STR#2086 related Fixes :

  This one was really tough to track, understand:
In fact, 
the problem was comming from the misplacement of the menu window,
which itself came from invalid measurement,
which itself came from invalid fl_witdh() measurement,
but only when fl_gc is not valid because fl_width() relies on Win32 on the call
of GetTextExtentPoint32W which can't succeed if the HDC(here fl_gc) is not valid !

Now the fix:
A best-effort algorithm has been furthered to supply a valid fltk hdc if we can have one or a screen hdc if no fltk window is found by fl::first_window().

Note that when fl_gc is NULL inside fl_width() call, it can happen that Fl_Window::current() is not null but invalid (already deleted).
Finally, in the case of the buggy menu window observed here, this  fl_gc was set to NULL just after an Fl_Menu_Window deletion and re-creation in Fl_Menu_Item::pulldown().

Also added a comment to describe the new fl_width() behavior.



git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@6540 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

1 files changed, 14 insertions, 1 deletions

diff --git a/src/fl_font_win32.cxx b/src/fl_font_win32.cxx
index 42ca214d3..0155dfcea 100644
--- a/src/fl_font_win32.cxx
+++ b/src/fl_font_win32.cxx
@@ -182,11 +182,24 @@ double fl_width(unsigned int c) {
     fl_fontsize->width[r] = (int*) malloc(sizeof(int) * 0x0400);
     SIZE s;
     unsigned short i = 0, ii = r * 0x400;
+    // The following code is a best effort algorithm to further	a valid fl_gc
+    // if no fl_gc is available at the time we call fl_width()
+    // We first choose a gc from the first fltk window, 
+    // if it is null then the gc from the current screen (GetDC(NULL)).
+    // This should solve STR #2086
+    HDC gc = fl_gc;
+    HWND hWnd = 0;
+    if (!gc) {
+	gc = GetDC(hWnd);
+    }
+    if (!gc)
+	Fl::fatal("Invalid graphic context: fl_width() failed because no valid HDC was found!");
     for (; i < 0x400; i++) {
-      GetTextExtentPoint32W(fl_gc, (WCHAR*)&ii, 1, &s);
+      GetTextExtentPoint32W(gc, (WCHAR*)&ii, 1, &s);
       fl_fontsize->width[r][i] = s.cx;
       ii++;
     }
+    if (gc && gc!=fl_gc) ReleaseDC(hWnd, gc);
   }
   return (double) fl_fontsize->width[r][c & 0x03FF];
 }