/*
 * Copyright 2005, Stephan Aßmus <superstippi@gmx.de>. All rights reserved.
 * Distributed under the terms of the MIT License.
 *
 * DrawingMode implementing B_OP_SUBTRACT on B_RGBA32.
 *
 */

#ifndef DRAWING_MODE_SUBTRACT_H
#define DRAWING_MODE_SUBTRACT_H

#include <SupportDefs.h>

#include "DrawingMode.h"
#include "PatternHandler.h"

// BLEND_SUBTRACT
#define BLEND_SUBTRACT(d, r, g, b, a) \
{ \
        pixel32 _p; \
        _p.data32 = *(uint32*)d; \
        uint8 rt = max_c(0, _p.data8[2] - (r)); \
        uint8 gt = max_c(0, _p.data8[1] - (g)); \
        uint8 bt = max_c(0, _p.data8[0] - (b)); \
        BLEND(d, rt, gt, bt, a); \
}

// ASSIGN_SUBTRACT
#define ASSIGN_SUBTRACT(d, r, g, b) \
{ \
        pixel32 _p; \
        _p.data32 = *(uint32*)d; \
        d[0] = max_c(0, _p.data8[0] - (b)); \
        d[1] = max_c(0, _p.data8[1] - (g)); \
        d[2] = max_c(0, _p.data8[2] - (r)); \
        d[3] = 255; \
}


// blend_pixel_subtract
void
blend_pixel_subtract(int x, int y, const color_type& c, uint8 cover,
                                         agg_buffer* buffer, const PatternHandler* pattern)
{
        uint8* p = buffer->row_ptr(y) + (x << 2);
        rgb_color color = pattern->ColorAt(x, y);
        if (cover == 255) {
                ASSIGN_SUBTRACT(p, color.red, color.green, color.blue);
        } else {
                BLEND_SUBTRACT(p, color.red, color.green, color.blue, cover);
        }
}

// blend_hline_subtract
void
blend_hline_subtract(int x, int y, unsigned len, 
                                         const color_type& c, uint8 cover,
                                         agg_buffer* buffer, const PatternHandler* pattern)
{
        uint8* p = buffer->row_ptr(y) + (x << 2);
        if (cover == 255) {
                do {
                        rgb_color color = pattern->ColorAt(x, y);

                        ASSIGN_SUBTRACT(p, color.red, color.green, color.blue);

                        p += 4;
                        x++;
                } while(--len);
        } else {
                do {
                        rgb_color color = pattern->ColorAt(x, y);

                        BLEND_SUBTRACT(p, color.red, color.green, color.blue, cover);

                        x++;
                        p += 4;
                } while(--len);
        }
}

// blend_solid_hspan_subtract
void
blend_solid_hspan_subtract(int x, int y, unsigned len, 
                                                   const color_type& c, const uint8* covers,
                                                   agg_buffer* buffer, const PatternHandler* pattern)
{
        uint8* p = buffer->row_ptr(y) + (x << 2);
        do {
                rgb_color color = pattern->ColorAt(x, y);
                if (*covers) {
                        if (*covers == 255) {
                                ASSIGN_SUBTRACT(p, color.red, color.green, color.blue);
                        } else {
                                BLEND_SUBTRACT(p, color.red, color.green, color.blue, *covers);
                        }
                }
                covers++;
                p += 4;
                x++;
        } while(--len);
}



// blend_solid_vspan_subtract
void
blend_solid_vspan_subtract(int x, int y, unsigned len, 
                                                   const color_type& c, const uint8* covers,
                                                   agg_buffer* buffer, const PatternHandler* pattern)
{
        uint8* p = buffer->row_ptr(y) + (x << 2);
        do {
                rgb_color color = pattern->ColorAt(x, y);
                if (*covers) {
                        if (*covers == 255) {
                                ASSIGN_SUBTRACT(p, color.red, color.green, color.blue);
                        } else {
                                BLEND_SUBTRACT(p, color.red, color.green, color.blue, *covers);
                        }
                }
                covers++;
                p += buffer->stride();
                y++;
        } while(--len);
}


// blend_color_hspan_subtract
void
blend_color_hspan_subtract(int x, int y, unsigned len, 
                                                   const color_type* colors, 
                                                   const uint8* covers, uint8 cover,
                                                   agg_buffer* buffer, const PatternHandler* pattern)
{
        uint8* p = buffer->row_ptr(y) + (x << 2);
        if (covers) {
                // non-solid opacity
                do {
                        if (*covers && colors->a > 0) {
                                if (*covers == 255) {
                                        ASSIGN_SUBTRACT(p, colors->r, colors->g, colors->b);
                                } else {
                                        BLEND_SUBTRACT(p, colors->r, colors->g, colors->b, *covers);
                                }
                        }
                        covers++;
                        p += 4;
                        ++colors;
                } while(--len);
        } else {
                // solid full opcacity
                if (cover == 255) {
                        do {
                                if (colors->a > 0) {
                                        ASSIGN_SUBTRACT(p, colors->r, colors->g, colors->b);
                                }
                                p += 4;
                                ++colors;
                        } while(--len);
                // solid partial opacity
                } else if (cover) {
                        do {
                                if (colors->a > 0) {
                                        BLEND_SUBTRACT(p, colors->r, colors->g, colors->b, cover);
                                }
                                p += 4;
                                ++colors;
                        } while(--len);
                }
        }
}

#endif // DRAWING_MODE_SUBTRACT_H