gvdevice_gd.c

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/*************************************************************************
 * Copyright (c) 2011 AT&T Intellectual Property 
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors: Details at https://graphviz.org
 *************************************************************************/
 
#include "config.h"
#include "gdioctx_wrapper.h"
 
#include <assert.h>
#include <gvc/gvplugin_device.h>
#include <gvc/gvio.h>
#include <limits.h>
 
#include <gd.h>
#include <stdbool.h>
#include <stddef.h>
#include <string.h>
 
int gvdevice_gd_putBuf (gdIOCtx *context, const void *buffer, int len)
{
    gd_context_t *gd_context = get_containing_context(context);
    assert(len >= 0);
    const size_t result = gvwrite(gd_context->job, buffer, (size_t)len);
    assert(result <= (size_t)len);
    return (int)result;
}
 
void gvdevice_gd_putC (gdIOCtx *context, int C)
{
    gd_context_t *gd_context = get_containing_context(context);
    char c = (char)C;
 
    gvwrite(gd_context->job, &c, 1);
}
 
#ifdef HAVE_PANGOCAIRO
typedef enum {
        FORMAT_GIF,
        FORMAT_JPEG,
        FORMAT_PNG,
        FORMAT_WBMP,
        FORMAT_GD,
        FORMAT_GD2,
        FORMAT_XBM,
} format_type;
 
static void gd_format(GVJ_t * job)
{
    gdImagePtr im;
    unsigned int x, y;
    const unsigned char *data = job->imagedata;
    unsigned int width = job->width;
    unsigned int height = job->height;
    gd_context_t gd_context;
    memset(&gd_context, 0, sizeof(gd_context));
 
    gd_context.ctx.putBuf = gvdevice_gd_putBuf;
    gd_context.ctx.putC = gvdevice_gd_putC;
    gd_context.job = job;
 
    assert(width <= INT_MAX);
    assert(height <= INT_MAX);
    im = gdImageCreateTrueColor((int)width, (int)height);
    switch (job->device.id) {
#ifdef HAVE_GD_PNG
    case FORMAT_PNG:
        for (y = 0; y < height; y++) {
            for (x = 0; x < width; x++) {
                const int r = *data++;
                const int g = *data++;
                const int b = *data++;
                // gd’s alpha is 7-bit, so scale down ÷2 from our 8-bit
                const int alpha = *data++ >> 1;
                const int color = r | (g << 8) | (b << 16) | ((0x7f - alpha) << 24);
                im->tpixels[y][x] = color;
            }
        }
        break;
#endif
    default:
/* pick an off-white color, so that transparent backgrounds look white in jpgs */
#define TRANSPARENT 0x7ffffffe
 
        gdImageColorTransparent(im, TRANSPARENT);
        gdImageAlphaBlending(im, false);
        for (y = 0; y < height; y++) {
            for (x = 0; x < width; x++) {
                const int r = *data++;
                const int g = *data++;
                const int b = *data++;
                // gd’s alpha is 7-bit, so scale down ÷2 from our 8-bit
                const int alpha = *data++ >> 1;
                const int color = r | (g << 8) | (b << 16) | ((0x7f - alpha) << 24);
                if (alpha >= 0x20)
                    /* if not > 75% transparent */
                    im->tpixels[y][x] = color;
                else
                    im->tpixels[y][x] = TRANSPARENT;
            }
        }
        break;
    }
 
    switch (job->device.id) {
#ifdef HAVE_GD_GIF
    case FORMAT_GIF:
        gdImageTrueColorToPalette(im, 0, 256);
        gdImageGifCtx(im, &gd_context.ctx);
        break;
#endif
 
#ifdef HAVE_GD_JPEG
    case FORMAT_JPEG:
        /*
         * Write IM to OUTFILE as a JFIF-formatted JPEG image, using
         * quality JPEG_QUALITY.  If JPEG_QUALITY is in the range
         * 0-100, increasing values represent higher quality but also
         * larger image size.  If JPEG_QUALITY is negative, the
         * IJG JPEG library's default quality is used (which should
         * be near optimal for many applications).  See the IJG JPEG
         * library documentation for more details.
         */ 
#define JPEG_QUALITY -1
        gdImageJpegCtx(im, &gd_context.ctx, JPEG_QUALITY);
        break;
#endif
 
#ifdef HAVE_GD_PNG
    case FORMAT_PNG:
        gdImageTrueColorToPalette(im, 0, 256);
        gdImagePngCtx(im, &gd_context.ctx);
        break;
#endif
 
    case FORMAT_GD:
        gdImageGd(im, job->output_file);
        break;
 
    case FORMAT_GD2:
#define GD2_CHUNKSIZE 128
#define GD2_RAW 1
#define GD2_COMPRESSED 2
        gdImageGd2(im, job->output_file, GD2_CHUNKSIZE, GD2_COMPRESSED);
        break;
 
#ifdef HAVE_GD_GIF
    case FORMAT_WBMP:
        {
            /* Use black for the foreground color for the B&W wbmp image. */
            int black = gdImageColorResolveAlpha(im, 0, 0, 0, gdAlphaOpaque);
            gdImageWBMPCtx(im, black, &gd_context.ctx);
        }
        break;
#endif
 
        break;
    default:
        break;
    }
 
    gdImageDestroy(im);
}
 
static gvdevice_engine_t gd_engine = {
    NULL,               /* gd_initialize */
    gd_format,
    NULL,               /* gd_finalize */
};
 
static gvdevice_features_t device_features_gd = {
    GVDEVICE_BINARY_FORMAT
      | GVDEVICE_DOES_TRUECOLOR,/* flags */
    {0.,0.},                    /* default margin - points */
    {0.,0.},                    /* default page width, height - points */
    {96.,96.},                  /* dpi */
};
 
static gvdevice_features_t device_features_gd_no_writer = {
    GVDEVICE_BINARY_FORMAT
      | GVDEVICE_NO_WRITER
      | GVDEVICE_DOES_TRUECOLOR,/* flags */
    {0.,0.},                    /* default margin - points */
    {0.,0.},                    /* default page width, height - points */
    {96.,96.},                  /* dpi */
};
#endif
 
gvplugin_installed_t gvdevice_gd_types[] = {
#ifdef HAVE_PANGOCAIRO
 
#ifdef HAVE_GD_GIF
    {FORMAT_GIF, "gif:cairo", 10, &gd_engine, &device_features_gd},
    {FORMAT_WBMP, "wbmp:cairo", 5, &gd_engine, &device_features_gd},
#endif
 
#ifdef HAVE_GD_JPEG
    {FORMAT_JPEG, "jpe:cairo", 5, &gd_engine, &device_features_gd},
    {FORMAT_JPEG, "jpeg:cairo", 5, &gd_engine, &device_features_gd},
    {FORMAT_JPEG, "jpg:cairo", 5, &gd_engine, &device_features_gd},
#endif
 
#ifdef HAVE_GD_PNG
    {FORMAT_PNG, "png:cairo", 5, &gd_engine, &device_features_gd},
#endif
 
    {FORMAT_GD, "gd:cairo", 5, &gd_engine, &device_features_gd_no_writer},
    {FORMAT_GD2, "gd2:cairo", 5, &gd_engine, &device_features_gd_no_writer},
 
#endif
    {0, NULL, 0, NULL, NULL}
};