view src/render/software/SDL_blendline.c @ 5172:ededa1ccf91c

Switched the SDL 1.2 compatibility to use the window surface, so it's fast even when there's no hardware acceleration available. This means that the YUV overlay now uses software, but that's okay since fast YUV code should be using the textures now anyway.
author Sam Lantinga <slouken@libsdl.org>
date Thu, 03 Feb 2011 21:13:55 -0800
parents 4d39eeaad00b
children d976b67150c5
line wrap: on
line source

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2010 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library 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
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga
    slouken@libsdl.org
*/
#include "SDL_config.h"

#include "SDL_draw.h"
#include "SDL_blendline.h"
#include "SDL_blendpoint.h"


static void
SDL_BlendLine_RGB2(SDL_Surface * dst, int x1, int y1, int x2, int y2,
                   SDL_BlendMode blendMode, Uint8 _r, Uint8 _g, Uint8 _b, Uint8 _a,
                   SDL_bool draw_end)
{
    const SDL_PixelFormat *fmt = dst->format;
    unsigned r, g, b, a, inva;

    if (blendMode == SDL_BLENDMODE_BLEND || blendMode == SDL_BLENDMODE_ADD) {
        r = DRAW_MUL(_r, _a);
        g = DRAW_MUL(_g, _a);
        b = DRAW_MUL(_b, _a);
        a = _a;
    } else {
        r = _r;
        g = _g;
        b = _b;
        a = _a;
    }
    inva = (a ^ 0xff);

    if (y1 == y2) {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            HLINE(Uint16, DRAW_SETPIXEL_BLEND_RGB, draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            HLINE(Uint16, DRAW_SETPIXEL_ADD_RGB, draw_end);
            break;
        default:
            HLINE(Uint16, DRAW_SETPIXEL_RGB, draw_end);
            break;
        }
    } else if (x1 == x2) {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            VLINE(Uint16, DRAW_SETPIXEL_BLEND_RGB, draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            VLINE(Uint16, DRAW_SETPIXEL_ADD_RGB, draw_end);
            break;
        default:
            VLINE(Uint16, DRAW_SETPIXEL_RGB, draw_end);
            break;
        }
    } else if (ABS(x1 - x2) == ABS(y1 - y2)) {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            DLINE(Uint16, DRAW_SETPIXEL_BLEND_RGB, draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            DLINE(Uint16, DRAW_SETPIXEL_ADD_RGB, draw_end);
            break;
        default:
            DLINE(Uint16, DRAW_SETPIXEL_RGB, draw_end);
            break;
        }
    } else {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            AALINE(x1, y1, x2, y2,
                   DRAW_SETPIXELXY2_BLEND_RGB, DRAW_SETPIXELXY2_BLEND_RGB,
                   draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            AALINE(x1, y1, x2, y2,
                   DRAW_SETPIXELXY2_ADD_RGB, DRAW_SETPIXELXY2_ADD_RGB,
                   draw_end);
            break;
        default:
            AALINE(x1, y1, x2, y2,
                   DRAW_SETPIXELXY2_RGB, DRAW_SETPIXELXY2_BLEND_RGB,
                   draw_end);
            break;
        }
    }
}

static void
SDL_BlendLine_RGB555(SDL_Surface * dst, int x1, int y1, int x2, int y2,
                     SDL_BlendMode blendMode, Uint8 _r, Uint8 _g, Uint8 _b, Uint8 _a,
                     SDL_bool draw_end)
{
    const SDL_PixelFormat *fmt = dst->format;
    unsigned r, g, b, a, inva;

    if (blendMode == SDL_BLENDMODE_BLEND || blendMode == SDL_BLENDMODE_ADD) {
        r = DRAW_MUL(_r, _a);
        g = DRAW_MUL(_g, _a);
        b = DRAW_MUL(_b, _a);
        a = _a;
    } else {
        r = _r;
        g = _g;
        b = _b;
        a = _a;
    }
    inva = (a ^ 0xff);

