allow passing -1 range to SetScrollbar() to indicate the the scrollbar should be disabled and use this to implement wxSHOW_SB_ALWAYS in the generic wxScrollHelper

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@57535 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/generic/scrolwin.h

@@ -35,9 +35,10 @@ private:
     void DoAdjustScrollbar(int orient,
                            int clientSize,
                            int virtSize,
-                           int& pixelsPerUnit,
+                           int pixelsPerUnit,
                            int& scrollUnits,
                            int& scrollPosition,
+                           int& scrollLinesPerPage,
                            wxScrollbarVisibility visibility);
 
 

interface/wx/window.h

@@ -2368,7 +2368,10 @@ public:
         @param thumbSize
             The size of the thumb, or visible portion of the scrollbar, in scroll units.
         @param range
-            The maximum position of the scrollbar.
+            The maximum position of the scrollbar. Value of -1 can be used to
+            ask for the scrollbar to be shown but in the disabled state: this
+            can be used to avoid removing the scrollbar even when it is not
+            needed (currently this is only implemented in wxMSW port).
         @param refresh
             @true to redraw the scrollbar, @false otherwise.
 

samples/scroll/scroll.cpp

@@ -452,7 +452,7 @@ public:
                            wxDefaultPosition, wxDefaultSize,
                            wxBORDER_SUNKEN)
     {
-        m_nLines = 100;
+        m_nLines = 50;
         m_winSync = NULL;
         m_inDoSync = false;
 
@@ -621,7 +621,7 @@ private:
     void OnTestAuto(wxCommandEvent& WXUNUSED(event)) { new MyAutoFrame(this); }
 
     void OnToggleSync(wxCommandEvent& event);
-    void OnToggleScrollbar(wxCommandEvent& event);
+    void OnScrollbarVisibility(wxCommandEvent& event);
 
     MyScrolledWindowBase *m_win1,
                          *m_win2;
@@ -835,7 +835,7 @@ const wxWindowID Scroll_Test_Sub    = wxWindow::NewControlId();
 const wxWindowID Scroll_Test_Auto   = wxWindow::NewControlId();
 
 const wxWindowID Scroll_TglBtn_Sync = wxWindow::NewControlId();
-const wxWindowID Scroll_TglBtn_Scrollbar = wxWindow::NewControlId();
+const wxWindowID Scroll_Radio_ShowScrollbar = wxWindow::NewControlId();
 
 BEGIN_EVENT_TABLE(MyFrame,wxFrame)
     EVT_MENU(wxID_ABOUT, MyFrame::OnAbout)
@@ -848,7 +848,7 @@ BEGIN_EVENT_TABLE(MyFrame,wxFrame)
     EVT_MENU(Scroll_Test_Auto, MyFrame::OnTestAuto)
 
     EVT_TOGGLEBUTTON(Scroll_TglBtn_Sync, MyFrame::OnToggleSync)
-    EVT_TOGGLEBUTTON(Scroll_TglBtn_Scrollbar, MyFrame::OnToggleScrollbar)
+    EVT_RADIOBOX(Scroll_Radio_ShowScrollbar, MyFrame::OnScrollbarVisibility)
 END_EVENT_TABLE()
 
 MyFrame::MyFrame()
@@ -879,10 +879,12 @@ MyFrame::MyFrame()
     SetMenuBar( mbar );
 
 
+    wxPanel *panel = new wxPanel(this);
+
     const wxSizerFlags flagsExpand(wxSizerFlags(1).Expand());
 
     wxSizer *topsizer = new wxBoxSizer(wxVERTICAL);
-    topsizer->Add(new wxStaticText(this, wxID_ANY,
+    topsizer->Add(new wxStaticText(panel, wxID_ANY,
         "The windows below should behave in the same way, even though\n"
         "they're implemented quite differently, see the code for details.\n"
         "\n"
@@ -891,28 +893,39 @@ MyFrame::MyFrame()
         "don't be surprised by this."),
         wxSizerFlags().Centre().Border());
 
