img_png.c

微型浏览器

/*******************************************************************************
 *
 * img_png.h 
 *                   
 * Original code from dillo http://dillo.sourceforge.net
 *
 * Hacked by Garett Spencley for Cheetah Web Browser
 * 
 * Copyright (C) 1999 Geoff Lane <[e-mail]>
 * Copyright (C) 2000 Luca Rota, Jorge Arellano Cid, Eric Gaudet
 * Copyright (C) 2001 Garett Spencley <[e-mail]>
 * 
 * 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 2, 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, write to the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 
 *
 *******************************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <gtk/gtk.h>

#include <png.h>

#include "img_png.h"
#include "debug.h"

#define DATASIZE  (png->ipbufsize - png->ipbufstart)
#define BLACK     0
#define WHITE     255

enum prog_state {
	IS_finished, IS_init, IS_nextdata
};

/*
 * This holds the data that must be saved between calls to this module.
 * Each time it is called it is supplied with a vector of data bytes
 * obtained from the web server. The module can process any amount of the
 * supplied data.  The next time the module is called, the vector may be
 * extended with additional data bytes to be processed.  The module must
 * keep track of the current start and cursor position of the input data
 * vector.  As complete output rasters are determined they are sent out of
 * the module for additional processing.
 *
 * NOTE:  There is no external control of the splitting of the input data
 * vector (only this module understands PNG format data.) This means that
 * the complete state of a PNG image being processed must be held in the
 * structure below so that processing can be suspended or resumed at any
 * point within an input image.
 *
 * In the case of the libpng library, it maintains it's own state in
 * png_ptr and into_ptr so the FSM is very simple - much simpler than the
 * ones for XBM and PNM are.
 */

struct _PngImage {

	ImageData *Image;	/* Image meta data */

	double display_exponent;	/* gamma correction */
	gulong width;		/* png image width */
	gulong height;		/* png image height */
	png_structp png_ptr;	/* libpng private data */
	png_infop info_ptr;	/* libpng private info */
	guchar *image_data;	/* decoded image data    */
	guchar **row_pointers;	/* pntr to row starts    */
	jmp_buf jmpbuf;		/* png error processing */
	gint error;		/* error flag */
	gint rowbytes;		/* No. bytes in image row */
	short passes;
	short channels;		/* No. image channels */

/*
 * 0                                              last byte
 * +-------+-+-----------------------------------+-+
 * |       | |     -- data to be processed --    | |
 * +-------+-+-----------------------------------+-+
 * ^        ^                                     ^
 * ipbuf    ipbufstart                            ipbufsize
 */

	guchar *ipbuf;		/* image data in buffer */
	gint ipbufstart;	/* first valid image byte */
	gint ipbufsize;		/* size of valid data in */

	enum prog_state state;	/* FSM current state  */

	guchar *linebuf;	/* o/p raster data */

};

static void Png_error_handling(png_structp png_ptr, png_const_charp msg)
{
   PngImage *png;

   g_print("Png_error_handling: %s\n", msg);
   png = png_get_error_ptr(png_ptr);

   png->error = 1;
   png->state = IS_finished;

   longjmp(png->jmpbuf, 1);
}

static void Png_datainfo_callback(png_structp png_ptr, png_infop info_ptr)
{
	PngImage *png;
   	gint color_type;
   	gint bit_depth;
   	gint interlace_type;
   	guint i;
	char *buf;
   	double gamma;

	debug_print("Png_datainfo_callback:\n");

   	png = png_get_progressive_ptr(png_ptr);
	g_return_if_fail(png != NULL);

   	png_get_IHDR(png_ptr, info_ptr, &png->width, &png->height, &bit_depth, &color_type, 
					&interlace_type, NULL, NULL);

   	debug_print("Png_datainfo_callback: png->width  = %ld\n", png->width);
   	debug_print("Png_datainfo_callback: png->height = %ld\n", png->height);

   	/* we need RGB/RGBA in the end */
   	if (color_type == PNG_COLOR_TYPE_PALETTE && bit_depth <= 8) {
    	/* Convert indexed images to RGB */
      	png_set_expand (png_ptr);
   	} else if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8) {
    	/* Convert grayscale to RGB */
      	png_set_expand (png_ptr);
   	} else if (png_get_valid (png_ptr, info_ptr, PNG_INFO_tRNS)) {
      	/* We have transparency header, convert it to alpha channel */
      	png_set_expand(png_ptr);
   	} else if (bit_depth < 8) {
      	png_set_expand(png_ptr);
   	}

