Make wxGTK's wxScrolledWindow set m_x/xScrollLines to 0

if scrollbars disappear (instead of 1) as per wxMSW.
  Expose m_x/yScrollLines in public getters.
  Correct window origin for scrolled window in RTL.


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@41186 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/scrolwin.h

@@ -68,6 +68,10 @@ public:
     int GetScrollPageSize(int orient) const;
     void SetScrollPageSize(int orient, int pageSize);
 
+    // get the number of lines the window can scroll, 
+    // returns 0 if no scrollbars are there.
+    int GetScrollLines( int orient ) const;
+
     // Set the x, y scrolling increments.
     void SetScrollRate( int xstep, int ystep );
 

src/generic/scrlwing.cpp

@@ -844,6 +844,15 @@ void wxScrollHelper::GetScrollPixelsPerUnit (int *x_unit, int *y_unit) const
         *y_unit = m_yScrollPixelsPerLine;
 }
 
+
+int wxScrollHelper::GetScrollLines( int orient ) const
+{
+    if ( orient == wxHORIZONTAL )
+        return m_xScrollLines;
+    else
+        return m_yScrollLines;
+}
+
 int wxScrollHelper::GetScrollPageSize(int orient) const
 {
     if ( orient == wxHORIZONTAL )
@@ -881,7 +890,7 @@ void wxScrollHelper::Scroll( int x_pos, int y_pos )
 
         // Calculate page size i.e. number of scroll units you get on the
         // current client window
-        int noPagePositions = (int) ( (w/(double)m_xScrollPixelsPerLine) + 0.5 );
+        int noPagePositions = w/m_xScrollPixelsPerLine;
         if (noPagePositions < 1) noPagePositions = 1;
 
         // Correct position if greater than extent of canvas minus
@@ -889,7 +898,8 @@ void wxScrollHelper::Scroll( int x_pos, int y_pos )
         m_xScrollPosition = wxMin( m_xScrollLines-noPagePositions, m_xScrollPosition );
         m_xScrollPosition = wxMax( 0, m_xScrollPosition );
 
-        if (old_x != m_xScrollPosition) {
+        if (old_x != m_xScrollPosition)
+        {
             m_win->SetScrollPos( wxHORIZONTAL, m_xScrollPosition );
             m_targetWindow->ScrollWindow( (old_x-m_xScrollPosition)*m_xScrollPixelsPerLine, 0,
                                           GetScrollRect() );
@@ -902,7 +912,7 @@ void wxScrollHelper::Scroll( int x_pos, int y_pos )
 
         // Calculate page size i.e. number of scroll units you get on the
         // current client window
-        int noPagePositions = (int) ( (h/(double)m_yScrollPixelsPerLine) + 0.5 );
+        int noPagePositions = h/m_yScrollPixelsPerLine;
         if (noPagePositions < 1) noPagePositions = 1;
 
         // Correct position if greater than extent of canvas minus
@@ -910,7 +920,8 @@ void wxScrollHelper::Scroll( int x_pos, int y_pos )
         m_yScrollPosition = wxMin( m_yScrollLines-noPagePositions, m_yScrollPosition );
         m_yScrollPosition = wxMax( 0, m_yScrollPosition );
 
-        if (old_y != m_yScrollPosition) {
+        if (old_y != m_yScrollPosition)
+        {
             m_win->SetScrollPos( wxVERTICAL, m_yScrollPosition );
             m_targetWindow->ScrollWindow( 0, (old_y-m_yScrollPosition)*m_yScrollPixelsPerLine,
                                           GetScrollRect() );

src/gtk/dcclient.cpp

@@ -26,6 +26,7 @@
 #endif
 
 #include "wx/fontutil.h"
+#include "wx/scrolwin.h"
 
 #include "wx/gtk/win_gtk.h"
 #include "wx/gtk/private.h"
@@ -326,11 +327,40 @@ wxWindowDC::wxWindowDC( wxWindow *window )
     
     if (m_owner && m_owner->m_wxwindow && (m_owner->GetLayoutDirection() == wxLayout_RightToLeft))
     {
+        // reverse sense
         m_signX = -1;
-        gint width;
-        gdk_window_get_geometry( GTK_PIZZA(m_owner->m_wxwindow)->bin_window,
-                                 NULL, NULL, &width, NULL, NULL );
-        m_deviceOriginX = width;;
+        
+        // origin in the upper right corner
+        wxScrolledWindow *sw = wxDynamicCast( m_owner, wxScrolledWindow );
+        if (sw)
+        {
+            // We cannot use just the virtual size here, because
+            // the virtual size may be less than the visible area
+            // due to rounding errors of the scroll steps. If the
+            // horizontal scroll step is 10 pixels and the virtual
+            // area is 97 pixels, we should be able to see or scroll
+            // to 100 pixels, so the origin is at -100, not -97.
+            if (sw->GetScrollLines(wxHORIZONTAL) == 0)
+            {
+                int client_width = m_owner->GetClientSize().x;
+                m_deviceOriginX = client_width;
+            }
+            else
+            {
+                int scroll_step = 0;
+                sw->GetScrollPixelsPerUnit( &scroll_step, NULL );
+                int client_width = m_owner->GetClientSize().x;
+                int virtual_size = sw->GetVirtualSize().x;
+                int steps = (virtual_size + scroll_step - 1) / scroll_step;
+                int width = steps * scroll_step + (client_width % scroll_step);
+                m_deviceOriginX = width;
+            }
+        }
+        else
+        {
+            int client_width = m_owner->GetClientSize().x;
+            m_deviceOriginX = client_width;
+        }
     }
 }
 

src/gtk/scrolwin.cpp

@@ -88,24 +88,36 @@ void wxScrollHelperNative::DoAdjustScrollbar(GtkRange* range,
                                              int *lines,
                                              int *linesPerPage)
 {
-    // GtkRange won't allow upper == lower, so for disabled state use [0,1]
-    //   with a page size of 1. This will also clamp position to 0.
-    int upper = 1;
-    int page_size = 1;
     if (pixelsPerLine > 0 && winSize > 0 && winSize < virtSize)
     {
-        upper = (virtSize + pixelsPerLine - 1) / pixelsPerLine;
-        page_size = winSize / pixelsPerLine;
+        int upper = (virtSize + pixelsPerLine - 1) / pixelsPerLine;
+        int page_size = winSize / pixelsPerLine;
+        
+        *lines = upper;
+        *linesPerPage = page_size;
+
+        GtkAdjustment* adj = range->adjustment;
+        adj->step_increment = 1;
+        adj->page_increment =
+        adj->page_size = page_size;
+        gtk_range_set_range(range, 0, upper);
     }
+    else
+    {
+        // GtkRange won't allow upper == lower, so for disabled state use [0,1]
+        //   with a page size of 1. This will also clamp position to 0.
+        int upper = 1;
+        int page_size = 1;
 
-    *lines = upper;
-    *linesPerPage = page_size;
+        *lines = 0;
+        *linesPerPage = 0;
 
-    GtkAdjustment* adj = range->adjustment;
-    adj->step_increment = 1;
-    adj->page_increment =
-    adj->page_size = page_size;
-    gtk_range_set_range(range, 0, upper);
+        GtkAdjustment* adj = range->adjustment;
+        adj->step_increment = 1;
+        adj->page_increment =
+        adj->page_size = page_size;
+        gtk_range_set_range(range, 0, upper);
+    }
 }
 
 void wxScrollHelperNative::AdjustScrollbars()