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Diffstat (limited to 'drivers/png/example.c')
| -rw-r--r-- | drivers/png/example.c | 879 |
1 files changed, 0 insertions, 879 deletions
diff --git a/drivers/png/example.c b/drivers/png/example.c deleted file mode 100644 index 7171d9847e..0000000000 --- a/drivers/png/example.c +++ /dev/null @@ -1,879 +0,0 @@ - -#if 0 /* in case someone actually tries to compile this */ - -/* example.c - an example of using libpng - * Last changed in libpng 1.5.19 [August 21, 2014] - * Maintained 1998-2014 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-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. - * To the extent possible under law, the authors have waived all copyright and - * related or neighboring rights to this file. - * - * This file does not currently compile, because it is missing certain - * parts, like allocating memory to hold an image. You will have to - * supply these parts to get it to compile. For an example of a minimal - * working PNG reader/writer, see pngtest.c, included in this distribution; - * 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 - * libpng version 1.0.6. If you want to be able to run your code with older - * versions of libpng, you must define the macro yourself (but only if it - * is not already defined by libpng!). - */ - -#ifndef png_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() - * returns zero if the image is a PNG and nonzero if it isn't a PNG. - * - * The function check_if_png() shown here, but not used, returns nonzero (true) - * if the file can be opened and is a PNG, 0 (false) otherwise. - * - * If this call is successful, and you are going to keep the file open, - * you should call png_set_sig_bytes(png_ptr, PNG_BYTES_TO_CHECK); once - * you have created the png_ptr, so that libpng knows your application - * has read that many bytes from the start of the file. Make sure you - * don't call png_set_sig_bytes() with more than 8 bytes read or give it - * an incorrect number of bytes read, or you will either have read too - * many bytes (your fault), or you are telling libpng to read the wrong - * number of magic bytes (also your fault). - * - * Many applications already read the first 2 or 4 bytes from the start - * of the image to determine the file type, so it would be easiest just - * to pass the bytes to png_sig_cmp() or even skip that if you know - * you have a PNG file, and call png_set_sig_bytes(). - */ -#define PNG_BYTES_TO_CHECK 4 -int check_if_png(char *file_name, FILE **fp) -{ - char buf[PNG_BYTES_TO_CHECK]; - - /* Open the prospective PNG file. */ - if ((*fp = fopen(file_name, "rb")) == NULL) - return 0; - - /* Read in some of the signature bytes */ - if (fread(buf, 1, PNG_BYTES_TO_CHECK, *fp) != PNG_BYTES_TO_CHECK) - return 0; - - /* Compare the first PNG_BYTES_TO_CHECK bytes of the signature. - Return nonzero (true) if they match */ - - return(!png_sig_cmp(buf, (png_size_t)0, PNG_BYTES_TO_CHECK)); -} - -/* Read a PNG file. You may want to return an error code if the read - * fails (depending upon the failure). There are two "prototypes" given - * here - one where we are given the filename, and we need to open the - * file, and the other where we are given an open file (possibly with - * some or all of the magic bytes read - see comments above). - */ -#ifdef open_file /* prototype 1 */ -void read_png(char *file_name) /* We need to open the file */ -{ - png_structp png_ptr; - png_infop info_ptr; - int sig_read = 0; - png_uint_32 width, height; - int bit_depth, color_type, interlace_type; - FILE *fp; - - if ((fp = fopen(file_name, "rb")) == NULL) - return (ERROR); - -#else no_open_file /* prototype 2 */ -void read_png(FILE *fp, int sig_read) /* File is already open */ -{ - png_structp png_ptr; - png_infop info_ptr; - png_uint_32 width, height; - int bit_depth, color_type, interlace_type; -#endif no_open_file /* Only use one prototype! */ - - /* Create and initialize the png_struct with the desired error handler - * functions. If you want to use the default