6 files changed, 88 insertions, 1 deletions
diff --git a/src/drivers/Cocoa/Fl_Cocoa_Window_Driver.H b/src/drivers/Cocoa/Fl_Cocoa_Window_Driver.H
index 0e4244ba7..2251391a2 100644
--- a/src/drivers/Cocoa/Fl_Cocoa_Window_Driver.H
+++ b/src/drivers/Cocoa/Fl_Cocoa_Window_Driver.H
@@ -98,6 +98,7 @@ public:
   //this one is in Fl_cocoa.mm because it uses Objective-c
   virtual void wait_for_expose();
   static void draw_layer_to_context(CALayer *layer, CGContextRef gc, int w, int h);
+  virtual int scroll(int src_x, int src_y, int src_w, int src_h, int dest_x, int dest_y, void (*draw_area)(void*, int,int,int,int), void* data);
 };
 
 
diff --git a/src/drivers/Cocoa/Fl_Cocoa_Window_Driver.cxx b/src/drivers/Cocoa/Fl_Cocoa_Window_Driver.cxx
index c202da51f..0d98ff108 100644
--- a/src/drivers/Cocoa/Fl_Cocoa_Window_Driver.cxx
+++ b/src/drivers/Cocoa/Fl_Cocoa_Window_Driver.cxx
@@ -18,7 +18,8 @@
 
 
 #include "../../config_lib.h"
-#include "Fl_Cocoa_Window_Driver.h"
+#include "Fl_Cocoa_Window_Driver.H"
+#include "../Quartz/Fl_Quartz_Graphics_Driver.H"
 #include <FL/Fl_Double_Window.H>
 #include <FL/Fl_Overlay_Window.H>
 #include <FL/fl_draw.H>
@@ -274,6 +275,16 @@ void Fl_Cocoa_Window_Driver::decoration_sizes(int *top, int *left,  int *right,
   *bottom = 2;
 }
 
+int Fl_Cocoa_Window_Driver::scroll(int src_x, int src_y, int src_w, int src_h, int dest_x, int dest_y, void (*draw_area)(void*, int,int,int,int), void* data)
+{
+  CGImageRef img = Fl_X::CGImage_from_window_rect(Fl_Window::current(), src_x, src_y, src_w, src_h);
+  if (img) {
+    ((Fl_Quartz_Graphics_Driver*)fl_graphics_driver)->draw_CGImage(img,dest_x,dest_y,src_w,src_h,0,0,src_w,src_h);
+    CFRelease(img);
+  }
+  return 0;
+}
+
 //
 // End of "$Id$".
 //
diff --git a/src/drivers/WinAPI/Fl_WinAPI_Window_Driver.H b/src/drivers/WinAPI/Fl_WinAPI_Window_Driver.H
index a6fa71ec4..3c2b002db 100644
--- a/src/drivers/WinAPI/Fl_WinAPI_Window_Driver.H
+++ b/src/drivers/WinAPI/Fl_WinAPI_Window_Driver.H
@@ -98,6 +98,8 @@ public:
   // this one is implemented in Fl_win32.cxx
   virtual void capture_titlebar_and_borders(Fl_Shared_Image*& top, Fl_Shared_Image*& left, Fl_Shared_Image*& bottom, Fl_Shared_Image*& right);
   virtual void wait_for_expose();
+  virtual int scroll(int src_x, int src_y, int src_w, int src_h, int dest_x, int dest_y,
+                     void (*draw_area)(void*, int,int,int,int), void* data);
 };
 
 
diff --git a/src/drivers/WinAPI/Fl_WinAPI_Window_Driver.cxx b/src/drivers/WinAPI/Fl_WinAPI_Window_Driver.cxx
index 6833b83ec..04c7a8edd 100644
--- a/src/drivers/WinAPI/Fl_WinAPI_Window_Driver.cxx
+++ b/src/drivers/WinAPI/Fl_WinAPI_Window_Driver.cxx
@@ -625,6 +625,61 @@ void Fl_WinAPI_Window_Driver::decoration_sizes(int *top, int *left,  int *right,
   *top += GetSystemMetrics(SM_CYCAPTION);
 }
 
