SDL2_rotozoom.h File Reference

(986a3bf)

#include <math.h>
#include "localconsts.h"
#include <SDL.h>

Go to the source code of this file.

Macros
#define	SMOOTHING_OFF   0
	Disable anti-aliasing (no smoothing). More...
#define	SMOOTHING_ON   1
	Enable anti-aliasing (smoothing). More...
#define	SDL2_ROTOZOOM_SCOPE   extern

Functions
SDL_Surface *	rotozoomSurface (SDL_Surface *src, double angle, double zoom, int smooth)
	Rotates and zooms a surface and optional anti-aliasing. More...
SDL_Surface *	rotozoomSurfaceXY (SDL_Surface *src, double angle, double zoomx, double zoomy, int smooth)
	Rotates and zooms a surface with different horizontal and vertival scaling factors and optional anti-aliasing. More...
void	rotozoomSurfaceSize (int width, int height, double angle, double zoom, int *dstwidth, int *dstheight)
	Returns the size of the resulting target surface for a rotozoomSurface() call. More...
void	rotozoomSurfaceSizeXY (int width, int height, double angle, double zoomx, double zoomy, int *dstwidth, int *dstheight)
	Returns the size of the resulting target surface for a rotozoomSurfaceXY() call. More...
SDL_Surface *	zoomSurface (SDL_Surface *src, double zoomx, double zoomy, int smooth)
	Zoom a surface by independent horizontal and vertical factors with optional smoothing. More...
void	zoomSurfaceSize (int width, int height, double zoomx, double zoomy, int *dstwidth, int *dstheight)
	Calculates the size of the target surface for a zoomSurface() call. More...
SDL_Surface *	shrinkSurface (SDL_Surface *src, int factorx, int factory)
	Shrink a surface by an integer ratio using averaging. More...
SDL_Surface *	rotateSurface90Degrees (SDL_Surface *src, int numClockwiseTurns)
	Rotates a 8/16/24/32 bit surface in increments of 90 degrees. More...

Macro Definition Documentation

SDL2_ROTOZOOM_SCOPE

#define SDL2_ROTOZOOM_SCOPE   extern

Definition at line 78 of file SDL2_rotozoom.h.

SMOOTHING_OFF

#define SMOOTHING_OFF   0

Disable anti-aliasing (no smoothing).

Definition at line 59 of file SDL2_rotozoom.h.

SMOOTHING_ON

#define SMOOTHING_ON   1

Enable anti-aliasing (smoothing).

Definition at line 64 of file SDL2_rotozoom.h.

Function Documentation

rotateSurface90Degrees()

SDL_Surface* rotateSurface90Degrees	(	SDL_Surface *	src,
		int	numClockwiseTurns
	)

Rotates a 8/16/24/32 bit surface in increments of 90 degrees.

Specialized 90 degree rotator which rotates a 'src' surface in 90 degree increments clockwise returning a new surface. Faster than rotozoomer since no scanning or interpolation takes place. Input surface must be 8/16/24/32 bit. (code contributed by J. Schiller, improved by C. Allport and A. Schiffler)

Parameters

src	Source surface to rotate.
numClockwiseTurns	Number of clockwise 90 degree turns to apply to the source.

Returns

The new, rotated surface; or nullptr for surfaces with incorrect input format.

< Surface is in video memory

< Use asynchronous blits if possible

< Surface is RLE encoded

< Surface is in video memory

< Use asynchronous blits if possible

< Surface is RLE encoded

< Surface is in video memory

< Use asynchronous blits if possible

< Surface is RLE encoded

< Surface is in video memory

< Use asynchronous blits if possible

< Surface is RLE encoded

Definition at line 914 of file SDL2_rotozoom.cpp.

{
    int row, col, newWidth, newHeight;
    int bpp, bpr;
    SDL_Surface* dst;
    Uint8* srcBuf;
    Uint8* dstBuf;
    int normalizedClockwiseTurns;
 
    /* Has to be a valid surface pointer and be a Nbit surface where n is divisible by 8 */
    if (!src ||
        !src->format)
    {
        SDL_SetError("NULL source surface or source surface format");
        return nullptr;
    }
 
    if ((src->format->BitsPerPixel % 8) != 0)
    {
        SDL_SetError("Invalid source surface bit depth");
        return nullptr;
    }
 
    /* normalize numClockwiseTurns */
    normalizedClockwiseTurns = (numClockwiseTurns % 4);
    if (normalizedClockwiseTurns < 0)
    {
        normalizedClockwiseTurns += 4;
    }
 
    /* If turns are even, our new width/height will be the same as the source surface */
    if (normalizedClockwiseTurns % 2)
    {
        newWidth = src->h;
        newHeight = src->w;
    }
    else
    {
        newWidth = src->w;
        newHeight = src->h;
    }
 
    dst = SDL_CreateRGBSurface(src->flags,
        newWidth,
        newHeight,
        src->format->BitsPerPixel,
        src->format->Rmask,
        src->format->Gmask,
        src->format->Bmask,
        src->format->Amask);
    if (!dst)
    {
        SDL_SetError("Could not create destination surface");
        return nullptr;
    }
 
    if (SDL_MUSTLOCK(src))
    {
        SDL_LockSurface(src);
    }
    if (SDL_MUSTLOCK(dst))
    {
        SDL_LockSurface(dst);
    }
 
