From 7b7cd6da61b1fcc0f2a3ecce2cb9e6c42782c717 Mon Sep 17 00:00:00 2001
From: Henning Makholm <henning@makholm.net>
Date: Fri, 27 Jan 2006 18:00:00 -0500
Subject: Import of release 0.7

---
(limited to 'pixels.h')

diff --git a/pixels.h b/pixels.h
new file mode 100644
index 0000000..8d8ea2e
--- /dev/null
+++ b/pixels.h
@@ -0,0 +1,118 @@
+/* Pixel and tile functions for xcftools
+ *
+ * Copyright (C) 2006  Henning Makholm
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#ifndef PIXELS_H
+#define PIXELS_H
+
+#include "xcftools.h"
+
+/* MACROS FOR INTERNAL PIXEL ORDERING HERE */
+/*=========================================*/
+/* In principle the internal representation of pixels may change.
+ * - this was supposed to allow an optimization where a layer could
+ * be represented as a pointer into the mmapped xcf file, if
+ * alignment, bpp, and endianness agreed (the point was that the
+ * pixel representation had to agree with the endianness).
+ *
+ * However, it turns out that the current Gimp _always_ saves images
+ * with RLE encoding of tiles, so such an effort would be in vain.
+ *
+ * Just for modularity, nevertheless try to isolate knowledge of
+ * the RGBA-to-machine-word packing in this section of the
+ * header file. Define new macros if necessary.
+ *
+ * Given that we don't have to agree with the uncompressed
+ * RLE format, we choose to have the alpha in the _least_
+ * significant byte on all archs - it is tested and used more
+ * often than the visible channels.
+ */
+typedef uint32_t rgba ;
+
+#define ALPHA_SHIFT 0
+#define RED_SHIFT 8
+#define GREEN_SHIFT 16
+#define BLUE_SHIFT 24
+
+#define ALPHA(rgba) ((uint8_t)(rgba))
+#define FULLALPHA(rgba) ((uint8_t)(rgba) == 255)
+#define NULLALPHA(rgba) ((uint8_t)(rgba) == 0)
+#define NEWALPHA(rgb,a) (((rgba)(rgb) & 0xFFFFFF00) + (a))
+
+extern const uint8_t scaletable[256][256] ;
+extern const rgba graytable[256] ;
+extern rgba colormap[256] ;
+extern unsigned colormapLength ;
+void initLayer(struct xcfLayer *);
+void initColormap();
+
+int degrayPixel(rgba); /* returns -1 for non-gray pixels */
+
+/* ******************************************************* */
+
+#define TILEXn(dim,tx) \
+    ((tx)==(dim).tilesx ? (dim).c.r : (dim).c.l + ((tx)*TILE_WIDTH))
+#define TILEYn(dim,ty) \
+    ((ty)==(dim).tilesy ? (dim).c.b : (dim).c.t + ((ty)*TILE_HEIGHT))
+
+#if __i386__
+/* This is probably the only common architecture where small constants
+ * are more efficient for byte operations.
+ */
+typedef int8_t summary_t ;
+typedef short int refcount_t ;
+#else
+typedef int summary_t ;
+typedef int refcount_t ;
+#endif
+
+#define TILESUMMARY_UPTODATE 8
+#define TILESUMMARY_ALLNULL 4
+#define TILESUMMARY_ALLFULL 2
+#define TILESUMMARY_CRISP   1 /* everyting either null or full */
+struct Tile {
+  refcount_t refcount ;
+  summary_t summary ; /* a combination of TIMESUMMARY_FOO constatns */
+  unsigned count ;
+  rgba pixels[TILE_WIDTH * TILE_HEIGHT];
+};
+/* Actually, the Tile structures that get allocated many not have
+ * room for that many pixels. We subtract the space for those we don't
+ * use - which is Not Legal C, but ought to be portable.
+ *  OTOH, one can also use a static struct Tile for temporary storage.
+ */
+
+
+#define assertTileCompatibility(t1,t2) assert((t1)->count==(t2)->count)
+
+struct Tile *newTile(struct rect);
+struct Tile *forkTile(struct Tile*);
+void freeTile(struct Tile*);
+#define invalidateSummary(tile,mask) \
+  do{ assert((tile)->refcount==1); (tile)->summary &= mask; } while(0)
+summary_t __ATTRIBUTE__((pure)) tileSummary(struct Tile *);
+
+void fillTile(struct Tile*,rgba);
+
+/* applyMask() destructively changes tile,
+ * applyMask() gets ownership of mask
+ */
+void applyMask(struct Tile *tile, struct Tile *mask);
+
+struct Tile *getLayerTile(struct xcfLayer *,const struct rect *);
+
+#endif /* FLATTEN_H */
--
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