sdl_gfxprimitives.c

sdl的gfx开发包

/* 

 SDL_gfxPrimitives - Graphics primitives for SDL surfaces

 LGPL (c) A. Schiffler

*/

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>

#include "SDL_gfxPrimitives.h"
#include "SDL_gfxPrimitives_font.h"

/* -===================- */

/* ----- Defines for pixel clipping tests */

#define clip_xmin(surface) surface->clip_rect.x
#define clip_xmax(surface) surface->clip_rect.x+surface->clip_rect.w-1
#define clip_ymin(surface) surface->clip_rect.y
#define clip_ymax(surface) surface->clip_rect.y+surface->clip_rect.h-1

/* ----- Pixel - fast, no blending, no locking, clipping */

int fastPixelColorNolock(SDL_Surface * dst, Sint16 x, Sint16 y, Uint32 color)
{
    int bpp;
    Uint8 *p;

    /*
     * Honor clipping setup at pixel level 
     */
    if ((x >= clip_xmin(dst)) && (x <= clip_xmax(dst)) && (y >= clip_ymin(dst)) && (y <= clip_ymax(dst))) {

	/*
	 * Get destination format 
	 */
	bpp = dst->format->BytesPerPixel;
	p = (Uint8 *) dst->pixels + y * dst->pitch + x * bpp;
	switch (bpp) {
	case 1:
	    *p = color;
	    break;
	case 2:
	    *(Uint16 *) p = color;
	    break;
	case 3:
	    if (SDL_BYTEORDER == SDL_BIG_ENDIAN) {
		p[0] = (color >> 16) & 0xff;
		p[1] = (color >> 8) & 0xff;
		p[2] = color & 0xff;
	    } else {
		p[0] = color & 0xff;
		p[1] = (color >> 8) & 0xff;
		p[2] = (color >> 16) & 0xff;
	    }
	    break;
	case 4:
	    *(Uint32 *) p = color;
	    break;
	}			/* switch */


    }

    return (0);
}

/* ----- Pixel - fast, no blending, no locking, no clipping */

/* (faster but dangerous, make sure we stay in surface bounds) */

int fastPixelColorNolockNoclip(SDL_Surface * dst, Sint16 x, Sint16 y, Uint32 color)
{
    int bpp;
    Uint8 *p;

    /*
     * Get destination format 
     */
    bpp = dst->format->BytesPerPixel;
    p = (Uint8 *) dst->pixels + y * dst->pitch + x * bpp;
    switch (bpp) {
    case 1:
	*p = color;
	break;
    case 2:
	*(Uint16 *) p = color;
	break;
    case 3:
	if (SDL_BYTEORDER == SDL_BIG_ENDIAN) {
	    p[0] = (color >> 16) & 0xff;
	    p[1] = (color >> 8) & 0xff;
	    p[2] = color & 0xff;
	} else {
	    p[0] = color & 0xff;
	    p[1] = (color >> 8) & 0xff;
	    p[2] = (color >> 16) & 0xff;
	}
	break;
    case 4:
	*(Uint32 *) p = color;
	break;
    }				/* switch */

    return (0);
}

/* ----- Pixel - fast, no blending, locking, clipping */

int fastPixelColor(SDL_Surface * dst, Sint16 x, Sint16 y, Uint32 color)
{
    int result;

    /*
     * Lock the surface 
     */
    if (SDL_MUSTLOCK(dst)) {
	if (SDL_LockSurface(dst) < 0) {
	    return (-1);
	}
    }

    result = fastPixelColorNolock(dst, x, y, color);

    /*
     * Unlock surface 
     */
    if (SDL_MUSTLOCK(dst)) {
	SDL_UnlockSurface(dst);
    }

    return (result);
}

/* ----- Pixel - fast, no blending, locking, RGB input */

int fastPixelRGBA(SDL_Surface * dst, Sint16 x, Sint16 y, Uint8 r, Uint8 g, Uint8 b, Uint8 a)
{
    Uint32 color;

    /*
     * Setup color 
     */
    color = SDL_MapRGBA(dst->format, r, g, b, a);

    /*
     * Draw 
     */
    return (fastPixelColor(dst, x, y, color));

