Add one argument to Fl_Screen_Driver::read_win_rectangle()

The new argument gives the window to be captured, or NULL to indicate capture
from the current offscreen.
Calling this function becomes easier because less dependent on global variables.

src/Fl_Screen_Driver.H

@@ -150,8 +150,10 @@ public:
    A platform may also use its read_win_rectangle() implementation to capture
    window decorations (e.g., title bar). In that case, it is called by
    Fl_XXX_Window_Driver::capture_titlebar_and_borders().
+   
+   win is the window to capture from, or NULL to capture from the current offscreen
    */
-  virtual Fl_RGB_Image *read_win_rectangle(int X, int Y, int w, int h) {return NULL;}
+  virtual Fl_RGB_Image *read_win_rectangle(int X, int Y, int w, int h, Fl_Window *win) {return NULL;}
   static void write_image_inside(Fl_RGB_Image *to, Fl_RGB_Image *from, int to_x, int to_y);
   static Fl_RGB_Image *traverse_to_gl_subwindows(Fl_Group *g, int x, int y, int w, int h,
                                                  Fl_RGB_Image *full_img);

src/Fl_Screen_Driver.cxx

@@ -196,8 +196,7 @@ Fl_RGB_Image *Fl_Screen_Driver::traverse_to_gl_subwindows(Fl_Group *g, int x, in
     full_img = plugin->rectangle_capture(g, x, y, w, h);
   }
   else if ( g->as_window() ) {
-    if (Fl_Window::current() != g) g->as_window()->make_current();
-    full_img = Fl::screen_driver()->read_win_rectangle(x, y, w, h);
+    full_img = Fl::screen_driver()->read_win_rectangle(x, y, w, h, g->as_window());
   }
   if (!full_img) return NULL;
   float full_img_scale =  (full_img && w > 0 ? float(full_img->data_w())/w : 1);

src/Fl_win32.cxx

@@ -2719,14 +2719,14 @@ void Fl_WinAPI_Window_Driver::capture_titlebar_and_borders(Fl_RGB_Image *&top, F
   // capture the 4 window sides from screen
   Fl_WinAPI_Screen_Driver *dr = (Fl_WinAPI_Screen_Driver *)Fl::screen_driver();
   if (htop) {
-    top = dr->read_win_rectangle_unscaled(r.left, r.top, r.right - r.left, htop);
+    top = dr->read_win_rectangle_unscaled(r.left, r.top, r.right - r.left, htop, 0);
     if (scaling != 1)
       top->scale(ww, htop / scaling, 0, 1);
   }
   if (wsides) {
-    left = dr->read_win_rectangle_unscaled(r.left, r.top + htop, wsides, h() * scaling);
-    right = dr->read_win_rectangle_unscaled(r.right - wsides, r.top + htop, wsides, h() * scaling);
-    bottom = dr->read_win_rectangle_unscaled(r.left, r.bottom - hbottom, ww, hbottom);
+    left = dr->read_win_rectangle_unscaled(r.left, r.top + htop, wsides, h() * scaling, 0);
+    right = dr->read_win_rectangle_unscaled(r.right - wsides, r.top + htop, wsides, h() * scaling, 0);
+    bottom = dr->read_win_rectangle_unscaled(r.left, r.bottom - hbottom, ww, hbottom, 0);
     if (scaling != 1) {
       left->scale(wsides, h(), 0, 1);
       right->scale(wsides, h(), 0, 1);

src/drivers/Cocoa/Fl_Cocoa_Screen_Driver.H

@@ -99,7 +99,7 @@ public:
   virtual APP_SCALING_CAPABILITY rescalable() { return SYSTEMWIDE_APP_SCALING; }
   virtual float scale(int n) {return scale_;}
   virtual void scale(int n, float f) { scale_ = f;}
-  virtual Fl_RGB_Image *read_win_rectangle(int X, int Y, int w, int h);
+  virtual Fl_RGB_Image *read_win_rectangle(int X, int Y, int w, int h, Fl_Window *win);
 private:
   float scale_;
 };

src/drivers/Cocoa/Fl_Cocoa_Screen_Driver.cxx

@@ -339,11 +339,11 @@ void Fl_Cocoa_Screen_Driver::offscreen_size(Fl_Offscreen off, int &width, int &h
   height = CGBitmapContextGetHeight(off);
 }
 
