Wayland: add support for multiple high or low DPI displays

7 files changed, 107 insertions, 46 deletions

diff --git a/FL/Fl_Window.H b/FL/Fl_Window.H
index 7ea3fd8ec..ef4d78007 100644
--- a/FL/Fl_Window.H
+++ b/FL/Fl_Window.H
@@ -526,17 +526,6 @@ public:
   */
   void make_current();
 
-  /**
-    Changes the cursor for this window.
-
-    This always calls the system. If you are changing the cursor a lot
-    you may want to keep track of how you set it in a static variable
-    and call this only if the new cursor is different.
-
-    The type Fl_Cursor is an enumeration defined in <FL/Enumerations.H>.
-
-    \see cursor(const Fl_RGB_Image*, int, int), default_cursor()
-  */
   void cursor(Fl_Cursor);
   void cursor(const Fl_RGB_Image*, int, int);
   void default_cursor(Fl_Cursor);
diff --git a/README.Wayland.txt b/README.Wayland.txt
index 65a5c3a36..a07969b7e 100644
--- a/README.Wayland.txt
+++ b/README.Wayland.txt
@@ -96,12 +96,9 @@ a minimized window has no effect.
 it's currently not possible for an app to be notified of changes to the content of
 the system clipboard, that is, Fl::add_clipboard_notify() has no effect.
 
-* With GTK-style window titlebars, narrow windows are silently forced to be wide enough
+* Narrow windows with a titlebar are silently forced to be wide enough
 for the titlebar to display window buttons and a few letters of the title.
 
-* The library should support multi-display configurations in principle, but has not been
-tested in that situation.
-
 * Text input methods have been tested without any understanding of the writing systems,
 so feedback on this subject would be helpful.
 
diff --git a/documentation/src/wayland.dox b/documentation/src/wayland.dox
index 1e38611ef..c99dac9b1 100644
--- a/documentation/src/wayland.dox
+++ b/documentation/src/wayland.dox
@@ -451,19 +451,19 @@ displaying dragged text in a DnD operation.
 
 \section wayland-display Displays and HighDPI support
 
-Wayland uses the concept of seat of type <tt>struct wl_seat</tt> which encompasses displays,
-a keyboard, a mouse, and a trackpad. It might be possible for an app to deal with several seats,
-but that has not been tested with FLTK yet. Each seat may contain one or more displays, which
-Wayland calls outputs, of type <tt>struct wl_output</tt>.
-
-As written above, function \c registry_handle_global() discovers available seats at start-up time.
-This function also associates a 'listener' to each display
-by calling function \c wl_output_add_listener(). This 'listener' is an array of callback function
+Wayland uses the concept of <em>seat</em> of type <tt>struct wl_seat</tt> which encompasses displays,
+a keyboard, a mouse, and a trackpad. Although Wayland may be in principle able to deal with several
+seats, FLTK's Wayland platform is conceived for one seat only. That seat may contain one or more
+displays, which Wayland calls <em>outputs</em>, of type <tt>struct wl_output</tt>.
+
+As written above, function \c registry_handle_global() discovers the available seat at start-up time.
+This function also associates a listener to each display connected to the system
+by calling function \c wl_output_add_listener(). This listener is an array of callback function
 pointers among which one (\c output_mode) runs when the display is resized and another
 (\c output_scale) when the Wayland scale factor (see below) is changed.
 FLTK defines type <tt>struct Fl_Wayland_Screen_Driver::output</tt> (see \ref output)
 to store display size and scaling information.
-One such record is created for each display. FLTK uses 2 distinct scaling parameters under Wayland:
+One such record is created for each display. FLTK uses 2 distinct scaling parameters for each display:
 - <tt>int wld_scale;</tt>. This member variable of
 <tt>struct Fl_Wayland_Screen_Driver::output</tt> typically equals 1 for standard, and 2 for
 HighDPI displays. Its value is set by the Wayland compositor for each display with the effect
diff --git a/src/drivers/Wayland/Fl_Wayland_Screen_Driver.cxx b/src/drivers/Wayland/Fl_Wayland_Screen_Driver.cxx
index 4e67f3943..0875f4e1f 100644
--- a/src/drivers/Wayland/Fl_Wayland_Screen_Driver.cxx
+++ b/src/drivers/Wayland/Fl_Wayland_Screen_Driver.cxx
@@ -179,7 +179,6 @@ static void do_set_cursor(struct seat *seat, struct wl_cursor *wl_cursor = NULL)
             image->hotspot_x / scale,
             image->hotspot_y / scale);
   wl_surface_attach(seat->cursor_surface, buffer, 0, 0);
-  wl_surface_set_buffer_scale(seat->cursor_surface, scale);
   wl_surface_damage_buffer(seat->cursor_surface, 0, 0,
          image->width, image->height);
   wl_surface_commit(seat->cursor_surface);
@@ -258,7 +257,8 @@ static void pointer_enter(void *data,
 {
   Fl_Window *win = event_coords_from_surface(surface, surface_x, surface_y);
   if (!win) return;
-  struct wl_cursor *cursor = fl_wl_xid(win)->custom_cursor;// use custom cursor if present
+  // use custom cursor if present
+  struct wl_cursor *cursor = fl_wl_xid(win)->custom_cursor ? fl_wl_xid(win)->custom_cursor->wl_cursor : NULL;
   struct seat *seat = (struct seat*)data;
   do_set_cursor(seat, cursor);
   seat->serial = serial;
@@ -412,6 +412,7 @@ static void cursor_surface_enter(void *data,
         struct wl_surface *wl_surface,
         struct wl_output *wl_output)
 {
+  // Runs when the seat's cursor_surface enters a display
   struct seat *seat = (struct seat*)data;
   struct pointer_output *pointer_output;
 
