libart 2.3.16

[swftools.git] / lib / art / art_uta_ops.c

diff --git a/lib/art/art_uta_ops.c b/lib/art/art_uta_ops.c
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+++ b/lib/art/art_uta_ops.c
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+/* Libart_LGPL - library of basic graphic primitives
+ * Copyright (C) 1998-2000 Raph Levien
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include "config.h"
+#include "art_uta_ops.h"
+
+#include <string.h>
+#include "art_misc.h"
+#include "art_uta.h"
+
+#ifndef MIN
+#define MIN(a,b) ((a) < (b) ? (a) : (b))
+#endif
+
+#ifndef MAX
+#define MAX(a,b) ((a) > (b) ? (a) : (b))
+#endif
+
+/**
+ * art_uta_union: Compute union of two uta's.
+ * @uta1: One uta.
+ * @uta2: The other uta.
+ *
+ * Computes the union of @uta1 and @uta2. The union is approximate,
+ * but coverage is guaranteed over all pixels included in either of
+ * the arguments, ie more pixels may be covered than the "exact"
+ * union.
+ *
+ * Note: this routine is used in the Gnome Canvas to accumulate the
+ * region that needs to be repainted. However, since it copies over
+ * the entire uta (which might be largish) even when the update may be
+ * small, it can be a performance bottleneck. There are two approaches
+ * to this problem, both of which are probably worthwhile. First, the
+ * generated uta's should always be limited to the visible window,
+ * thus guaranteeing that uta's never become large. Second, there
+ * should be a new, destructive union operation that only touches a
+ * small part of the uta when the update is small.
+ *
+ * Return value: The new union uta.
+ **/
+ArtUta *
+art_uta_union (ArtUta *uta1, ArtUta *uta2)
+{
+  ArtUta *uta;
+  int x0, y0, x1, y1;
+  int x, y;
+  int ix, ix1, ix2;
+  ArtUtaBbox bb, bb1, bb2;
+
+  x0 = MIN(uta1->x0, uta2->x0);
+  y0 = MIN(uta1->y0, uta2->y0);
+  x1 = MAX(uta1->x0 + uta1->width, uta2->x0 + uta2->width);
+  y1 = MAX(uta1->y0 + uta1->height, uta2->y0 + uta2->height);
+  uta = art_uta_new (x0, y0, x1, y1);
+
+  /* could move the first two if/else statements out of the loop */
+  ix = 0;
+  for (y = y0; y < y1; y++)
+    {
+      ix1 = (y - uta1->y0) * uta1->width + x0 - uta1->x0;
+      ix2 = (y - uta2->y0) * uta2->width + x0 - uta2->x0;
+      for (x = x0; x < x1; x++)
+       {
+         if (x < uta1->x0 || y < uta1->y0 ||
+             x >= uta1->x0 + uta1->width || y >= uta1->y0 + uta1->height)
+           bb1 = 0;
+         else
+           bb1 = uta1->utiles[ix1];
+
+         if (x < uta2->x0 || y < uta2->y0 ||
+             x >= uta2->x0 + uta2->width || y >= uta2->y0 + uta2->height)
+           bb2 = 0;
+         else
+           bb2 = uta2->utiles[ix2];
+
+         if (bb1 == 0)
+           bb = bb2;
+         else if (bb2 == 0)
+           bb = bb1;
+         else
+           bb = ART_UTA_BBOX_CONS(MIN(ART_UTA_BBOX_X0(bb1),
+                                      ART_UTA_BBOX_X0(bb2)),
+                                  MIN(ART_UTA_BBOX_Y0(bb1),
+                                      ART_UTA_BBOX_Y0(bb2)),
+                                  MAX(ART_UTA_BBOX_X1(bb1),
+                                      ART_UTA_BBOX_X1(bb2)),
+                                  MAX(ART_UTA_BBOX_Y1(bb1),
+                                      ART_UTA_BBOX_Y1(bb2)));
+         uta->utiles[ix] = bb;
+         ix++;
+         ix1++;
+         ix2++;
+       }
+    }
+  return uta;
+}