Introduce HiDPI + rescaling support for the X11 platform (+ partial support for WIN32)

Corresponds to STR #3320
1) HiDPI support consists in detecting the adequate scaling factor for the screen on which
FLTK maps a window, and scaling all FLTK units by this factor. FLTK tries to detect the correct
value of this factor at startup (see more details below). Environment variable
FLTK_SCALING_FACTOR can also be used to set this value.
2) Rescaling support consists in changing the scaling factor of all FLTK windows
in reply to ctrl/+/-/0/ keystrokes.

More details for the various platforms :

- X11: Support is very advanced. Some details need still to be improved.
Automatic detection of the correct starting value of the scaling factor works well
with the gnome desktop. The present code contains no support for this on
other desktops.  FLTK_SCALING_FACTOR provides a workaround.

-WIN32: Support is incomplete at this point, although many test
applications have partial or complete HiDPI and scaling support.
The current value of the system's scaling factor is correctly detected
at application startup. Apps respond to changes of this value in real time.
Support needs to define the FLTK_HIDPI_SUPPORT preprocessor variable
at compile time. This way, standard builds produce a code with the
default WIN32 HiDPI support, that is, where all graphics goes to an internal
buffer that gets enlarged by the system and then mapped to the HiDPI
display. To experiment with (or develop) the new HiDPI support requires
a modified build procedure in which  FLTK_HIDPI_SUPPORT is defined
at compile time. When the support will be complete, the requirement for the
definition of this preprocessor variable will be removed. The present commit
contains support for a single scaling factor. Eventually, per-screen scaling
factors should be implemented, as done for X11.

- MacOS: this commit does not give new HiDPI for this platform.
Eventually, window rescaling in reply to command/+/-/0/ is desirable.
Per-screen scaling factor makes no sense on this platform because
the OS itself takes care of the difference between the resolutions of
traditional and retina displays.


git-svn-id: file:///fltk/svn/fltk/branches/branch-1.4@12239 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

1 files changed, 134 insertions, 47 deletions

diff --git a/src/Fl_x.cxx b/src/Fl_x.cxx
index d1fa939f8..ac56e64aa 100644
--- a/src/Fl_x.cxx
+++ b/src/Fl_x.cxx
@@ -3,7 +3,7 @@
 //
 // X specific code for the Fast Light Tool Kit (FLTK).
 //
-// Copyright 1998-2016 by Bill Spitzak and others.
+// Copyright 1998-2017 by Bill Spitzak and others.
 //
 // This library is free software. Distribution and use rights are outlined in
 // the file "COPYING" which should have been included with this file.  If this
@@ -719,14 +719,23 @@ void Fl_X11_Screen_Driver::close_display() {
   XCloseDisplay(fl_display);
 }
 
-
-void Fl_X11_Screen_Driver::get_mouse(int &xx, int &yy) {
+int Fl_X11_Screen_Driver::get_mouse_unscaled(int &mx, int &my) {
   open_display();
   Window root = RootWindow(fl_display, fl_screen);
-  Window c; int mx,my,cx,cy; unsigned int mask;
-  XQueryPointer(fl_display,root,&root,&c,&mx,&my,&cx,&cy,&mask);
-  xx = mx;
-  yy = my;
+  Window c; int cx,cy; unsigned int mask;
+  XQueryPointer(fl_display, root, &root, &c, &mx, &my, &cx, &cy, &mask);
+#if USE_XFT
+  return screen_num_unscaled(mx, my);
+#else
+  return screen_num(mx, my);
+#endif
+}
+
+
+void Fl_X11_Screen_Driver::get_mouse(int &xx, int &yy) {
+  float s = scale(get_mouse_unscaled(xx, yy));
+  xx = xx/s;
+  yy = yy/s;
 }
 
 ////////////////////////////////////////////////////////////////
@@ -1079,14 +1088,18 @@ char fl_key_vector[32]; // used by Fl::get_key()
 static int px, py;
 static ulong ptime;
 
-static void set_event_xy() {
+static void set_event_xy(Fl_Window *win) {
 #  if CONSOLIDATE_MOTION
   send_motion = 0;
 #  endif
-  Fl::e_x_root  = fl_xevent->xbutton.x_root;
-  Fl::e_x       = fl_xevent->xbutton.x;
-  Fl::e_y_root  = fl_xevent->xbutton.y_root;
-  Fl::e_y       = fl_xevent->xbutton.y;
+  float s = 1;
+#if USE_XFT
+  s = Fl::screen_driver()->scale(win->driver()->screen_num());
+#endif
+  Fl::e_x_root  = fl_xevent->xbutton.x_root/s;
+  Fl::e_x       = fl_xevent->xbutton.x/s;
+  Fl::e_y_root  = fl_xevent->xbutton.y_root/s;
+  Fl::e_y       = fl_xevent->xbutton.y/s;
   Fl::e_state   = fl_xevent->xbutton.state << 16;
   fl_event_time = fl_xevent->xbutton.time;
 #  ifdef __sgi
@@ -1203,12 +1216,6 @@ static KeySym fl_KeycodeToKeysym(Display *d, KeyCode k, unsigned i) {
   return XKeycodeToKeysym(d, k, i);
 }
 
