Fix STR#2695 & 2697: correct computation of work areas with multiple screens.

This introduces 3 new functions
static void Fl::screen_work_area(X,Y,W,H)
static void Fl::screen_work_area(X,Y,W,H,mx,my)
static void Fl::screen_work_area(X,Y,W,H,screen_no)
that compute screen work areas and are used by FLTK to position menu windows.

The Fl::x(),y(),w(),h() functions are made consistent across platforms: they return
the origin/size of the work area of the main screen (as far as possible, see below).

On the Mac OS platform, all screen functions reflect changes in screen number and 
positions without requiring the application to restart.

On the X11 platform, I did not find an API to compute the main screen work area
in all conditions. What's used does compute the correct work area when there's
a single screen, but not when there are several, because it returns an area that
encompasses all screens. The implemented workaround is that Fl::x(),y(),w(),h() 
and Fl::screen_work_area(X,Y,W,H,0) return the exact work area when there's 
a single screen, and return the full screen area when there are several.


git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@9084 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

1 files changed, 75 insertions, 25 deletions

diff --git a/src/screen_xywh.cxx b/src/screen_xywh.cxx
index 9ceb8630e..878b9bf9a 100644
--- a/src/screen_xywh.cxx
+++ b/src/screen_xywh.cxx
@@ -47,6 +47,7 @@ typedef BOOL (WINAPI* fl_gmi_func)(HMONITOR, LPMONITORINFO);
 static fl_gmi_func fl_gmi = NULL; // used to get a proc pointer for GetMonitorInfoA
 
 static RECT screens[16];
+static RECT work_area[16];
 static float dpi[16][2];
 
 static BOOL CALLBACK screen_cb(HMONITOR mon, HDC, LPRECT r, LPARAM) {
@@ -60,8 +61,11 @@ static BOOL CALLBACK screen_cb(HMONITOR mon, HDC, LPRECT r, LPARAM) {
   if (fl_gmi(mon, &mi)) {
     screens[num_screens] = mi.rcMonitor;
 // If we also want to record the work area, we would also store mi.rcWork at this point
-//  work_area[num_screens] = mi.rcWork;
-
+    work_area[num_screens] = mi.rcWork;
+/*fl_alert("screen %d %d,%d,%d,%d work %d,%d,%d,%d",num_screens,
+	 screens[num_screens].left,screens[num_screens].right,screens[num_screens].top,screens[num_screens].bottom,
+    work_area[num_screens].left,work_area[num_screens].right,work_area[num_screens].top,work_area[num_screens].bottom);
+*/
     // find the pixel size
     if (mi.cbSize == sizeof(mi)) {
       HDC screen = CreateDC(mi.szDevice, NULL, NULL, NULL);
@@ -107,6 +111,7 @@ static void screen_init() {
   screens[0].left      = 0;
   screens[0].right  = GetSystemMetrics(SM_CXSCREEN);
   screens[0].bottom = GetSystemMetrics(SM_CYSCREEN);
+  work_area[0] = screens[0];
 }
 #elif defined(__APPLE__)
 static XRectangle screens[16];
@@ -124,12 +129,23 @@ static void screen_init() {
     screens[i].y      = int(r.origin.y);
     screens[i].width  = int(r.size.width);
     screens[i].height = int(r.size.height);
-    CGSize s = CGDisplayScreenSize(displays[i]);
-    dpi_h[i] = screens[i].width / (s.width/25.4);
-    dpi_v[i] = screens[i].height / (s.height/25.4);
+//fprintf(stderr,"screen %d %dx%dx%dx%d\n",i,screens[i].x,screens[i].y,screens[i].width,screens[i].height);
+    if (CGDisplayScreenSize != NULL) {
+      CGSize s = CGDisplayScreenSize(displays[i]); // from 10.3
+      dpi_h[i] = screens[i].width / (s.width/25.4);
+      dpi_v[i] = screens[i].height / (s.height/25.4);
+      }
+    else {
+      dpi_h[i] = dpi_v[i] = 75.;
+      }
   }
   num_screens = count;
 }
+
+void Fl_X::mac_screen_init() {
+  screen_init();
+  }
+
 #elif HAVE_XINERAMA
 #  include <X11/extensions/Xinerama.h>
 