stderr and longjump method, - * you can supply NULL for the last three parameters. We also supply the - * the compiler header file version, so that we know if the application - * was compiled with a compatible version of the library. REQUIRED - */ - png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, - png_voidp user_error_ptr, user_error_fn, user_warning_fn); - - if (png_ptr == NULL) - { - fclose(fp); - return (ERROR); - } - - /* Allocate/initialize the memory for image information. REQUIRED. */ - info_ptr = png_create_info_struct(png_ptr); - if (info_ptr == NULL) - { - fclose(fp); - png_destroy_read_struct(&png_ptr, NULL, NULL); - return (ERROR); - } - - /* Set error handling if you are using the setjmp/longjmp method (this is - * the normal method of doing things with libpng). REQUIRED unless you - * set up your own error handlers in the png_create_read_struct() earlier. - */ - - if (setjmp(png_jmpbuf(png_ptr))) - { - /* Free all of the memory associated with the png_ptr and info_ptr */ - png_destroy_read_struct(&png_ptr, &info_ptr, NULL); - fclose(fp); - /* If we get here, we had a problem reading the file */ - return (ERROR); - } - - /* One of the following I/O initialization methods is REQUIRED */ -#ifdef streams /* PNG file I/O method 1 */ - /* Set up the input control if you are using standard C streams */ - png_init_io(png_ptr, fp); - -#else no_streams /* PNG file I/O method 2 */ - /* If you are using replacement read functions, instead of calling - * png_init_io() here you would call: - */ - png_set_read_fn(png_ptr, (void *)user_io_ptr, user_read_fn); - /* where user_io_ptr is a structure you want available to the callbacks */ -#endif no_streams /* Use only one I/O method! */ - - /* If we have already read some of the signature */ - png_set_sig_bytes(png_ptr, sig_read); - -#ifdef hilevel - /* - * 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 - * quantizing, filling, setting background, and doing gamma - * adjustment), then you can read the entire image (including - * pixels) into the info structure with this call: - */ - png_read_png(png_ptr, info_ptr, png_transforms, NULL); - -#else - /* OK, you're doing it the hard way, with the lower-level functions */ - - /* The call to png_read_info() gives us all of the information from the - * PNG file before the first IDAT (image data chunk). REQUIRED - */ - png_read_info(png_ptr, info_ptr); - - png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, - &interlace_type, NULL, NULL); - - /* Set up the data transformations you want. Note that these are all - * optional. Only call them if you want/need them. Many of the - * transformations only work on specific types of images, and many - * are mutually exclusive. - */ - - /* Tell libpng to strip 16 bits/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). - */ - png_set_strip_alpha(png_ptr); - - /* Extract multiple pixels with bit depths of 1, 2, and 4 from a single - * byte into separate bytes (useful for paletted and grayscale images). - */ - png_set_packing(png_ptr); - - /* Change the order of packed pixels to least significant bit first - * (not useful if you are using png_set_packing). */ - png_set_packswap(png_ptr); - - /* Expand paletted colors into true RGB triplets */ - if (color_type == PNG_COLOR_TYPE_PALETTE) - png_set_palette_to_rgb(png_ptr); - - /* Expand grayscale images to the full 8 bits from 1, 2, or 4 bits/pixel */ - if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8) - png_set_expand_gray_1_2_4_to_8(png_ptr); - - /* Expand paletted or RGB images with transparency to full alpha channels - * so the data will be available as RGBA quartets. - */ - if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) - png_set_tRNS_to_alpha(png_ptr); - - /* Set the background color to draw transparent and alpha images over. - * It is possible to set the red, green, and blue components directly - * for paletted images instead of supplying a palette index. Note that - * even if the PNG file supplies a background, you are not required to - * use it - you