+int Fl_WinAPI_Window_Driver::scroll(int src_x, int src_y, int src_w, int src_h, int dest_x, int dest_y,
+                   void (*draw_area)(void*, int,int,int,int), void* data)
+{
+  typedef int (WINAPI* fl_GetRandomRgn_func)(HDC, HRGN, INT);
+  static fl_GetRandomRgn_func fl_GetRandomRgn = 0L;
+  static char first_time = 1;
+  // We will have to do some Region magic now, so let's see if the
+  // required function is available (and it should be staring w/Win95)
+  if (first_time) {
+    HMODULE hMod = GetModuleHandle("GDI32.DLL");
+    if (hMod) {
+      fl_GetRandomRgn = (fl_GetRandomRgn_func)GetProcAddress(hMod, "GetRandomRgn");
+    }
+    first_time = 0;
+  }
+  // Now check if the source scrolling area is fully visible.
+  // If it is, we will do a quick scroll and just update the
+  // newly exposed area. If it is not, we go the safe route and
+  // re-render the full area instead.
+  // Note 1: we could go and find the areas that are actually
+  // obscured and recursively call fl_scroll for the newly found
+  // rectangles. However, this practice would rely on the
+  // elements of the undocumented Rgn structure.
+  // Note 2: although this method should take care of most
+  // multi-screen solutions, it will not solve issues scrolling
+  // from a different resolution screen onto another.
+  // Note 3: this has been tested with image maps, too.
+  HDC gc = (HDC)fl_graphics_driver->gc();
+  if (fl_GetRandomRgn) {
+    // get the DC region minus all overlapping windows
+    HRGN sys_rgn = CreateRectRgn(0, 0, 0, 0);
+    fl_GetRandomRgn(gc, sys_rgn, 4);
+    // now get the source scrolling rectangle
+    HRGN src_rgn = CreateRectRgn(src_x, src_y, src_x+src_w, src_y+src_h);
+    POINT offset = { 0, 0 };
+    if (GetDCOrgEx(gc, &offset)) {
+      OffsetRgn(src_rgn, offset.x, offset.y);
+    }
+    // see if all source pixels are available in the system region
+    // Note: we could be a bit more merciful and subtract the
+    // scroll destination region as well.
+    HRGN dst_rgn = CreateRectRgn(0, 0, 0, 0);
+    int r = CombineRgn(dst_rgn, src_rgn, sys_rgn, RGN_DIFF);
+    DeleteObject(dst_rgn);
+    DeleteObject(src_rgn);
+    DeleteObject(sys_rgn);
+    if (r != NULLREGION) {
+      return 1;
+    }
+  }
+  // Great, we can do an accelerated scroll instead of re-rendering
+  BitBlt(gc, dest_x, dest_y, src_w, src_h, gc, src_x, src_y,SRCCOPY);
+  return 0;
+}
+
 //
 // End of "$Id$".
 //
diff --git a/src/drivers/X11/Fl_X11_Window_Driver.H b/src/drivers/X11/Fl_X11_Window_Driver.H
index 2c4c432aa..cf71bb935 100644
--- a/src/drivers/X11/Fl_X11_Window_Driver.H
+++ b/src/drivers/X11/Fl_X11_Window_Driver.H
@@ -114,6 +114,7 @@ public:
   virtual void wait_for_expose();
   virtual int can_do_overlay();
   virtual void redraw_overlay();
+  virtual int scroll(int src_x, int src_y, int src_w, int src_h, int dest_x, int dest_y, void (*draw_area)(void*, int,int,int,int), void* data);
 };
 
 
diff --git a/src/drivers/X11/Fl_X11_Window_Driver.cxx b/src/drivers/X11/Fl_X11_Window_Driver.cxx
index 06343fb1b..538a728a6 100644
--- a/src/drivers/X11/Fl_X11_Window_Driver.cxx
+++ b/src/drivers/X11/Fl_X11_Window_Driver.cxx
@@ -658,6 +658,23 @@ void Fl_X11_Window_Driver::erase_menu() {
 #endif
 }
 
+int Fl_X11_Window_Driver::scroll(int src_x, int src_y, int src_w, int src_h, int dest_x, int dest_y,
+                                 void (*draw_area)(void*, int,int,int,int), void* data)
+{
+  XCopyArea(fl_display, fl_window, fl_window, (GC)fl_graphics_driver->gc(),
+            src_x, src_y, src_w, src_h, dest_x, dest_y);
+  // we have to sync the display and get the GraphicsExpose events! (sigh)
+  for (;;) {
+    XEvent e; XWindowEvent(fl_display, fl_window, ExposureMask, &e);
+    if (e.type == NoExpose) break;
+    // otherwise assume it is a GraphicsExpose event:
+    draw_area(data, e.xexpose.x, e.xexpose.y,
+              e.xexpose.width, e.xexpose.height);
+    if (!e.xgraphicsexpose.count) break;
+  }
+  return 0;
+}
+
 //
 // End of "$Id$".
 //