Fix Fl_X11_Window_Driver::capture_titlebar_and_borders() for scaled, partially visible windows

2 files changed, 23 insertions, 19 deletions

diff --git a/src/drivers/X11/Fl_X11_Screen_Driver.cxx b/src/drivers/X11/Fl_X11_Screen_Driver.cxx
index d71ef7486..43482bb1a 100644
--- a/src/drivers/X11/Fl_X11_Screen_Driver.cxx
+++ b/src/drivers/X11/Fl_X11_Screen_Driver.cxx
@@ -772,20 +772,20 @@ Fl_RGB_Image *Fl_X11_Screen_Driver::read_win_rectangle(int X, int Y, int w, int
   int allow_outside = w < 0;    // negative w allows negative X or Y, that is, window frame
   if (w < 0) w = - w;
   
+  float s = allow_outside ? Fl::screen_driver()->scale(Fl_Window::current()->screen_num()) : Fl_Surface_Device::surface()->driver()->scale();
+  int ws = w * s, hs = h * s, Xs = X*s, Ys = Y*s;
+  
 #  ifdef __sgi
   if (XReadDisplayQueryExtension(fl_display, &i, &i)) {
-    image = XReadDisplay(fl_display, fl_window, X, Y, w, h, 0, NULL);
+    image = XReadDisplay(fl_display, fl_window, Xs, Ys, ws, hs, 0, NULL);
   } else
 #  else
     image = 0;
 #  endif // __sgi
   
-  float s = Fl_Surface_Device::surface()->driver()->scale();
-  int ws = w * s, hs = h * s;
-  
   if (!image) {
     // fetch absolute coordinates
-    int dx, dy, dxs, dys, sx, sy, sw, sh;
+    int dx, dy, sx, sy, sw, sh;
     Window child_win;
     
     Fl_Window *win;
@@ -793,31 +793,31 @@ Fl_RGB_Image *Fl_X11_Screen_Driver::read_win_rectangle(int X, int Y, int w, int
     else win = fl_find(fl_window);
     if (win) {
       XTranslateCoordinates(fl_display, fl_window,
-                            RootWindow(fl_display, fl_screen), X*s, Y*s, &dxs, &dys, &child_win);
-      dx = dxs/s; dy = dys/s;
+                            RootWindow(fl_display, fl_screen), Xs, Ys, &dx, &dy, &child_win);
       // screen dimensions
       Fl::screen_xywh(sx, sy, sw, sh, Fl_Window_Driver::driver(win)->screen_num());
+      sx *= s; sy *= s; sw *= s; sh *= s;
     }
     if (win && !allow_outside && int(s) != s) {
       ws = (w+1)*s-1;
       hs = (h+1)*s-1;
-      if (int(X*s) + ws >= win->w()*s) ws = win->w()*s - int(X*s) -1;
-      if (int(Y*s) + hs >= win->h()*s) hs = win->h()*s - int(Y*s) -1;
+      if (Xs + ws >= int(win->w()*s)) ws = win->w()*s - Xs -1;
+      if (Ys + hs >= int(win->h()*s)) hs = win->h()*s - Ys -1;
      }
     if (ws < 1) ws = 1;
     if (hs < 1) hs = 1;
-    if (!win || (dx >= sx && dy >= sy && dxs + ws <= (sx+sw)*s && dys + hs <= (sy+sh)*s) ) {
+    if (!win || (dx >= sx && dy >= sy && dx + ws <= sx+sw && dy + hs <= sy+sh) ) {
       // the image is fully contained, we can use the traditional method
       // however, if the window is obscured etc. the function will still fail. Make sure we
       // catch the error and continue, otherwise an exception will be thrown.
       XErrorHandler old_handler = XSetErrorHandler(xgetimageerrhandler);
-      image = XGetImage(fl_display, fl_window, int(X*s), int(Y*s), ws, hs, AllPlanes, ZPixmap);
+      image = XGetImage(fl_display, fl_window, Xs, Ys, ws, hs, AllPlanes, ZPixmap);
       XSetErrorHandler(old_handler);
     } else {
       // image is crossing borders, determine visible region
       int nw, nh, noffx, noffy;
-      noffx = fl_subimage_offsets(sx, sw, dx, w, nw);
-      noffy = fl_subimage_offsets(sy, sh, dy, h, nh);
+      noffx = fl_subimage_offsets(sx, sw, dx, ws, nw);
+      noffy = fl_subimage_offsets(sy, sh, dy, hs, nh);
       if (nw <= 0 || nh <= 0) return 0;
       
