graphics.c

/* hacktv - Analogue video transmitter for the HackRF                    */
/*=======================================================================*/
/* Copyright 2020 Philip Heron <phil@sanslogic.co.uk>                    */
/*                                                                       */
/* This program is free software: you can redistribute it and/or modify  */
/* it under the terms of the GNU General Public License as published by  */
/* the Free Software Foundation, either version 3 of the License, or     */
/* (at your option) any later version.                                   */
/*                                                                       */
/* This program is distributed in the hope that it will be useful,       */
/* but WITHOUT ANY WARRANTY; without even the implied warranty of        */
/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         */
/* GNU General Public License for more details.                          */
/*                                                                       */
/* You should have received a copy of the GNU General Public License     */
/* along with this program.  If not, see <http://www.gnu.org/licenses/>. */

/*
 * Inspiration from  http://zarb.org/~gc/html/libpng.html
 *
 * Modified by Yoshimasa Niwa to support all possible colour types.
 */

#include "video.h"
#include "hacktv.h"
#include "resources.h"

const pngs_t png_logos[] = {
	{ "hacktv",         _png_hacktv,         IMG_POS_TR, sizeof(_png_hacktv) },
	{ "cartoonnetwork", _png_cartoonnetwork, IMG_POS_TR, sizeof(_png_cartoonnetwork) },
	{ "tv1000",         _png_tv1000,         IMG_POS_TR, sizeof(_png_tv1000) },
	{ "filmnet1",       _png_filmnet1,       IMG_POS_TR, sizeof(_png_filmnet1) },
	{ "canal+",         _png_canalplus,      IMG_POS_TR, sizeof(_png_canalplus) },
	{ "eurotica",       _png_eurotica,       IMG_POS_TR, sizeof(_png_eurotica) },
	{ "mtv",            _png_mtv,            IMG_POS_TR, sizeof(_png_mtv) },
	{ "tac",            _png_tac,            IMG_POS_TR, sizeof(_png_tac) },
	{ "filmnet",        _png_filmnet,        IMG_POS_TR, sizeof(_png_filmnet) },
	{ "multichoice",    _png_multichoice,    IMG_POS_TR, sizeof(_png_multichoice) },
	{ "skyone",         _png_skyone,         IMG_POS_TL, sizeof(_png_skyone) },
	{ "sky",            _png_sky,            IMG_POS_BR, sizeof(_png_sky) },
	{ NULL,             NULL,                0,          0 }
};

const pngs_t png_tests[] = {
	{ "pm5544",         _png_test_pm5544, IMG_POS_CENTRE,  sizeof(_png_test_pm5544) },
	{ "pm5644",         _png_test_pm5644, IMG_POS_CENTRE,  sizeof(_png_test_pm5644) },
	{ "fubk",           _png_test_fubk,   IMG_POS_CENTRE,  sizeof(_png_test_fubk) },
	{ "ueitm",          _png_test_ueitm,  IMG_POS_CENTRE,  sizeof(_png_test_ueitm) },
	{ NULL,             NULL,             0,           0 }
};

static void _open_png_memory(png_mem_t *r, const uint8_t *data, int size)
{
	r->size = size;
	r->data = data;
	r->cursor = data;
}

static size_t _read_png_memory(png_mem_t *r, uint8_t *dst, size_t n)
{
	size_t bytes_till_end = r->data + r->size - r->cursor;
	if (n > bytes_till_end) n = bytes_till_end;
	memcpy(dst, r->cursor, n);
	r->cursor += n;
	return n;
}

static void _read_png_memory_callback(png_struct *png_str, png_byte *data, png_size_t length)
{
	png_mem_t *r = (png_mem_t*) png_get_io_ptr(png_str);
	png_size_t bytesread = _read_png_memory(r, data, length);
	if (bytesread != length) png_error(png_str, "Read Error!");
}

static int _read_png_data(image_t *image, const pngs_t *pngs) 
{
	int y;
	
	uint8_t buf[8];
	png_mem_t reader;
	_open_png_memory(&reader, pngs->png->data, pngs->size);
	_read_png_memory(&reader, buf, 8);
	
	/* Ensure that it is, in fact, valid PNG data */
	if(png_sig_cmp((png_const_bytep) buf, (png_size_t) 0, 8))
	{
		fprintf(stderr,"Warning: %s is not a valid PNG data.\n", image->name);
		return(HACKTV_ERROR);
	}
	
	/* Define png structure */
	png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
	
	/* Allocate/initialize the memory for image information. */
	png_infop info_ptr = png_create_info_struct(png_ptr);
	if (info_ptr == NULL)
	{
		png_destroy_read_struct(&png_ptr, NULL, NULL);
		fprintf(stderr,"Warning: Error allocating memory for data %s.\n", image->name);
		return (HACKTV_OUT_OF_MEMORY);
	}
	
	png_byte color_type;
	png_byte bit_depth;
	
