wxCaret now uses backing store instead of forcing window refresh each time the

caret is hidden; the non blinking carets work too


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@8403 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

include/wx/caret.h

@@ -196,5 +196,31 @@ private:
     #include "wx/generic/caret.h"
 #endif // platform
 
+// ----------------------------------------------------------------------------
+// wxCaretSuspend: a simple class which hides the caret in its ctor and
+// restores it in the dtor, this should be used when drawing on the screen to
+// avoid overdrawing the caret
+// ----------------------------------------------------------------------------
+
+class WXDLLEXPORT wxCaretSuspend
+{
+public:
+    wxCaretSuspend(wxWindow *win)
+    {
+        m_caret = win->GetCaret();
+        if ( m_caret )
+            m_caret->Hide();
+    }
+
+    ~wxCaretSuspend()
+    {
+        if ( m_caret )
+            m_caret->Show();
+    }
+
+private:
+    wxCaret *m_caret;
+};
+
 #endif // _WX_CARET_H_BASE_
 

include/wx/generic/caret.h

@@ -73,6 +73,12 @@ private:
     // GTK specific initialization
     void InitGeneric();
 
+    // the bitmap holding the part of window hidden by the caret when it was
+    // at (m_xOld, m_yOld)
+    wxBitmap      m_bmpUnderCaret;
+    int           m_xOld,
+                  m_yOld;
+
     wxCaretTimer  m_timer;
     bool          m_blinkedOut,     // TRUE => caret hidden right now
                   m_hasFocus;       // TRUE => our window has focus

samples/caret/caret.cpp

@@ -358,6 +358,7 @@ void MyCanvas::OnSize( wxSizeEvent &event )
 //     would use GetUpdateRegion() and iterate over rectangles it contains
 void MyCanvas::OnPaint( wxPaintEvent &WXUNUSED(event) )
 {
+    wxCaretSuspend cs(this);
     wxPaintDC dc( this );
     PrepareDC( dc );
     dc.Clear();
@@ -382,8 +383,6 @@ void MyCanvas::OnPaint( wxPaintEvent &WXUNUSED(event) )
 
 void MyCanvas::OnChar( wxKeyEvent &event )
 {
-    bool refresh = FALSE;
-
     switch ( event.KeyCode() )
     {
         case WXK_LEFT:
@@ -418,10 +417,17 @@ void MyCanvas::OnChar( wxKeyEvent &event )
         default:
             if ( !event.AltDown() && wxIsprint(event.KeyCode()) )
             {
-                CharAt(m_xCaret, m_yCaret) = (wxChar)event.KeyCode();
+                wxChar ch = (wxChar)event.KeyCode();
-                NextChar();
+                CharAt(m_xCaret, m_yCaret) = ch;
 
-                refresh = TRUE;
+                wxCaretSuspend cs(this);
+                wxClientDC dc(this);
+                dc.SetFont(m_font);
+                dc.SetBackgroundMode(wxSOLID); // overwrite old value
+                dc.DrawText(ch, m_xMargin + m_xCaret * m_widthChar,
+                                m_yMargin + m_yCaret * m_heightChar );
+
+                NextChar();
             }
             else
             {
@@ -430,8 +436,5 @@ void MyCanvas::OnChar( wxKeyEvent &event )
     }
 
     DoMoveCaret();
-
-    if ( refresh )
-        Refresh();
 }
 

src/generic/caret.cpp

@@ -33,6 +33,7 @@
 #ifndef WX_PRECOMP
     #include "wx/window.h"
     #include "wx/dcclient.h"
+    #include "wx/dcmemory.h"
 #endif //WX_PRECOMP
 
