add LODEPNG_NO_COMPILE_CRC compile option

4 files changed, 93 insertions, 9 deletions

diff --git a/examples/example_4bit_palette.cpp b/examples/example_4bit_palette.cpp
index f495cca..a5e610d 100644
--- a/examples/example_4bit_palette.cpp
+++ b/examples/example_4bit_palette.cpp
@@ -55,7 +55,7 @@ int main(int argc, char *argv[])
 
   //create encoder and set settings and info (optional)
   lodepng::State state;
-  
+
   //generate palette
   for(int i = 0; i < 16; i++)
   {
@@ -63,20 +63,20 @@ int main(int argc, char *argv[])
     unsigned char g = 127 * (1 + std::sin(2 * i * 6.28318531 / 16));
     unsigned char b = 127 * (1 + std::sin(3 * i * 6.28318531 / 16));
     unsigned char a = 63 * (1 + std::sin(8 * i * 6.28318531 / 16)) + 128; /*alpha channel of the palette (tRNS chunk)*/
-    
+
     //palette must be added both to input and output color mode, because in this
     //sample both the raw image and the expected PNG image use that palette.
     lodepng_palette_add(&state.info_png.color, r, g, b, a);
     lodepng_palette_add(&state.info_raw, r, g, b, a);
   }
-  
+
   //both the raw image and the encoded image must get colorType 3 (palette)
   state.info_png.color.colortype = LCT_PALETTE; //if you comment this line, and create the above palette in info_raw instead, then you get the same image in a RGBA PNG.
   state.info_png.color.bitdepth = 4;
   state.info_raw.colortype = LCT_PALETTE;
   state.info_raw.bitdepth = 4;
   state.encoder.auto_convert = 0; //we specify ourselves exactly what output PNG color mode we want
-  
+
   //generate some image
   const unsigned w = 511;
   const unsigned h = 511;
@@ -87,13 +87,13 @@ int main(int argc, char *argv[])
   {
     size_t byte_index = (y * w + x) / 2;
     bool byte_half = (y * w + x) % 2 == 1;
-    
+
     int color = (int)(4 * ((1 + std::sin(2.0 * 6.28318531 * x / (double)w))
                          + (1 + std::sin(2.0 * 6.28318531 * y / (double)h))) );
 
     image[byte_index] |= (unsigned char)(color << (byte_half ? 0 : 4));
   }
-  
+
   //encode and save
   std::vector<unsigned char> buffer;
   unsigned error = lodepng::encode(buffer, image.empty() ? 0 : &image[0], w, h, state);
diff --git a/examples/example_encode_type.cpp b/examples/example_encode_type.cpp
new file mode 100644
index 0000000..d1de926
--- /dev/null
+++ b/examples/example_encode_type.cpp
@@ -0,0 +1,79 @@
+/*

+LodePNG Examples

+

+Copyright (c) 2005-2015 Lode Vandevenne

+

+This software is provided 'as-is', without any express or implied

+warranty. In no event will the authors be held liable for any damages

+arising from the use of this software.

+

+Permission is granted to anyone to use this software for any purpose,

+including commercial applications, and to alter it and redistribute it

+freely, subject to the following restrictions:

+

+    1. The origin of this software must not be misrepresented; you must not

+    claim that you wrote the original software. If you use this software

+    in a product, an acknowledgment in the product documentation would be

+    appreciated but is not required.

+

+    2. Altered source versions must be plainly marked as such, and must not be

+    misrepresented as being the original software.

+

+    3. This notice may not be removed or altered from any source

+    distribution.

