png.c

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const char * const rcsid_gtk_png_c =
    "$Id: png.c 9190 2008-06-01 08:53:05Z anmaster $";
/*
    Crossfire client, a client program for the crossfire program.

    Copyright (C) 2001 Mark Wedel & Crossfire Development Team

    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 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, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

    The author can be reached via e-mail to crossfire-devel@real-time.com
*/


#include <config.h>
#include <stdlib.h>
#include <sys/stat.h>
#ifndef WIN32
#include <unistd.h>
#endif
#include <png.h>
#include <client-types.h>
#include <client.h>

/* Pick up the gtk headers we need */
#include <gtk/gtk.h>
#ifndef WIN32
#include <gdk/gdkx.h>
#else
#include <gdk/gdkwin32.h>
#endif
#include <gdk/gdkkeysyms.h>


/* Defines for PNG return values */
/* These should be in a header file, but currently our calling functions
 * routines just check for nonzero return status and don't really care
 * why the load failed.
 */
#define PNGX_NOFILE     1
#define PNGX_OUTOFMEM   2
#define PNGX_DATA       3

static uint8 *data_cp;
static int data_len, data_start;

static void user_read_data(png_structp png_ptr, png_bytep data, png_size_t length) {
    memcpy(data, data_cp + data_start, length);
    data_start += length;
}

uint8 *png_to_data(uint8 *data, int len, uint32 *width, uint32 *height)
{
    uint8 *pixels=NULL;
    static png_bytepp   rows=NULL;
    static int rows_byte=0;

    png_structp png_ptr;
    png_infop   info_ptr;
    int bit_depth, color_type, interlace_type, compression_type, y;

    data_len=len;
    data_cp = data;
    data_start=0;

    png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,
                                     NULL, NULL, NULL);

    if (!png_ptr) {
        return NULL;
    }
    info_ptr = png_create_info_struct (png_ptr);

    if (!info_ptr) {
        png_destroy_read_struct (&png_ptr, NULL, NULL);
        return NULL;
    }
    if (setjmp (png_ptr->jmpbuf)) {
        png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
        return NULL;
    }

    png_set_read_fn(png_ptr, NULL, user_read_data);
    png_read_info (png_ptr, info_ptr);
    /*
     * This seems to bug on at least one system (other than mine)
     * http://www.metalforge.net/cfmb/viewtopic.php?t=1085
     *
     * I think its actually a bug in libpng. This function dies with an
     * error based on image width. However I've produced a work around
     * using the indivial functions. Repeated below.
     *
    png_get_IHDR(png_ptr, info_ptr, (png_uint_32*)width, (png_uint_32*)height, &bit_depth,
                 &color_type, &interlace_type, &compression_type, &filter_type);
    */
    *width = png_get_image_width(png_ptr, info_ptr);
    *   height = png_get_image_height(png_ptr, info_ptr);
    bit_depth = png_get_bit_depth(png_ptr, info_ptr);
    color_type = png_get_color_type(png_ptr, info_ptr);
    interlace_type = png_get_interlace_type(png_ptr, info_ptr);
    compression_type = png_get_compression_type(png_ptr, info_ptr);
    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)) {

                /* If we have transparency header, convert it to alpha
                   channel */
                png_set_expand(png_ptr);

    } else if (bit_depth < 8) {

                /* If we have < 8 scale it up to 8 */
                png_set_expand(png_ptr);


                /* Conceivably, png_set_packing() is a better idea;
                 * God only knows how libpng works
                 */
    }
        /* If we are 16-bit, convert to 8-bit */
    if (bit_depth == 16) {
                png_set_strip_16(png_ptr);
    }

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

        /* If interlaced, handle that */
    if (interlace_type != PNG_INTERLACE_NONE) {
                png_set_interlace_handling(png_ptr);
    }