-static void fl_init_workarea()
-{
-  Fl_X11_Screen_Driver *drv = (Fl_X11_Screen_Driver*)Fl::screen_driver();
-  drv->init_workarea();
-}
-
 int fl_handle(const XEvent& thisevent)
 {
   XEvent xevent = thisevent;
@@ -1241,13 +1248,17 @@ int fl_handle(const XEvent& thisevent)
   if( XRRUpdateConfiguration_f && xevent.type == randrEventBase + RRScreenChangeNotify) {
     XRRUpdateConfiguration_f(&xevent);
     Fl::call_screen_init();
-    fl_init_workarea();
+#if USE_XFT
+    float factor = Fl::screen_driver()->default_scale_factor();
+    for (int screen = 0; screen <= Fl::screen_count(); screen++)
+      Fl::screen_driver()->rescale_all_windows_from_screen(screen, factor);
+#endif // USE_XFT
     Fl::handle(FL_SCREEN_CONFIGURATION_CHANGED, NULL);
   }
-#endif
+#endif // USE_XRANDR
 
   if (xevent.type == PropertyNotify && xevent.xproperty.atom == fl_NET_WORKAREA) {
-    fl_init_workarea();
+    Fl::screen_driver()->init_workarea();
   }
   
   switch (xevent.type) {
@@ -1647,8 +1658,17 @@ fprintf(stderr,"\n");*/
 #  endif
 
   case GraphicsExpose:
-    window->damage(FL_DAMAGE_EXPOSE, xevent.xexpose.x, xevent.xexpose.y,
-                   xevent.xexpose.width, xevent.xexpose.height);
+    {
+#if USE_XFT
+      int ns = window->driver()->screen_num();
+      float s = Fl::screen_driver()->scale(ns);
+      window->damage(FL_DAMAGE_EXPOSE, xevent.xexpose.x/s, xevent.xexpose.y/s,
+                     xevent.xexpose.width/s + 2, xevent.xexpose.height/s + 2);
+#else
+      window->damage(FL_DAMAGE_EXPOSE, xevent.xexpose.x, xevent.xexpose.y,
+                     xevent.xexpose.width, xevent.xexpose.height);
+#endif
+     }
     return 1;
 
   case FocusIn:
@@ -1867,13 +1887,13 @@ fprintf(stderr,"\n");*/
     // replace XK_ISO_Left_Tab (Shift-TAB) with FL_Tab (modifier flags are set correctly by X11)
     if (Fl::e_keysym == 0xfe20) Fl::e_keysym = FL_Tab;
 
-    set_event_xy();
+    set_event_xy(window);
     Fl::e_is_click = 0; }
     break;
   
   case ButtonPress:
     Fl::e_keysym = FL_Button + xevent.xbutton.button;
-    set_event_xy();
+    set_event_xy(window);
     Fl::e_dx = Fl::e_dy = 0;
     if (xevent.xbutton.button == Button4) {
       Fl::e_dy = -1; // Up
@@ -1924,7 +1944,7 @@ fprintf(stderr,"\n");*/
     break;
 
   case MotionNotify:
-    set_event_xy();
+    set_event_xy(window);
 #  if CONSOLIDATE_MOTION
     send_motion = fl_xmousewin = window;
     in_a_window = true;
@@ -1938,7 +1958,7 @@ fprintf(stderr,"\n");*/
 
   case ButtonRelease:
     Fl::e_keysym = FL_Button + xevent.xbutton.button;
-    set_event_xy();
+    set_event_xy(window);
     Fl::e_state &= ~(FL_BUTTON1 << (xevent.xbutton.button-1));
     if (xevent.xbutton.button == Button4 ||
         xevent.xbutton.button == Button5) return 0;
@@ -1951,7 +1971,7 @@ fprintf(stderr,"\n");*/
   case EnterNotify:
     if (xevent.xcrossing.detail == NotifyInferior) break;
     // XInstallColormap(fl_display, Fl_X::i(window)->colormap);
-    set_event_xy();
+    set_event_xy(window);
     Fl::e_state = xevent.xcrossing.state << 16;
     event = FL_ENTER;
 