should use the (solid) application background if it has one. - */ - - png_color_16 my_background, *image_background; - - if (png_get_bKGD(png_ptr, info_ptr, &image_background)) - png_set_background(png_ptr, image_background, - PNG_BACKGROUND_GAMMA_FILE, 1, 1.0); - else - png_set_background(png_ptr, &my_background, - PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0); - - /* Some suggestions as to how to get a screen gamma value - * - * Note that screen gamma is the display_exponent, which includes - * the CRT_exponent and any correction for viewing conditions - */ - if (/* We have a user-defined screen gamma value */) - { - screen_gamma = user-defined screen_gamma; - } - /* This is one way that applications share the same screen gamma value */ - else if ((gamma_str = getenv("SCREEN_GAMMA")) != NULL) - { - screen_gamma = atof(gamma_str); - } - /* If we don't have another value */ - else - { - screen_gamma = PNG_DEFAULT_sRGB; /* A good guess for a PC monitor - in a dimly lit room */ - screen_gamma = PNG_GAMMA_MAC_18 or 1.0; /* Good guesses for Mac systems */ - } - - /* Tell libpng to handle the gamma conversion for you. The final call - * is a good guess for PC generated images, but it should be configurable - * by the user at run time by the user. It is strongly suggested that - * your application support gamma correction. - */ - - int intent; - - if (png_get_sRGB(png_ptr, info_ptr, &intent)) - png_set_gamma(png_ptr, screen_gamma, PNG_DEFAULT_sRGB); - else - { - double image_gamma; - if (png_get_gAMA(png_ptr, info_ptr, &image_gamma)) - png_set_gamma(png_ptr, screen_gamma, image_gamma); - else - png_set_gamma(png_ptr, screen_gamma, 0.45455); - } - -#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) - { - int num_palette; - png_colorp palette; - - /* 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 quantized */ - png_color 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 */ - else if (png_get_PLTE(png_ptr, info_ptr, &palette, &num_palette)) - { - png_uint_16p histogram = NULL; - - png_get_hIST(png_ptr, info_ptr, &histogram); - - 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); - - /* If you want to shift the pixel values from the range [0,255] or - * [0,65535] to the original [0,7] or [0,31], or whatever range the - * colors were originally in: - */ - if (png_get_valid(png_ptr, info_ptr, PNG_INFO_sBIT)) - { - png_color_8p sig_bit_p; - - png_get_sBIT(png_ptr, info_ptr, &sig_bit_p); - png_set_shift(png_ptr, sig_bit_p); - } - - /* Flip the RGB pixels to BGR (or RGBA to BGRA) */ - if (color_type & PNG_COLOR_MASK_COLOR) - png_set_bgr(png_ptr); - - /* Swap the RGBA or GA data to ARGB or AG (or BGRA to ABGR) */ - png_set_swap_alpha(png_ptr); - - /* Swap bytes of 16-bit files to least significant byte first */ - png_set_swap(png_ptr); - - /* Add filler (or alpha) byte (before/after each RGB triplet) */ - png_set_filler(png_ptr, 0xff, PNG_FILLER_AFTER); - -#ifdef PNG_READ_INTERLACING_SUPPORTED - /* Turn on interlace handling. REQUIRED if you are not using - * png_read_image(). To see how to handle interlacing passes, - * see the png_read_row() method below: - */ - number_passes = png_set_interlace_handling(png_ptr); -#else - number_passes = 1; -#endif /* PNG_READ_INTERLACING_SUPPORTED */ - - - /* Optional call to gamma correct and add the background to the palette - * and update info structure. REQUIRED if you are expecting libpng to - * update the palette for you (ie you selected such a transform above). - */ - png_read_update_info(png_ptr, info_ptr); - - /* Allocate the memory to hold the image using the fields of info_ptr. */ - - /* The easiest way to read the image: */ - png_bytep row_pointers[height]; - - /* Clear the pointer array */ - for (row = 0; row < height; row++) - row_pointers[row] = NULL; - - for (row = 0; row < height; row++) - row_pointers[row] = png_malloc(png_ptr, png_get_rowbytes(png_ptr, - info_ptr)); - - /* Now it's time to read the image. One of these methods is REQUIRED */ -#ifdef entire /* Read the entire image in one go */ - png_read_image(png_ptr, row_pointers); - -#else no_entire /* Read the image one or more scanlines at a time */ - /* The other way to read images - deal with interlacing: */ - - for (pass = 0; pass < number_passes; pass++) - { -#ifdef single /* Read the image a single row at a time */ - for (y = 0; y < height; y++) - { - png_read_rows(png_ptr, &row_pointers[y], NULL, 1); - } - -#else no_single /* Read the image several rows at a time */ - for (y = 0; y < height; y += number_of_rows) - { -#ifdef sparkle /* Read the image using the "sparkle" effect. */ - png_read_rows(png_ptr, &row_pointers[y], NULL, - number_of_rows); -#else no_sparkle /* Read the image using the "rectangle" effect */ - png_read_rows(png_ptr, NULL, &row_pointers[y], - number_of_rows); -#endif no_sparkle /* Use only one of these two methods */ - } - - /* If you want to display the image after every pass, do so here */ -#endif no_single /* Use only one of these two methods */ - } -#endif no_entire /* Use only one of these two methods */ - - /* Read rest of file, and get additional chunks in info_ptr - REQUIRED */ - png_read_end(png_ptr, info_ptr); -#endif hilevel - - /* At this point you have read the entire image */ - - /* Clean up after the read, and free any memory allocated - REQUIRED */ - png_destroy_read_struct(&png_ptr, &info_ptr, NULL); - - /* Close the file */ - fclose(fp); - - /* That's it */ - return (OK); -} - -/* Progressively read a file */ - -int -initialize_png_reader(png_structp *png_ptr, png_infop *info_ptr) -{ - /* Create and initialize the png_struct with the desired error handler - * functions. If you want to use the default stderr and longjump method, - * you can supply NULL for the last three parameters. We also check that - * the library version is compatible in case we are using dynamically - * linked libraries. - */ - *png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, - png_voidp user_error_ptr, user_error_fn, user_warning_fn); - - if (*png_ptr == NULL) - { - *info_ptr = NULL; - return (ERROR); - } - - *info_ptr = png_create_info_struct(png_ptr); - - if (*info_ptr == NULL) - { - png_destroy_read_struct(png_ptr, info_ptr, NULL); - return (ERROR); - } - - if (setjmp(png_jmpbuf((*png_ptr)))) - { - png_destroy_read_struct(png_ptr, info_ptr, NULL); - return (ERROR); - } - - /* This one's new. You will need to provide all three - * function callbacks, even if you aren't using them all. - * If you aren't using all functions, you can specify NULL - * parameters. Even when all three functions are NULL, - * you need to call png_set_progressive_read_fn(). - * These functions shouldn't be dependent on global or - * static variables if you are decoding several images - * simultaneously. You should store stream specific data - * in a separate struct, given as the second parameter, - * and retrieve the pointer from inside the callbacks using - * the function png_get_progressive_ptr(png_ptr). - */ - png_set_progressive_read_fn(*png_ptr, (void *)stream_data, - info_callback, row_callback, end_callback); - - return (OK); -} - -int -process_data(png_structp *png_ptr, png_infop *info_ptr, - png_bytep buffer, png_uint_32 length) -{ - if (setjmp(png_jmpbuf((*png_ptr)))) - { - /* Free the png_ptr and info_ptr memory on error */ - png_destroy_read_struct(png_ptr, info_ptr, NULL); - return (ERROR); - } - - /* This one's new also. Simply give it chunks of data as - * they arrive from the data stream (in order, of course). - * On segmented machines, don't give it any more than 64K. - * The library seems to run fine with sizes of 4K, although - * you can give it much less if necessary (I assume you can - * give it chunks of 1 byte, but I haven't tried with less - * than 256 bytes yet). When this function returns, you may - * want to display any rows that were generated in the row - * callback, if you aren't already displaying them there. - */ - png_process_data(*png_ptr, *info_ptr, buffer, length); - return (OK); -} - -info_callback(png_structp png_ptr, png_infop info) -{ - /* Do any setup here, including setting