}

/* ----- Pixel - fast, no blending, no locking RGB input */

int fastPixelRGBANolock(SDL_Surface * dst, Sint16 x, Sint16 y, Uint8 r, Uint8 g, Uint8 b, Uint8 a)
{
    Uint32 color;

    /*
     * Setup color 
     */
    color = SDL_MapRGBA(dst->format, r, g, b, a);

    /*
     * Draw 
     */
    return (fastPixelColorNolock(dst, x, y, color));
}

/* PutPixel routine with alpha blending, input color in destination format */

/* New, faster routine - default blending pixel */

int _putPixelAlpha(SDL_Surface * surface, Sint16 x, Sint16 y, Uint32 color, Uint8 alpha)
{
    Uint32 Rmask = surface->format->Rmask, Gmask =
	surface->format->Gmask, Bmask = surface->format->Bmask, Amask = surface->format->Amask;
    Uint32 R, G, B, A = 0;

    if (x >= clip_xmin(surface) && x <= clip_xmax(surface)
	&& y >= clip_ymin(surface) && y <= clip_ymax(surface)) {

	switch (surface->format->BytesPerPixel) {
	case 1:{		/* Assuming 8-bpp */
		if (alpha == 255) {
		    *((Uint8 *) surface->pixels + y * surface->pitch + x) = color;
		} else {
		    Uint8 *pixel = (Uint8 *) surface->pixels + y * surface->pitch + x;

		    Uint8 dR = surface->format->palette->colors[*pixel].r;
		    Uint8 dG = surface->format->palette->colors[*pixel].g;
		    Uint8 dB = surface->format->palette->colors[*pixel].b;
		    Uint8 sR = surface->format->palette->colors[color].r;
		    Uint8 sG = surface->format->palette->colors[color].g;
		    Uint8 sB = surface->format->palette->colors[color].b;

		    dR = dR + ((sR - dR) * alpha >> 8);
		    dG = dG + ((sG - dG) * alpha >> 8);
		    dB = dB + ((sB - dB) * alpha >> 8);

		    *pixel = SDL_MapRGB(surface->format, dR, dG, dB);
		}
	    }
	    break;

	case 2:{		/* Probably 15-bpp or 16-bpp */
		if (alpha == 255) {
		    *((Uint16 *) surface->pixels + y * surface->pitch / 2 + x) = color;
		} else {
		    Uint16 *pixel = (Uint16 *) surface->pixels + y * surface->pitch / 2 + x;
		    Uint32 dc = *pixel;

		    R = ((dc & Rmask) + (((color & Rmask) - (dc & Rmask)) * alpha >> 8)) & Rmask;
		    G = ((dc & Gmask) + (((color & Gmask) - (dc & Gmask)) * alpha >> 8)) & Gmask;
		    B = ((dc & Bmask) + (((color & Bmask) - (dc & Bmask)) * alpha >> 8)) & Bmask;
		    if (Amask)
			A = ((dc & Amask) + (((color & Amask) - (dc & Amask)) * alpha >> 8)) & Amask;

		    *pixel = R | G | B | A;
		}
	    }
	    break;

	case 3:{		/* Slow 24-bpp mode, usually not used */
		Uint8 *pix = (Uint8 *) surface->pixels + y * surface->pitch + x * 3;
		Uint8 rshift8 = surface->format->Rshift / 8;
		Uint8 gshift8 = surface->format->Gshift / 8;
		Uint8 bshift8 = surface->format->Bshift / 8;
		Uint8 ashift8 = surface->format->Ashift / 8;


		if (alpha == 255) {
		    *(pix + rshift8) = color >> surface->format->Rshift;
		    *(pix + gshift8) = color >> surface->format->Gshift;
		    *(pix + bshift8) = color >> surface->format->Bshift;
		    *(pix + ashift8) = color >> surface->format->Ashift;
		} else {
		    Uint8 dR, dG, dB, dA = 0;
		    Uint8 sR, sG, sB, sA = 0;

		    pix = (Uint8 *) surface->pixels + y * surface->pitch + x * 3;