@@ -428,9 +429,13 @@ static void cursor_surface_enter(void *data,
   if (win) {
     Fl_Wayland_Window_Driver *driver = Fl_Wayland_Window_Driver::driver(win);
 //fprintf(stderr, "cursor_surface_enter: cursor_default=%d standard_cursor=%d\n", driver->cursor_default(), driver->standard_cursor());
-    struct wl_cursor *cursor = fl_wl_xid(win)->custom_cursor;
-    if (cursor) do_set_cursor(seat, cursor);
-    else if (driver->cursor_default()) driver->set_cursor(driver->cursor_default());
+    struct wld_window *xid = fl_wl_xid(win);
+    struct wld_window::custom_cursor *custom = xid->custom_cursor;
+    if (custom) {
+      // Change custom cursor's width & height according to display's wld_scale
+      driver->set_cursor_4args(custom->rgb, custom->hotx, custom->hoty, false);
+      do_set_cursor(seat, xid->custom_cursor->wl_cursor);
+    } else if (driver->cursor_default()) driver->set_cursor(driver->cursor_default());
     else win->cursor(driver->standard_cursor());
   }
 }
@@ -448,6 +453,14 @@ static void cursor_surface_leave(void *data,
       free(pointer_output);
     }
   }
+  try_update_cursor(seat);
+  // maintain custom window cursor
+  Fl_Window *win = Fl::first_window();
+  if (win) {
+    struct wld_window *xid = fl_wl_xid(win);
+    if (xid->custom_cursor) do_set_cursor(seat, xid->custom_cursor->wl_cursor);
+  }
+
 }
 
 static struct wl_surface_listener cursor_surface_listener = {
@@ -962,6 +975,17 @@ static void output_scale(void *data, struct wl_output *wl_output, int32_t factor
   Fl_Wayland_Screen_Driver::output *output = (Fl_Wayland_Screen_Driver::output*)data;
   output->wld_scale = factor;
 //fprintf(stderr,"output_scale: wl_output=%p factor=%d\n",wl_output, factor);
+  // rescale cursors of windows that map here and have a custom cursor
+  Fl_Window *win = Fl::first_window();
+  while (win) {
+    struct wld_window *xid = fl_wl_xid(win);
+    if (xid->custom_cursor && wl_output_get_user_data(wl_output) == xid->output) {
+      Fl_Wayland_Window_Driver *driver = Fl_Wayland_Window_Driver::driver(win);
+      driver->set_cursor_4args(xid->custom_cursor->rgb,
+                               xid->custom_cursor->hotx, xid->custom_cursor->hoty, false);
+    };
+    win = Fl::next_window(win);
+  }
 }
 
 
diff --git a/src/drivers/Wayland/Fl_Wayland_Window_Driver.H b/src/drivers/Wayland/Fl_Wayland_Window_Driver.H
index 3ae9ed320..1bf85a1c1 100644
--- a/src/drivers/Wayland/Fl_Wayland_Window_Driver.H
+++ b/src/drivers/Wayland/Fl_Wayland_Window_Driver.H
@@ -60,7 +60,7 @@ private:
   static bool in_flush; // useful for progressive window drawing
   static Fl_Wayland_Plugin *gl_plugin();
   Fl_Cursor standard_cursor_; // window's standard custom kind
-  void delete_cursor_(struct wld_window *);
+  void delete_cursor_(struct wld_window *, bool keep_rgb = false);
   struct gl_start_support *gl_start_support_; // for support of gl_start/gl_finish
 public:
   inline Fl_Cursor standard_cursor() { return standard_cursor_; };
@@ -116,6 +116,7 @@ public:
   // --- window cursor stuff
   int set_cursor(Fl_Cursor) FL_OVERRIDE;
   int set_cursor(const Fl_RGB_Image*, int, int) FL_OVERRIDE;
+  int set_cursor_4args(const Fl_RGB_Image*, int, int, bool);
 
