cgm.c

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//      PLplot cgm device driver.
//

//
// This driver generates CGM (computer graphics metafiles) files (bit of a
// tautology that... 'computer graphics metaFILES FILES' - oh well).
//
// The CGM format is vector-based and is widely used as an interchange
// format between drawing and plotting programs. Although I have never
// looked at them, there are apparently both Java applets and browser
// plug-ins for displaying CGM files on web pages.
//
// This plplot driver supports lines, polylines (they make a difference to
// CGM files), fills, and line widths. It is limited to 256 colours, which
// should not be a problem. The plplot CGM driver's source (cgm.c) was
// derived largely from the gd driver (gd.c).
//
// The plplot driver requires libcd.a. libcd.a is very similar to libgd.a
// and has a similar licencing agreement behind it. Unlike libgd,
// development of libcd seems to have crawled to a halt back in 1998 with
// V1.3 of the library. The original host site for the library no longer
// exists, so probably the best source of the library presently is:
//
// http://www.pa.msu.edu/reference/cgmdraw_ref.html
// http://www.pa.msu.edu/ftp/pub/unix/
//

//
// Two options are supported by the driver via the -drvopt command line
// toggle.
//
// By default CGM files don't have a background as such. The driver adds
// support for different backgrounds by colouring in a large rectangle
// underneath everything else. If for some reason you want the "raw plotted
// junk" and aren't really interested in having an obtrusive piece of paper
// in the back, use the command line toggle "-drvopt no_paper=1" to turn off
// this background paper.
//
// By default the CGM files generated by this driver try to make edges of
// polygons (ie fills) "invisible", which is something CGM files can do.
// Some programs (ie CoreDraw) ignore this field and draw edges in anyway.
// By setting "-drvopt force_edges=1" the driver will render edges on all
// filled polygons, and will set their colour to the same as the polygon.
// Most drivers should not need this, but if you see lines that you don't
// think you should be seeing in your viewer, try this toggle.
//

//
// Driver supports a hack that manipulates the colour palette when
// a light background is selected. This is basically to make sure
// there are not two "whites" when -bg ffffff is issued at the
// command line.
//
// Related to this change, there is an ability to swap the "new"
// black colour (index 15) with the red colour (index 2) by issuing
// the command line "-hack" option. I like this for web pages, because
// I think that black looks nicer than red (on white) for default
// plotting. That is why it can be enabled with -hack, in case you
// don't like it working this way.
//
// For me, these two changes make it easy to switch from a "screen friendly"
// black background with red first plotting colour, to a "web friendly"
// white background with a black first plotting colour.
//
// These features are enabled on a driver level by defining
// "SWAP_BALCK_WHEN_WHITE". If you wan't the driver to behave 100% like other
// drivers, comment out the define
//

#define SWAP_BALCK_WHEN_WHITE

#include "plDevs.h"

#ifdef PLD_cgm

#include "plplotP.h"
#include "drivers.h"

#include <cd.h>

// Device info
PLDLLIMPEXP_DRIVER const char* plD_DEVICE_INFO_cgm = "cgm:CGM file:0:cgm:44:cgm\n";

// Prototypes for functions in this file.

static void     fill_polygon( PLStream *pls );
static void     setcmap( PLStream *pls );
static void     plD_init_cgm_Dev( PLStream *pls );

// top level declarations

// In an attempt to fix a problem with the hidden line removal functions
// that results in hidden lines *not* being removed from "small" plot
// pages (ie, like a normal video screen), a "virtual" page of much
// greater size is used to trick the algorithm into working correctly.
// If, in future, this gets fixed on its own, then don't define
// "use_experimental_hidden_line_hack"
//

#define use_experimental_hidden_line_hack

static int    force_edges        = 0;
static int    disable_background = 0;

static DrvOpt cgm_options[] = { { "force_edges", DRV_INT, &force_edges,        "Force edges to be drawn on filled polygongs (0|1)" },
                                { "no_paper",    DRV_INT, &disable_background, "Disable background (0|1)"                          },
                                { NULL,          DRV_INT, NULL,                NULL                                                } };


// Struct to hold device-specific info.

typedef struct
{
    cdImagePtr im_out;                          // Graphics pointer
    PLINT      cgmx;
    PLINT      cgmy;