any of the transformations - * mentioned in the Reading PNG files section. For now, you _must_ - * call either png_start_read_image() or png_read_update_info() - * after all the transformations are set (even if you don't set - * any). You may start getting rows before png_process_data() - * returns, so this is your last chance to prepare for that. - */ -} - -row_callback(png_structp png_ptr, png_bytep new_row, - png_uint_32 row_num, int pass) -{ - /* - * This function is called for every row in the image. If the - * image is interlaced, and you turned on the interlace handler, - * this function will be called for every row in every pass. - * - * In this function you will receive a pointer to new row data from - * libpng called new_row that is to replace a corresponding row (of - * the same data format) in a buffer allocated by your application. - * - * The new row data pointer "new_row" may be NULL, indicating there is - * no new data to be replaced (in cases of interlace loading). - * - * If new_row is not NULL then you need to call - * png_progressive_combine_row() to replace the corresponding row as - * shown below: - */ - - /* Get pointer to corresponding row in our - * PNG read buffer. - */ - png_bytep old_row = ((png_bytep *)our_data)[row_num]; - -#ifdef PNG_READ_INTERLACING_SUPPORTED - /* 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 - * may make your life easier. - * - * For the non-NULL rows of interlaced images, you must call - * png_progressive_combine_row() passing in the new row and the - * old row, as demonstrated above. You can call this function for - * NULL rows (it will just return) and for non-interlaced images - * (it just does the png_memcpy for you) if it will make the code - * easier. Thus, you can just do this for all cases: - */ - - png_progressive_combine_row(png_ptr, old_row, new_row); - - /* where old_row is what was displayed for previous rows. Note - * that the first pass (pass == 0 really) will completely cover - * the old row, so the rows do not have to be initialized. After - * the first pass (and only for interlaced images), you will have - * to pass the current row as new_row, and the function will combine - * the old row and the new row. - */ -#endif /* PNG_READ_INTERLACING_SUPPORTED */ -} - -end_callback(png_structp png_ptr, png_infop info) -{ - /* This function is called when the whole image has been read, - * including any chunks after the image (up to and including - * the IEND). You will usually have the same info chunk as you - * had in the header, although some data may have been added - * to the comments and time fields. - * - * Most people won't do much here, perhaps setting a flag that - * marks the image as finished. - */ -} - -/* Write a png file */ -void write_png(char *file_name /* , ... other image information ... */) -{ - FILE *fp; - png_structp png_ptr; - png_infop info_ptr; - png_colorp palette; - - /* Open the file */ - fp = fopen(file_name, "wb"); - if (fp == NULL) - return (ERROR); - - /* Create and initialize the png_struct with the desired error handler - * functions. If you want to use the default stderr and longjump method, - * you can supply NULL for the last three parameters. We also check that - * the library version is compatible with the one used at compile time, - * in case we are using dynamically linked libraries. REQUIRED. - */ - png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, - png_voidp user_error_ptr, user_error_fn, user_warning_fn); - - if (png_ptr == NULL) - { - fclose(fp); - return (ERROR); - } - - /* Allocate/initialize the image information data. REQUIRED */ - info_ptr = png_create_info_struct(png_ptr); - if (info_ptr == NULL) - { - fclose(fp); - png_destroy_write_struct(&png_ptr, NULL); - return (ERROR); - } - - /* Set error handling. REQUIRED if you aren't supplying your own - * error handling functions in the png_create_write_struct() call. - */ - if (setjmp(png_jmpbuf(png_ptr))) - { - /* If we get here, we had a problem writing the file */ - fclose(fp); - png_destroy_write_struct(&png_ptr, &info_ptr); - return (ERROR); - } - - /* One of the following I/O initialization functions is REQUIRED */ - -#ifdef streams /* I/O initialization method 1 */ - /* Set up the output control if you are using standard C streams */ - png_init_io(png_ptr, fp); - -#else no_streams /* I/O initialization method 2 */ - /* If you are using replacement write functions, instead of calling - * png_init_io() here you would call - */ - png_set_write_fn(png_ptr, (void *)user_io_ptr, user_write_fn, - user_IO_flush_function); - /* where user_io_ptr is a structure you want available to the callbacks */ -#endif no_streams /* Only use one initialization method */ - -#ifdef hilevel - /* This is the easy way. Use it if you already have all the - * image info living in the structure. You could "|" many - * PNG_TRANSFORM flags into the png_transforms integer here. - */ - png_write_png(png_ptr, info_ptr, png_transforms, NULL); - -#else - /* This is the hard way */ - - /* Set the image information here. Width and height are up to 2^31, - * bit_depth is one of 1, 2, 4, 8, or 16, but valid values also depend on - * the color_type selected. color_type is one of PNG_COLOR_TYPE_GRAY, - * PNG_COLOR_TYPE_GRAY_ALPHA, PNG_COLOR_TYPE_PALETTE, PNG_COLOR_TYPE_RGB, - * or PNG_COLOR_TYPE_RGB_ALPHA. interlace is either PNG_INTERLACE_NONE or - * PNG_INTERLACE_ADAM7, and the compression_type and filter_type MUST - * currently be PNG_COMPRESSION_TYPE_BASE and PNG_FILTER_TYPE_BASE. REQUIRED - */ - png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, PNG_COLOR_TYPE_???, - PNG_INTERLACE_????, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE); - - /* Set the palette if there is one. REQUIRED for indexed-color images */ - palette = (png_colorp)png_malloc(png_ptr, PNG_MAX_PALETTE_LENGTH - * png_sizeof(png_color)); - /* ... Set palette colors ... */ - png_set_PLTE(png_ptr, info_ptr, palette, PNG_MAX_PALETTE_LENGTH); - /* You must not free palette here, because png_set_PLTE only makes a link to - * the palette that you malloced. Wait until you are about to destroy - * the png structure. - */ - - /* 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); - - - /* Optional gamma chunk is strongly suggested if you have any guess - * as to the correct gamma of the image. - */ - png_set_gAMA(png_ptr, info_ptr, gamma); - - /* Optionally write comments into the image */ - { - png_text text_ptr[3]; - - char key0[]="Title"; - char text0[]="Mona Lisa"; - text_ptr[0].key = key0; - text_ptr[0].text = text0; - 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; - - char key1[]="Author"; - char text1[]="Leonardo DaVinci"; - text_ptr[1].key = key1; - text_ptr[1].text = text1; - 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; - - char key2[]="Description"; - char text2[]="<long text>"; - text_ptr[2].key = key2; - text_ptr[2].text = text2; - text_ptr[2].compression = PNG_TEXT_COMPRESSION_zTXt; - text_ptr[2].itxt_length = 0; - text_ptr[2].lang = NULL; - text_ptr[2].lang_key = NULL; - - png_set_text(write_ptr, write_info_ptr, text_ptr, 3); - } - - /* Other optional chunks like cHRM, bKGD, tRNS, tIME, oFFs, pHYs */ - - /* Note that if sRGB is present the gAMA and cHRM chunks must be ignored - * on read and, if your application chooses to write them, they must - * be written in accordance with the sRGB profile - */ - - /* Write the file header information. REQUIRED */ - png_write_info(png_ptr, info_ptr); - - /* If you want, you can write the info in two steps, in case you need to - * write your private chunk ahead of PLTE: - * - * png_write_info_before_PLTE(write_ptr, write_info_ptr); - * write_my_chunk(); - * png_write_info(png_ptr, info_ptr); - * - * However, given the level of known- and unknown-chunk support in 1.2.0 - * and up, this should no longer be necessary. - */ - - /* Once we write out the header, the compression type on the text - * chunk gets changed to PNG_TEXT_COMPRESSION_NONE_WR or - * PNG_TEXT_COMPRESSION_zTXt_WR, so it doesn't get written out again - * at the end. - */ - - /* Set up the