		    dR = *((pix) + rshift8);
		    dG = *((pix) + gshift8);
		    dB = *((pix) + bshift8);
		    dA = *((pix) + ashift8);

		    sR = (color >> surface->format->Rshift) & 0xff;
		    sG = (color >> surface->format->Gshift) & 0xff;
		    sB = (color >> surface->format->Bshift) & 0xff;
		    sA = (color >> surface->format->Ashift) & 0xff;

		    dR = dR + ((sR - dR) * alpha >> 8);
		    dG = dG + ((sG - dG) * alpha >> 8);
		    dB = dB + ((sB - dB) * alpha >> 8);
		    dA = dA + ((sA - dA) * alpha >> 8);

		    *((pix) + rshift8) = dR;
		    *((pix) + gshift8) = dG;
		    *((pix) + bshift8) = dB;
		    *((pix) + ashift8) = dA;
		}
	    }
	    break;

	case 4:{		/* Probably 32-bpp */
		if (alpha == 255) {
		    *((Uint32 *) surface->pixels + y * surface->pitch / 4 + x) = color;
		} else {
		    Uint32 *pixel = (Uint32 *) surface->pixels + y * surface->pitch / 4 + x;
		    Uint32 dc = *pixel;

		    R = ((dc & Rmask) + (((color & Rmask) - (dc & Rmask)) * alpha >> 8)) & Rmask;
		    G = ((dc & Gmask) + (((color & Gmask) - (dc & Gmask)) * alpha >> 8)) & Gmask;
		    B = ((dc & Bmask) + (((color & Bmask) - (dc & Bmask)) * alpha >> 8)) & Bmask;
		    if (Amask)
			A = ((dc & Amask) + (((color & Amask) - (dc & Amask)) * alpha >> 8)) & Amask;

		    *pixel = R | G | B | A;
		}
	    }
	    break;
	}
    }

    return (0);
}

/* ----- Pixel - pixel draw with blending enabled if a<255 */

int pixelColor(SDL_Surface * dst, Sint16 x, Sint16 y, Uint32 color)
{
    Uint8 alpha;
    Uint32 mcolor;
    int result = 0;

    /*
     * Lock the surface 
     */
    if (SDL_MUSTLOCK(dst)) {
	if (SDL_LockSurface(dst) < 0) {
	    return (-1);
	}
    }

    /*
     * Setup color 
     */
    alpha = color & 0x000000ff;
    mcolor =
	SDL_MapRGBA(dst->format, (color & 0xff000000) >> 24,
		    (color & 0x00ff0000) >> 16, (color & 0x0000ff00) >> 8, alpha);

    /*
     * Draw 
     */
    result = _putPixelAlpha(dst, x, y, mcolor, alpha);

    /*
     * Unlock the surface 
     */
    if (SDL_MUSTLOCK(dst)) {
	SDL_UnlockSurface(dst);
    }

    return (result);
}

int pixelColorNolock(SDL_Surface * dst, Sint16 x, Sint16 y, Uint32 color)
{
    Uint8 alpha;
    Uint32 mcolor;
    int result = 0;

    /*
     * Setup color 
     */
    alpha = color & 0x000000ff;
    mcolor =
	SDL_MapRGBA(dst->format, (color & 0xff000000) >> 24,
		    (color & 0x00ff0000) >> 16, (color & 0x0000ff00) >> 8, alpha);

    /*
     * Draw 
     */
    result = _putPixelAlpha(dst, x, y, mcolor, alpha);

    return (result);
}


/* Filled rectangle with alpha blending, color in destination format */

int _filledRectAlpha(SDL_Surface * surface, Sint16 x1, Sint16 y1, Sint16 x2, Sint16 y2, Uint32 color, Uint8 alpha)
{
    Uint32 Rmask = surface->format->Rmask, Gmask =
	surface->format->Gmask, Bmask = surface->format->Bmask, Amask = surface->format->Amask;
    Uint32 R, G, B, A = 0;
    Sint16 x, y;

    switch (surface->format->BytesPerPixel) {
    case 1:{			/* Assuming 8-bpp */
	    Uint8 *row, *pixel;
	    Uint8 dR, dG, dB;

