/* Copyright (C) 2006-2010 Artifex Software, Inc.
   All Rights Reserved.

   This software is provided AS-IS with no warranty, either express or
   implied.

   This software is distributed under license and may not be copied, modified
   or distributed except as expressly authorized under the terms of that
   license.  Refer to licensing information at http://www.artifex.com/
   or contact Artifex Software, Inc.,  7 Mt. Lassen  Drive - Suite A-134,
   San Rafael, CA  94903, U.S.A., +1(415)492-9861, for further information.
*/

/* XPS interpreter - PNG image support */

#include "ghostxps.h"

#include "stream.h"
#include "strimpl.h"
#include "gsstate.h"

/* silence a warning where #if SHARE_LIBPNG is used when it's undefined */
#ifndef SHARE_LIBPNG
#define SHARE_LIBPNG 0
#endif
#include "png_.h"

/*
 * PNG using libpng directly (no gs wrappers)
 */

struct xps_png_io_s
{
    byte *ptr;
    byte *lim;
};

static void
xps_png_read(png_structp png, png_bytep data, png_size_t length)
{
    struct xps_png_io_s *io = png_get_io_ptr(png);
    if (io->ptr + length > io->lim)
        png_error(png, "Read Error");
    memcpy(data, io->ptr, length);
    io->ptr += length;
}

static png_voidp
xps_png_malloc(png_structp png, png_size_t size)
{
    gs_memory_t *mem = png_get_mem_ptr(png);
    return gs_alloc_bytes(mem, size, "libpng");
}

static void
xps_png_free(png_structp png, png_voidp ptr)
{
    gs_memory_t *mem = png_get_mem_ptr(png);
    gs_free_object(mem, ptr, "libpng");
}

/* This only determines if we have an alpha value */
int
xps_png_has_alpha(xps_context_t *ctx, byte *rbuf, int rlen)
{
    png_structp png;
    png_infop info;
    struct xps_png_io_s io;
    int has_alpha;

    /*
     * Set up PNG structs and input source
     */

    io.ptr = rbuf;
    io.lim = rbuf + rlen;

    png = png_create_read_struct_2(PNG_LIBPNG_VER_STRING,
            NULL, NULL, NULL,
            ctx->memory, xps_png_malloc, xps_png_free);
    if (!png) {
        gs_warn("png_create_read_struct");
        return 0;
    }

    info = png_create_info_struct(png);
    if (!info) {
        gs_warn("png_create_info_struct");
        return 0;
    }

    png_set_read_fn(png, &io, xps_png_read);
    png_set_crc_action(png, PNG_CRC_WARN_USE, PNG_CRC_WARN_USE);

    /*
     * Jump to here on errors.
     */

    if (setjmp(png_jmpbuf(png)))
    {
        png_destroy_read_struct(&png, &info, NULL);
        gs_warn("png reading failed");
        return 0;
    }

    /*
     * Read PNG header
     */

    png_read_info(png, info);

    switch (png_get_color_type(png, info))
    {
    case PNG_COLOR_TYPE_PALETTE:
    case PNG_COLOR_TYPE_GRAY:
    case PNG_COLOR_TYPE_RGB:
        has_alpha = 0;
        break;

    case PNG_COLOR_TYPE_GRAY_ALPHA:
    case PNG_COLOR_TYPE_RGB_ALPHA:
        has_alpha = 1;
        break;

    default:
        gs_warn("cannot handle this png color type");
        has_alpha = 0;
        break;
    }

    /*
     * Clean up memory.
     */

    png_destroy_read_struct(&png, &info, NULL);

    return has_alpha;
}

int
xps_decode_png(xps_context_t *ctx, byte *rbuf, int rlen, xps_image_t *image)
{
    png_structp png;
    png_infop info;
    struct xps_png_io_s io;
    int npasses;
    int pass;
    int y;

    /*
     * Set up PNG structs and input source
     */

    io.ptr = rbuf;
    io.lim = rbuf + rlen;

    png = png_create_read_struct_2(PNG_LIBPNG_VER_STRING,
            NULL, NULL, NULL,
            ctx->memory, xps_png_malloc, xps_png_free);
    if (!png)
        return gs_throw(-1, "png_create_read_struct");

    info = png_create_info_struct(png);
    if (!info)
        return gs_throw(-1, "png_create_info_struct");

    png_set_read_fn(png, &io, xps_png_read);
    png_set_crc_action(png, PNG_CRC_WARN_USE, PNG_CRC_WARN_USE);

    /*
     * Jump to here on errors.
     */

    if (setjmp(png_jmpbuf(png)))
    {
        png_destroy_read_struct(&png, &info, NULL);
        return gs_throw(-1, "png reading failed");
    }

    /*
     * Read PNG header
     */

    png_read_info(png, info);

    if (png_get_interlace_type(png, info) == PNG_INTERLACE_ADAM7)
    {
        npasses = png_set_interlace_handling(png);
    }
    else
    {
        npasses = 1;
    }

    if (png_get_color_type(png, info) == PNG_COLOR_TYPE_PALETTE)
    {
        png_set_palette_to_rgb(png);
    }

    if (png_get_valid(png, info, PNG_INFO_tRNS))
    {
        /* this will also expand the depth to 8-bits */
        png_set_tRNS_to_alpha(png);
    }

    png_read_update_info(png, info);

    image->width = png_get_image_width(png, info);
    image->height = png_get_image_height(png, info);
    image->comps = png_get_channels(png, info);
    image->bits = png_get_bit_depth(png, info);

    /* See if we have an icc profile */
    if (info->iccp_profile != NULL)
    {
        image->profilesize = info->iccp_proflen;
        image->profile = xps_alloc(ctx, info->iccp_proflen);
        if (image->profile)
        {
            /* If we can't create it, just ignore */
            memcpy(image->profile, info->iccp_profile, info->iccp_proflen);
        }
    }

    switch (png_get_color_type(png, info))
    {
    case PNG_COLOR_TYPE_GRAY:
        image->colorspace = ctx->gray;
        image->hasalpha = 0;
        break;

    case PNG_COLOR_TYPE_RGB:
        image->colorspace = ctx->srgb;
        image->hasalpha = 0;
        break;

    case PNG_COLOR_TYPE_GRAY_ALPHA:
        image->colorspace = ctx->gray;
        image->hasalpha = 1;
        break;

    case PNG_COLOR_TYPE_RGB_ALPHA:
        image->colorspace = ctx->srgb;
        image->hasalpha = 1;
        break;

    default:
        return gs_throw(-1, "cannot handle this png color type");
    }

    /*
     * Extract DPI, default to 96 dpi
     */

    image->xres = 96;
    image->yres = 96;

    if (info->valid & PNG_INFO_pHYs)
    {
        png_uint_32 xres, yres;
        int unit;
        png_get_pHYs(png, info, &xres, &yres, &unit);
        if (unit == PNG_RESOLUTION_METER)
        {
            image->xres = xres * 0.0254 + 0.5;
            image->yres = yres * 0.0254 + 0.5;
        }
    }

    /*
     * Read rows, filling transformed output into image buffer.
     */

    image->stride = (image->width * image->comps * image->bits + 7) / 8;

    image->samples = xps_alloc(ctx, image->stride * image->height);

    for (pass = 0; pass < npasses; pass++)
    {
        for (y = 0; y < image->height; y++)
        {
            png_read_row(png, image->samples + (y * image->stride), NULL);
        }
    }

    /*
     * Clean up memory.
     */

    png_destroy_read_struct(&png, &info, NULL);

    return gs_okay;
}