@@ -1967,7 +1987,7 @@ fprintf(stderr,"\n");*/
 
   case LeaveNotify:
     if (xevent.xcrossing.detail == NotifyInferior) break;
-    set_event_xy();
+    set_event_xy(window);
     Fl::e_state = xevent.xcrossing.state << 16;
     fl_xmousewin = 0;
     in_a_window = false; // make do_queued_events produce FL_LEAVE event
@@ -1992,10 +2012,39 @@ fprintf(stderr,"\n");*/
     Window cr; int X, Y, W = actual.width, H = actual.height;
     XTranslateCoordinates(fl_display, fl_xid(window), actual.root,
                           0, 0, &X, &Y, &cr);
+#if USE_XFT // detect when window changes screen
+    int num = 0;
+    Fl_X11_Screen_Driver *d = (Fl_X11_Screen_Driver*)Fl::screen_driver();
+    num = d->screen_num_unscaled(X, Y, actual.width, actual.height);
+    Fl_X11_Window_Driver *wd = Fl_X11_Window_Driver::driver(window);
+    int olds = wd->screen_num();
+    float s = d->scale(num);
+    if (num != olds) {
+      if (s != d->scale(olds) &&
+          !Fl_X11_Window_Driver::data_for_resize_window_between_screens_.busy &&
+          window->user_data() != &Fl_X11_Screen_Driver::transient_scale_display) {
+        Fl_X11_Window_Driver::data_for_resize_window_between_screens_.busy = true;
+        Fl_X11_Window_Driver::data_for_resize_window_between_screens_.screen = num;
+        // resize_after_screen_change() works also if called here, but calling it
+        // a second later gives a more pleasant user experience when moving windows between distinct screens
+        Fl::add_timeout(1, Fl_X11_Window_Driver::resize_after_screen_change, window);
+      }
+      wd->screen_num(num);
+    }
+#endif // USE_XFT
 
     // tell Fl_Window about it and set flag to prevent echoing:
     resize_bug_fix = window;
+#if USE_XFT    
+    if (!Fl_X11_Window_Driver::data_for_resize_window_between_screens_.busy &&
+       ( W != int(window->w()*s) || H != int(window->h()*s) ) ) {
+        window->resize(X/s, Y/s, W/s, H/s);
+    } else {
+      window->position(X/s, Y/s);
+    }
+#else
     window->resize(X, Y, W, H);
+#endif
     break; // allow add_handler to do something too
     }
 
@@ -2017,7 +2066,13 @@ fprintf(stderr,"\n");*/
     // tell Fl_Window about it and set flag to prevent echoing:
     if ( !wasXExceptionRaised() ) {
       resize_bug_fix = window;
-      window->position(xpos, ypos);
+#if USE_XFT
+      int ns = window->driver()->screen_num();
+      float s = Fl::screen_driver()->scale(ns);
+#else
+      float s = 1;
+#endif
+      window->position(xpos/s, ypos/s);
     }
     break;
     }
@@ -2066,15 +2121,16 @@ void Fl_X11_Window_Driver::resize(int X,int Y,int W,int H) {
   }
 
   if (resize_from_program && shown()) {
+    float s = Fl::screen_driver()->scale(screen_num());
     if (is_a_resize) {
       if (!pWindow->resizable()) pWindow->size_range(w(), h(), w(), h());
       if (is_a_move) {
-        XMoveResizeWindow(fl_display, fl_xid(pWindow), X, Y, W>0 ? W : 1, H>0 ? H : 1);
+        XMoveResizeWindow(fl_display, fl_xid(pWindow), X*s, Y*s, W>0 ? W*s : 1, H>0 ? H*s : 1);
       } else {
-        XResizeWindow(fl_display, fl_xid(pWindow), W>0 ? W : 1, H>0 ? H : 1);
+        XResizeWindow(fl_display, fl_xid(pWindow), W>0 ? W*s : 1, H>0 ? H*s : 1);
       }
     } else
-      XMoveWindow(fl_display, fl_xid(pWindow), X, Y);
+      XMoveWindow(fl_display, fl_xid(pWindow), X*s, Y*s);
   }
 }
 