+*/

+

+//g++ -I ./ lodepng.cpp examples/example_encode_type.cpp -ansi -pedantic -Wall -Wextra -O3

+

+

+

+/*

+This example shows how to enforce a certain color type of the PNG image when

+encoding a PNG (because by default, LodePNG automatically chooses an optimal

+color type, no matter what your raw data's colro type is)

+*/

+

+#include <cmath>

+#include <iostream>

+

+#include "lodepng.h"

+

+int main(int argc, char *argv[])

+{

+  //check if user gave a filename

+  if(argc < 2)

+  {

+    std::cout << "please provide a filename to save to" << std::endl;

+    return 0;

+  }

+

+  //generate some image

+  const unsigned w = 256;

+  const unsigned h = 256;

+  std::vector<unsigned char> image(w * h * 4);

+  for(unsigned y = 0; y < h; y++)

+  for(unsigned x = 0; x < w; x++)

+  {

+    int index = y * w * 4 + x * 4;

+    image[index + 0] = 0;

+    image[index + 1] = 0;

+    image[index + 2] = 0;

+    image[index + 3] = 255;

+  }

+

+  // we're going to encode with a state rather than a convenient function, because enforcing a color type requires setting options

+  lodepng::State state;

+  // input color type

+  state.info_raw.colortype = LCT_RGBA;

+  state.info_raw.bitdepth = 8;

+  // output color type

+  state.info_png.color.colortype = LCT_RGBA;

+  state.info_png.color.bitdepth = 8;

+  state.encoder.auto_convert = 0; // without this, it would ignore the output color type specified above and choose an optimal one instead

+

+  //encode and save

+  std::vector<unsigned char> buffer;

+  unsigned error = lodepng::encode(buffer, &image[0], w, h, state);

+  if(error) std::cout << "encoder error " << error << ": "<< lodepng_error_text(error) << std::endl;

+  else lodepng::save_file(buffer, argv[1]);

+}

diff --git a/lodepng.cpp b/lodepng.cpp
index 326b952..ee87d04 100644
--- a/lodepng.cpp
+++ b/lodepng.cpp
@@ -1,5 +1,5 @@
 /*
-LodePNG version 20150418
+LodePNG version 20150912
 
 Copyright (c) 2005-2015 Lode Vandevenne
 
@@ -42,7 +42,7 @@ Rename this file to lodepng.cpp to use it for C++, or to lodepng.c to use it for
 #pragma warning( disable : 4996 ) /*VS does not like fopen, but fopen_s is not standard C so unusable here*/
 #endif /*_MSC_VER */
 
-const char* LODEPNG_VERSION_STRING = "20150418";
+const char* LODEPNG_VERSION_STRING = "20150912";
 
 /*
 This source file is built up in the following large parts. The code sections
@@ -2296,6 +2296,8 @@ const LodePNGDecompressSettings lodepng_default_decompress_settings = {0, 0, 0,
 /* / CRC32                                                                  / */
 /* ////////////////////////////////////////////////////////////////////////// */
 
+
+#ifndef LODEPNG_NO_COMPILE_CRC
 /* CRC polynomial: 0xedb88320 */
 static unsigned lodepng_crc32_table[256] = {
            0u, 1996959894u, 3993919788u, 2567524794u,  124634137u, 1886057615u, 3915621685u, 2657392035u,
@@ -2344,6 +2346,7 @@ unsigned lodepng_crc32(const unsigned char* buf, size_t len)
   }
   return c ^ 0xffffffffL;
 }
+#endif /* !LODEPNG_NO_COMPILE_CRC */
 
 /* ////////////////////////////////////////////////////////////////////////// */
 /* / Reading and writing single bits and bytes from/to stream for LodePNG   / */
diff --git a/lodepng.h b/lodepng.h
index 74e4495..59f0dda 100644
--- a/lodepng.h
+++ b/lodepng.h
@@ -1,5 +1,5 @@
 /*
-LodePNG version 20150418
+LodePNG version 20150912
 
 Copyright (c) 2005-2015 Lode Vandevenne
 
@@ -41,6 +41,8 @@ to disable code sections, which can give faster compile time and smaller binary.
 The "NO_COMPILE" defines are designed to be used to pass as defines to the
 compiler command to disable them without modifying this header, e.g.
 -DLODEPNG_NO_COMPILE_ZLIB for gcc.
+In addition to those below, you can also define LODEPNG_NO_COMPILE_CRC to
+allow implementing a custom lodepng_crc32.
 */
 /*deflate & zlib. If disabled, you must specify alternative zlib functions in
 the custom_zlib field of the compress and decompress settings*/