diff options
Diffstat (limited to 'src/3rdparty/libpng/example.c')
| -rw-r--r-- | src/3rdparty/libpng/example.c | 75 |
1 files changed, 47 insertions, 28 deletions
diff --git a/src/3rdparty/libpng/example.c b/src/3rdparty/libpng/example.c index 8c5d87b..c0d27f4 100644 --- a/src/3rdparty/libpng/example.c +++ b/src/3rdparty/libpng/example.c @@ -2,15 +2,15 @@ #if 0 /* in case someone actually tries to compile this */ /* example.c - an example of using libpng - * Last changed in libpng 1.4.0 [January 3, 2010] + * Last changed in libpng 1.5.4 [July 7, 2011] * This file has been placed in the public domain by the authors. - * Maintained 1998-2010 Glenn Randers-Pehrson + * Maintained 1998-2011 Glenn Randers-Pehrson * Maintained 1996, 1997 Andreas Dilger) * Written 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) */ /* This is an example of how to use libpng to read and write PNG files. - * The file libpng.txt is much more verbose then this. If you have not + * The file libpng-manual.txt is much more verbose then this. If you have not * read it, do so first. This was designed to be a starting point of an * implementation. This is not officially part of libpng, is hereby placed * in the public domain, and therefore does not require a copyright notice. @@ -22,6 +22,10 @@ * see also the programs in the contrib directory. */ +#define _POSIX_SOURCE 1 /* libpng and zlib are POSIX-compliant. You may + * change this if your application uses non-POSIX + * extensions. */ + #include "png.h" /* The png_jmpbuf() macro, used in error handling, became available in @@ -31,7 +35,7 @@ */ #ifndef png_jmpbuf -# define png_jmpbuf(png_ptr) ((png_ptr)->jmpbuf) +# define png_jmpbuf(png_ptr) ((png_ptr)->png_jmpbuf) #endif /* Check to see if a file is a PNG file using png_sig_cmp(). png_sig_cmp() @@ -160,7 +164,7 @@ void read_png(FILE *fp, unsigned int sig_read) /* File is already open */ * If you have enough memory to read in the entire image at once, * and you need to specify only transforms that can be controlled * with one of the PNG_TRANSFORM_* bits (this presently excludes - * dithering, filling, setting background, and doing gamma + * quantizing, filling, setting background, and doing gamma * adjustment), then you can read the entire image (including * pixels) into the info structure with this call: */ @@ -183,8 +187,15 @@ void read_png(FILE *fp, unsigned int sig_read) /* File is already open */ * are mutually exclusive. */ - /* Tell libpng to strip 16 bit/color files down to 8 bits/color */ + /* Tell libpng to strip 16 bit/color files down to 8 bits/color. + * Use accurate scaling if it's available, otherwise just chop off the + * low byte. + */ +#ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED + png_set_scale_16(png_ptr); +#else png_set_strip_16(png_ptr); +#endif /* Strip alpha bytes from the input data without combining with the * background (not recommended). @@ -271,7 +282,8 @@ void read_png(FILE *fp, unsigned int sig_read) /* File is already open */ png_set_gamma(png_ptr, screen_gamma, 0.45455); } - /* Dither RGB files down to 8 bit palette or reduce palettes +#ifdef PNG_READ_QUANTIZE_SUPPORTED + /* Quantize RGB files down to 8 bit palette or reduce palettes * to the number of colors available on your screen. */ if (color_type & PNG_COLOR_MASK_COLOR) @@ -282,10 +294,10 @@ void read_png(FILE *fp, unsigned int sig_read) /* File is already open */ /* This reduces the image to the application supplied palette */ if (/* We have our own palette */) { - /* An