    if (y1 == y2) {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            HLINE(Uint16, DRAW_SETPIXEL_BLEND_RGB555, draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            HLINE(Uint16, DRAW_SETPIXEL_ADD_RGB555, draw_end);
            break;
        default:
            HLINE(Uint16, DRAW_SETPIXEL_RGB555, draw_end);
            break;
        }
    } else if (x1 == x2) {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            VLINE(Uint16, DRAW_SETPIXEL_BLEND_RGB555, draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            VLINE(Uint16, DRAW_SETPIXEL_ADD_RGB555, draw_end);
            break;
        default:
            VLINE(Uint16, DRAW_SETPIXEL_RGB555, draw_end);
            break;
        }
    } else if (ABS(x1 - x2) == ABS(y1 - y2)) {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            DLINE(Uint16, DRAW_SETPIXEL_BLEND_RGB555, draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            DLINE(Uint16, DRAW_SETPIXEL_ADD_RGB555, draw_end);
            break;
        default:
            DLINE(Uint16, DRAW_SETPIXEL_RGB555, draw_end);
            break;
        }
    } else {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            AALINE(x1, y1, x2, y2,
                   DRAW_SETPIXELXY_BLEND_RGB555, DRAW_SETPIXELXY_BLEND_RGB555,
                   draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            AALINE(x1, y1, x2, y2,
                   DRAW_SETPIXELXY_ADD_RGB555, DRAW_SETPIXELXY_ADD_RGB555,
                   draw_end);
            break;
        default:
            AALINE(x1, y1, x2, y2,
                   DRAW_SETPIXELXY_RGB555, DRAW_SETPIXELXY_BLEND_RGB555,
                   draw_end);
            break;
        }
    }
}

static void
SDL_BlendLine_RGB565(SDL_Surface * dst, int x1, int y1, int x2, int y2,
                     SDL_BlendMode blendMode, Uint8 _r, Uint8 _g, Uint8 _b, Uint8 _a,
                     SDL_bool draw_end)
{
    const SDL_PixelFormat *fmt = dst->format;
    unsigned r, g, b, a, inva;

    if (blendMode == SDL_BLENDMODE_BLEND || blendMode == SDL_BLENDMODE_ADD) {
        r = DRAW_MUL(_r, _a);
        g = DRAW_MUL(_g, _a);
        b = DRAW_MUL(_b, _a);
        a = _a;
    } else {
        r = _r;
        g = _g;
        b = _b;
        a = _a;
    }
    inva = (a ^ 0xff);

    if (y1 == y2) {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            HLINE(Uint16, DRAW_SETPIXEL_BLEND_RGB565, draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            HLINE(Uint16, DRAW_SETPIXEL_ADD_RGB565, draw_end);
            break;
        default:
            HLINE(Uint16, DRAW_SETPIXEL_RGB565, draw_end);
            break;
        }
    } else if (x1 == x2) {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            VLINE(Uint16, DRAW_SETPIXEL_BLEND_RGB565, draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            VLINE(Uint16, DRAW_SETPIXEL_ADD_RGB565, draw_end);
            break;
        default:
            VLINE(Uint16, DRAW_SETPIXEL_RGB565, draw_end);
            break;
        }
    } else if (ABS(x1 - x2) == ABS(y1 - y2)) {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            DLINE(Uint16, DRAW_SETPIXEL_BLEND_RGB565, draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            DLINE(Uint16, DRAW_SETPIXEL_ADD_RGB565, draw_end);
            break;
        default:
            DLINE(Uint16, DRAW_SETPIXEL_RGB565, draw_end);
            break;
        }
    } else {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            AALINE(x1, y1, x2, y2,
                   DRAW_SETPIXELXY_BLEND_RGB565, DRAW_SETPIXELXY_BLEND_RGB565,
                   draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            AALINE(x1, y1, x2, y2,
                   DRAW_SETPIXELXY_ADD_RGB565, DRAW_SETPIXELXY_ADD_RGB565,
                   draw_end);
            break;
        default:
            AALINE(x1, y1, x2, y2,
                   DRAW_SETPIXELXY_RGB565, DRAW_SETPIXELXY_BLEND_RGB565,
                   draw_end);
            break;
        }
    }
}

static void
SDL_BlendLine_RGB4(SDL_Surface * dst, int x1, int y1, int x2, int y2,
                   SDL_BlendMode blendMode, Uint8 _r, Uint8 _g, Uint8 _b, Uint8 _a,
                   SDL_bool draw_end)
{
    const SDL_PixelFormat *fmt = dst->format;
    unsigned r, g, b, a, inva;

    if (blendMode == SDL_BLENDMODE_BLEND || blendMode == SDL_BLENDMODE_ADD) {
        r = DRAW_MUL(_r, _a);
        g = DRAW_MUL(_g, _a);
        b = DRAW_MUL(_b, _a);
        a = _a;
    } else {
        r = _r;
        g = _g;
        b = _b;
        a = _a;
    }
    inva = (a ^ 0xff);