-Fl_RGB_Image *Fl_Cocoa_Screen_Driver::read_win_rectangle(int X, int Y, int w, int h)
+Fl_RGB_Image *Fl_Cocoa_Screen_Driver::read_win_rectangle(int X, int Y, int w, int h, Fl_Window *window)
 {
   int bpp, bpr, depth = 4;
   uchar *base, *p;
-  if (!fl_window) { // read from offscreen buffer
+  if (!window) { // read from offscreen buffer
     float s = 1;
     CGContextRef src = (CGContextRef)Fl_Surface_Device::surface()->driver()->gc();  // get bitmap context
     base = (uchar *)CGBitmapContextGetData(src);  // get data
@@ -373,7 +373,7 @@ Fl_RGB_Image *Fl_Cocoa_Screen_Driver::read_win_rectangle(int X, int Y, int w, in
     }
     bpr = 0;
   } else { // read from window
-    Fl_Cocoa_Window_Driver *d = Fl_Cocoa_Window_Driver::driver(Fl_Window::current());
+    Fl_Cocoa_Window_Driver *d = Fl_Cocoa_Window_Driver::driver(window);
     CGImageRef cgimg = d->CGImage_from_window_rect(X, Y, w, h, false);
     if (!cgimg) {
       return NULL;

src/drivers/GDI/Fl_GDI_Image_Surface_Driver.cxx

@@ -89,7 +89,7 @@ void Fl_GDI_Image_Surface_Driver::untranslate() {
 
 Fl_RGB_Image* Fl_GDI_Image_Surface_Driver::image()
 {
-  Fl_RGB_Image *image = Fl::screen_driver()->read_win_rectangle( 0, 0, width, height);
+  Fl_RGB_Image *image = Fl::screen_driver()->read_win_rectangle( 0, 0, width, height, 0);
   return image;
 }
 

src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.H

@@ -75,8 +75,8 @@ public:
   virtual void remove_timeout(Fl_Timeout_Handler cb, void *argp);
   virtual int dnd(int unused);
   virtual int compose(int &del);
-  virtual Fl_RGB_Image *read_win_rectangle(int X, int Y, int w, int h);
-  Fl_RGB_Image *read_win_rectangle_unscaled(int X, int Y, int w, int h);
+  virtual Fl_RGB_Image *read_win_rectangle(int X, int Y, int w, int h, Fl_Window *win);
+  Fl_RGB_Image *read_win_rectangle_unscaled(int X, int Y, int w, int h, Fl_Window *win);
   virtual int get_mouse(int &x, int &y);
   virtual void enable_im();
   virtual void disable_im();

src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx

@@ -501,7 +501,8 @@ Fl_WinAPI_Screen_Driver::read_win_rectangle(
                                             int   X,		// I - Left position
                                             int   Y,		// I - Top position
                                             int   w,		// I - Width of area to read
-                                            int   h)		// I - Height of area to read
+                                            int   h,		// I - Height of area to read
+                                            Fl_Window *win)     // I - window to capture from or NULL to capture from current offscreen
 {
   float s = Fl_Surface_Device::surface()->driver()->scale();
   int ws, hs;
@@ -512,10 +513,10 @@ Fl_WinAPI_Screen_Driver::read_win_rectangle(
     if (ws < 1) ws = 1;
     if (hs < 1) hs = 1;
   }
-  return read_win_rectangle_unscaled(X*s, Y*s, ws, hs);
+  return read_win_rectangle_unscaled(X*s, Y*s, ws, hs, win);
 }
 
-Fl_RGB_Image *Fl_WinAPI_Screen_Driver::read_win_rectangle_unscaled(int X, int Y, int w, int h)
+Fl_RGB_Image *Fl_WinAPI_Screen_Driver::read_win_rectangle_unscaled(int X, int Y, int w, int h, Fl_Window *win)
 {
   int	d = 3;			// Depth of image
   int alpha = 0; uchar *p = NULL;
@@ -569,6 +570,7 @@ Fl_RGB_Image *Fl_WinAPI_Screen_Driver::read_win_rectangle_unscaled(int X, int Y,
   bi.bmiHeader.biClrImportant = 0;
   
