libart 2.3.16

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

diff --git a/lib/art/art_gray_svp.c b/lib/art/art_gray_svp.c
new file mode 100644 (file)
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+++ b/lib/art/art_gray_svp.c
@@ -0,0 +1,123 @@
+/* Libart_LGPL - library of basic graphic primitives
+ * Copyright (C) 1998 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.
+ */
+
+/* Render a sorted vector path into a graymap. */
+
+#include "config.h"
+#include "art_gray_svp.h"
+
+#include <string.h>    /* for memset */
+#include "art_misc.h"
+
+#include "art_svp.h"
+#include "art_svp_render_aa.h"
+
+typedef struct _ArtGraySVPData ArtGraySVPData;
+
+struct _ArtGraySVPData {
+  art_u8 *buf;
+  int rowstride;
+  int x0, x1;
+};
+
+static void
+art_gray_svp_callback (void *callback_data, int y,
+                      int start, ArtSVPRenderAAStep *steps, int n_steps)
+{
+  ArtGraySVPData *data = (ArtGraySVPData *)callback_data;
+  art_u8 *linebuf;
+  int run_x0, run_x1;
+  int running_sum = start;
+  int x0, x1;
+  int k;
+
+#if 0
+  printf ("start = %d", start);
+  running_sum = start;
+  for (k = 0; k < n_steps; k++)
+    {
+      running_sum += steps[k].delta;
+      printf (" %d:%d", steps[k].x, running_sum >> 16);
+    }
+  printf ("\n");
+#endif
+
+  linebuf = data->buf;
+  x0 = data->x0;
+  x1 = data->x1;
+
+  if (n_steps > 0)
+    {
+      run_x1 = steps[0].x;
+      if (run_x1 > x0)
+       memset (linebuf, running_sum >> 16, run_x1 - x0);
+
+      for (k = 0; k < n_steps - 1; k++)
+       {
+         running_sum += steps[k].delta;
+         run_x0 = run_x1;
+         run_x1 = steps[k + 1].x;
+         if (run_x1 > run_x0)
+           memset (linebuf + run_x0 - x0, running_sum >> 16, run_x1 - run_x0);
+       }
+      running_sum += steps[k].delta;
+      if (x1 > run_x1)
+       memset (linebuf + run_x1 - x0, running_sum >> 16, x1 - run_x1);
+    }
+  else
+    {
+      memset (linebuf, running_sum >> 16, x1 - x0);
+    }
+
+  data->buf += data->rowstride;
+}
+
+/**
+ * art_gray_svp_aa: Render the vector path into the bytemap.
+ * @svp: The SVP to render.
+ * @x0: The view window's left coord.
+ * @y0: The view window's top coord.
+ * @x1: The view window's right coord.
+ * @y1: The view window's bottom coord.
+ * @buf: The buffer where the bytemap is stored.
+ * @rowstride: the rowstride for @buf.
+ *
+ * Each pixel gets a value proportional to the area within the pixel
+ * overlapping the (filled) SVP. Pixel (x, y) is stored at:
+ *
+ *    @buf[(y - * @y0) * @rowstride + (x - @x0)]
+ *
+ * All pixels @x0 <= x < @x1, @y0 <= y < @y1 are generated. A
+ * stored value of zero is no coverage, and a value of 255 is full
+ * coverage. The area within the pixel (x, y) is the region covered
+ * by [x..x+1] and [y..y+1].
+ **/
+void
+art_gray_svp_aa (const ArtSVP *svp,
+                int x0, int y0, int x1, int y1,
+                art_u8 *buf, int rowstride)
+{
+  ArtGraySVPData data;
+
+  data.buf = buf;
+  data.rowstride = rowstride;
+  data.x0 = x0;
+  data.x1 = x1;
+  art_svp_render_aa (svp, x0, y0, x1, y1, art_gray_svp_callback, &data);
+}