From 3ec704b4221ee4d66ebb1cb98f1dc1017f68bec3 Mon Sep 17 00:00:00 2001
From: Robin Dunn <robin@alldunn.com>
Date: Wed, 9 Jul 2008 01:37:32 +0000
Subject: [PATCH] Applied patch from Ticket #9563.  Use just the rectangle of
 the widget with the focus when deciding if scrolling is needed, instead of
 the rect of the parent of the widget/child of the target window.  This fixes
 some flickering when a panel of widgets is used inside the scrolled window,
 and also a total lack of scrolling if the focused widget is out of view but
 the upper-left corner of the panel is in view.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@54552 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
---
 src/generic/scrlwing.cpp | 59 ++++++++++++++++++++++++++++++++++------
 1 file changed, 51 insertions(+), 8 deletions(-)

diff --git a/src/generic/scrlwing.cpp b/src/generic/scrlwing.cpp
index 13f1e7e5e0..45a6e21f3c 100644
--- a/src/generic/scrlwing.cpp
+++ b/src/generic/scrlwing.cpp
@@ -1341,21 +1341,64 @@ void wxScrollHelper::HandleOnChildFocus(wxChildFocusEvent& event)
     if ( win == m_targetWindow )
         return; // nothing to do
 
-    while ( win->GetParent() != m_targetWindow )
+    // Fixing ticket: http://trac.wxwidgets.org/ticket/9563
+    // When a child inside a wxControlContainer receives a focus, the
+    // wxControlContainer generates an artificial wxChildFocusEvent for
+    // itself, telling its parent that 'it' received the focus. The effect is
+    // that this->HandleOnChildFocus is called twice, first with the
+    // artificial wxChildFocusEvent and then with the original event.  We need
+    // to ignore the artificial event here or otherwise HandleOnChildFocus
+    // would first scroll the target window to make the entire
+    // wxControlContainer visible and immediately afterwards scroll the target
+    // window again to make the child widget visible. This leads to ugly
+    // flickering when using nested wxPanels/wxScrolledWindows.
+    //
+    // Ignore this event if 'win' is derived from wxControlContainer AND its
+    // parent is the m_targetWindow AND 'win' is not actually reciving the
+    // focus (win != FindFocus).  TODO: This affects all wxControlContainer
+    // objects, but wxControlContainer is not part of the wxWidgets RTTI and
+    // so wxDynamicCast(win, wxControlContainer) does not compile.  Find a way
+    // to determine if 'win' derives from wxControlContainer. Until then,
+    // testing if 'win' derives from wxPanel will probably get >90% of all
+    // cases.
+
+    wxWindow *actual_focus=wxWindow::FindFocus();
+    if (win != actual_focus &&
+        wxDynamicCast(win, wxPanel) != 0 &&
+        win->GetParent() == m_targetWindow)
+        // if win is a wxPanel and receives the focus, it should not be
+        // scrolled into view
+        return; 
+
+    wxSize view(m_targetWindow->GetClientSize());
+
+    // For composite controls such as wxComboCtrl we should try to fit the
+    // entire control inside the visible area of the target window, not just
+    // the focused child of the control. Otherwise we'd make only the textctrl
+    // part of a wxComboCtrl visible and the button would still be outside the
+    // scrolled area.  But do so only if the parent fits *entirely* inside the
+    // scrolled window. In other situations, such as nested wxPanel or
+    // wxScrolledWindows, the parent might be way to big to fit inside the
+    // scrolled window. If that is the case, then make only the focused window
+    // visible
+    if ( win->GetParent() != m_targetWindow)
     {
-        win = win->GetParent();
-        if ( !win )
-            return; // event is not from a child of the target window
+        wxWindow *parent=win->GetParent();
+        wxSize parent_size=parent->GetSize();
+        if (parent_size.GetWidth() <= view.GetWidth() &&
+            parent_size.GetHeight() <= view.GetHeight())
+            // make the immediate parent visible instead of the focused control
+            win=parent; 
     }
 
     // if the child is not fully visible, try to scroll it into view:
     int stepx, stepy;
     GetScrollPixelsPerUnit(&stepx, &stepy);
 
-    // NB: we don't call CalcScrolledPosition() on win->GetPosition() here,
-    //     because children' positions are already scrolled
-    wxRect winrect(win->GetPosition(), win->GetSize());
-    wxSize view(m_targetWindow->GetClientSize());
+    // 'win' position coordinates are relative to it's parent
+    // convert them so that they are relative to the m_targetWindow viewing area
+    wxRect winrect(m_targetWindow->ScreenToClient(win->GetScreenPosition()),
+                   win->GetSize());
 
     int startx, starty;
     GetViewStart(&startx, &starty);