check if colortable has some alpha components

Common/ColorTable.cpp

-// $Id: ColorTable.cpp,v 1.11 2002-05-20 18:28:24 geuzaine Exp $
+// $Id: ColorTable.cpp,v 1.12 2002-08-27 02:03:34 geuzaine Exp $
 //
 // Copyright (C) 1997 - 2002 C. Geuzaine, J.-F. Remacle
 //
@@ -264,4 +264,11 @@ void ColorTable_Print(GmshColorTable *ct, FILE *fp){
 
 }
 
-
+int ColorTable_IsAlpha(GmshColorTable *ct){
+  int i, a;
+  for (i=0;i<ct->size;i++) {
+    a = UNPACK_ALPHA( ct->table[i] );
+    if(a<255) return 1;
+  }
+  return 0;
+}

Common/ColorTable.h

@@ -48,8 +48,8 @@ typedef struct{
 
 // float parameters indices
 
-#define COLORTABLE_CURVE     0  // curvature */
-#define COLORTABLE_BIAS      1  // offset */
+#define COLORTABLE_CURVE     0  // curvature
+#define COLORTABLE_BIAS      1  // offset
 #define COLORTABLE_ALPHAPOW  2  // alpha channel power
 #define COLORTABLE_ALPHAVAL  3  // alpha channel value
 #define COLORTABLE_BETA      4  // beta coeff for brighten
@@ -59,5 +59,6 @@ void ColorTable_Recompute (GmshColorTable * ct, int rgb_flag, int alpha_flag);
 void ColorTable_Copy(GmshColorTable *ct);
 void ColorTable_Paste(GmshColorTable *ct);
 void ColorTable_Print(GmshColorTable *ct, FILE *fp) ;
+int  ColorTable_IsAlpha(GmshColorTable *ct) ;
 
 #endif