// GD does "funny" things with the colour map.
// It can't guarantee that the colours will be where you think they are.
// So we need this "colour_index" table to store where the colour we
// requested happens to be. Messy, but it works.
//

    int colour_index[256];                      // Colour "index" table

//
// I use two colours for both fill and line drawing - a "last colour" and
// "current colour". The driver only switches colours if they have changed
// and are used. If no fills are ever done, then the instruction to set the
// fill colour is never sent to the CGM file. Should make for smaller and
// more efficient files (I guess).
//

    int   colour;                               // Current Colour
    int   last_line_colour;                     // Last line colour used
    int   fill_colour;                          // Current Fill colour
    int   last_fill_colour;                     // Last Fill colour used

    int   totcol;                               // Total number of colours
    int   ncol1;                                // Actual size of ncol1 we got
    PLFLT scale;                                // scaling factor to "blow up" to
                                                // the "virtual" page in removing hidden lines
    int   force_edges;                          // Forces edges to be drawn in fills
    int   disable_background;                   // Turns off background rectangle
} cgm_Dev;

void plD_init_cgm( PLStream * );
void plD_line_cgm( PLStream *, short, short, short, short );
void plD_polyline_cgm( PLStream *, short *, short *, PLINT );
void plD_eop_cgm( PLStream * );
void plD_bop_cgm( PLStream * );
void plD_tidy_cgm( PLStream * );
void plD_state_cgm( PLStream *, PLINT );
void plD_esc_cgm( PLStream *, PLINT, void * );


void plD_dispatch_init_cgm( PLDispatchTable *pdt )
{
#ifndef ENABLE_DYNDRIVERS
    pdt->pl_MenuStr = "CGM (Computer Graphics metafile) file";
    pdt->pl_DevName = "cgm";
#endif
    pdt->pl_type     = plDevType_FileOriented;
    pdt->pl_seq      = 44;
    pdt->pl_init     = (plD_init_fp) plD_init_cgm;
    pdt->pl_line     = (plD_line_fp) plD_line_cgm;
    pdt->pl_polyline = (plD_polyline_fp) plD_polyline_cgm;
    pdt->pl_eop      = (plD_eop_fp) plD_eop_cgm;
    pdt->pl_bop      = (plD_bop_fp) plD_bop_cgm;
    pdt->pl_tidy     = (plD_tidy_fp) plD_tidy_cgm;
    pdt->pl_state    = (plD_state_fp) plD_state_cgm;
    pdt->pl_esc      = (plD_esc_fp) plD_esc_cgm;
}


//--------------------------------------------------------------------------
// plD_init_cgm_Dev()
//
//--------------------------------------------------------------------------

static void
plD_init_cgm_Dev( PLStream *pls )
{
    cgm_Dev *dev;

// Allocate and initialize device-specific data

    if ( pls->dev != NULL )
        free( (void *) pls->dev );

    pls->dev = calloc( 1, (size_t) sizeof ( cgm_Dev ) );
    if ( pls->dev == NULL )
        plexit( "plD_init_cgm_Dev: Out of memory." );

    dev = (cgm_Dev *) pls->dev;

// Check for and set up driver options

    plParseDrvOpts( cgm_options );
    dev->force_edges        = force_edges;        // force edges (for corel draw etc...)
    dev->disable_background = disable_background; // Disable background

    dev->colour           = 1;                    // Set a fall back pen colour in case user doesn't
    dev->fill_colour      = dev->colour;          // initially set fill and line colour the same
    dev->last_fill_colour = -1;                   // set to -1 = unallocated
    dev->last_line_colour = -1;                   // set to -1 = unallocated
}

//--------------------------------------------------------------------------
// plD_init_cgm()
//
// Initialize device.
//--------------------------------------------------------------------------

void plD_init_cgm( PLStream *pls )
{
    cgm_Dev *dev = NULL;

    pls->termin    = 0;         // Not an interactive device
    pls->icol0     = 1;
    pls->bytecnt   = 0;
    pls->page      = 0;
    pls->dev_fill0 = 1;         // Can do solid fills

    if ( !pls->colorset )
        pls->color = 1;                       // Is a color device

    if ( pls->width < 1 )
        pls->width = 1;                       // set a legal line width

// Initialize family file info
    plFamInit( pls );