    /* pad it to 4 bytes to make processing easier */
    if (!(color_type & PNG_COLOR_MASK_ALPHA))
        png_set_filler(png_ptr, 255, PNG_FILLER_AFTER);

    /* Update the info the reflect our transformations */
    png_read_update_info(png_ptr, info_ptr);
    /* re-read due to transformations just made */
    /*
     * See above for error description
    png_get_IHDR(png_ptr, info_ptr, (png_uint_32*)width, (png_uint_32*)height, &bit_depth,
                 &color_type, &interlace_type, &compression_type, &filter_type);
    */
    *width = png_get_image_width(png_ptr, info_ptr);
    *height = png_get_image_height(png_ptr, info_ptr);
    bit_depth = png_get_bit_depth(png_ptr, info_ptr);
    color_type = png_get_color_type(png_ptr, info_ptr);
    interlace_type = png_get_interlace_type(png_ptr, info_ptr);
    compression_type = png_get_compression_type(png_ptr, info_ptr);

    pixels = (uint8*)malloc(*width * *height * 4);

    if (!pixels) {
        png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
        LOG(LOG_CRITICAL,"gtk::png_to_data","Out of memory - exiting");
        exit(1);
    }

    /* the png library needs the rows, but we will just return the raw data */
    if (rows_byte == 0) {
        rows =(png_bytepp) malloc(sizeof(char*) * *height);
        rows_byte=*height;
    } else if (*height > rows_byte) {
        rows =(png_bytepp) realloc(rows, sizeof(char*) * *height);
        rows_byte=*height;
    }
    if (!rows) {
        png_destroy_read_struct (&png_ptr, &info_ptr, NULL);
        return NULL;
    }

    for (y=0; y<*height; y++)
        rows[y] = pixels + y * *width * 4;

    png_read_image(png_ptr, rows);
    png_destroy_read_struct (&png_ptr, &info_ptr, NULL);

    return pixels;
}


/* rescale_png_image takes png data and scales it accordingly.
 * This function is based on pnmscale, but has been modified to support alpha
 * channel - instead of blending the alpha channel, it takes the most opaque
 * value - blending it is not likely to give sane results IMO - for any image
 * that has transparent information, if we blended the alpha, the result would
 * be the edges of that region being partially transparent.
 * This function has also been re-written to use more static data - in the
 * case of the client, it will be called thousands of times, so it doesn't make
 * sense to free the data and then re-allocate it.
 *
 * For pixels that are fully transparent, the end result after scaling is they
 * will be tranparent black.  This is a needed effect for blending to work properly.
 *
 * This function returns a new pointer to the scaled image data.  This is
 * malloc'd data, so should be freed at some point to prevent leaks.
 * This function does not modify the data passed to it - the caller is responsible
 * for freeing it if it is no longer needed.
 *
 * function arguments:
 * data: PNG data - really, this is any 4 byte per pixel data, in RGBA format.
 * *width, *height: The source width and height.  These values are modified
 *   to contain the new image size.
 * scale: percentage size that new image should be.  100 is a same size
 *    image - values larger than 100 will result in zoom, values less than
 *    100 will result in a shrinkage.
 */

/* RATIO is used to know what units scale is - in this case, a percentage, so
 * it is set to 100
 */
#define RATIO   100

#define MAX_IMAGE_WIDTH         1024
#define MAX_IMAGE_HEIGHT        1024
#define BPP 4

uint8 *rescale_rgba_data(uint8 *data, int *width, int *height, int scale)
{
    static int xrow[BPP * MAX_IMAGE_WIDTH], yrow[BPP*MAX_IMAGE_HEIGHT];
    static uint8 *nrows[MAX_IMAGE_HEIGHT];