-    m_win1 = new MyScrolledWindowDumb(this);
+    m_win1 = new MyScrolledWindowDumb(panel);
-    m_win2 = new MyScrolledWindowSmart(this);
+    m_win2 = new MyScrolledWindowSmart(panel);
 
     wxSizer *sizerScrollWin = new wxBoxSizer(wxHORIZONTAL);
     sizerScrollWin->Add(m_win1, flagsExpand);
     sizerScrollWin->Add(m_win2, flagsExpand);
     topsizer->Add(sizerScrollWin, flagsExpand);
 
-    const wxSizerFlags flagsHBorder(wxSizerFlags().Border(wxLEFT | wxRIGHT));
+    const wxSizerFlags
+        flagsHBorder(wxSizerFlags().Centre().Border(wxLEFT | wxRIGHT));
 
     wxSizer *sizerBtns = new wxBoxSizer(wxHORIZONTAL);
-    sizerBtns->Add(new wxToggleButton(this, Scroll_TglBtn_Sync, "S&ynchronize"),
+
+    // the radio buttons are in the same order as wxSHOW_SB_XXX values but
+    // offset by 1
+    const wxString visibilities[] = { "&never", "&default", "&always" };
+    wxRadioBox *radio = new wxRadioBox(panel, Scroll_Radio_ShowScrollbar,
+                                       "Left &scrollbar visibility: ",
+                                       wxDefaultPosition, wxDefaultSize,
+                                       WXSIZEOF(visibilities), visibilities);
+    radio->SetSelection(wxSHOW_SB_DEFAULT + 1);
+    sizerBtns->Add(radio, flagsHBorder);
+
+    sizerBtns->Add(new wxToggleButton(panel, Scroll_TglBtn_Sync, "S&ynchronize"),
                    flagsHBorder);
 
-    wxToggleButton *btn =new wxToggleButton(this, Scroll_TglBtn_Scrollbar,
-                                            "&Show scrollbar");
-    btn->SetValue(true);
-    sizerBtns->Add(btn, flagsHBorder);
     topsizer->Add(sizerBtns, wxSizerFlags().Centre().Border());
 
-    SetSizer(topsizer);
+    panel->SetSizer(topsizer);
 
+    wxSize size = panel->GetBestSize();
+    SetSizeHints(size);
+    SetClientSize(2*size);
 
     Show();
 }
@@ -931,11 +944,10 @@ void MyFrame::OnToggleSync(wxCommandEvent& event)
     }
 }
 
-void MyFrame::OnToggleScrollbar(wxCommandEvent& event)
+void MyFrame::OnScrollbarVisibility(wxCommandEvent& event)
 {
     m_win1->ShowScrollbars(wxSHOW_SB_NEVER,
-                           event.IsChecked() ? wxSHOW_SB_ALWAYS
+                           wxScrollbarVisibility(event.GetSelection() - 1));
-                                             : wxSHOW_SB_NEVER);
 }
 
 void MyFrame::OnQuit(wxCommandEvent &WXUNUSED(event))

src/generic/scrlwing.cpp

@@ -1232,28 +1232,20 @@ void
 wxScrollHelper::DoAdjustScrollbar(int orient,
                                   int clientSize,
                                   int virtSize,
-                                  int& pixelsPerUnit,
+                                  int pixelsPerUnit,
                                   int& scrollUnits,
                                   int& scrollPosition,
+                                  int& scrollLinesPerPage,
                                   wxScrollbarVisibility visibility)
 {
-    if ( visibility == wxSHOW_SB_NEVER )
-    {
-        m_win->SetScrollbar(orient, 0, 0, 0);
-        return;
-    }
-
     // scroll lines per page: if 0, no scrolling is needed
-    int unitsPerPage;
-
     // check if we need scrollbar in this direction at all
-    if ( pixelsPerUnit == 0 ||
+    if ( pixelsPerUnit == 0 || clientSize >= virtSize )
-            (clientSize >= virtSize && visibility != wxSHOW_SB_ALWAYS) )
     {
         // scrolling is disabled or unnecessary
         scrollUnits =
         scrollPosition = 0;
-        unitsPerPage = 0;
+        scrollLinesPerPage = 0;
     }
     else // might need scrolling
     {
@@ -1261,23 +1253,23 @@ wxScrollHelper::DoAdjustScrollbar(int orient,
         scrollUnits = (virtSize + pixelsPerUnit - 1) / pixelsPerUnit;
 