@@ -183,19 +199,11 @@ int Fl::screen_count() {
   return num_screens ? num_screens : 1;
 }
 
-/**
-  Gets the bounding box of a screen
-  that contains the specified screen position \p mx, \p my
-  \param[out]  X,Y,W,H the corresponding screen bounding box
-  \param[in] mx, my the absolute screen position
-*/
-void Fl::screen_xywh(int &X, int &Y, int &W, int &H, int mx, int my) {
+static int find_screen_with_point(int mx, int my) {
   int screen = 0;
-  int i;
-
   if (num_screens < 0) screen_init();
-
-  for (i = 0; i < num_screens; i ++) {
+  
+  for (int i = 0; i < num_screens; i ++) {
     int sx, sy, sw, sh;
     Fl::screen_xywh(sx, sy, sw, sh, i);
     if ((mx >= sx) && (mx < (sx+sw)) && (my >= sy) && (my < (sy+sh))) {
@@ -203,12 +211,62 @@ void Fl::screen_xywh(int &X, int &Y, int &W, int &H, int mx, int my) {
       break;
     }
   }
+  return screen;
+}
+
+/**
+  Gets the bounding box of a screen
+  that contains the specified screen position \p mx, \p my
+  \param[out]  X,Y,W,H the corresponding screen bounding box
+  \param[in] mx, my the absolute screen position
+*/
+void Fl::screen_xywh(int &X, int &Y, int &W, int &H, int mx, int my) {
+  screen_xywh(X, Y, W, H, find_screen_with_point(mx, my));
+}
 
-  screen_xywh(X, Y, W, H, screen);
+
+/**
+ Gets the bounding box of the work area of a screen
+ that contains the specified screen position \p mx, \p my
+ \param[out]  X,Y,W,H the work area bounding box
+ \param[in] mx, my the absolute screen position
+ */
+void Fl::screen_work_area(int &X, int &Y, int &W, int &H, int mx, int my) {
+  screen_work_area(X, Y, W, H, find_screen_with_point(mx, my));
+}
+
+/**
+ Gets the bounding box of the work area of the given screen.
+ \param[out]  X,Y,W,H the work area bounding box
+ \param[in] n the screen number (0 to Fl::screen_count() - 1)
+ \see void screen_xywh(int &x, int &y, int &w, int &h, int mx, int my)
+*/
+void Fl::screen_work_area(int &X, int &Y, int &W, int &H, int n) {
+  if (num_screens < 0) screen_init();
+  if (n < 0 || n >= num_screens) n = 0;
+#ifdef WIN32
+  X = work_area[n].left;
+  Y = work_area[n].top;
+  W = work_area[n].right - X;
+  H = work_area[n].bottom - Y;
+#elif defined(__APPLE__)
+  Fl_X::screen_work_area(X, Y, W, H, n);
+#else
+  if (n == 0) { // for the main screen, these return the work area
+    X = Fl::x();
+    Y = Fl::y();
+    W = Fl::w();
+    H = Fl::h();
+    }
+  else { // for other screens, work area is full screen,
+    screen_xywh(X, Y, W, H, n);
+    }
+#endif
 }
 
 /**
   Gets the screen bounding rect for the given screen.
+  Under MSWindows, Mac OS X, and the Gnome desktop, screen #0 contains the menubar/taskbar
   \param[out]  X,Y,W,H the corresponding screen bounding box
   \param[in] n the screen number (0 to Fl::screen_count() - 1)
   \see void screen_xywh(int &x, int &y, int &w, int &h, int mx, int my)
@@ -233,18 +291,10 @@ void Fl::screen_xywh(int &X, int &Y, int &W, int &H, int n) {
     H = GetSystemMetrics(SM_CYSCREEN);
   }
 #elif defined(__APPLE__)
-  if (num_screens > 0) {
     X = screens[n].x;
     Y = screens[n].y;
     W = screens[n].width;
     H = screens[n].height;
-  } else {
-    /* Fallback if something is broken... */
-    X = Fl::x();
-    Y = Fl::y();
-    W = Fl::w();
-    H = Fl::h();
-  }
 #else
 #if HAVE_XINERAMA
   if (num_screens > 0 && screens) {