Porting efforts, minimal Android stuff, cleanup.

- Moving code around for Fl_Double_Window, but not yet happy
- Tested CMake for Android cross compilation. Very happy!

git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3-porting@11142 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

2 files changed, 87 insertions, 0 deletions

diff --git a/src/drivers/GDI/Fl_GDI_Graphics_Driver.cxx b/src/drivers/GDI/Fl_GDI_Graphics_Driver.cxx
index 6e782b2b5..0eaf23752 100644
--- a/src/drivers/GDI/Fl_GDI_Graphics_Driver.cxx
+++ b/src/drivers/GDI/Fl_GDI_Graphics_Driver.cxx
@@ -36,6 +36,92 @@ Fl_Graphics_Driver *Fl_Graphics_Driver::newMainGraphicsDriver()
   return new Fl_GDI_Graphics_Driver();
 }
 
+// Code used to switch output to an off-screen window.  See macros in
+// win32.H which save the old state in local variables.
+
+typedef struct { BYTE a; BYTE b; BYTE c; BYTE d; } FL_BLENDFUNCTION;
+typedef BOOL (WINAPI* fl_alpha_blend_func)
+(HDC,int,int,int,int,HDC,int,int,int,int,FL_BLENDFUNCTION);
+static fl_alpha_blend_func fl_alpha_blend = NULL;
+static FL_BLENDFUNCTION blendfunc = { 0, 0, 255, 1};
+
+/*
+ * This function checks if the version of MSWindows that we
+ * curently run on supports alpha blending for bitmap transfers
+ * and finds the required function if so.
+ */
+char Fl_GDI_Graphics_Driver::can_do_alpha_blending() {
+  static char been_here = 0;
+  static char can_do = 0;
+  // do this test only once
+  if (been_here) return can_do;
+  been_here = 1;
+  // load the library that implements alpha blending
+  HMODULE hMod = LoadLibrary("MSIMG32.DLL");
+  // give up if that doesn't exist (Win95?)
+  if (!hMod) return 0;
+  // now find the blending function inside that dll
+  fl_alpha_blend = (fl_alpha_blend_func)GetProcAddress(hMod, "AlphaBlend");
+  // give up if we can't find it (Win95)
+  if (!fl_alpha_blend) return 0;
+  // we have the call, but does our display support alpha blending?
+  // get the desktop's device context
+  HDC dc = GetDC(0L);
+  if (!dc) return 0;
+  // check the device capabilities flags. However GetDeviceCaps
+  // does not return anything useful, so we have to do it manually:
+
+  HBITMAP bm = CreateCompatibleBitmap(dc, 1, 1);
+  HDC new_gc = CreateCompatibleDC(dc);
+  int save = SaveDC(new_gc);
+  SelectObject(new_gc, bm);
+  /*COLORREF set = */ SetPixel(new_gc, 0, 0, 0x01010101);
+  BOOL alpha_ok = fl_alpha_blend(dc, 0, 0, 1, 1, new_gc, 0, 0, 1, 1, blendfunc);
+  RestoreDC(new_gc, save);
+  DeleteDC(new_gc);
+  DeleteObject(bm);
+  ReleaseDC(0L, dc);
+
+  if (alpha_ok) can_do = 1;
+  return can_do;
+}
+
+HDC fl_makeDC(HBITMAP bitmap) {
+  HDC new_gc = CreateCompatibleDC(fl_gc);
+  SetTextAlign(new_gc, TA_BASELINE|TA_LEFT);
+  SetBkMode(new_gc, TRANSPARENT);
+#if USE_COLORMAP
+  if (fl_palette) SelectPalette(new_gc, fl_palette, FALSE);
+#endif
+  SelectObject(new_gc, bitmap);
+  return new_gc;
+}
+
+void Fl_GDI_Graphics_Driver::copy_offscreen(int x,int y,int w,int h,HBITMAP bitmap,int srcx,int srcy) {
+  HDC new_gc = CreateCompatibleDC(fl_gc);
+  int save = SaveDC(new_gc);
+  SelectObject(new_gc, bitmap);
+  BitBlt(fl_gc, x, y, w, h, new_gc, srcx, srcy, SRCCOPY);
+  RestoreDC(new_gc, save);
+  DeleteDC(new_gc);
+}
+
+void Fl_GDI_Graphics_Driver::copy_offscreen_with_alpha(int x,int y,int w,int h,HBITMAP bitmap,int srcx,int srcy) {
+  HDC new_gc = CreateCompatibleDC(fl_gc);
+  int save = SaveDC(new_gc);
+  SelectObject(new_gc, bitmap);
+  BOOL alpha_ok = 0;
+  // first try to alpha blend
+  if ( fl_can_do_alpha_blending() ) {
+    alpha_ok = fl_alpha_blend(fl_gc, x, y, w, h, new_gc, srcx, srcy, w, h, blendfunc);
+  }
+  // if that failed (it shouldn't), still copy the bitmap over, but now alpha is 1
+  if (!alpha_ok) {
+    BitBlt(fl_gc, x, y, w, h, new_gc, srcx, srcy, SRCCOPY);
+  }
+  RestoreDC(new_gc, save);
+  DeleteDC(new_gc);
+}
 
 //
 // End of "$Id$".
diff --git a/src/drivers/GDI/Fl_GDI_Graphics_Driver.h b/src/drivers/GDI/Fl_GDI_Graphics_Driver.h
index 1dd62a4e6..2dbdbe430 100644
--- a/src/drivers/GDI/Fl_GDI_Graphics_Driver.h
+++ b/src/drivers/GDI/Fl_GDI_Graphics_Driver.h
@@ -41,6 +41,7 @@ public:
   static const char *class_id;
   const char *class_name() {return class_id;};
   virtual int has_feature(driver_feature mask) { return mask & NATIVE; }
+  char can_do_alpha_blending();
 
   // --- bitmap stuff
   Fl_Bitmask create_bitmask(int w, int h, const uchar *array);