// Prompt for a file name if not already set
    plOpenFile( pls );

// Allocate and initialize device-specific data
    plD_init_cgm_Dev( pls );
    dev = (cgm_Dev *) pls->dev;

    // set dpi and page size defaults if the user has not already set
    // these with -dpi or -geometry command line options or with
    // plspage.

    if ( pls->xdpi <= 0. || pls->ydpi <= 0. )
    {
        // Use recommended default pixels per inch.
        plspage( PLPLOT_DEFAULT_PIXELS_PER_INCH, PLPLOT_DEFAULT_PIXELS_PER_INCH, 0, 0, 0, 0 );
    }

    if ( pls->xlength == 0 || pls->ylength == 0 )
    {
        // Use recommended default pixel width and height.
        plspage( 0., 0., PLPLOT_DEFAULT_WIDTH_PIXELS, PLPLOT_DEFAULT_HEIGHT_PIXELS, 0, 0 );
    }

    pls->graphx = GRAPHICS_MODE;

    dev->cgmx = pls->xlength - 1;       // should I use -1 or not???
    dev->cgmy = pls->ylength - 1;

#ifdef use_experimental_hidden_line_hack

    if ( dev->cgmx > dev->cgmy ) // Work out the scaling factor for the
    {                            // "virtual" (oversized) page
        dev->scale = (PLFLT) ( PIXELS_X - 1 ) / (PLFLT) dev->cgmx;
    }
    else
    {
        dev->scale = (PLFLT) PIXELS_Y / (PLFLT) dev->cgmy;
    }
#else

    dev->scale = 1.;

#endif

// Convert DPI to pixels/mm
    plP_setpxl( dev->scale * pls->xdpi / PLPLOT_MM_PER_INCH, dev->scale * pls->ydpi / PLPLOT_MM_PER_INCH );

    plP_setphy( 0, dev->scale * dev->cgmx, 0, dev->scale * dev->cgmy );
}

//--------------------------------------------------------------------------
// plD_line_cgm()
//
// Draw a line in the current color from (x1,y1) to (x2,y2).
//--------------------------------------------------------------------------

void
plD_line_cgm( PLStream *pls, short x1a, short y1a, short x2a, short y2a )
{
    cgm_Dev *dev = (cgm_Dev *) pls->dev;
    int     x1   = x1a / dev->scale, y1 = y1a / dev->scale, x2 = x2a / dev->scale, y2 = y2a / dev->scale;
    y1 = y1;
    y2 = y2;

//
// Determine if the colour has changed since the last time a line was
// drawn. If it has, then set the colour NOW otherwise, keep on going like
// "nuthin happened".
//

    if ( dev->last_line_colour != dev->colour )
    {
        cdSetLineColor( dev->im_out, dev->colour );
        dev->last_line_colour = dev->colour;
    }

    cdLine( dev->im_out, x1, y1, x2, y2 );
}

//--------------------------------------------------------------------------
// plD_polyline_cgm()
//
// Draw a polyline in the current color.
//--------------------------------------------------------------------------

void
plD_polyline_cgm( PLStream *pls, short *xa, short *ya, PLINT npts )
{
    cgm_Dev *dev = (cgm_Dev *) pls->dev;
    PLINT   i;
    cdPoint *points = NULL;

    if ( ( points = calloc( npts, (size_t) sizeof ( cdPoint ) ) ) == NULL )
    {
        plexit( "Memory allocation error in \"plD_polyline_cgm\"" );
    }

    for ( i = 0; i < npts; i++ )
    {
        points[i].x = xa[i] / dev->scale;
        points[i].y = ( ya[i] / dev->scale );
    }

//
// Determine if the colour has changed since the last time a line was
// drawn. If it has, then set the colour NOW otherwise, keep on going like
// "nuthin happened".
//

    if ( dev->last_line_colour != dev->colour )
    {
        cdSetLineColor( dev->im_out, dev->colour );
        dev->last_line_colour = dev->colour;
    }

    cdPolyLine( dev->im_out, points, npts );
    free( points );
}


//--------------------------------------------------------------------------
// fill_polygon()
//
// Fill polygon described in points pls->dev_x[] and pls->dev_y[].
//--------------------------------------------------------------------------

static void
fill_polygon( PLStream *pls )
{
    cgm_Dev *dev = (cgm_Dev *) pls->dev;