 #include "wx/caret.h"
@@ -91,6 +92,10 @@ void wxCaret::InitGeneric()
 {
     m_hasFocus = TRUE;
     m_blinkedOut = FALSE;
+
+    m_xOld =
+    m_yOld = -1;
+    m_bmpUnderCaret.Create(m_width, m_height);
 }
 
 wxCaret::~wxCaret()
@@ -134,12 +139,12 @@ void wxCaret::DoMove()
         if ( !m_blinkedOut )
         {
             // hide it right now and it will be shown the next time it blinks
-            // unless it should be shown all the time in which case just show
-            // it at the new position
-            if ( m_timer.IsRunning() )
             Blink();
-            else
+
-                Refresh();
+            // but if the caret is not blinking, we should blink it back into
+            // visibility manually
+            if ( !m_timer.IsRunning() )
+                Blink();
         }
     }
     //else: will be shown at the correct location when it is shown
@@ -165,10 +170,14 @@ void wxCaret::OnKillFocus()
         // the caret must be shown - otherwise, if it is hidden now, it will
         // stay so until the focus doesn't return because it won't blink any
         // more
-        m_blinkedOut = FALSE;
-    }
 
-    Refresh();
+        // hide it first if it isn't hidden ...
+        if ( !m_blinkedOut )
+            Blink();
+
+        // .. and show it in the new style
+        Blink();
+    }
 }
 
 // ----------------------------------------------------------------------------
@@ -184,20 +193,32 @@ void wxCaret::Blink()
 
 void wxCaret::Refresh()
 {
-    if ( !m_blinkedOut )
+    wxClientDC dcWin(GetWindow());
+    wxMemoryDC dcMem;
+    dcMem.SelectObject(m_bmpUnderCaret);
+    if ( m_blinkedOut )
     {
-        wxClientDC dc(GetWindow());
+        // restore the old image
-        DoDraw(&dc);
+        dcWin.Blit(m_xOld, m_yOld, m_width, m_height,
+                   &dcMem, 0, 0);
+        m_xOld =
+        m_yOld = -1;
     }
     else
     {
-        // FIXME can't be less efficient than this... we probably should use
+        if ( m_xOld == -1 && m_yOld == -1 )
-        //       backing store for the caret instead of leaving all the burden
+        {
-        //       of correct refresh logic handling to the user code
+            // save the part we're going to overdraw
+            dcMem.Blit(0, 0, m_width, m_height,
+                       &dcWin, m_x, m_y);
+            m_xOld = m_x;
+            m_yOld = m_y;
+        }
+        //else: we already saved the image below the caret, don't do it any
+        //      more
 
-        // NB: +1 is needed!
+        // and draw the caret there
-        wxRect rect(m_x, m_y, m_width + 1, m_height + 1);
+        DoDraw(&dcWin);
-        GetWindow()->Refresh(FALSE, &rect);
     }
 }
 
@@ -205,19 +226,14 @@ void wxCaret::DoDraw(wxDC *dc)
 {
     dc->SetPen( *wxBLACK_PEN );
 
-    // VZ: Robert's code for I-shaped caret - this is nice but doesn't look
+    dc->SetBrush(*(m_hasFocus ? wxBLACK_BRUSH : wxTRANSPARENT_BRUSH));
-    //     at all the same as the MSW version and I don't know how to indicate
+    dc->SetPen(*wxBLACK_PEN);
-    //     that the window has focus or not with such caret
+
-#if 0
+    // VZ: unfortunately, the rectangle comes out a pixel smaller when this is
-    dc->DrawLine( m_x, m_y, m_x+m_width, m_y );
+    //     done under wxGTK - no idea why
-    dc->DrawLine( m_x, m_y+m_height, m_x+m_width, m_y+m_height );
+    //dc->SetLogicalFunction(wxINVERT);
-    dc->DrawLine( m_x+(m_width/2), m_y, m_x+(m_width/2), m_y+m_height );
+
-//  dc->DrawLine( m_x+(m_width/2)+1, m_y, m_x+(m_width/2)+1, m_y+m_height );
+    dc->DrawRectangle(m_x, m_y, m_width, m_height);
-#else // 1
-    if ( m_hasFocus )
-        dc->SetBrush( *wxBLACK_BRUSH );
-    dc->DrawRectangle( m_x, m_y, m_width, m_height );
-#endif // 0/1
 }
 
 #endif // wxUSE_CARET