	    Uint8 sR = surface->format->palette->colors[color].r;
	    Uint8 sG = surface->format->palette->colors[color].g;
	    Uint8 sB = surface->format->palette->colors[color].b;

	    for (y = y1; y <= y2; y++) {
		row = (Uint8 *) surface->pixels + y * surface->pitch;
		for (x = x1; x <= x2; x++) {
		    pixel = row + x;

		    dR = surface->format->palette->colors[*pixel].r;
		    dG = surface->format->palette->colors[*pixel].g;
		    dB = surface->format->palette->colors[*pixel].b;

		    dR = dR + ((sR - dR) * alpha >> 8);
		    dG = dG + ((sG - dG) * alpha >> 8);
		    dB = dB + ((sB - dB) * alpha >> 8);

		    *pixel = SDL_MapRGB(surface->format, dR, dG, dB);
		}
	    }
	}
	break;

    case 2:{			/* Probably 15-bpp or 16-bpp */
	    Uint16 *row, *pixel;
	    Uint32 dR = (color & Rmask), dG = (color & Gmask), dB = (color & Bmask), dA = (color & Amask);

	    for (y = y1; y <= y2; y++) {
		row = (Uint16 *) surface->pixels + y * surface->pitch / 2;
		for (x = x1; x <= x2; x++) {
		    pixel = row + x;

		    R = ((*pixel & Rmask) + ((dR - (*pixel & Rmask)) * alpha >> 8)) & Rmask;
		    G = ((*pixel & Gmask) + ((dG - (*pixel & Gmask)) * alpha >> 8)) & Gmask;
		    B = ((*pixel & Bmask) + ((dB - (*pixel & Bmask)) * alpha >> 8)) & Bmask;
		    if (Amask)
			A = ((*pixel & Amask) + ((dA - (*pixel & Amask)) * alpha >> 8)) & Amask;

		    *pixel = R | G | B | A;
		}
	    }
	}
	break;

    case 3:{			/* Slow 24-bpp mode, usually not used */
	    Uint8 *row, *pix;
	    Uint8 dR, dG, dB, dA;
	    Uint8 rshift8 = surface->format->Rshift / 8;
	    Uint8 gshift8 = surface->format->Gshift / 8;
	    Uint8 bshift8 = surface->format->Bshift / 8;
	    Uint8 ashift8 = surface->format->Ashift / 8;

	    Uint8 sR = (color >> surface->format->Rshift) & 0xff;
	    Uint8 sG = (color >> surface->format->Gshift) & 0xff;
	    Uint8 sB = (color >> surface->format->Bshift) & 0xff;
	    Uint8 sA = (color >> surface->format->Ashift) & 0xff;

	    for (y = y1; y <= y2; y++) {
		row = (Uint8 *) surface->pixels + y * surface->pitch;
		for (x = x1; x <= x2; x++) {
		    pix = row + x * 3;

		    dR = *((pix) + rshift8);
		    dG = *((pix) + gshift8);
		    dB = *((pix) + bshift8);
		    dA = *((pix) + ashift8);

		    dR = dR + ((sR - dR) * alpha >> 8);
		    dG = dG + ((sG - dG) * alpha >> 8);
		    dB = dB + ((sB - dB) * alpha >> 8);
		    dA = dA + ((sA - dA) * alpha >> 8);

		    *((pix) + rshift8) = dR;
		    *((pix) + gshift8) = dG;
		    *((pix) + bshift8) = dB;
		    *((pix) + ashift8) = dA;
		}
	    }

	}
	break;

    case 4:{			/* Probably 32-bpp */
	    Uint32 *row, *pixel;
	    Uint32 dR = (color & Rmask), dG = (color & Gmask), dB = (color & Bmask), dA = (color & Amask);

	    for (y = y1; y <= y2; y++) {
		row = (Uint32 *) surface->pixels + y * surface->pitch / 4;
		for (x = x1; x <= x2; x++) {
		    pixel = row + x;