    PLINT   i;
    cdPoint *points = NULL;

    if ( pls->dev_npts < 1 )
        return;

    if ( ( points = calloc( pls->dev_npts, (size_t) sizeof ( cdPoint ) ) ) == NULL )
    {
        plexit( "Memory allocation error in \"plD_fill_polygon_cgm\"" );
    }

    for ( i = 0; i < pls->dev_npts; i++ )
    {
        points[i].x = pls->dev_x[i] / dev->scale;
        points[i].y = ( pls->dev_y[i] / dev->scale );
    }


//
// Determine if the fill colour has changed since the last time a fill was
// done. If it has, then set the colour NOW otherwise, keep on going like
// "nuthin happened". If it's the first time, we will know 'cause the the
// "last_fill_colour" will be -1.
//

    if ( ( dev->fill_colour != dev->last_fill_colour ) || ( dev->force_edges == 1 ) )
    {
        cdSetFillColor( dev->im_out, dev->fill_colour );

//
// Due to a bug in cd V1.3, we have to set the edge colour to the fill
// colour. This is despite telling the library edges should be invisible.
// Seems the invisible edges only work with rectangles.
//

        if ( dev->force_edges == 1 )
        {
            cdSetEdgeColor( dev->im_out, dev->fill_colour );
            cdSetEdgeVis( dev->im_out, 1 );
        }

        dev->last_fill_colour = dev->fill_colour;
    }

    cdPolygon( dev->im_out, points, pls->dev_npts );

    if ( dev->force_edges == 1 )
        cdSetEdgeVis( dev->im_out, 0 );                          // Turn edges off now

    free( points );
}

//--------------------------------------------------------------------------
// setcmap()
//
// Sets up color palette.
//--------------------------------------------------------------------------

static void
setcmap( PLStream *pls )
{
    int     i, ncol1 = pls->ncol1;
    int     ncol0 = pls->ncol0, total_colours;
    PLColor cmap1col;
    cgm_Dev *dev = (cgm_Dev *) pls->dev;
    PLFLT   tmp_colour_pos;

    cdImageColorClear( dev->im_out );           // UNDOCUMENTED FUNCTION TO RESET THE
    // INTERNAL COLOUR TABLE OF THE
    // CD DRIVER. Seems to work and fix
    // the errors

    if ( ncol0 > cdMaxColors / 2 )              // Check for ridiculous number of colours
    {                                           // in ncol0, and appropriately adjust the
        plwarn( "Too many colours in cmap0." ); // number, issuing a
        ncol0      = cdMaxColors / 2;           // warning if it does
        pls->ncol0 = ncol0;
    }

    dev->totcol = 0;                           // Reset the number of colours counter to zero

    total_colours = ncol0 + ncol1;             // Work out how many colours are wanted

    if ( total_colours > cdMaxColors )         // Do some rather modest error
    {                                          // checking to make sure that
        total_colours = cdMaxColors;           // we are not defining more colours
        ncol1         = total_colours - ncol0; // than we have room for.

        if ( ncol1 <= 0 )
        {
            plexit( "Problem setting colourmap in CGM driver." );
        }
    }

    dev->ncol1 = ncol1; // The actual size of ncol1, regardless of what was asked.
                        // This is dependent on colour slots available.
                        // It might well be the same as ncol1.
                        //

// Initialize cmap 0 colors

    if ( ncol0 > 0 ) // make sure the program actually asked for cmap0 first
    {
#ifdef SWAP_BALCK_WHEN_WHITE

//
// Do a kludge to add a "black" colour back to the palette if the
// background is "almost white" (ie changed through -bg).
//
// Also includes an "optional" change to swap the red colour (1) with the
// black colour (15), which is off by default. (I don't like the red being
// the 'default' colour "1" on a "white" background, or for that matter
// yellow being "2", but I can live more with yellow at number two.)
// Just use "-hack" from the command line to make it take effect.
//
//

        if ( ( pls->ncol0 > 15 ) && ( pls->cmap0[0].r > 227 ) && ( pls->cmap0[0].g > 227 ) && ( pls->cmap0[0].b > 227 ) )
        {
            if ( pls->hack != 1 ) // just set colour 15 to black
            {
                pls->cmap0[15].r = 0;
                pls->cmap0[15].g = 0;
                pls->cmap0[15].b = 0;
            }
            else // swap colour 15 and colour 1
            {
                pls->cmap0[15].r = pls->cmap0[1].r;
                pls->cmap0[15].g = pls->cmap0[1].g;
                pls->cmap0[15].b = pls->cmap0[1].b;

                pls->cmap0[1].r = 0;
                pls->cmap0[1].g = 0;
                pls->cmap0[1].b = 0;
            }
        }

