diff options
Diffstat (limited to 'png.c')
| -rw-r--r-- | png.c | 143 |
1 files changed, 143 insertions, 0 deletions
@@ -0,0 +1,143 @@ +#include "png-wbg.h" + +#include <stdlib.h> +#include <stdio.h> +#include <stdbool.h> +#include <string.h> +#include <assert.h> + +#include <png.h> +#include <pixman.h> + +#define LOG_MODULE "png" +#define LOG_ENABLE_DBG 0 +#include "log.h" +#include "stride.h" + +pixman_image_t * +png_load(const char *path) +{ + pixman_image_t *pix = NULL; + + FILE *fp = NULL; + png_structp png_ptr = NULL; + png_infop info_ptr = NULL; + png_bytepp row_pointers = NULL; + uint8_t *image_data = NULL; + + /* open file and test for it being a png */ + if ((fp = fopen(path, "rb")) == NULL) { + //LOG_ERRNO("%s: failed to open", path); + goto err; + } + + /* Verify PNG header */ + uint8_t header[8] = {0}; + if (fread(header, 1, 8, fp) != 8 || png_sig_cmp(header, 0, 8)) { + // LOG_ERR("%s: not a PNG", path); + goto err; + } + + /* Prepare for reading the PNG */ + if ((png_ptr = png_create_read_struct( + PNG_LIBPNG_VER_STRING, NULL, NULL, NULL)) == NULL || + (info_ptr = png_create_info_struct(png_ptr)) == NULL) + { + LOG_ERR("%s: failed to initialize libpng", path); + goto err; + } + + if (setjmp(png_jmpbuf(png_ptr))) { + LOG_ERR("%s: libpng error", path); + goto err; + } + + png_init_io(png_ptr, fp); + png_set_sig_bytes(png_ptr, 8); + + /* Get meta data */ + png_read_info(png_ptr, info_ptr); + int width = png_get_image_width(png_ptr, info_ptr); + int height = png_get_image_height(png_ptr, info_ptr); + png_byte color_type = png_get_color_type(png_ptr, info_ptr); + png_byte bit_depth __attribute__((unused)) = png_get_bit_depth(png_ptr, info_ptr); + int channels __attribute__((unused)) = png_get_channels(png_ptr, info_ptr); + + LOG_DBG("%s: %dx%d@%hhubpp, %d channels", path, width, height, bit_depth, channels); + + png_set_packing(png_ptr); + png_set_interlace_handling(png_ptr); + png_set_strip_16(png_ptr); /* "pack" 16-bit colors to 8-bit */ + png_set_bgr(png_ptr); + + /* pixman expects pre-multiplied alpha */ + png_set_alpha_mode(png_ptr, PNG_ALPHA_PREMULTIPLIED, 1.0); + + /* Tell libpng to expand to RGB(A) when necessary, and tell pixman + * whether we have alpha or not */ + pixman_format_code_t format; + switch (color_type) { + case PNG_COLOR_TYPE_GRAY: + case PNG_COLOR_TYPE_GRAY_ALPHA: + LOG_DBG("%d-bit gray%s", bit_depth, + color_type == PNG_COLOR_TYPE_GRAY_ALPHA ? "+alpha" : ""); + + if (bit_depth < 8) + png_set_expand_gray_1_2_4_to_8(png_ptr); + + png_set_gray_to_rgb(png_ptr); + format = color_type == PNG_COLOR_TYPE_GRAY ? PIXMAN_r8g8b8 : PIXMAN_a8r8g8b8; + break; + + case PNG_COLOR_TYPE_PALETTE: + LOG_DBG("%d-bit colormap%s", bit_depth, + png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS) ? "+tRNS" : ""); + + png_set_palette_to_rgb(png_ptr); + if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS)) { + png_set_tRNS_to_alpha(png_ptr); + format = PIXMAN_a8r8g8b8; + } else + format = PIXMAN_r8g8b8; + break; + + case PNG_COLOR_TYPE_RGB: + LOG_DBG("RGB"); + format = PIXMAN_r8g8b8; + break; + + case PNG_COLOR_TYPE_RGBA: + LOG_DBG("RGBA"); + format = PIXMAN_a8r8g8b8; + break; + } + + png_read_update_info(png_ptr, info_ptr); + + size_t row_bytes __attribute__((unused)) = png_get_rowbytes(png_ptr, info_ptr); + int stride = stride_for_format_and_width(format, width); + image_data = malloc(height * stride); + + LOG_DBG("stride=%d, row-bytes=%zu", stride, row_bytes); + assert(stride >= row_bytes); + + row_pointers = malloc(height * sizeof(png_bytep)); + for (int i = 0; i < height; i++) + row_pointers[i] = &image_data[i * stride]; + + png_read_image(png_ptr, row_pointers); + + pix = pixman_image_create_bits_no_clear( + format, width, height, (uint32_t *)image_data, stride); + +err: + if (pix == NULL) + free(image_data); + free(row_pointers); + if (png_ptr != NULL) + png_destroy_read_struct(&png_ptr, &info_ptr, NULL); + if (fp != NULL) + fclose(fp); + + return pix; +} |