@@ -2179,7 +2235,7 @@ void Fl_X11_Window_Driver::fullscreen_on() {
     right = fullscreen_screen_right();
     
     if ((top < 0) || (bottom < 0) || (left < 0) || (right < 0)) {
-      top = Fl::screen_num(x(), y(), w(), h());
+      top = screen_num();
       bottom = top;
       left = top;
       right = top;
@@ -2361,11 +2417,31 @@ void Fl_X::make_xid(Fl_Window* win, XVisualInfo *visual, Colormap colormap)
     fl_background_pixel = -1;
     mask |= CWBackPixel;
   }
-
+  // reproduce the window cursor if a window is hidden and then recreated (e.g., rescaled)
+  attr.cursor = Fl_X11_Window_Driver::driver(win)->current_cursor_;
+  mask |= CWCursor;
+  float s = 1;
+#if USE_XFT
+  //compute adequate screen where to put the window
+  int nscreen = 0;
+  if (win->parent()) {
+    nscreen = win->top_window()->driver()->screen_num();
+  } else if (win->force_position() && Fl_X11_Window_Driver::driver(win)->screen_num_ >= 0) {
+    nscreen = win->driver()->screen_num();
+  } else {
+    Fl_Window *hint = Fl::first_window();
+    if (hint) {
+      nscreen = hint->top_window()->driver()->screen_num();
+    }
+  }
+  Fl_X11_Window_Driver::driver(win)->screen_num(nscreen);
+  s = Fl::screen_driver()->scale(nscreen);
+//if (!win->parent()) printf("win creation on screen #%d\n", nscreen);
+#endif
   Fl_X* xp =
     set_xid(win, XCreateWindow(fl_display,
                                root,
-                               X, Y, W, H,
+                               X*s, Y*s, W*s, H*s,
                                0, // borderwidth
                                visual->depth,
                                InputOutput,
@@ -2525,12 +2601,20 @@ void Fl_X11_Window_Driver::sendxjunk() {
 
   XSizeHints *hints = XAllocSizeHints();
   // memset(&hints, 0, sizeof(hints)); jreiser suggestion to fix purify?
-  hints->min_width = minw();
-  hints->min_height = minh();
-  hints->max_width = maxw();
-  hints->max_height = maxh();
-  hints->width_inc = dw();
-  hints->height_inc = dh();
+  float s = Fl::screen_driver()->scale(screen_num());
+
+  hints->min_width = s*minw();
+  hints->min_height = s*minh();
+  hints->max_width = s*maxw();
+  hints->max_height = s*maxh();
+  if (int(s) == s) { // use win size increment value only if scale is an integer. Is it possible to do better?
+    hints->width_inc = s*dw();
+    hints->height_inc = s*dh();
+  } else {
+    hints->width_inc = 0;
+    hints->height_inc = 0;
+  }
+  
   hints->win_gravity = StaticGravity;
 
   // see the file /usr/include/X11/Xm/MwmUtil.h:
@@ -2547,8 +2631,8 @@ void Fl_X11_Window_Driver::sendxjunk() {
       // unfortunately we can't set just one maximum size.  Guess a
       // value for the other one.  Some window managers will make the
       // window fit on screen when maximized, others will put it off screen:
-      if (hints->max_width < hints->min_width) hints->max_width = Fl::w();
-      if (hints->max_height < hints->min_height) hints->max_height = Fl::h();
+      if (hints->max_width < hints->min_width) hints->max_width = Fl::w()*s;
+      if (hints->max_height < hints->min_height) hints->max_height = Fl::h()*s;
     }
     if (hints->width_inc && hints->height_inc) hints->flags |= PResizeInc;
     if (aspect()) {
@@ -2566,8 +2650,8 @@ void Fl_X11_Window_Driver::sendxjunk() {
 
   if (force_position()) {
     hints->flags |= USPosition;
-    hints->x = w->x();
-    hints->y = w->y();
+    hints->x = s*w->x();
+    hints->y = s*w->y();
   }
 
   if (!w->border()) {
@@ -2730,6 +2814,7 @@ int Fl_X11_Window_Driver::set_cursor(Fl_Cursor c) {
 #undef cache_cursor
 
   XDefineCursor(fl_display, fl_xid(pWindow), xc);
+  current_cursor_ = xc;
 
   return 1;
 }
@@ -2895,6 +2980,7 @@ void printFront(Fl_Widget *o, void *data)
   //printer.print_window_part( win, 0,0, win->w(), win->h(), - win->w()/2, - win->h()/2 );
 #else  
   printer.print_window(win);
+  //printer.print_window_part( win, 0,0, win->w(), win->h(), 0,0 );
 #endif
 
   printer.end_page();
@@ -2909,8 +2995,9 @@ void copyFront(Fl_Widget *o, void *data)
   Fl_Window *win = Fl::first_window();
   if (!win) return;
   Fl_Copy_Surface *surf = new Fl_Copy_Surface(win->decorated_w(), win->decorated_h());
-  surf->set_current();
+  Fl_Surface_Device::push_current(surf);
   surf->draw_decorated_window(win); // draw the window content
+  Fl_Surface_Device::pop_current();
   delete surf; // put the window on the clipboard
   o->window()->show();
 }