#endif

        for ( i = 0; i < ncol0; i++ )
        {
            if ( (
                     dev->colour_index[i] = cdImageColorAllocate( dev->im_out,
                         pls->cmap0[i].r, pls->cmap0[i].g, pls->cmap0[i].b )
                     ) == -1 )
            {
                plwarn( "Problem setting cmap0 in CGM driver." );
            }
            else
                ++dev->totcol; // count the number of colours we use as we use them
        }
    }

// Initialize any remaining slots for cmap1


    if ( ncol1 > 0 ) // make sure that we want to define cmap1 first
    {
        for ( i = 0; i < ncol1; i++ )
        {
            if ( ncol1 < pls->ncol1 ) // Check the dynamic range of colours
            {
                //
                // Ok, now if we have less colour slots available than are being
                // defined by pls->ncol1, then we still want to use the full
                // dynamic range of cmap1 as best we can, so what we do is work
                // out an approximation to the index in the full dynamic range
                // in cases when pls->ncol1 exceeds the number of free colours.
                //

                tmp_colour_pos = i > 0 ? pls->ncol1 * ( (PLFLT) i / ncol1 ) : 0;
                plcol_interp( pls, &cmap1col, (int) tmp_colour_pos, pls->ncol1 );
            }
            else
            {
                plcol_interp( pls, &cmap1col, i, ncol1 );
            }


            if ( (
                     dev->colour_index[i + pls->ncol0] = cdImageColorAllocate( dev->im_out,
                         cmap1col.r, cmap1col.g, cmap1col.b )
                     ) == -1 )
            {
                plwarn( "Problem setting cmap1 in CGM driver." );
            }
            else
                ++dev->totcol; // count the number of colours we use as we use them
        }
    }
}


//--------------------------------------------------------------------------
// plD_state_cgm()
//
// Handle change in PLStream state (color, pen width, fill attribute, etc).
//--------------------------------------------------------------------------

void
plD_state_cgm( PLStream *pls, PLINT op )
{
    cgm_Dev *dev = (cgm_Dev *) pls->dev;
    PLFLT   tmp_colour_pos;

    switch ( op )
    {
    case PLSTATE_WIDTH:
        cdSetLineWidth( dev->im_out, pls->width );
        break;

    case PLSTATE_COLOR0:
        dev->colour = pls->icol0;
        if ( dev->colour == PL_RGB_COLOR )
        {
            int r = pls->curcolor.r;
            int g = pls->curcolor.g;
            int b = pls->curcolor.b;
            if ( dev->totcol < cdMaxColors )
            {
                if ( (
                         dev->colour_index[++dev->totcol] = cdImageColorAllocate( dev->im_out, r, g, b )
                         ) == -1 )
                    plwarn( "Problem changing colour in \"PLSTATE_COLOR0\"" );
                else
                    dev->colour = dev->totcol;
            }
        }
        dev->fill_colour = dev->colour;
        break;

    case PLSTATE_COLOR1:
        //
        // Start by checking to see if we have to compensate for cases where
        // we don't have the full dynamic range of cmap1 at our disposal
        //
        if ( dev->ncol1 < pls->ncol1 )
        {
            tmp_colour_pos = dev->ncol1 * ( (PLFLT) pls->icol1 / ( pls->ncol1 > 0 ? pls->ncol1 : 1 ) );
            dev->colour    = pls->ncol0 + (int) tmp_colour_pos;
        }
        else
            dev->colour = pls->ncol0 + pls->icol1;

        dev->fill_colour = dev->colour;
        break;


    case PLSTATE_CMAP0:
    case PLSTATE_CMAP1:
        //
        //  Code to redefine the entire palette
        //
        if ( pls->color )
            setcmap( pls );
        break;
    }
}