    if (y1 == y2) {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            HLINE(Uint32, DRAW_SETPIXEL_BLEND_RGB, draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            HLINE(Uint32, DRAW_SETPIXEL_ADD_RGB, draw_end);
            break;
        default:
            HLINE(Uint32, DRAW_SETPIXEL_RGB, draw_end);
            break;
        }
    } else if (x1 == x2) {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            VLINE(Uint32, DRAW_SETPIXEL_BLEND_RGB, draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            VLINE(Uint32, DRAW_SETPIXEL_ADD_RGB, draw_end);
            break;
        default:
            VLINE(Uint32, DRAW_SETPIXEL_RGB, draw_end);
            break;
        }
    } else if (ABS(x1 - x2) == ABS(y1 - y2)) {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            DLINE(Uint32, DRAW_SETPIXEL_BLEND_RGB, draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            DLINE(Uint32, DRAW_SETPIXEL_ADD_RGB, draw_end);
            break;
        default:
            DLINE(Uint32, DRAW_SETPIXEL_RGB, draw_end);
            break;
        }
    } else {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            AALINE(x1, y1, x2, y2,
                   DRAW_SETPIXELXY4_BLEND_RGB, DRAW_SETPIXELXY4_BLEND_RGB,
                   draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            AALINE(x1, y1, x2, y2,
                   DRAW_SETPIXELXY4_ADD_RGB, DRAW_SETPIXELXY4_ADD_RGB,
                   draw_end);
            break;
        default:
            AALINE(x1, y1, x2, y2,
                   DRAW_SETPIXELXY4_RGB, DRAW_SETPIXELXY4_BLEND_RGB,
                   draw_end);
            break;
        }
    }
}

static void
SDL_BlendLine_RGBA4(SDL_Surface * dst, int x1, int y1, int x2, int y2,
                    SDL_BlendMode blendMode, Uint8 _r, Uint8 _g, Uint8 _b, Uint8 _a,
                    SDL_bool draw_end)
{
    const SDL_PixelFormat *fmt = dst->format;
    unsigned r, g, b, a, inva;

    if (blendMode == SDL_BLENDMODE_BLEND || blendMode == SDL_BLENDMODE_ADD) {
        r = DRAW_MUL(_r, _a);
        g = DRAW_MUL(_g, _a);
        b = DRAW_MUL(_b, _a);
        a = _a;
    } else {
        r = _r;
        g = _g;
        b = _b;
        a = _a;
    }
    inva = (a ^ 0xff);

    if (y1 == y2) {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            HLINE(Uint32, DRAW_SETPIXEL_BLEND_RGBA, draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            HLINE(Uint32, DRAW_SETPIXEL_ADD_RGBA, draw_end);
            break;
        default:
            HLINE(Uint32, DRAW_SETPIXEL_RGBA, draw_end);
            break;
        }
    } else if (x1 == x2) {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            VLINE(Uint32, DRAW_SETPIXEL_BLEND_RGBA, draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            VLINE(Uint32, DRAW_SETPIXEL_ADD_RGBA, draw_end);
            break;
        default:
            VLINE(Uint32, DRAW_SETPIXEL_RGBA, draw_end);
            break;
        }
    } else if (ABS(x1 - x2) == ABS(y1 - y2)) {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            DLINE(Uint32, DRAW_SETPIXEL_BLEND_RGBA, draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            DLINE(Uint32, DRAW_SETPIXEL_ADD_RGBA, draw_end);
            break;
        default:
            DLINE(Uint32, DRAW_SETPIXEL_RGBA, draw_end);
            break;
        }
    } else {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            AALINE(x1, y1, x2, y2,
                   DRAW_SETPIXELXY4_BLEND_RGBA, DRAW_SETPIXELXY4_BLEND_RGBA,
                   draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            AALINE(x1, y1, x2, y2,
                   DRAW_SETPIXELXY4_ADD_RGBA, DRAW_SETPIXELXY4_ADD_RGBA,
                   draw_end);
            break;
        default:
            AALINE(x1, y1, x2, y2,
                   DRAW_SETPIXELXY4_RGBA, DRAW_SETPIXELXY4_BLEND_RGBA,
                   draw_end);
            break;
        }
    }
}