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

   	/* Get and set gamma information. Beware: gamma correction 2.2 will
       only work on PC's. todo: select screen gamma correction for other 
       platforms. */
   	if (png_get_gAMA(png_ptr, info_ptr, &gamma))
    	png_set_gamma(png_ptr, 2.2, gamma);

   	/* Convert gray scale to RGB */
   	if (color_type == PNG_COLOR_TYPE_GRAY ||
    	color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {
      	png_set_gray_to_rgb(png_ptr);
   	}

   	/* Interlaced */
   	if (interlace_type != PNG_INTERLACE_NONE) 
      	png->passes = png_set_interlace_handling(png_ptr);

   	/* get libpng to update it's state */
   	png_read_update_info(png_ptr, info_ptr);

   	png_get_IHDR(png_ptr, info_ptr, &png->width, &png->height, &bit_depth, &color_type, 
					&interlace_type, NULL, NULL);

   	png->rowbytes = png_get_rowbytes(png_ptr, info_ptr);
   	png->channels = png_get_channels(png_ptr, info_ptr);

   	/* init Dillo specifics */

   	debug_print("Png_datainfo_callback: rowbytes = %d\n", png->rowbytes);
   	debug_print("Png_datainfo_callback: width    = %ld\n", png->width);
   	debug_print("Png_datainfo_callback: height   = %ld\n", png->height);

   	png->image_data = (guchar *) g_malloc(png->rowbytes * png->height);
   	png->row_pointers = (guchar **) g_malloc(png->height * sizeof(guchar *));

   	for (i = 0; i < png->height; i++)
    	png->row_pointers[i] = png->image_data + (i * png->rowbytes);

   	png->linebuf = g_malloc(3 * png->width);

	buf = g_malloc(png->width * png->height * 3);
	Image_set_parms(png->Image, buf, png->width, png->height, IMG_TYPE_RGB);
}

static void Png_datarow_callback(png_structp png_ptr, png_bytep new_row, png_uint_32 row_num, gint pass)
{
	PngImage *png;
	guint i;

	if (!new_row)		/* work to do? */
		return;

	png = png_get_progressive_ptr(png_ptr);

	png_progressive_combine_row(png_ptr, png->row_pointers[row_num], new_row);

	switch (png->channels) {

	case 3:
		Image_write(png->Image, png->image_data + (row_num * png->rowbytes), row_num, TRUE);
		break;
	case 4:
		{
			/* todo: get the backgound color from the parent 
			 * of the image widget -- Livio.                 */
			gint a, bg_red, bg_green, bg_blue;
			guchar *pl = png->linebuf;
			guchar *data = png->image_data + (row_num * png->rowbytes);

			/* todo: maybe change prefs.bg_color to `a_Dw_widget_get_bg_color`,
			 * when background colors are correctly implementated */

		/*	bg_blue = (prefs.bg_color) & 0xFF;
			bg_green = (prefs.bg_color >> 8) & 0xFF;
			bg_red = (prefs.bg_color >> 16) & 0xFF; */

			bg_blue = DW_PAINT_DEFAULT_BGND & 0xFF;
			bg_green = (DW_PAINT_DEFAULT_BGND >> 8) & 0xFF;
			bg_red = (DW_PAINT_DEFAULT_BGND >> 16) & 0xFF; 

			for (i = 0; i < png->width; i++) {
				a = *(data + 3);

				if (a == 255) {
					*(pl++) = *(data++);
					*(pl++) = *(data++);
					*(pl++) = *(data++);
					data++;
				} else if (a == 0) {
					*(pl++) = bg_red;
					*(pl++) = bg_green;
					*(pl++) = bg_blue;
					data += 4;
				} else {
					png_composite(*(pl++), *(data++), a, bg_red);
					png_composite(*(pl++), *(data++), a, bg_green);
					png_composite(*(pl++), *(data++), a, bg_blue);
					data++;
				}
			}
			Image_write(png->Image, png->linebuf, row_num, TRUE);
			break;
		}
	default:
		g_print("Png_datarow_callback: unexpected number of channels = %d\n", png->channels);
		abort();
	}
}