//--------------------------------------------------------------------------
// plD_esc_cgm()
//
// Escape function.
//--------------------------------------------------------------------------

void plD_esc_cgm( PLStream *pls, PLINT op, void *ptr )
{
    switch ( op )
    {
    case PLESC_FILL:    // fill
        fill_polygon( pls );
        break;
    }
}

//--------------------------------------------------------------------------
// plD_bop_cgm()
//
// Set up for the next page.
// Advance to next family file if necessary (file output).
//--------------------------------------------------------------------------

void plD_bop_cgm( PLStream *pls )
{
    cgm_Dev *dev;

    plGetFam( pls );
// force new file if pls->family set for all subsequent calls to plGetFam
// n.b. putting this after plGetFam call is important since plinit calls
// bop, and you don't want the familying sequence started until after
// that first call to bop.

    pls->famadv = 1;

    pls->page++;

// n.b. pls->dev can change because of an indirect call to plD_init_cgm
// from plGetFam if familying is enabled.  Thus, wait to define dev until
// now.

    dev = (cgm_Dev *) pls->dev;

    if ( pls->page == 1 )
    {
        dev->im_out = cdImageCreate( pls->xlength, pls->ylength );
    }
    else if ( pls->family != 1 )
    {
        cdCgmNewPic( dev->im_out, 0 );
    }

    setcmap( pls );

// Continue to initialise the driver

    cdSetFillStyle( dev->im_out, 1 ); // Set solid fills

//
// Due to a border being drawn around the edge of the image, we also
// manually, then turn them off again to make edges turn off. By
// default the driver thinks they are off, so when we tell the driver
// to turn them off it says "they are already off, I wont do anything"
// but in reality they are on by default. So what we do is turn them ON
// manually, then turn them OFF later.
//
// Due to a boarder being drawn around the edge of the image, we also
// want the edges turned on so we can lay down a rectangle coloured in
// the background colour at the start. Once we have drawn our
// background box, we then turn edges off for the rest of the page.
//

    cdSetEdgeVis( dev->im_out, 1 ); // turn edges on so we can turn them off!

    if ( dev->disable_background != 1 )
    {
        cdSetEdgeWidth( dev->im_out, pls->xlength / 5 );                      // set edge to *really* wide so we can cover the edge of the page completelt
        cdSetEdgeColor( dev->im_out, 0 );                                     // set the edge colour to the background colour so we can make a coloured page
        cdSetFillColor( dev->im_out, 0 );                                     // set fill colour to background colour so we have a coloured page
        cdRectangle( dev->im_out, 0, 0, pls->xlength - 1, pls->ylength - 1 ); // Draw a coloured rectangle to act as our "paper"
    }

    cdSetEdgeVis( dev->im_out, 0 );            // Turn edges off now
    cdSetEdgeWidth( dev->im_out, 0 );          // Just to be 100% sure

    cdSetLineType( dev->im_out, 1 );           // set solid lines
    cdSetLineWidth( dev->im_out, pls->width ); // set initial line width for each page
}

//--------------------------------------------------------------------------
// plD_tidy_cgm()
//
// Close graphics file or otherwise clean up.
//--------------------------------------------------------------------------

void plD_tidy_cgm( PLStream *pls )
{
    cgm_Dev *dev = (cgm_Dev *) pls->dev;

    if ( pls->family != 1 )
    {
        cdImageCgm( dev->im_out, pls->OutFile );
    }

    cdImageDestroy( dev->im_out );
    plCloseFile( pls );
    free_mem( pls->dev );
}

//--------------------------------------------------------------------------
// plD_eop_cgm()
//
// End of page.
//--------------------------------------------------------------------------

void plD_eop_cgm( PLStream *pls )
{
    cgm_Dev *dev = (cgm_Dev *) pls->dev;
    int     i;

    if ( pls->family == 1 )
    {
        cdImageCgm( dev->im_out, pls->OutFile );
    }
    for ( i = 0; i < cdMaxColors; ++i )
        dev->colour_index[i] = -1;

    dev->fill_colour      = dev->colour; // initially set fill and line colour the same
    dev->last_fill_colour = -1;          // set to -1 = unallocated
    dev->last_line_colour = -1;          // set to -1 = unallocated
}


//#endif


#else
int
pldummy_cgm()
{
    return 0;
}

#endif                          // cgm