+
+
+//-----------------------------------------------------------------------------
+
+// GRG, Dic/99
+// Counts and returns the number of different colours. Optionally stops
+// when it exceeds 'stopafter' different colours. This is useful, for
+// example, to see if the image can be saved as 8-bit (256 colour or
+// less, in this case it would be invoked as CountColours(256)). Default
+// value for stopafter is -1 (don't care).
+//
+unsigned long wxImage::CountColours( unsigned long stopafter )
+{
+ wxHashTable h;
+ wxNode *node;
+ wxHNode *hnode;
+ unsigned char r, g, b, *p;
+ unsigned long size, nentries, key;
+
+ p = GetData();
+ size = GetWidth() * GetHeight();
+ nentries = 0;
+
+ for (unsigned long j = 0; (j < size) && (nentries <= stopafter) ; j++)
+ {
+ r = *(p++);
+ g = *(p++);
+ b = *(p++);
+ key = (r << 16) | (g << 8) | b;
+
+ hnode = (wxHNode *) h.Get(key);
+
+ if (!hnode)
+ {
+ h.Put(key, (wxObject *)(new wxHNode));
+ nentries++;
+ }
+ }
+
+ // delete all HNodes
+ h.BeginFind();
+ while ((node = h.Next()) != NULL)
+ delete (wxHNode *)node->GetData();
+
+ return nentries;
+}
+
+
+// GRG, Dic/99
+// Computes the histogram of the image and fills a hash table, indexed
+// with integer keys built as 0xRRGGBB, containing wxHNode objects. Each
+// wxHNode contains an 'index' (useful to build a palette with the image
+// colours) and a 'value', which is the number of pixels in the image with
+// that colour.
+//
+unsigned long wxImage::ComputeHistogram( wxHashTable &h )
+{
+ unsigned char r, g, b, *p;
+ unsigned long size, nentries, key;
+ wxHNode *hnode;
+
+ p = GetData();
+ size = GetWidth() * GetHeight();
+ nentries = 0;
+
+ for (unsigned long j = 0; j < size; j++)
+ {
+ r = *(p++);
+ g = *(p++);
+ b = *(p++);
+ key = (r << 16) | (g << 8) | b;
+
+ hnode = (wxHNode *) h.Get(key);
+
+ if (hnode)
+ hnode->value++;
+ else
+ {
+ hnode = new wxHNode();
+ hnode->index = nentries++;
+ hnode->value = 1;
+
+ h.Put(key, (wxObject *)hnode);
+ }
+ }
+
+ return nentries;
+}
+
+
projects / wxWidgets.git / blobdiff