       // allocate the image
@@ -831,8 +831,8 @@ Fl_RGB_Image *Fl_X11_Screen_Driver::read_win_rectangle(int X, int Y, int w, int
       }
       
       XErrorHandler old_handler = XSetErrorHandler(xgetimageerrhandler);
-      XImage *subimg = XGetSubImage(fl_display, fl_window, (X + noffx)*s, (Y + noffy)*s,
-                                    nw*s, nh*s, AllPlanes, ZPixmap, image, noffx*s, noffy*s);
+      XImage *subimg = XGetSubImage(fl_display, fl_window, Xs + noffx, Ys + noffy,
+                                    nw, nh, AllPlanes, ZPixmap, image, noffx, noffy);
       XSetErrorHandler(old_handler);
       if (!subimg) {
         XDestroyImage(image);
diff --git a/src/drivers/X11/Fl_X11_Window_Driver.cxx b/src/drivers/X11/Fl_X11_Window_Driver.cxx
index 34313ce26..e2ed5d073 100644
--- a/src/drivers/X11/Fl_X11_Window_Driver.cxx
+++ b/src/drivers/X11/Fl_X11_Window_Driver.cxx
@@ -391,14 +391,17 @@ void Fl_X11_Window_Driver::free_icons() {
  The top and bottom images extend from left of the left border to right of the right border.
  
  This function exploits a feature of Fl_X11_Screen_Driver::read_win_rectangle() which,
- when called with negative 4th argument, captures the window decoration.
+ when called with negative 3rd argument, captures the window decoration.
+ Other requirements to capture the window decoration:
+ - fl_window is the parent window of the top window
+ - Fl_Window::current() is the top window
  */
 void Fl_X11_Window_Driver::capture_titlebar_and_borders(Fl_RGB_Image*& top, Fl_RGB_Image*& left, Fl_RGB_Image*& bottom, Fl_RGB_Image*& right)
 {
   top = left = bottom = right = NULL;
   if (pWindow->decorated_h() == h()) return;
   Window from = fl_window;
-  Fl_Surface_Device::push_current( Fl_Display_Device::display_device() );
+  Fl_Window *oldcurrent = Fl_Window::current();
   Window root, parent, *children, child_win, xid = fl_xid(pWindow);
   unsigned n = 0;
   int do_it;
@@ -411,9 +414,10 @@ void Fl_X11_Window_Driver::capture_titlebar_and_borders(Fl_RGB_Image*& top, Fl_R
   float s = Fl::screen_driver()->scale(screen_num());
   htop /= s; wsides /= s;
   fl_window = parent;
+  current(pWindow);
   if (htop) {
     top = Fl::screen_driver()->read_win_rectangle(0, 0, - (w() + 2 * wsides), htop);
-    top->scale(w() + 2 * wsides, htop, 0, 1);
+    if (top) top->scale(w() + 2 * wsides, htop, 0, 1);
   }
   if (wsides) {
     left = Fl::screen_driver()->read_win_rectangle(0, htop, -wsides, h());
@@ -428,7 +432,7 @@ void Fl_X11_Window_Driver::capture_titlebar_and_borders(Fl_RGB_Image*& top, Fl_R
     if (bottom) {
       bottom->scale(w() + 2*wsides, wsides, 0, 1);
     }  }
-  Fl_Surface_Device::pop_current();
+  current(oldcurrent);
   fl_window = from;
 }