    /* Figure out new height/width */
    int new_width = *width  * scale / RATIO, new_height = *height * scale / RATIO;

    int sourcerow=0, ytoleft, ytofill, xtoleft, xtofill, dest_column=0, source_column=0, needcol,
        destrow=0;
    int x,y;
    uint8 *ndata;
    uint8 r,g,b,a;

    if (*width > MAX_IMAGE_WIDTH || new_width > MAX_IMAGE_WIDTH
    || *height > MAX_IMAGE_HEIGHT || new_height > MAX_IMAGE_HEIGHT)
    {
        LOG(LOG_CRITICAL,"gtk::rescale_rgba_data","Image too big");
        exit(0);
    }

    /* clear old values these may have */
    memset(yrow, 0, sizeof(int) * *height * BPP);

    ndata = (uint8*)malloc(new_width * new_height * BPP);

    for (y=0; y<new_height; y++)
        nrows[y] = (png_bytep) (ndata + y * new_width * BPP);

    ytoleft = scale;
    ytofill = RATIO;

    for (y=0,sourcerow=0; y < new_height; y++) {
        memset(xrow, 0, sizeof(int) * *width * BPP);
        while (ytoleft < ytofill) {
            for (x=0; x< *width; ++x) {
                /* Only want to copy the data if this is not a transperent pixel.
                 * If it is transparent, the color information is has is probably
                 * bogus, and blending that makes the results look worse.
                 */
                if (data[(sourcerow * *width + x)*BPP+3] > 0 ) {
                    yrow[x*BPP] += ytoleft * data[(sourcerow * *width + x)*BPP]/RATIO;
                    yrow[x*BPP+1] += ytoleft * data[(sourcerow * *width + x)*BPP+1]/RATIO;
                    yrow[x*BPP+2] += ytoleft * data[(sourcerow * *width + x)*BPP+2]/RATIO;
                }
                /* Alpha is a bit special - we don't want to blend it -
                 * we want to take whatever is the more opaque value.
                 */
                if (data[(sourcerow * *width + x)*BPP+3] > yrow[x*BPP+3])
                    yrow[x*BPP+3] = data[(sourcerow * *width + x)*BPP+3];
            }
            ytofill -= ytoleft;
            ytoleft = scale;
            if (sourcerow < *height)
                sourcerow++;
        }

        for (x=0; x < *width; ++x) {
            if (data[(sourcerow * *width + x)*BPP+3] > 0 ) {
                xrow[x*BPP] = yrow[x*BPP] + ytofill * data[(sourcerow * *width + x)*BPP] / RATIO;
                xrow[x*BPP+1] = yrow[x*BPP+1] + ytofill * data[(sourcerow * *width + x)*BPP+1] / RATIO;
                xrow[x*BPP+2] = yrow[x*BPP+2] + ytofill * data[(sourcerow * *width + x)*BPP+2] / RATIO;
            }
            if (data[(sourcerow * *width + x)*BPP+3] > xrow[x*BPP+3])
                xrow[x*BPP+3] = data[(sourcerow * *width + x)*BPP+3];
            yrow[x*BPP]=0; yrow[x*BPP+1]=0; yrow[x*BPP+2]=0; yrow[x*BPP+3]=0;
        }

        ytoleft -= ytofill;
        if (ytoleft <= 0) {
            ytoleft = scale;
            if (sourcerow < *height)
                sourcerow++;
        }

        ytofill = RATIO;
        xtofill = RATIO;
        dest_column = 0;
        source_column=0;
        needcol=0;
        r=0; g=0; b=0; a=0;

        for (x=0; x< *width; x++) {
            xtoleft = scale;

            while (xtoleft >= xtofill) {
                if (needcol) {
                    dest_column++;
                    r=0; g=0; b=0; a=0;
                }

                if (xrow[source_column*BPP+3] > 0) {
                    r += xtofill * xrow[source_column*BPP] / RATIO;
                    g += xtofill * xrow[1+source_column*BPP] / RATIO;
                    b += xtofill * xrow[2+source_column*BPP] / RATIO;
                }
                if (xrow[3+source_column*BPP] > a)
                    a = xrow[3+source_column*BPP];