   // copy bitmap from original DC (Window, Fl_Offscreen, ...)
+  if (win && Fl_Window::current() != win) win->make_current();
   HDC gc = (HDC)fl_graphics_driver->gc();
   HDC hdc = CreateCompatibleDC(gc);
   HBITMAP hbm = CreateCompatibleBitmap(gc,w,h);

src/drivers/X11/Fl_X11_Screen_Driver.H

@@ -95,7 +95,7 @@ public:
   virtual int compose(int &del);
   virtual void compose_reset();
   virtual int text_display_can_leak();
-  virtual Fl_RGB_Image *read_win_rectangle(int X, int Y, int w, int h);
+  virtual Fl_RGB_Image *read_win_rectangle(int X, int Y, int w, int h, Fl_Window *win);
   virtual int get_mouse(int &x, int &y);
   virtual void enable_im();
   virtual void disable_im();

src/drivers/X11/Fl_X11_Screen_Driver.cxx

@@ -745,7 +745,7 @@ extern "C" {
   }
 }
 
-Fl_RGB_Image *Fl_X11_Screen_Driver::read_win_rectangle(int X, int Y, int w, int h)
+Fl_RGB_Image *Fl_X11_Screen_Driver::read_win_rectangle(int X, int Y, int w, int h, Fl_Window *win)
 {
   XImage	*image;		// Captured image
   int		i, maxindex;	// Looping vars
@@ -772,12 +772,14 @@ 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();
+  Window xid = (win && !allow_outside ? fl_xid(win) : fl_window);
+
+  float s = allow_outside ? Fl::screen_driver()->scale(win->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, Xs, Ys, ws, hs, 0, NULL);
+    image = XReadDisplay(fl_display, xid, Xs, Ys, ws, hs, 0, NULL);
   } else
 #  else
     image = 0;
@@ -788,11 +790,8 @@ Fl_RGB_Image *Fl_X11_Screen_Driver::read_win_rectangle(int X, int Y, int w, int
     int dx, dy, sx, sy, sw, sh;
     Window child_win;
     
-    Fl_Window *win;
-    if (allow_outside) win = Fl_Window::current();
-    else win = fl_find(fl_window);
     if (win) {
-      XTranslateCoordinates(fl_display, fl_window,
+      XTranslateCoordinates(fl_display, xid,
                             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());
@@ -811,7 +810,7 @@ Fl_RGB_Image *Fl_X11_Screen_Driver::read_win_rectangle(int X, int Y, int w, int
       // 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, Xs, Ys, ws, hs, AllPlanes, ZPixmap);
+      image = XGetImage(fl_display, xid, Xs, Ys, ws, hs, AllPlanes, ZPixmap);
       XSetErrorHandler(old_handler);
     } else {
       // image is crossing borders, determine visible region
@@ -831,7 +830,7 @@ 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, Xs + noffx, Ys + noffy,
+      XImage *subimg = XGetSubImage(fl_display, xid, Xs + noffx, Ys + noffy,
                                     nw, nh, AllPlanes, ZPixmap, image, noffx, noffy);
       XSetErrorHandler(old_handler);
       if (!subimg) {

src/drivers/X11/Fl_X11_Window_Driver.cxx

@@ -392,16 +392,14 @@ void Fl_X11_Window_Driver::free_icons() {
  
  This function exploits a feature of Fl_X11_Screen_Driver::read_win_rectangle() which,
  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
+ Other requirement to capture the window decoration:
+   fl_window is the parent window of 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_Window *oldcurrent = Fl_Window::current();
   Window root, parent, *children, child_win, xid = fl_xid(pWindow);
   unsigned n = 0;
   int do_it;
@@ -414,25 +412,23 @@ 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 = Fl::screen_driver()->read_win_rectangle(0, 0, - (w() + 2 * wsides), htop, pWindow);
     if (top) top->scale(w() + 2 * wsides, htop, 0, 1);
   }
   if (wsides) {
-    left = Fl::screen_driver()->read_win_rectangle(0, htop, -wsides, h());
+    left = Fl::screen_driver()->read_win_rectangle(0, htop, -wsides, h(), pWindow);
     if (left) {
       left->scale(wsides, h(), 0, 1);
     }
-    right = Fl::screen_driver()->read_win_rectangle(w() + wsides, htop, -wsides, h());
+    right = Fl::screen_driver()->read_win_rectangle(w() + wsides, htop, -wsides, h(), pWindow);
     if (right) {
       right->scale(wsides, h(), 0, 1);
     }
-    bottom = Fl::screen_driver()->read_win_rectangle(0, htop + h(), -(w() + 2*wsides), hbottom);
+    bottom = Fl::screen_driver()->read_win_rectangle(0, htop + h(), -(w() + 2*wsides), hbottom, pWindow);
     if (bottom) {
       bottom->scale(w() + 2*wsides, wsides, 0, 1);
     }  }
-  current(oldcurrent);
   fl_window = from;
 }
 

