Ensure there is valid context for DrawRectangle

[wxWidgets.git] / src / generic / vscroll.cpp

diff --git a/src/generic/vscroll.cpp b/src/generic/vscroll.cpp
index a98c29da79d1a7c68a6025582cd3141c04baf68c..589451775c9f6d0c436e0452e069fa4af4ff0e37 100644 (file)
--- a/src/generic/vscroll.cpp
+++ b/src/generic/vscroll.cpp
@@ -31,6 +31,8 @@
 
 #include "wx/vscroll.h"
 
+#include "wx/utils.h"   // For wxMin/wxMax().
+
 // ============================================================================
 // wxVarScrollHelperEvtHandler declaration
 // ============================================================================
@@ -97,10 +99,6 @@ bool wxVarScrollHelperEvtHandler::ProcessEvent(wxEvent& event)
     if ( wasSkipped )
         event.Skip(false);
 
-    // reset the skipped flag to false as it might have been set to true in
-    // ProcessEvent() above
-    event.Skip(false);
-
     if ( evType == wxEVT_SCROLLWIN_TOP ||
          evType == wxEVT_SCROLLWIN_BOTTOM ||
          evType == wxEVT_SCROLLWIN_LINEUP ||
@@ -127,8 +125,7 @@ bool wxVarScrollHelperEvtHandler::ProcessEvent(wxEvent& event)
     }
 #endif // wxUSE_MOUSEWHEEL
 
-    if ( processed )
-        event.Skip(wasSkipped);
+    event.Skip(wasSkipped);
 
     return processed;
 }
@@ -313,14 +310,17 @@ size_t wxVarScrollHelperBase::GetNewScrollPosition(wxScrollWinEvent& event) cons
     }
     else if ( evtType == wxEVT_SCROLLWIN_PAGEUP )
     {
-        return FindFirstVisibleFromLast(m_unitFirst);
+        // Page up should do at least as much as line up.
+        return wxMin(FindFirstVisibleFromLast(m_unitFirst),
+                    m_unitFirst ? m_unitFirst - 1 : 0);
     }
     else if ( evtType == wxEVT_SCROLLWIN_PAGEDOWN )
     {
+        // And page down should do at least as much as line down.
         if ( GetVisibleEnd() )
-            return GetVisibleEnd() - 1;
+            return wxMax(GetVisibleEnd() - 1, m_unitFirst + 1);
         else
-            return GetVisibleEnd();
+            return wxMax(GetVisibleEnd(), m_unitFirst + 1);
     }
     else if ( evtType == wxEVT_SCROLLWIN_THUMBRELEASE )
     {
@@ -487,10 +487,10 @@ void wxVarScrollHelperBase::RefreshUnits(size_t from, size_t to)
         to = GetVisibleEnd();
 
     // calculate the rect occupied by these units on screen
-    int orient_size, nonorient_size, orient_pos;
-    orient_size = nonorient_size = orient_pos = 0;
+    int orient_size = 0,
+        orient_pos = 0;
 
-    nonorient_size = GetNonOrientationTargetSize();
+    int nonorient_size = GetNonOrientationTargetSize();
 
     for ( size_t nBefore = GetVisibleBegin();
           nBefore < from;
@@ -674,6 +674,39 @@ bool wxVarScrollHelperBase::DoScrollPages(int pages)
 
 void wxVarScrollHelperBase::HandleOnSize(wxSizeEvent& event)
 {
+    if ( m_unitMax )
+    {
+        // sometimes change in varscrollable window's size can result in
+        // unused empty space after the last item. Fix it by decrementing
+        // first visible item position according to the available space.
+
+        // determine free space
+        const wxCoord sWindow = GetOrientationTargetSize();
+        wxCoord s = 0;
+        size_t unit;
+        for ( unit = m_unitFirst; unit < m_unitMax; ++unit )
+        {
+            if ( s > sWindow )
+                break;
+
+            s += OnGetUnitSize(unit);
+        }
+        wxCoord freeSpace = sWindow - s;
+
+        // decrement first visible item index as long as there is free space
+        size_t idealUnitFirst;
+        for ( idealUnitFirst = m_unitFirst;
+              idealUnitFirst > 0;
+              idealUnitFirst-- )
+        {
+            wxCoord us = OnGetUnitSize(idealUnitFirst-1);
+            if ( freeSpace < us )
+                break;
+            freeSpace -= us;
+        }
+        m_unitFirst = idealUnitFirst;
+    }
+
     UpdateScrollbar();
 
     event.Skip();
@@ -794,7 +827,7 @@ void wxVarHVScrollHelper::RefreshRowColumn(size_t row, size_t column)
         h_rect.x += OnGetColumnWidth(n);
     }
 
-    // refresh but specialize the behavior if we have a single target window
+    // refresh but specialize the behaviour if we have a single target window
     if ( wxVarVScrollHelper::GetTargetWindow() == wxVarHScrollHelper::GetTargetWindow() )
     {
         v_rect.x = h_rect.x;
@@ -861,7 +894,7 @@ void wxVarHVScrollHelper::RefreshRowsColumns(size_t fromRow, size_t toRow,
         h_rect.width += OnGetColumnWidth(nBetween);
     }
 
-    // refresh but specialize the behavior if we have a single target window
+    // refresh but specialize the behaviour if we have a single target window
     if ( wxVarVScrollHelper::GetTargetWindow() == wxVarHScrollHelper::GetTargetWindow() )
     {
         v_rect.x = h_rect.x;
@@ -936,7 +969,7 @@ IMPLEMENT_ABSTRACT_CLASS(wxHVScrolledWindow, wxPanel)
 // wxVarVScrollLegacyAdaptor
 // ===========================================================================
 
-size_t wxVarVScrollLegacyAdaptor::GetFirstVisibleLine() const 
+size_t wxVarVScrollLegacyAdaptor::GetFirstVisibleLine() const
 { return GetVisibleRowsBegin(); }
 
 size_t wxVarVScrollLegacyAdaptor::GetLastVisibleLine() const
@@ -953,13 +986,13 @@ void wxVarVScrollLegacyAdaptor::RefreshLine(size_t line)
 
 void wxVarVScrollLegacyAdaptor::RefreshLines(size_t from, size_t to)
 { RefreshRows(from, to); }
-        
+
 bool wxVarVScrollLegacyAdaptor::ScrollToLine(size_t line)
 { return ScrollToRow(line); }
 
 bool wxVarVScrollLegacyAdaptor::ScrollLines(int lines)
 { return ScrollRows(lines); }
-        
+
 bool wxVarVScrollLegacyAdaptor::ScrollPages(int pages)
 { return ScrollRowPages(pages); }