[trunk] Add a small helper to spli ppm into 3 pgm files

Update issue 235

tests/CMakeLists.txt

@@ -98,3 +98,5 @@ if(BUILD_JPIP)
       -DEXPECTED_MD5=${md5} -P ${PROJECT_SOURCE_DIR}/cmake/JPIPTestDriver.cmake)
   endif()
 endif()
+
+add_executable(ppm2rgb3 ppm2rgb3.c)

tests/ppm2rgb3.c

@@ -0,0 +1,132 @@
+/*
+ * Copyright (c) 2014, Mathieu Malaterre <mathieu.malaterre@voxxl.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS `AS IS'
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/*
+ * Technically on UNIX, one can simply call `ppmtorgb3`, but on my system it
+ * did not work. So I had to write my own.
+ */
+
+#include <stdio.h>  /* fprintf */
+#include <string.h> /* strcmp */
+#include <stdlib.h> /* malloc */
+
+static const char magic[] = "P6";
+
+static int readheader( FILE *ppm, int *X, int *Y, int *bpp )
+{
+  char buffer[256];
+  char strbuffer[256];
+  char *line;
+  int n;
+
+  *X = *Y = *bpp = 0;
+
+  line = fgets(buffer, sizeof(buffer), ppm);
+  if( !line ) return 0;
+  n = sscanf(buffer, "%255[^\r\n]", strbuffer);
+  if( n != 1 ) return 0;
+  if( strcmp(strbuffer, magic ) != 0 ) return 0;
+
+  /* skip comments */
+  while( fgets(buffer, sizeof(buffer), ppm) && *buffer == '#' )
+    {
+    }
+  n = sscanf(buffer, "%d %d", X,Y);
+  if( n != 2 ) return 0;
+  line = fgets(buffer, sizeof(buffer), ppm);
+  if( !line ) return 0;
+  n = sscanf(buffer, "%d", bpp);
+  if( n != 1 ) return 0;
+  if( *bpp != 255 ) return 0;
+
+  return 1;
+}
+
+static int writeoutput( const char *fn, FILE *ppm, int X, int Y, int bpp )
+{
+  FILE *outf[] = {NULL, NULL, NULL};
+  int i, x, y = 0;
+  char outfn[256];
+  static const char *exts[3] = {
+    "red",
+    "grn",
+    "blu"
+  };
+  char *image_line = NULL;
+  int ok = 0;
+
+  /* write single comp as PGM: P5 */
+  for( i = 0; i < 3; ++i )
+    {
+    snprintf( outfn, sizeof(outfn), "%s.%s.pgm", fn, exts[i] );
+    outf[i] = fopen( outfn, "wb" );
+    if( !outf[i] ) goto cleanup;
+    /* write header */
+    fprintf( outf[i], "P5\n" );
+    fprintf( outf[i], "%d %d\n", X, Y );
+    fprintf( outf[i], "%d\n", bpp );
+    }
+
+  /* write pixel data */
+  image_line = (char*)malloc( (size_t)X * 3 * sizeof(char) );
+  if( !image_line ) goto cleanup;
+  while( fread(image_line, sizeof(char), (size_t)X * 3, ppm) == (size_t)X * 3 )
+    {
+    for( x = 0; x < X; ++x )
+      for( i = 0; i < 3; ++i )
+        if( fputc( image_line[3*x+i], outf[i] ) == EOF ) goto cleanup;
+    ++y;
+    }
+  if( y == Y )
+    ok = 1;
+cleanup:
+  free(image_line);
+  for( i = 0; i < 3; ++i )
+    if( outf[i] ) fclose( outf[i] );
+
+  return ok;
+}
+
+int main(int argc, char *argv[])
+{
+  const char *fn;
+  FILE *ppm = NULL;
+  int X, Y, bpp;
+  int ok = 0;
+
+  if( argc < 2 ) goto cleanup;
+  fn = argv[1];
+  ppm = fopen( fn, "rb" );
+
+  if( !readheader( ppm, &X, &Y, &bpp ) ) goto cleanup;
+
+  if( !writeoutput(fn, ppm, X, Y, bpp ) ) goto cleanup;
+
+  ok = 1;
+cleanup:
+  if(ppm) fclose(ppm);
+  return ok ? EXIT_SUCCESS : EXIT_FAILURE;
+}