static void Png_dataend_callback(png_structp png_ptr, png_infop info_ptr)
{
	PngImage *png;

	debug_print("Png_dataend_callback...");

	png = png_get_progressive_ptr(png_ptr);
	png->state = IS_finished;
}

void Png_close(PngImage *png)
{
	if(!png) return;

	if (png->image_data != NULL)
		g_free(png->image_data);

	if (png->row_pointers != NULL)
		g_free(png->row_pointers);

	if (png->linebuf != NULL)
		g_free(png->linebuf);

	if (setjmp(png->jmpbuf))
		png_destroy_read_struct(&png->png_ptr, &png->info_ptr, NULL);

	g_free(png);
}

void Png_write(PngImage *png, void *Buf, size_t Size)
{
	/* Let's make some sound if we have been called with no data */
	g_return_if_fail(Buf != NULL && Size > 0);

	debug_print("Png_write: BufSize = %d", Size);

	/* Keep local copies so we don't have to pass multiple args to
	 * a number of functions. */

	png->ipbuf      = Buf;
	png->ipbufsize = Size;

	/* start/resume the FSM here */

	while (png->state != IS_finished && DATASIZE) {

		switch (png->state) {

		case IS_init:

			if(DATASIZE < 8) 
				return;	/* need MORE data */

			/* check the image signature - DON'T update ipbufstart! */
			if (!png_check_sig(png->ipbuf, DATASIZE)) {
				/* you lied to me about it being a PNG image */
				png->state = IS_finished;
				break;
			}

			/* OK, it looks like a PNG image, lets do some set up stuff */
			png->png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, png, (png_error_ptr) Png_error_handling, (png_error_ptr) Png_error_handling);
			g_return_if_fail(png->png_ptr != NULL);
			png->info_ptr = png_create_info_struct(png->png_ptr);
			g_return_if_fail(png->png_ptr != NULL);

			setjmp(png->jmpbuf);

			if (!png->error) {
				png_set_progressive_read_fn(png->png_ptr, png, Png_datainfo_callback,	/* performs local init functions */
							    Png_datarow_callback,	/* performs per row action */
							    Png_dataend_callback);	/* performs cleanup actions */
				png->state = IS_nextdata;
			}


			break;

		case IS_nextdata:

			
			if (setjmp(png->jmpbuf)) {
				png->state = IS_finished;
			} else if (!png->error) {
				png_process_data(png->png_ptr, png->info_ptr, png->ipbuf + png->ipbufstart, DATASIZE);
				png->ipbufstart += DATASIZE;
			}
			break;

		default:
			g_warning("PNG decoder: bad state = %d\n", png->state);
			abort();
		}
	}
}

/*
 * Create the image state data that must be kept between calls
 */

PngImage *Png_new(ImageData * Image)
{
	PngImage *png = g_malloc(sizeof(PngImage));

	png->Image = Image;
	png->state = IS_init;
	png->error = 0;
	png->ipbuf = NULL;
	png->ipbufstart = 0;
	png->ipbufsize = 0;
	png->linebuf = NULL;
	png->linebuf = NULL;
	png->row_pointers = NULL;
	png->image_data = NULL;

	return png;
}

/*
 * MIME handler for "image/png" type
 * (Sets Png_callback or a_Dicache_callback as the cache-client)
 */

DwWidget *a_Png_image(const char *Type, ImageData *image, void **Data)
{
/*
 * Type: MIME type
 * Ptr:  points to a Web structure
 * Call: Dillo calls this with more data/eod
 * Data: raw image data
 */

	debug_print("a_Png_image: Type = %s", Type);
	debug_print("a_Png_image: libpng - Compiled %s; using %s.", PNG_LIBPNG_VER_STRING, png_libpng_ver);
	debug_print("a_Png_image: zlib   - Compiled %s; using %s.\n", ZLIB_VERSION, zlib_version);

	if(!image)
		image = Image_new(0, 0, NULL, DW_PAINT_DEFAULT_BGND);

	*Data = image;

	return DW_WIDGET(image);
}