static void
SDL_BlendLine_RGB888(SDL_Surface * dst, int x1, int y1, int x2, int y2,
                     SDL_BlendMode blendMode, Uint8 _r, Uint8 _g, Uint8 _b, Uint8 _a,
                     SDL_bool draw_end)
{
    const SDL_PixelFormat *fmt = dst->format;
    unsigned r, g, b, a, inva;

    if (blendMode == SDL_BLENDMODE_BLEND || blendMode == SDL_BLENDMODE_ADD) {
        r = DRAW_MUL(_r, _a);
        g = DRAW_MUL(_g, _a);
        b = DRAW_MUL(_b, _a);
        a = _a;
    } else {
        r = _r;
        g = _g;
        b = _b;
        a = _a;
    }
    inva = (a ^ 0xff);

    if (y1 == y2) {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            HLINE(Uint32, DRAW_SETPIXEL_BLEND_RGB888, draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            HLINE(Uint32, DRAW_SETPIXEL_ADD_RGB888, draw_end);
            break;
        default:
            HLINE(Uint32, DRAW_SETPIXEL_RGB888, draw_end);
            break;
        }
    } else if (x1 == x2) {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            VLINE(Uint32, DRAW_SETPIXEL_BLEND_RGB888, draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            VLINE(Uint32, DRAW_SETPIXEL_ADD_RGB888, draw_end);
            break;
        default:
            VLINE(Uint32, DRAW_SETPIXEL_RGB888, draw_end);
            break;
        }
    } else if (ABS(x1 - x2) == ABS(y1 - y2)) {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            DLINE(Uint32, DRAW_SETPIXEL_BLEND_RGB888, draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            DLINE(Uint32, DRAW_SETPIXEL_ADD_RGB888, draw_end);
            break;
        default:
            DLINE(Uint32, DRAW_SETPIXEL_RGB888, draw_end);
            break;
        }
    } else {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            AALINE(x1, y1, x2, y2,
                   DRAW_SETPIXELXY_BLEND_RGB888, DRAW_SETPIXELXY_BLEND_RGB888,
                   draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            AALINE(x1, y1, x2, y2,
                   DRAW_SETPIXELXY_ADD_RGB888, DRAW_SETPIXELXY_ADD_RGB888,
                   draw_end);
            break;
        default:
            AALINE(x1, y1, x2, y2,
                   DRAW_SETPIXELXY_RGB888, DRAW_SETPIXELXY_BLEND_RGB888,
                   draw_end);
            break;
        }
    }
}

static void
SDL_BlendLine_ARGB8888(SDL_Surface * dst, int x1, int y1, int x2, int y2,
                       SDL_BlendMode blendMode, Uint8 _r, Uint8 _g, Uint8 _b, Uint8 _a,
                       SDL_bool draw_end)
{
    const SDL_PixelFormat *fmt = dst->format;
    unsigned r, g, b, a, inva;

    if (blendMode == SDL_BLENDMODE_BLEND || blendMode == SDL_BLENDMODE_ADD) {
        r = DRAW_MUL(_r, _a);
        g = DRAW_MUL(_g, _a);
        b = DRAW_MUL(_b, _a);
        a = _a;
    } else {
        r = _r;
        g = _g;
        b = _b;
        a = _a;
    }
    inva = (a ^ 0xff);

    if (y1 == y2) {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            HLINE(Uint32, DRAW_SETPIXEL_BLEND_ARGB8888, draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            HLINE(Uint32, DRAW_SETPIXEL_ADD_ARGB8888, draw_end);
            break;
        default:
            HLINE(Uint32, DRAW_SETPIXEL_ARGB8888, draw_end);
            break;
        }
    } else if (x1 == x2) {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            VLINE(Uint32, DRAW_SETPIXEL_BLEND_ARGB8888, draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            VLINE(Uint32, DRAW_SETPIXEL_ADD_ARGB8888, draw_end);
            break;
        default:
            VLINE(Uint32, DRAW_SETPIXEL_ARGB8888, draw_end);
            break;
        }
    } else if (ABS(x1 - x2) == ABS(y1 - y2)) {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            DLINE(Uint32, DRAW_SETPIXEL_BLEND_ARGB8888, draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            DLINE(Uint32, DRAW_SETPIXEL_ADD_ARGB8888, draw_end);
            break;
        default:
            DLINE(Uint32, DRAW_SETPIXEL_ARGB8888, draw_end);
            break;
        }
    } else {
        switch (blendMode) {
        case SDL_BLENDMODE_BLEND:
            AALINE(x1, y1, x2, y2,
                   DRAW_SETPIXELXY_BLEND_ARGB8888, DRAW_SETPIXELXY_BLEND_ARGB8888,
                   draw_end);
            break;
        case SDL_BLENDMODE_ADD:
            AALINE(x1, y1, x2, y2,
                   DRAW_SETPIXELXY_ADD_ARGB8888, DRAW_SETPIXELXY_ADD_ARGB8888,
                   draw_end);
            break;
        default:
            AALINE(x1, y1, x2, y2,
                   DRAW_SETPIXELXY_ARGB8888, DRAW_SETPIXELXY_BLEND_ARGB8888,
                   draw_end);
            break;
        }
    }
}