   void shape(const Fl_Image* img) FL_OVERRIDE;
   void capture_titlebar_and_borders(Fl_RGB_Image*& top, Fl_RGB_Image*& left, Fl_RGB_Image*& bottom, Fl_RGB_Image*& right) FL_OVERRIDE;
@@ -136,14 +137,18 @@ struct wld_window {
   struct wl_surface *wl_surface;
   struct fl_wld_buffer *buffer;
   struct xdg_surface *xdg_surface;
-  union {
+  enum Fl_Wayland_Window_Driver::kind kind;
+  union { // for each value of kind
     struct libdecor_frame *frame;
     struct wl_subsurface *subsurface;
     struct xdg_popup *xdg_popup;
     struct xdg_toplevel *xdg_toplevel;
   };
-  struct wl_cursor *custom_cursor; // non-null when using custom cursor
-  enum Fl_Wayland_Window_Driver::kind kind;
+  struct custom_cursor {
+    struct wl_cursor *wl_cursor;
+    const Fl_RGB_Image *rgb;
+    int hotx, hoty;
+  } *custom_cursor; // non-null when using custom cursor
   int configured_width;
   int configured_height;
   int floating_width;
diff --git a/src/drivers/Wayland/Fl_Wayland_Window_Driver.cxx b/src/drivers/Wayland/Fl_Wayland_Window_Driver.cxx
index 82186560e..ac634fa5c 100644
--- a/src/drivers/Wayland/Fl_Wayland_Window_Driver.cxx
+++ b/src/drivers/Wayland/Fl_Wayland_Window_Driver.cxx
@@ -78,9 +78,10 @@ Fl_Wayland_Window_Driver::Fl_Wayland_Window_Driver(Fl_Window *win) : Fl_Window_D
   subRect_ = NULL;
 }
 
-void Fl_Wayland_Window_Driver::delete_cursor_(struct wld_window *xid) {
-  struct wl_cursor *wl_cursor = xid->custom_cursor;
-  if (wl_cursor) {
+void Fl_Wayland_Window_Driver::delete_cursor_(struct wld_window *xid, bool keep_rgb) {
+  struct wld_window::custom_cursor *custom = xid->custom_cursor;
+  if (custom) {
+    struct wl_cursor *wl_cursor = custom->wl_cursor;
     struct cursor_image *new_image = (struct cursor_image*)wl_cursor->images[0];
     struct fl_wld_buffer *offscreen = (struct fl_wld_buffer *)wl_buffer_get_user_data(new_image->buffer);
     struct wld_window fake_xid;
@@ -92,6 +93,8 @@ void Fl_Wayland_Window_Driver::delete_cursor_(struct wld_window *xid) {
     free(wl_cursor);
     Fl_Wayland_Screen_Driver *scr_driver = (Fl_Wayland_Screen_Driver*)Fl::screen_driver();
     if (scr_driver->default_cursor() == wl_cursor) scr_driver->default_cursor(scr_driver->xc_arrow);
+    if (!keep_rgb) delete custom->rgb;
+    delete custom;
     xid->custom_cursor = NULL;
   }
 }
@@ -637,6 +640,7 @@ static void surface_enter(void *data, struct wl_surface *wl_surface, struct wl_o
   if (output == NULL)
     return;
 
+//printf("surface_enter win=%p wl_output=%p wld_scale=%d\n", window->fl_win, wl_output, output->wld_scale);
   window->output = output;
   Fl_Wayland_Window_Driver *win_driver = Fl_Wayland_Window_Driver::driver(window->fl_win);
   if (!window->fl_win->parent()) { // for top-level, set its screen number
@@ -652,15 +656,23 @@ static void surface_enter(void *data, struct wl_surface *wl_surface, struct wl_o
       i++;
     }
   }
+  if (window->kind == Fl_Wayland_Window_Driver::POPUP) {
+    Fl_Wayland_Graphics_Driver::buffer_release(window);
+    window->fl_win->redraw();
+  } else {
+    win_driver->is_a_rescale(true);
+    window->fl_win->size(window->fl_win->w(), window->fl_win->h());
+    win_driver->is_a_rescale(false);
+    if (window->fl_win->as_gl_window())
+      wl_surface_set_buffer_scale(window->wl_surface, output->wld_scale);
+  }
 }
 