array of colors to which the image should be dithered */ + /* An array of colors to which the image should be quantized */ png_color std_color_cube[MAX_SCREEN_COLORS]; - png_set_dither(png_ptr, std_color_cube, MAX_SCREEN_COLORS, + png_set_quantize(png_ptr, std_color_cube, MAX_SCREEN_COLORS, MAX_SCREEN_COLORS, NULL, 0); } /* This reduces the image to the palette supplied in the file */ @@ -295,10 +307,11 @@ void read_png(FILE *fp, unsigned int sig_read) /* File is already open */ png_get_hIST(png_ptr, info_ptr, &histogram); - png_set_dither(png_ptr, palette, num_palette, + png_set_quantize(png_ptr, palette, num_palette, max_screen_colors, histogram, 0); } } +#endif /* PNG_READ_QUANTIZE_SUPPORTED */ /* Invert monochrome files to have 0 as white and 1 as black */ png_set_invert_mono(png_ptr); @@ -509,20 +522,17 @@ row_callback(png_structp png_ptr, png_bytep new_row, * shown below: */ - /* Check if row_num is in bounds. */ - if ((row_num >= 0) && (row_num < height)) - { - /* Get pointer to corresponding row in our - * PNG read buffer. - */ - png_bytep old_row = ((png_bytep *)our_data)[row_num]; - - /* If both rows are allocated then copy the new row - * data to the corresponding row data. - */ - if ((old_row != NULL) && (new_row != NULL)) - png_progressive_combine_row(png_ptr, old_row, new_row); - } + /* Get pointer to corresponding row in our + * PNG read buffer. + */ + png_bytep old_row = ((png_bytep *)our_data)[row_num]; + + /* If both rows are allocated then copy the new row + * data to the corresponding row data. + */ + if ((old_row != NULL) && (new_row != NULL)) + png_progressive_combine_row(png_ptr, old_row, new_row); + /* * The rows and passes are called in order, so you don't really * need the row_num and pass, but I'm supplying them because it @@ -656,14 +666,18 @@ void write_png(char *file_name /* , ... other image information ... */) /* Optional significant bit (sBIT) chunk */ png_color_8 sig_bit; + /* If we are dealing with a grayscale image then */ sig_bit.gray = true_bit_depth; + /* Otherwise, if we are dealing with a color image then */ sig_bit.red = true_red_bit_depth; sig_bit.green = true_green_bit_depth; sig_bit.blue = true_blue_bit_depth; + /* If the image has an alpha channel then */ sig_bit.alpha = true_alpha_bit_depth; + png_set_sBIT(png_ptr, info_ptr, &sig_bit); @@ -676,17 +690,21 @@ void write_png(char *file_name /* , ... other image information ... */) text_ptr[0].key = "Title"; text_ptr[0].text = "Mona Lisa"; text_ptr[0].compression = PNG_TEXT_COMPRESSION_NONE; + text_ptr[0].itxt_length = 0; + text_ptr[0].lang = NULL; + text_ptr[0].lang_key = NULL; text_ptr[1].key = "Author"; text_ptr[1].text = "Leonardo DaVinci"; text_ptr[1].compression = PNG_TEXT_COMPRESSION_NONE; + text_ptr[1].itxt_length = 0; + text_ptr[1].lang = NULL; + text_ptr[1].lang_key = NULL; text_ptr[2].key = "Description"; text_ptr[2].text = "<long text>"; text_ptr[2].compression = PNG_TEXT_COMPRESSION_zTXt; -#ifdef PNG_iTXt_SUPPORTED - text_ptr[0].lang = NULL; - text_ptr[1].lang = NULL; + text_ptr[2].itxt_length = 0; text_ptr[2].lang = NULL; -#endif + text_ptr[2].lang_key = NULL; png_set_text(png_ptr, info_ptr, text_ptr, 3); /* Other optional chunks like cHRM, bKGD, tRNS, tIME, oFFs, pHYs */ @@ -751,6 +769,7 @@ void write_png(char *file_name /* , ... other image information ... */) /* Turn on interlace handling if you are not using png_write_image() */ if (interlacing) number_passes = png_set_interlace_handling(png_ptr); + else number_passes = 1; |