transformations you want. Note that these are - * all optional. Only call them if you want them. - */ - - /* Invert monochrome pixels */ - png_set_invert_mono(png_ptr); - - /* Shift the pixels up to a legal bit depth and fill in - * as appropriate to correctly scale the image. - */ - png_set_shift(png_ptr, &sig_bit); - - /* Pack pixels into bytes */ - png_set_packing(png_ptr); - - /* Swap location of alpha bytes from ARGB to RGBA */ - png_set_swap_alpha(png_ptr); - - /* Get rid of filler (OR ALPHA) bytes, pack XRGB/RGBX/ARGB/RGBA into - * RGB (4 channels -> 3 channels). The second parameter is not used. - */ - png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE); - - /* Flip BGR pixels to RGB */ - png_set_bgr(png_ptr); - - /* Swap bytes of 16-bit files to most significant byte first */ - png_set_swap(png_ptr); - - /* Swap bits of 1-bit, 2-bit, 4-bit packed pixel formats */ - png_set_packswap(png_ptr); - - /* Turn on interlace handling if you are not using png_write_image() */ - if (interlacing != 0) - number_passes = png_set_interlace_handling(png_ptr); - - else - number_passes = 1; - - /* The easiest way to write the image (you may have a different memory - * layout, however, so choose what fits your needs best). You need to - * use the first method if you aren't handling interlacing yourself. - */ - png_uint_32 k, height, width; - - /* In this example, "image" is a one-dimensional array of bytes */ - png_byte image[height*width*bytes_per_pixel]; - - png_bytep row_pointers[height]; - - if (height > PNG_UINT_32_MAX/png_sizeof(png_bytep)) - png_error (png_ptr, "Image is too tall to process in memory"); - - /* Set up pointers into your "image" byte array */ - for (k = 0; k < height; k++) - row_pointers[k] = image + k*width*bytes_per_pixel; - - /* One of the following output methods is REQUIRED */ - -#ifdef entire /* Write out the entire image data in one call */ - png_write_image(png_ptr, row_pointers); - - /* The other way to write the image - deal with interlacing */ - -#else no_entire /* Write out the image data by one or more scanlines */ - - /* The number of passes is either 1 for non-interlaced images, - * or 7 for interlaced images. - */ - for (pass = 0; pass < number_passes; pass++) - { - /* Write a few rows at a time. */ - png_write_rows(png_ptr, &row_pointers[first_row], number_of_rows); - - /* If you are only writing one row at a time, this works */ - for (y = 0; y < height; y++) - png_write_rows(png_ptr, &row_pointers[y], 1); - } -#endif no_entire /* Use only one output method */ - - /* You can write optional chunks like tEXt, zTXt, and tIME at the end - * as well. Shouldn't be necessary in 1.2.0 and up as all the public - * chunks are supported and you can use png_set_unknown_chunks() to - * register unknown chunks into the info structure to be written out. - */ - - /* It is REQUIRED to call this to finish writing the rest of the file */ - png_write_end(png_ptr, info_ptr); -#endif hilevel - - /* If you png_malloced a palette, free it here (don't free info_ptr->palette, - * as recommended in versions 1.0.5m and earlier of this example; if - * libpng mallocs info_ptr->palette, libpng will free it). If you - * allocated it with malloc() instead of png_malloc(), use free() instead - * of png_free(). - */ - png_free(png_ptr, palette); - palette = NULL; - - /* Similarly, if you png_malloced any data that you passed in with - * png_set_something(), such as a hist or trans array, free it here, - * when you can be sure that libpng is through with it. - */ - png_free(png_ptr, trans); - trans = NULL; - /* Whenever you use png_free() it is a good idea to set the pointer to - * NULL in case your application inadvertently tries to png_free() it - * again. When png_free() sees a NULL it returns without action, thus - * avoiding the double-free security problem. - */ - - /* Clean up after the write, and free any memory allocated */ - png_destroy_write_struct(&png_ptr, &info_ptr); - - /* Close the file */ - fclose(fp); - - /* That's it */ - return (OK); -} - -#endif /* if 0 */ |