* Starting image resizing. X-wise resize works so far.

git-svn-id: file:///srv/caca.zoy.org/var/lib/svn/libpipi/trunk@2244 92316355-f0b4-4df1-b90c-862c8a59935f

genethumb/genethumb.c

@@ -1,5 +1,18 @@
+#include "config.h"
+#include "common.h"
+
+#include <pipi.h>
+
 int main(void)
 {
+    pipi_image_t *i, *j;
+
+    i = pipi_load("irc.png");
+    j = pipi_resize(i, 100, 200);
+    pipi_save(j, "irc.bmp");
+    pipi_free(i);
+    pipi_free(j);
+
     return 0;
 }
 

pipi/Makefile.am

@@ -17,6 +17,7 @@ libpipi_la_SOURCES = \
 	pipi_internals.h \
 	io.c \
 	pixels.c \
+	resize.c \
 	$(NULL)
 libpipi_la_CFLAGS = $(CFLAGS_EXTRA)
 libpipi_la_LDFLAGS = $(LDFLAGS_EXTRA) \

pipi/pipi.h

@@ -37,6 +37,8 @@ extern int pipi_getpixel(pipi_image_t const *img,
                          int x, int y, int *r, int *g, int *b);
 extern int pipi_setpixel(pipi_image_t *img, int x, int y, int r, int g, int b);
 
+extern pipi_image_t *pipi_resize(pipi_image_t const *, int, int);
+
 #ifdef __cplusplus
 }
 #endif

pipi/resize.c

@@ -0,0 +1,64 @@
+/*
+ *  libpipi       Proper image processing implementation library
+ *  Copyright (c) 2004-2008 Sam Hocevar <sam@zoy.org>
+ *                All Rights Reserved
+ *
+ *  $Id$
+ *
+ *  This library is free software. It comes without any warranty, to
+ *  the extent permitted by applicable law. You can redistribute it
+ *  and/or modify it under the terms of the Do What The Fuck You Want
+ *  To Public License, Version 2, as published by Sam Hocevar. See
+ *  http://sam.zoy.org/wtfpl/COPYING for more details.
+ */
+
+/*
+ * resize.c: image resizing functions
+ */
+
+#include "config.h"
+#include "common.h"
+
+#include "pipi_internals.h"
+#include "pipi.h"
+
+pipi_image_t *pipi_resize(pipi_image_t const *src, int w, int h)
+{
+    pipi_image_t *dst;
+    int x, y, x0, y0;
+    dst = pipi_new(w, h);
+
+    int sw = src->width;
+    int dw = dst->width;
+
+    for(y = 0, y0 = 0; y < dst->height; y++)
+    {
+        for(x = 0, x0 = 0; x < dst->width; x++)
+        {
+            int rem = 0, tot = 0;
+            int ar = 0, ag = 0, ab = 0;
+            int r = 0, g = 0, b = 0;
+            int n;
+
+            while(tot < sw)
+            {
+                if(rem == 0)
+                {
+                    pipi_getpixel(src, x0, y, &r, &g, &b);
+                    x0++;
+                    rem = dw;
+                }
+
+                n = (tot + rem <= sw) ? rem : sw - tot;
+                ar += n * r; ag += n * g; ab += n * b;
+                tot += n;
+                rem -= n;
+            }
+
+            pipi_setpixel(dst, x, y, ar / sw, ag / sw, ab / sw);
+        }
+    }
+
+    return dst;
+}
+