typedef void (*BlendLineFunc) (SDL_Surface * dst,
                               int x1, int y1, int x2, int y2,
                               SDL_BlendMode blendMode,
                               Uint8 r, Uint8 g, Uint8 b, Uint8 a,
                               SDL_bool draw_end);

static BlendLineFunc
SDL_CalculateBlendLineFunc(const SDL_PixelFormat * fmt)
{
    switch (fmt->BytesPerPixel) {
    case 2:
        if (fmt->Rmask == 0x7C00) {
            return SDL_BlendLine_RGB555;
        } else if (fmt->Rmask == 0xF800) {
            return SDL_BlendLine_RGB565;
        } else {
            return SDL_BlendLine_RGB2;
        }
        break;
    case 4:
        if (fmt->Rmask == 0x00FF0000) {
            if (fmt->Amask) {
                return SDL_BlendLine_ARGB8888;
            } else {
                return SDL_BlendLine_RGB888;
            }
        } else {
            if (fmt->Amask) {
                return SDL_BlendLine_RGBA4;
            } else {
                return SDL_BlendLine_RGB4;
            }
        }
    }
    return NULL;
}

int
SDL_BlendLine(SDL_Surface * dst, int x1, int y1, int x2, int y2,
              SDL_BlendMode blendMode, Uint8 r, Uint8 g, Uint8 b, Uint8 a)
{
    BlendLineFunc func;

    if (!dst) {
        SDL_SetError("SDL_BlendLine(): Passed NULL destination surface");
        return -1;
    }

    func = SDL_CalculateBlendLineFunc(dst->format);
    if (!func) {
        SDL_SetError("SDL_BlendLine(): Unsupported surface format");
        return -1;
    }

    /* Perform clipping */
    /* FIXME: We don't actually want to clip, as it may change line slope */
    if (!SDL_IntersectRectAndLine(&dst->clip_rect, &x1, &y1, &x2, &y2)) {
        return 0;
    }

    func(dst, x1, y1, x2, y2, blendMode, r, g, b, a, SDL_TRUE);
    return 0;
}

int
SDL_BlendLines(SDL_Surface * dst, const SDL_Point * points, int count,
               SDL_BlendMode blendMode, Uint8 r, Uint8 g, Uint8 b, Uint8 a)
{
    int i;
    int x1, y1;
    int x2, y2;
    SDL_bool draw_end;
    BlendLineFunc func;

    if (!dst) {
        SDL_SetError("SDL_BlendLines(): Passed NULL destination surface");
        return -1;
    }

    func = SDL_CalculateBlendLineFunc(dst->format);
    if (!func) {
        SDL_SetError("SDL_BlendLines(): Unsupported surface format");
        return -1;
    }

    for (i = 1; i < count; ++i) {
        x1 = points[i-1].x;
        y1 = points[i-1].y;
        x2 = points[i].x;
        y2 = points[i].y;

        /* Perform clipping */
        /* FIXME: We don't actually want to clip, as it may change line slope */
        if (!SDL_IntersectRectAndLine(&dst->clip_rect, &x1, &y1, &x2, &y2)) {
            continue;
        }

        /* Draw the end if it was clipped */
        draw_end = (x2 != points[i].x || y2 != points[i].y);

        func(dst, x1, y1, x2, y2, blendMode, r, g, b, a, draw_end);
    }
    if (points[0].x != points[count-1].x || points[0].y != points[count-1].y) {
        SDL_BlendPoint(dst, points[count-1].x, points[count-1].y,
                       blendMode, r, g, b, a);
    }
    return 0;
}

/* vi: set ts=4 sw=4 expandtab: */