trgt_gif.h

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/* === S Y N F I G ========================================================= */
/* === S T A R T =========================================================== */

#ifndef __SYNFIG_TRGT_GIF_H
#define __SYNFIG_TRGT_GIF_H

/* === H E A D E R S ======================================================= */

#include <synfig/target_scanline.h>
#include <synfig/string.h>
#include <synfig/smartfile.h>
#include <cstdio>
#include <synfig/surface.h>
#include <synfig/palette.h>
#include <synfig/targetparam.h>

/* === M A C R O S ========================================================= */

/* === T Y P E D E F S ===================================================== */

/* === C L A S S E S & S T R U C T S ======================================= */

class gif : public synfig::Target_Scanline
{
    SYNFIG_TARGET_MODULE_EXT
private:
    // Class for abstracting the
    // output of the codes
    struct bitstream
    {
        synfig::SmartFILE file;
        unsigned char pool;
        char curr_bit;
        bitstream():pool(0),curr_bit(0),curr_pos(0) {}
        bitstream(synfig::SmartFILE file):file(file),pool(0),curr_bit(0),curr_pos(0) {}
        unsigned char buffer[256];
        int curr_pos;

        // Pushes a single bit onto the bit
        void push_bit(bool bit)
        {
            if(bit)
                pool|=(1<<(curr_bit));
            curr_bit++;
            if(curr_bit==8)
                empty();
        }

        // Empties out the current pool into
        // the buffer. Calls 'dump()' if the
        // buffer is full.
        void empty()
        {
            buffer[curr_pos++]=pool;
            curr_bit=0;
            pool=0;
            if(curr_pos==255)dump();
        }

        // If there is anything in the
        // buffer or in the pool, it
        // dumps it to the filestream.
        // Buffer and pool are cleared.
        void dump()
        {
            if(curr_bit)
                empty();
            if(curr_pos || curr_bit)
            {
                fputc(curr_pos,file.get());
                fwrite(buffer,curr_pos,1,file.get());
                curr_pos=0;
            }
        }

        // Pushes a symbol of the given size
        // onto the bitstream.
        void push_value(int value, int size)
        {
            int i;
            for(i=0;i<size;i++)
                push_bit((value>>(i))&1);
        }
    };

    // Class for dealing with the LZW codes
    struct lzwcode
    {
        int value; // the data element or character
        int code; // lzwcode
        struct lzwcode* kids; // children of this node
        struct lzwcode* next; // siblings of this node

        lzwcode():value(0),code(0),kids(0),next(0) { }

        lzwcode *FindCode(int value)
        {
            lzwcode *node=this;

            // check the children (kids) of the node for the value
            for (node = node->kids; node != 0; node = node->next)
                if (node->value == value)
                    return(node);
            return(0);
        }

        void AddNode(unsigned short code, unsigned short value)
        {
            lzwcode *n = new lzwcode;

            // add a new child to node; the child will have code and value
            n->value = value;
            n->code = code;
            n->kids = 0;
            n->next = this->kids;
            this->kids = n;
        }

        static lzwcode * NewTable(int values)
        {
            int i;
            lzwcode * table = new lzwcode;

            table->kids = 0;
            for (i = 0; i < values; i++)
                table->AddNode( i, i);

            return(table);
        }

        // Destructor just deletes any
        // children and siblings.
        ~lzwcode()
        {
            if(kids)
                delete kids;
            if(next)
                delete next;
        }
    };

private:
    bitstream bs;
    synfig::String filename;
    synfig::SmartFILE file;
    int
        i,          // General-purpose index
        codesize,   // Current code size
        rootsize,   // Size of pixel bits (will be recalculated)
        nextcode;   // Next code to use
    lzwcode *table,*next,*node;

    synfig::Surface curr_surface;
    etl::surface<unsigned char> curr_frame;
    etl::surface<unsigned char> prev_frame;

    int imagecount;
    int cur_scanline;


    // GIF compression parameters
    bool lossy;
    bool multi_image;
    bool dithering;
    int color_bits;
    int iframe_density;
    int loop_count;
    bool local_palette;

    synfig::Palette curr_palette;

    void output_curr_palette();

public:
    gif(const char *filename, const synfig::TargetParam& /* params */);

    virtual bool set_rend_desc(synfig::RendDesc *desc);
    virtual bool init(synfig::ProgressCallback *cb);
    virtual bool start_frame(synfig::ProgressCallback *cb);
    virtual void end_frame();

    virtual ~gif();

    virtual synfig::Color * start_scanline(int scanline);
    virtual bool end_scanline(void);

};

/* === E N D =============================================================== */

#endif