		    R = ((*pixel & Rmask) + ((dR - (*pixel & Rmask)) * alpha >> 8)) & Rmask;
		    G = ((*pixel & Gmask) + ((dG - (*pixel & Gmask)) * alpha >> 8)) & Gmask;
		    B = ((*pixel & Bmask) + ((dB - (*pixel & Bmask)) * alpha >> 8)) & Bmask;
		    if (Amask)
			A = ((*pixel & Amask) + ((dA - (*pixel & Amask)) * alpha >> 8)) & Amask;

		    *pixel = R | G | B | A;
		}
	    }
	}
	break;
    }

    return (0);
}

/* Draw rectangle with alpha enabled from RGBA color. */

int filledRectAlpha(SDL_Surface * dst, Sint16 x1, Sint16 y1, Sint16 x2, Sint16 y2, Uint32 color)
{
    Uint8 alpha;
    Uint32 mcolor;
    int result = 0;

    /*
     * Lock the surface 
     */
    if (SDL_MUSTLOCK(dst)) {
	if (SDL_LockSurface(dst) < 0) {
	    return (-1);
	}
    }

    /*
     * Setup color 
     */
    alpha = color & 0x000000ff;
    mcolor =
	SDL_MapRGBA(dst->format, (color & 0xff000000) >> 24,
		    (color & 0x00ff0000) >> 16, (color & 0x0000ff00) >> 8, alpha);

    /*
     * Draw 
     */
    result = _filledRectAlpha(dst, x1, y1, x2, y2, mcolor, alpha);

    /*
     * Unlock the surface 
     */
    if (SDL_MUSTLOCK(dst)) {
	SDL_UnlockSurface(dst);
    }

    return (result);
}

/* Draw horizontal line with alpha enabled from RGBA color */

int HLineAlpha(SDL_Surface * dst, Sint16 x1, Sint16 x2, Sint16 y, Uint32 color)
{
    return (filledRectAlpha(dst, x1, y, x2, y, color));
}


/* Draw vertical line with alpha enabled from RGBA color */

int VLineAlpha(SDL_Surface * dst, Sint16 x, Sint16 y1, Sint16 y2, Uint32 color)
{
    return (filledRectAlpha(dst, x, y1, x, y2, color));
}


/* Pixel - using alpha weight on color for AA-drawing */

int pixelColorWeight(SDL_Surface * dst, Sint16 x, Sint16 y, Uint32 color, Uint32 weight)
{
    Uint32 a;

    /*
     * Get alpha 
     */
    a = (color & (Uint32) 0x000000ff);

    /*
     * Modify Alpha by weight 
     */
    a = ((a * weight) >> 8);

    return (pixelColor(dst, x, y, (color & (Uint32) 0xffffff00) | (Uint32) a));
}

/* Pixel - using alpha weight on color for AA-drawing - no locking */

int pixelColorWeightNolock(SDL_Surface * dst, Sint16 x, Sint16 y, Uint32 color, Uint32 weight)
{
    Uint32 a;

    /*
     * Get alpha 
     */
    a = (color & (Uint32) 0x000000ff);

    /*
     * Modify Alpha by weight 
     */
    a = ((a * weight) >> 8);

    return (pixelColorNolock(dst, x, y, (color & (Uint32) 0xffffff00) | (Uint32) a));
}

int pixelRGBA(SDL_Surface * dst, Sint16 x, Sint16 y, Uint8 r, Uint8 g, Uint8 b, Uint8 a)
{
    Uint32 color;

    /*
     * Check Alpha 
     */
    if (a == 255) {
	/*
	 * No alpha blending required 
	 */
	/*
	 * Setup color 
	 */
	color = SDL_MapRGBA(dst->format, r, g, b, a);
	/*
	 * Draw 
	 */
	return (fastPixelColor(dst, x, y, color));
    } else {
	/*
	 * Alpha blending required 
	 */
	/*
	 * Draw 
	 */
	return (pixelColor(dst, x, y, ((Uint32) r << 24) | ((Uint32) g << 16) | ((Uint32) b << 8) | (Uint32) a));
    }
}

/* ----- Horizontal line */

/* Just store color including alpha, no blending */

int hlineColorStore(SDL_Surface * dst, Sint16 x1, Sint16 x2, Sint16 y, Uint32 color)
{
    Sint16 left, right, top, bottom;
    Uint8 *pixel, *pixellast;
    int dx;