+// ----------------------------------------------------------------------------
+// helper functions
+// ----------------------------------------------------------------------------
+
+// decide whether we should create a DIB or a DDB for the given parameters
+//
+// NB: we always use DIBs under Windows CE as this is much simpler (even if
+// also less efficient...) and we obviously can't use them if there is no
+// DIB support compiled in at all
+#ifdef __WXWINCE__
+ static inline bool wxShouldCreateDIB(int, int, int, WXHDC) { return true; }
+
+ #define ALWAYS_USE_DIB
+#elif !wxUSE_WXDIB
+ // no sense in defining wxShouldCreateDIB() as we can't compile code
+ // executed if it is true, so we have to use #if's anyhow
+ #define NEVER_USE_DIB
+#else // wxUSE_WXDIB && !__WXWINCE__
+ static inline bool wxShouldCreateDIB(int w, int h, int d, WXHDC hdc)
+ {
+ // here is the logic:
+ //
+ // (a) if hdc is specified, the caller explicitly wants DDB
+ // (b) otherwise, create a DIB if depth >= 24 (we don't support 16bpp
+ // or less DIBs anyhow)
+ // (c) finally, create DIBs under Win9x even if the depth hasn't been
+ // explicitly specified but the current display depth is 24 or
+ // more and the image is "big", i.e. > 16Mb which is the
+ // theoretical limit for DDBs under Win9x
+ //
+ // consequences (all of which seem to make sense):
+ //
+ // (i) by default, DDBs are created (depth == -1 usually)
+ // (ii) DIBs can be created by explicitly specifying the depth
+ // (iii) using a DC always forces creating a DDB
+ return !hdc &&
+ (d >= 24 ||
+ (d == -1 &&
+ wxDIB::GetLineSize(w, wxDisplayDepth())*h > 16*1024*1024));
+ }
+
+ #define SOMETIMES_USE_DIB
+#endif // different DIB usage scenarious
+
projects / wxWidgets.git / blobdiff