Add al_get_display_adapter

Move the docs for the new adapter from "Monitor" to "Displays".

Fixes #1578

docs/src/refman/display.txt

@@ -425,6 +425,25 @@ The default setting is zero (don't care).
 
 See also: [al_get_new_display_refresh_rate]
 
+### API: al_get_new_display_adapter
+
+Gets the video adapter index where new displays
+will be created by the calling thread, if previously set with
+[al_set_new_display_adapter].
+Otherwise returns `ALLEGRO_DEFAULT_DISPLAY_ADAPTER`.
+
+See also: [al_set_new_display_adapter]
+
+### API: al_set_new_display_adapter
+
+Sets the adapter to use for new displays created by the calling thread.
+The adapter has a monitor attached to it. Information
+about the monitor can be gotten using [al_get_num_video_adapters]
+and [al_get_monitor_info].
+
+To return to the default behaviour, pass `ALLEGRO_DEFAULT_DISPLAY_ADAPTER`.
+
+See also: [al_get_num_video_adapters], [al_get_monitor_info]
 
 
 ## Display operations
@@ -610,7 +629,7 @@ to new sizes to conform constraints in next cases:
 
 * The specified display is resizable, not maximized and is not
     in fullscreen mode.
-* If the appropriate current display size (width or height) is less 
+* If the appropriate current display size (width or height) is less
     than the value of constraint. Applied to minimum constraints.
 * If the appropriate current display size (width or height) is greater
     than the value of constraint. Applied to maximum constraints.
@@ -627,6 +646,12 @@ If disabled, the specified display will stop using constraints.
 See also: [al_get_window_constraints], [al_set_window_constraints]
 
 
+### API: al_get_display_adapter
+
+Returns which adapter the window is currently placed on. Returns -1 if there
+was an error in determining the adapter.
+
+Since: 5.2.10
 
 ## Display settings
 

docs/src/refman/monitor.txt

@@ -28,26 +28,6 @@ typedef struct ALLEGRO_MONITOR_INFO
 
 See also: [al_get_monitor_info]
 
-## API: al_get_new_display_adapter
-
-Gets the video adapter index where new displays
-will be created by the calling thread, if previously set with
-[al_set_new_display_adapter].
-Otherwise returns `ALLEGRO_DEFAULT_DISPLAY_ADAPTER`.
-
-See also: [al_set_new_display_adapter]
-
-## API: al_set_new_display_adapter
-
-Sets the adapter to use for new displays created by the calling thread.
-The adapter has a monitor attached to it. Information
-about the monitor can be gotten using [al_get_num_video_adapters]
-and [al_get_monitor_info].
-
-To return to the default behaviour, pass `ALLEGRO_DEFAULT_DISPLAY_ADAPTER`.
-
-See also: [al_get_num_video_adapters], [al_get_monitor_info]
-
 ## API: al_get_monitor_info
 
 Get information about a monitor's position on the desktop.

examples/ex_windows.c

@@ -103,7 +103,8 @@ int main(int argc, char **argv)
             al_get_window_position(displays[i], &dx, &dy);
             dw = al_get_display_width(displays[i]);
             dh = al_get_display_height(displays[i]);
-            al_draw_textf(myfont, al_map_rgb(0, 0, 0), dw / 2, dh / 2 - 30, ALLEGRO_ALIGN_CENTRE, "Location: %d %d", dx, dy);
+            al_draw_textf(myfont, al_map_rgb(0, 0, 0), dw / 2, dh / 2 - 30, ALLEGRO_ALIGN_CENTRE, "Location: %d %d (adapter %d)",
+               dx, dy, al_get_display_adapter(displays[i]));
             if (jump_x[i] != INT_MAX && jump_y[i] != INT_MAX) {
                al_draw_textf(myfont, al_map_rgb(0, 0, 0), dw / 2, dh / 2 - 15, ALLEGRO_ALIGN_CENTRE,
                   "Last jumped to: %d %d (adapter %d)", jump_x[i], jump_y[i], jump_adapter[i]);

include/allegro5/display.h

@@ -157,6 +157,7 @@ AL_FUNC(void, al_set_display_icons, (ALLEGRO_DISPLAY *display, int num_icons, AL
 /* Stuff for multihead/window management */
 AL_FUNC(int, al_get_new_display_adapter, (void));
 AL_FUNC(void, al_set_new_display_adapter, (int adapter));
+AL_FUNC(int, al_get_display_adapter, (ALLEGRO_DISPLAY *display));
 AL_FUNC(void, al_set_new_window_position, (int x, int y));
 AL_FUNC(void, al_get_new_window_position, (int *x, int *y));
 AL_FUNC(void, al_set_window_position, (ALLEGRO_DISPLAY *display, int x, int y));

src/display.c

@@ -1,6 +1,6 @@
-/*         ______   ___    ___ 
+/*         ______   ___    ___
  *        /\  _  \ /\_ \  /\_ \
- *        \ \ \L\ \\//\ \ \//\ \      __     __   _ __   ___ 
+ *        \ \ \L\ \\//\ \ \//\ \      __     __   _ __   ___
  *         \ \  __ \ \ \ \  \ \ \   /'__`\ /'_ `\/\`'__\/ __`\
  *          \ \ \/\ \ \_\ \_ \_\ \_/\  __//\ \L\ \ \ \//\ \L\ \
  *           \ \_\ \_\/\____\/\____\ \____\ \____ \ \_\\ \____/
@@ -667,4 +667,22 @@ void al_apply_window_constraints(ALLEGRO_DISPLAY *display, bool onoff)
       display->vt->apply_window_constraints(display, onoff);
 }
 
+/* Function: al_get_display_adapter
+ */
+int al_get_display_adapter(ALLEGRO_DISPLAY *display)
+{
+   int x, y, adapter, num_adapters;
+   al_get_window_position(display, &x, &y);
+   num_adapters = al_get_num_video_adapters();
+   for (adapter = 0; adapter < num_adapters; adapter++) {
+      ALLEGRO_MONITOR_INFO mi;
+      al_get_monitor_info(adapter, &mi);
+      if (x >= mi.x1 && x < mi.x2 && y >= mi.y1 && y < mi.y2) {
+         return adapter;
+      }
+   }
+   return -1;
+}
+
+
 /* vim: set sts=3 sw=3 et: */