	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);
		
		fprintf(stderr,"Warning: Error reading data %s.\n", image->name);
		return (HACKTV_ERROR);
	};
	
	png_set_read_fn(png_ptr, (png_voidp) &reader, _read_png_memory_callback);
	
	/* Skip signature bytes */
	png_set_sig_bytes(png_ptr, 8);
	
	/* Read image details */
	png_read_info(png_ptr, info_ptr);
	
	image->width = png_get_image_width(png_ptr, info_ptr);
	image->height = png_get_image_height(png_ptr, info_ptr);
	color_type = png_get_color_type(png_ptr, info_ptr);
	bit_depth = png_get_bit_depth(png_ptr, info_ptr);
	
	/* Convert to 8-bit RBGA, if required */
	if(bit_depth == 16)
	{
		png_set_strip_16(png_ptr);
	}
	
	if(color_type == PNG_COLOR_TYPE_PALETTE)
	{
		png_set_palette_to_rgb(png_ptr);
	}
	
	if(color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
	{
		png_set_expand_gray_1_2_4_to_8(png_ptr);
	}
	
	if(png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
	{
		png_set_tRNS_to_alpha(png_ptr);
	}
	
	/* Fill alpha channel with 0xFF (white) if it's missing */
	if(color_type == PNG_COLOR_TYPE_RGB || color_type == PNG_COLOR_TYPE_GRAY || color_type == PNG_COLOR_TYPE_PALETTE)
	{
		png_set_filler(png_ptr, 0xFF, PNG_FILLER_AFTER);
	}
	
	if(color_type == PNG_COLOR_TYPE_GRAY || color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
	{
		png_set_gray_to_rgb(png_ptr);
	}
	
	/* Update PNG info with any changes from above */
	png_read_update_info(png_ptr, info_ptr);
	
	/* Allocate memory to image */
	image->row_pointers = (png_bytep*) malloc(sizeof(png_bytep) * image->height);
	
	for(y = 0; y < image->height; y++)
	{
		image->row_pointers[y] = (png_byte*) malloc(png_get_rowbytes(png_ptr, info_ptr));
	}
	
	/* Load image into memory */
	png_read_image(png_ptr, image->row_pointers);
	
	/* Free memory */
	png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
	
	return (HACKTV_OK);
}

int load_png(image_t *image, int width, int height, char *image_name, float scale, float ratio, int type)
{
	const pngs_t *pngs;
	image->name = image_name;
	
	/* Find the image */
	if(type == IMG_LOGO)
	{
		for(pngs = png_logos; pngs->name != NULL; pngs++)
		{	
			if(strcmp(image->name, pngs->name) == 0) break;
		}
		
		if(pngs->name == NULL)
		{
			fprintf(stderr, "\n%s: Unrecognised logo name.\n", image->name);
			fprintf(stderr, "\nValid values are:\n");
			
			for(pngs = png_logos; pngs->name != NULL; pngs++)
			{
				 fprintf(stderr,"\t-- %s\n", pngs->name);
			}
			return(HACKTV_ERROR);
		}
	}
	else
	{
		for(pngs = png_tests; pngs->name != NULL; pngs++)
		{	
			if(strcmp(image->name, pngs->name) == 0) break;
		}
		
		if(pngs->name == NULL)
		{
			fprintf(stderr, "\n%s: Unrecognised test pattern name.\n", image->name);
			fprintf(stderr, "\nValid values are:\n");
			
			for(pngs = png_tests; pngs->name != NULL; pngs++)
			{
				 fprintf(stderr,"\t-- %s\n", pngs->name);
			}
			return(HACKTV_ERROR);
		}
	}
	
	if(_read_png_data(image, pngs) == HACKTV_OK)
	{
		image->position = pngs->position;
		image->img_width = image->width * scale / ratio / ((float) height / (float) width);
		image->img_height = image->height * scale;
		int i, j, k;
		uint32_t *logo;
		
		logo = malloc(image->width * image->height * sizeof(uint32_t));
		image->logo = malloc(image->img_width * image->img_height * sizeof(uint32_t));
		
		for(i = image->height - 1, k = 0; i > -1 ; i--)
		{	
			png_bytep row = image->row_pointers[i];
			for(j = 0; j < image->width; j++, k++)
			{
				png_bytep px = &(row[j * 4]);
				logo[k] = px[3] << 24 | px[0] << 16 | px[1] << 8 | px[2] << 0;
			}
		}
		
		resize_bitmap(logo, image->logo, image->width, image->height, image->img_width, image->img_height);
		return(HACKTV_OK);
	}
	
	return(HACKTV_ERROR);
}


void overlay_image(uint32_t *framebuffer, image_t *l, int vid_width, int vid_height, int pos)
{
	int i, j, x, y, r, g, b, vi;
	float t;
	uint32_t c;
	int x_start = 0;
	int y_start = 0;