                nrows[destrow][dest_column * BPP] = r;
                nrows[destrow][1+dest_column * BPP] = g;
                nrows[destrow][2+dest_column * BPP] = b;
                nrows[destrow][3+dest_column * BPP] = a;
                xtoleft -= xtofill;
                xtofill = RATIO;
                needcol=1;
            }

            if (xtoleft > 0 ){
                if (needcol) {
                    dest_column++;
                    r=0; g=0; b=0; a=0;
                    needcol=0;
                }

                if (xrow[3+source_column*BPP] > 0) {
                    r += xtoleft * xrow[source_column*BPP] / RATIO;
                    g += xtoleft * xrow[1+source_column*BPP] / RATIO;
                    b += xtoleft * xrow[2+source_column*BPP] / RATIO;
                }
                if (xrow[3+source_column*BPP] > a)
                    a = xrow[3+source_column*BPP];

                xtofill -= xtoleft;
            }
            source_column++;
        }

        if (xtofill > 0 ) {
            source_column--;
            if (xrow[3+source_column*BPP] > 0) {
                r += xtofill * xrow[source_column*BPP] / RATIO;
                g += xtofill * xrow[1+source_column*BPP] / RATIO;
                b += xtofill * xrow[2+source_column*BPP] / RATIO;
            }
            if (xrow[3+source_column*BPP] > a)
                a = xrow[3+source_column*BPP];
        }

        /* Not positve, but without the bound checking for dest_column,
         * we were overrunning the buffer.  My guess is this only really
         * showed up if when the images are being scaled - there is probably
         * something like half a pixel left over.
         */
        if (!needcol && (dest_column < new_width)) {
            nrows[destrow][dest_column * BPP] = r;
            nrows[destrow][1+dest_column * BPP] = g;
            nrows[destrow][2+dest_column * BPP] = b;
            nrows[destrow][3+dest_column * BPP] = a;
        }
        destrow++;
    }
    *width = new_width;
    *height = new_height;
    return ndata;
}


/* This takes data that has already been converted into RGBA format (via
 * png_to_data above perhaps) and creates a GdkPixmap and GdkBitmap out
 * of it.
 * Return non zero on error (currently, no checks for error conditions is done
 */
int rgba_to_gdkpixmap(GdkWindow *window, uint8 *data,int width, int height,
                   GdkPixmap **pix, GdkBitmap **mask, GdkColormap *colormap)
{
    GdkGC       *gc, *gc_alpha;
    int         has_alpha=0, alpha;
    GdkColor  scolor;
    int x,y;

    *pix = gdk_pixmap_new(window, width, height, -1);

    gc=gdk_gc_new(*pix);
    gdk_gc_set_function(gc, GDK_COPY);

    *mask=gdk_pixmap_new(window, width, height,1);
    gc_alpha=gdk_gc_new(*mask);

    scolor.pixel=1;
    gdk_gc_set_foreground(gc_alpha, &scolor);
    gdk_draw_rectangle(*mask, gc_alpha, 1, 0, 0, width, height);

    scolor.pixel=0;
    gdk_gc_set_foreground(gc_alpha, &scolor);

    /* we need to draw the alpha channel.  The image may not in fact
     * have alpha, but no way to know at this point other than to try
     * and draw it.
     */
    for (y=0; y<height; y++) {
        for (x=0; x<width; x++) {
            alpha = data[(y * width + x) * 4 +3];
            /* Transparent bit */
            if (alpha==0) {
                gdk_draw_point(*mask, gc_alpha, x, y);
                has_alpha=1;
            }
        }
    }

    gdk_draw_rgb_32_image(*pix, gc,  0, 0, width, height, GDK_RGB_DITHER_NONE, data, width*4);
    if (!has_alpha) {
        gdk_pixmap_unref(*mask);
        *mask = NULL;
    }

    gdk_gc_destroy(gc_alpha);
    gdk_gc_destroy(gc);
    return 0;
}