         // Calculate the number of fully scroll units
-        unitsPerPage = clientSize / pixelsPerUnit;
+        scrollLinesPerPage = clientSize / pixelsPerUnit;
 
-        if (unitsPerPage >= scrollUnits)
+        if ( scrollLinesPerPage >= scrollUnits )
         {
             // we're big enough to not need scrolling
             scrollUnits =
             scrollPosition = 0;
-            unitsPerPage = 0;
+            scrollLinesPerPage = 0;
         }
         else // we do need a scrollbar
         {
-            if ( unitsPerPage < 1 )
+            if ( scrollLinesPerPage < 1 )
-                unitsPerPage = 1;
+                scrollLinesPerPage = 1;
 
             // Correct position if greater than extent of canvas minus
             // the visible portion of it or if below zero
-            const int posMax = scrollUnits - unitsPerPage;
+            const int posMax = scrollUnits - scrollLinesPerPage;
             if ( scrollPosition > posMax )
                 scrollPosition = posMax;
             else if ( scrollPosition < 0 )
@@ -1285,10 +1277,26 @@ wxScrollHelper::DoAdjustScrollbar(int orient,
         }
     }
 
-    m_win->SetScrollbar(orient, scrollPosition, unitsPerPage, scrollUnits);
+    // in wxSHOW_SB_NEVER case don't show the scrollbar even if it's needed, in
+    // wxSHOW_SB_ALWAYS case show the scrollbar even if it's not needed by
+    // passing a special range value to SetScrollbar()
+    int range wxDUMMY_INITIALIZE(0);
+    switch ( visibility )
+    {
+        case wxSHOW_SB_NEVER:
+            range = 0;
+            break;
 
-    // The amount by which we scroll when paging
+        case wxSHOW_SB_DEFAULT:
-    SetScrollPageSize(orient, unitsPerPage);
+            range = scrollUnits;
+            break;
+
+        case wxSHOW_SB_ALWAYS:
+            range = scrollUnits ? scrollUnits : -1;
+            break;
+    }
+
+    m_win->SetScrollbar(orient, scrollPosition, scrollLinesPerPage, range);
 }
 
 void wxScrollHelper::AdjustScrollbars()
@@ -1348,6 +1356,7 @@ void wxScrollHelper::AdjustScrollbars()
                           m_xScrollPixelsPerLine,
                           m_xScrollLines,
                           m_xScrollPosition,
+                          m_xScrollLinesPerPage,
                           m_xVisibility);
 
         DoAdjustScrollbar(wxVERTICAL,
@@ -1356,6 +1365,7 @@ void wxScrollHelper::AdjustScrollbars()
                           m_yScrollPixelsPerLine,
                           m_yScrollLines,
                           m_yScrollPosition,
+                          m_yScrollLinesPerPage,
                           m_yVisibility);
 
 

src/msw/window.cpp

@@ -963,6 +963,9 @@ void wxWindowMSW::MSWUpdateUIState(int action, int state)
 // scrolling stuff
 // ---------------------------------------------------------------------------
 
+namespace
+{
+
 inline int GetScrollPosition(HWND hWnd, int wOrient)
 {
 #ifdef __WXMICROWIN__
@@ -978,12 +981,19 @@ inline int GetScrollPosition(HWND hWnd, int wOrient)
 #endif
 }
 
+inline UINT WXOrientToSB(int orient)
+{
+    return orient == wxHORIZONTAL ? SB_HORZ : SB_VERT;
+}
+
+} // anonymous namespace
+
 int wxWindowMSW::GetScrollPos(int orient) const
 {
     HWND hWnd = GetHwnd();
     wxCHECK_MSG( hWnd, 0, _T("no HWND in GetScrollPos") );
 
-    return GetScrollPosition(hWnd, orient == wxHORIZONTAL ? SB_HORZ : SB_VERT);
+    return GetScrollPosition(hWnd, WXOrientToSB(orient));
 }
 