src/drivers/Xlib/Fl_Xlib_Copy_Surface_Driver.cxx

@@ -64,7 +64,7 @@ Fl_Xlib_Copy_Surface_Driver::~Fl_Xlib_Copy_Surface_Driver() {
   driver()->pop_clip();
   bool need_push = !is_current();
   if (need_push) Fl_Surface_Device::push_current(this);
-  Fl_RGB_Image *rgb = Fl::screen_driver()->read_win_rectangle(0, 0, width, height);
+  Fl_RGB_Image *rgb = Fl::screen_driver()->read_win_rectangle(0, 0, width, height, 0);
   if (need_push) Fl_Surface_Device::pop_current();
   Fl_X11_Screen_Driver::copy_image(rgb->array, rgb->w(), rgb->h(), 1);
   delete rgb;

src/drivers/Xlib/Fl_Xlib_Image_Surface_Driver.cxx

@@ -74,7 +74,7 @@ void Fl_Xlib_Image_Surface_Driver::untranslate() {
 
 Fl_RGB_Image* Fl_Xlib_Image_Surface_Driver::image()
 {
-  Fl_RGB_Image *image = Fl::screen_driver()->read_win_rectangle(0, 0, width, height);
+  Fl_RGB_Image *image = Fl::screen_driver()->read_win_rectangle(0, 0, width, height, 0);
   return image;
 }
 

src/fl_overlay.cxx

@@ -68,19 +68,19 @@ static void draw_current_rect() {
   if (s_bgE) { delete s_bgE; s_bgE = 0; }
   if (s_bgW) { delete s_bgW; s_bgW = 0; }
   if (pw>0 && ph>0) {
-    s_bgE = Fl::screen_driver()->read_win_rectangle( px+pw-1, py, 1, ph);
+    s_bgE = Fl::screen_driver()->read_win_rectangle( px+pw-1, py, 1, ph, Fl_Window::current());
     if(s_bgE && s_bgE->w() && s_bgE->h()) {
       s_bgE->scale(1, ph,0,1);
     }
-    s_bgW = Fl::screen_driver()->read_win_rectangle( px, py, 1, ph);
+    s_bgW = Fl::screen_driver()->read_win_rectangle( px, py, 1, ph, Fl_Window::current());
     if(s_bgW && s_bgW->w() && s_bgW->h()) {
       s_bgW->scale(1, ph,0,1);
     }
-    s_bgS = Fl::screen_driver()->read_win_rectangle( px, py+ph-1, pw, 1);
+    s_bgS = Fl::screen_driver()->read_win_rectangle( px, py+ph-1, pw, 1, Fl_Window::current());
     if(s_bgS && s_bgS->w() && s_bgS->h()) {
       s_bgS->scale(pw, 1,0,1);
     }
-    s_bgN = Fl::screen_driver()->read_win_rectangle( px, py, pw, 1);
+    s_bgN = Fl::screen_driver()->read_win_rectangle( px, py, pw, 1, Fl_Window::current());
     if(s_bgN && s_bgN->w() && s_bgN->h()) {
       s_bgN->scale(pw, 1,0,1);
     }

src/fl_read_image.cxx

@@ -43,7 +43,7 @@ uchar *fl_read_image(uchar *p, int X, int Y, int w, int h, int alpha) {
   uchar *image_data = NULL;
   Fl_RGB_Image *img;
   if (fl_find(fl_window) == 0) { // read from off_screen buffer
-    img = Fl::screen_driver()->read_win_rectangle(X, Y, w, h);
+    img = Fl::screen_driver()->read_win_rectangle(X, Y, w, h, 0);
     if (!img) {
       return NULL;
     }