    if (w != w_old)
+    if ( w != w_old )
     {
         // It is necessary to repeat the calculations in this case to avoid an
         // observed infinite series of size events, involving alternating
@@ -143,13 +147,10 @@ void wxScrollHelperNative::AdjustScrollbars()
         // AdjustScrollbars() to be called again. If the scrollbar visibility
         // is not correct before then, yet another resize will occur, possibly
         // leading to an unending series if the sizes are just right.
-        DoAdjustScrollbar(
-            m_win->m_scrollBar[wxWindow::ScrollDir_Horz], m_xScrollPixelsPerLine,
-            w, vw, &m_xScrollLines, &m_xScrollLinesPerPage);
+        DoAdjustHScrollbar(w, vw);
+
         m_targetWindow->GetClientSize(NULL, &h);
-        DoAdjustScrollbar(
-            m_win->m_scrollBar[wxWindow::ScrollDir_Vert], m_yScrollPixelsPerLine,
-            h, vh, &m_yScrollLines, &m_yScrollLinesPerPage);
+        DoAdjustVScrollbar(h, vh);
     }
 }
 
-- 
2.45.2