 static void surface_leave(void *data, struct wl_surface *wl_surface, struct wl_output *wl_output)
 {
-  struct wld_window *window = (struct wld_window*)data;
-  if (! window->wl_surface) return;
-  if (window->output->wl_output == wl_output) {
-    window->output = NULL;
-  }
+  // Do nothing because surface_leave old display arrives **after** surface_enter new display
+  //struct wld_window *window = (struct wld_window*)data;
+  //printf("surface_leave win=%p wl_output=%p\n", window->fl_win, wl_output);
 }
 
 static struct wl_surface_listener surface_listener = {
@@ -1453,6 +1465,21 @@ void Fl_Wayland_Window_Driver::label(const char *name, const char *iname) {
 
 
 int Fl_Wayland_Window_Driver::set_cursor(const Fl_RGB_Image *rgb, int hotx, int hoty) {
+  return set_cursor_4args(rgb, hotx, hoty, true);
+}
+
+
+int Fl_Wayland_Window_Driver::set_cursor_4args(const Fl_RGB_Image *rgb, int hotx, int hoty,
+                                               bool keep_copy) {
+  if (keep_copy) {
+    int ld = rgb->ld() ? rgb->ld() : rgb->data_w() * rgb->d();
+    uchar *data = new uchar[ld * rgb->data_h()];
+    memcpy(data, rgb->array, ld * rgb->data_h());
+    Fl_RGB_Image *rgb2 = new Fl_RGB_Image(data, rgb->data_w(), rgb->data_h(), rgb->d(), rgb->ld());
+    rgb2->alloc_array = 1;
+    rgb2->scale(rgb->w(), rgb->h());
+    rgb = rgb2;
+  }
 // build a new wl_cursor and its image
   struct wld_window *xid = (struct wld_window *)Fl_Window_Driver::xid(pWindow);
   struct wl_cursor *new_cursor = (struct wl_cursor*)malloc(sizeof(struct wl_cursor));
@@ -1482,12 +1509,15 @@ int Fl_Wayland_Window_Driver::set_cursor(const Fl_RGB_Image *rgb, int hotx, int
   Fl_Surface_Device::pop_current();
   delete img_surf;
   memcpy(offscreen->data, offscreen->draw_buffer, offscreen->data_size);
-  // delete the previous custom cursor, if there was one
-  delete_cursor_(xid);
+  // delete the previous custom cursor, if there was one, but keep its Fl_RGB_Image
+  delete_cursor_(xid, true);
   //have this new cursor used
-  xid->custom_cursor = new_cursor;
+  xid->custom_cursor = new struct wld_window::custom_cursor;
+  xid->custom_cursor->wl_cursor = new_cursor;
+  xid->custom_cursor->rgb = rgb;
+  xid->custom_cursor->hotx = hotx;
+  xid->custom_cursor->hoty = hoty;
   Fl_Wayland_Screen_Driver *scr_driver = (Fl_Wayland_Screen_Driver*)Fl::screen_driver();
-  scr_driver->default_cursor(xid->custom_cursor);
   return 1;
 }
 
diff --git a/src/fl_cursor.cxx b/src/fl_cursor.cxx
index 84ef9ff1e..681a98255 100644
--- a/src/fl_cursor.cxx
+++ b/src/fl_cursor.cxx
@@ -107,6 +107,18 @@ static void fallback_cursor(Fl_Window *w, Fl_Cursor c) {
 }
 
 
+/**
+  Changes the cursor for this window.
+
+  The window must be show()'n for this function to have any effect.
+  This always calls the system. If you are changing the cursor a lot
+  you may want to keep track of how you set it in a static variable
+  and call this only if the new cursor is different.
+
+  The type Fl_Cursor is an enumeration defined in <FL/Enumerations.H>.
+
+  \see cursor(const Fl_RGB_Image*, int, int), default_cursor()
+*/
 void Fl_Window::cursor(Fl_Cursor c) {
   int ret;
 
@@ -137,13 +149,17 @@ void Fl_Window::cursor(Fl_Cursor c) {
 }
 
 /**
-  Changes the cursor for this window.  This always calls the system. If
+  Changes the cursor for this window using the provided image as cursor's shape.
+  The window must be show()'n for this function to have any effect.
+  This always calls the system. If
   you are changing the cursor a lot you may want to keep track of how
   you set it in a static variable and call this only if the new cursor
   is different.
 
   The default cursor will be used if the provided image cannot be used
   as a cursor.
+  \param image Sets the cursor size and shape
+  \param hotx,hoty Sets the cursor's active location relatively to top-left of \c image when clicking
 
   \see cursor(Fl_Cursor), default_cursor()
 */