	/* Set logo positions */
	if(pos == IMG_POS_TR)
	{
		x_start = ((float) vid_width * 0.9) - ((float) l->img_width * 0.8);
		y_start = (float) (vid_height) * 0.08;
	}
	
	if(pos == IMG_POS_TL)
	{
		x_start = ((float) vid_width * 0.085);
		y_start = (float) (vid_height) * 0.08;
	}
	
	if(pos == IMG_POS_BR)
	{
		x_start = ((float) vid_width * 0.9) - ((float) l->img_width * 0.8);
		y_start = ((float) (vid_height) * 0.9) - ((float) l->img_height * 0.8);
	}
	
	if(pos == IMG_POS_BL)
	{
		x_start = ((float) vid_width * 0.085);
		y_start = ((float) (vid_height) * 0.90) - ((float) l->img_height * 0.8);
	}
	
	/* Set logo position - centre */
	if(pos == IMG_POS_CENTRE)
	{
		x_start = ((float) vid_width * 0.5) - ((float) l->img_width * 0.5);
		y_start = (float) (vid_height) * 0.095;
	}

	/* Set logo position - full screen */
	if(pos == IMG_POS_FULL)
	{
		x_start = ((float) vid_width * 0.5) - ((float) l->img_width * 0.5);
		y_start = 0;
	}
	
	/* Overlay image */
	for (y = 0, i = y_start; y < l->img_height; y++, i++) 
	{
		for(x = 0, j = x_start; x < l->img_width; x++, j++)
		{
			/* Only render image inside active video areas */
			if(j >= 0 && j < vid_width)
			{
				/* Get pixel */
				c = l->logo[x + ((l->img_height - y - 1) * l->img_width)];
				
				/* Calculate transparency level */
				t = 1.0 - (float) (c >> 24) / 0xFF;
				
				/* Set logo position */
				vi = i * vid_width + j;
				
				/* Apply transparency  */
				r = ((framebuffer[vi] >> 16) & 0xFF) * t + ((c >> 16) & 0xFF) * (1 - t);
				g = ((framebuffer[vi] >> 8)  & 0xFF) * t + ((c >> 8)  & 0xFF) * (1 - t);
				b = ((framebuffer[vi] >> 0)  & 0xFF) * t + ((c >> 0)  & 0xFF) * (1 - t);
				
				framebuffer[vi] = (r << 16 | g << 8 | b << 0);
			}
		}
	}
}

/* Inspiration from http://tech-algorithm.com/articles/bilinear-image-scaling/ */

void resize_bitmap(uint32_t *input, uint32_t *output, int old_width, int old_height, int new_width, int new_height) 
{
	int a, b, c, d, x, y, index;
	float x_ratio = ((float)(old_width - 1)) / new_width;
	float y_ratio = ((float)(old_height - 1)) / new_height;
	float x_diff, y_diff, blue, red, green, alpha;
	int offset = 0 ;
	
	for (int i = 0; i < new_height; i++) 
	{
		for (int j = 0; j < new_width; j++) 
		{
			x = (int)(x_ratio * j);
			y = (int)(y_ratio * i);
			x_diff = (x_ratio * j) - x;
			y_diff = (y_ratio * i) - y;
			index = (y * old_width + x);
			a = input[index];
			b = input[index + 1];
			c = input[index + old_width];
			d = input[index + old_width + 1];
			
			/* Blue */
			blue = (a & 0xFF) * ( 1- x_diff) * (1 - y_diff) + (b & 0xFF) * (x_diff) * (1 - y_diff) +
				   (c & 0xFF) * (y_diff) * (1 - x_diff)   + (d & 0xFF) * (x_diff * y_diff);
			
			/* Green */
			green = ((a >> 8) & 0xFF) * (1-x_diff) * (1 - y_diff) + ((b >> 8) & 0xFF) * (x_diff) * (1 - y_diff) +
					((c >> 8) & 0xFF) * (y_diff) * (1 - x_diff)   + ((d >> 8) & 0xFF) * (x_diff * y_diff);
			
			/* Reg */
			red = ((a >> 16) & 0xFF) * (1 - x_diff) * (1 - y_diff) + ((b >> 16) & 0xFF) * (x_diff) * (1-y_diff) +
				  ((c >> 16) & 0xFF) * (y_diff) * (1 - x_diff)   + ((d >> 16) & 0xFF) * (x_diff * y_diff);
			
			// /* Alpha */
			alpha = ((a >> 24) & 0xFF) * (1-x_diff) * (1 - y_diff) + ((b >> 24) & 0xFF) * (x_diff) * (1 - y_diff) +
					((c >> 24) & 0xFF) * (y_diff) * (1 - x_diff)   + ((d >> 24) & 0xFF) * (x_diff * y_diff);
			
			output[offset++] = 
					((((int) alpha) << 24) & 0xFF000000) |
					((((int) red)   << 16) & 0xFF0000)   |
					((((int) green) << 8)  & 0xFF00)     |
					((((int) blue)  << 0)  & 0xFF);
		}
	}
}