 // This now returns the whole range, not just the number
@@ -994,15 +1004,9 @@ int wxWindowMSW::GetScrollRange(int orient) const
     HWND hWnd = GetHwnd();
     if ( !hWnd )
         return 0;
-#if 0
-    ::GetScrollRange(hWnd, orient == wxHORIZONTAL ? SB_HORZ : SB_VERT,
-                     &minPos, &maxPos);
-#endif
     WinStruct<SCROLLINFO> scrollInfo;
     scrollInfo.fMask = SIF_RANGE;
-    if ( !::GetScrollInfo(hWnd,
+    if ( !::GetScrollInfo(hWnd, WXOrientToSB(orient), &scrollInfo) )
-                          orient == wxHORIZONTAL ? SB_HORZ : SB_VERT,
-                          &scrollInfo) )
     {
         // Most of the time this is not really an error, since the return
         // value can also be zero when there is no scrollbar yet.
@@ -1035,8 +1039,7 @@ void wxWindowMSW::SetScrollPos(int orient, int pos, bool refresh)
         info.fMask |= SIF_DISABLENOSCROLL;
     }
 
-    ::SetScrollInfo(hWnd, orient == wxHORIZONTAL ? SB_HORZ : SB_VERT,
+    ::SetScrollInfo(hWnd, WXOrientToSB(orient), &info, refresh);
-                    &info, refresh);
 }
 
 // New function that will replace some of the above.
@@ -1046,28 +1049,37 @@ void wxWindowMSW::SetScrollbar(int orient,
                                int range,
                                bool refresh)
 {
+    // We have to set the variables here to make them valid in events
+    // triggered by ::SetScrollInfo()
+    *(orient == wxHORIZONTAL ? &m_xThumbSize : &m_yThumbSize) = pageSize;
+
+    HWND hwnd = GetHwnd();
+    if ( !hwnd )
+        return;
+
     WinStruct<SCROLLINFO> info;
-    info.nPage = pageSize;
+    if ( range != -1 )
-    info.nMin = 0;              // range is nMax - nMin + 1
+    {
-    info.nMax = range - 1;      //  as both nMax and nMax are inclusive
+        info.nPage = pageSize;
-    info.nPos = pos;
+        info.nMin = 0;              // range is nMax - nMin + 1
+        info.nMax = range - 1;      //  as both nMax and nMax are inclusive
+        info.nPos = pos;
+
+        // enable the scrollbar if it had been disabled before by specifying
+        // SIF_DISABLENOSCROLL below: as we can't know whether this had been
+        // done or not just do it always
+        ::EnableScrollBar(hwnd, WXOrientToSB(orient), ESB_ENABLE_BOTH);
+    }
+    //else: leave all the fields to be 0
+
     info.fMask = SIF_RANGE | SIF_PAGE | SIF_POS;
-    if ( HasFlag(wxALWAYS_SHOW_SB) )
+    if ( HasFlag(wxALWAYS_SHOW_SB) || range == -1 )
     {
         // disable scrollbar instead of removing it then
         info.fMask |= SIF_DISABLENOSCROLL;
     }
 
-    HWND hWnd = GetHwnd();
+    ::SetScrollInfo(hwnd, WXOrientToSB(orient), &info, refresh);
-    if ( hWnd )
-    {
-        // We have to set the variables here to make them valid in events
-        // triggered by ::SetScrollInfo()
-        *(orient == wxHORIZONTAL ? &m_xThumbSize : &m_yThumbSize) = pageSize;
-
-        ::SetScrollInfo(hWnd, orient == wxHORIZONTAL ? SB_HORZ : SB_VERT,
-                        &info, refresh);
-    }
 }
 
 void wxWindowMSW::ScrollWindow(int dx, int dy, const wxRect *prect)
@@ -5783,8 +5795,7 @@ bool wxWindowMSW::MSWOnScroll(int orientation, WXWORD wParam,
             scrollInfo.fMask = SIF_TRACKPOS;
 
             if ( !::GetScrollInfo(GetHwnd(),
-                                  orientation == wxHORIZONTAL ? SB_HORZ
+                                  WXOrientToSB(orientation),
-                                                              : SB_VERT,
                                   &scrollInfo) )
             {
                 // Not necessarily an error, if there are no scrollbars yet.