neatvnc/src/pngfb.c

/*
 * This is not a part of the library. It's only used in tests, examples and
 * benchmarks.
 */

#include "neatvnc.h"

#include <stdlib.h>
#include <stdio.h>
#include <png.h>
#include <stdint.h>
#include <assert.h>
#include <libdrm/drm_fourcc.h>

struct nvnc_fb* read_png_file(const char* filename)
{
	int width, height;
	png_byte color_type;
	png_byte bit_depth;
	png_bytep* row_pointers = NULL;

	FILE* fp = fopen(filename, "rb");

	png_structp png =
	        png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
	if (!png)
		abort();

	png_infop info = png_create_info_struct(png);
	if (!info)
		abort();

	if (setjmp(png_jmpbuf(png)))
		abort();

	png_init_io(png, fp);

	png_read_info(png, info);

	width = png_get_image_width(png, info);
	height = png_get_image_height(png, info);
	color_type = png_get_color_type(png, info);
	bit_depth = png_get_bit_depth(png, info);

	// Read any color_type into 8bit depth, RGBA format.
	// See http://www.libpng.org/pub/png/libpng-manual.txt

	if (bit_depth == 16)
		png_set_strip_16(png);

	if (color_type == PNG_COLOR_TYPE_PALETTE)
		png_set_palette_to_rgb(png);

	// PNG_COLOR_TYPE_GRAY_ALPHA is always 8 or 16bit depth.
	if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
		png_set_expand_gray_1_2_4_to_8(png);

	if (png_get_valid(png, info, PNG_INFO_tRNS))
		png_set_tRNS_to_alpha(png);

	// These color_type don't have an alpha channel then fill it with 0xff.
	if (color_type == PNG_COLOR_TYPE_RGB ||
	    color_type == PNG_COLOR_TYPE_GRAY ||
	    color_type == PNG_COLOR_TYPE_PALETTE)
		png_set_filler(png, 0xFF, PNG_FILLER_AFTER);

	if (color_type == PNG_COLOR_TYPE_GRAY ||
	    color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
		png_set_gray_to_rgb(png);

	png_read_update_info(png, info);

	size_t row_bytes = png_get_rowbytes(png, info);
	assert(row_bytes == width * 4);
	struct nvnc_fb* fb = nvnc_fb_new(width, height, DRM_FORMAT_ABGR8888);
	assert(fb);

	uint8_t* addr = nvnc_fb_get_addr(fb);

	row_pointers = malloc(sizeof(png_bytep) * height);
	assert(row_pointers);

	for (int y = 0; y < height; ++y)
		row_pointers[y] = addr + y * row_bytes;

	png_read_image(png, row_pointers);

	free(row_pointers);
	fclose(fp);

	png_destroy_read_struct(&png, &info, NULL);

	return fb;
}