    /* Calculate byte-per-pixel */
    bpp = src->format->BitsPerPixel / 8;
 
    switch (normalizedClockwiseTurns)
    {
    case 0: /* Make a copy of the surface */
        {
            /* Unfortunately SDL_BlitSurface cannot be used to
            make a copy of the surface
            since it does not preserve alpha. */
 
            if (src->pitch == dst->pitch)
            {
                /* If the pitch is the same for both surfaces,
                the memory can be copied all at once. */
                memcpy(dst->pixels, src->pixels, (src->h * src->pitch));
            }
            else
            {
                /* If the pitch differs, copy each row separately */
                srcBuf = static_cast<Uint8*>(src->pixels);
                dstBuf = static_cast<Uint8*>(dst->pixels);
                bpr = src->w * bpp;
                for (row = 0; row < src->h; row++)
                {
                    memcpy(dstBuf, srcBuf, bpr);
                    srcBuf += src->pitch;
                    dstBuf += dst->pitch;
                }
            }
        }
        break;
 
        /* rotate clockwise */
    case 1: /* rotated 90 degrees clockwise */
        {
            for (row = 0; row < src->h; ++row)
            {
                srcBuf = static_cast<Uint8*>(src->pixels) +
                    (row * src->pitch);
                dstBuf = static_cast<Uint8*>(dst->pixels) +
                    (dst->w - row - 1) * bpp;
                for (col = 0; col < src->w; ++col)
                {
                    memcpy (dstBuf, srcBuf, bpp);
                    srcBuf += bpp;
                    dstBuf += dst->pitch;
                }
            }
        }
        break;
 
    case 2: /* rotated 180 degrees clockwise */
        {
            for (row = 0; row < src->h; ++row)
            {
                srcBuf = static_cast<Uint8*>(src->pixels) +
                    (row * src->pitch);
                dstBuf = static_cast<Uint8*>(dst->pixels) +
                    ((dst->h - row - 1) * dst->pitch) + (dst->w - 1) * bpp;
                for (col = 0; col < src->w; ++col)
                {
                    memcpy (dstBuf, srcBuf, bpp);
                    srcBuf += bpp;
                    dstBuf -= bpp;
                }
            }
        }
        break;
 
    case 3: /* rotated 270 degrees clockwise */
        {
            for (row = 0; row < src->h; ++row)
            {
                srcBuf = static_cast<Uint8*>(src->pixels) + (row * src->pitch);
                dstBuf = static_cast<Uint8*>(dst->pixels) +
                    (row * bpp) + (dst->h * dst->pitch);
                for (col = 0; col < src->w; ++col)
                {
                    memcpy (dstBuf, srcBuf, bpp);
                    srcBuf += bpp;
                    dstBuf -= dst->pitch;
                }
            }
        }
        break;
    default:
        break;
    }
    /* end switch */
 
    if (SDL_MUSTLOCK(src))
    {
        SDL_UnlockSurface(src);
    }
    if (SDL_MUSTLOCK(dst))
    {
        SDL_UnlockSurface(dst);
    }
 
    return dst;
}

rotozoomSurface()

SDL_Surface* rotozoomSurface	(	SDL_Surface *	src,
		double	angle,
		double	zoom,
		int	smooth
	)

Rotates and zooms a surface and optional anti-aliasing.

Rotates and zoomes a 32bit or 8bit 'src' surface to newly created 'dst' surface. 'angle' is the rotation in degrees and 'zoom' a scaling factor. If 'smooth' is set then the destination 32bit surface is anti-aliased. If the surface is not 8bit or 32bit RGBA/ABGR it will be converted into a 32bit RGBA format on the fly.

Parameters

src	The surface to rotozoom.
angle	The angle to rotate in degrees.
zoom	The scaling factor.
smooth	Antialiasing flag; set to SMOOTHING_ON to enable.

Returns

The new rotozoomed surface.

Definition at line 1204 of file SDL2_rotozoom.cpp.

{
    return rotozoomSurfaceXY(src, angle, zoom, zoom, smooth);
}

References rotozoomSurfaceXY().

rotozoomSurfaceSize()

void rotozoomSurfaceSize	(	int	width,
		int	height,
		double	angle,
		double	zoom,
		int *	dstwidth,
		int *	dstheight
	)

Returns the size of the resulting target surface for a rotozoomSurface() call.

Parameters

width	The source surface width.
height	The source surface height.
angle	The angle to rotate in degrees.
zoom	The scaling factor.
dstwidth	The calculated width of the rotozoomed destination surface.
dstheight	The calculated height of the rotozoomed destination surface.

Definition at line 1175 of file SDL2_rotozoom.cpp.

{
    double dummy_sanglezoom, dummy_canglezoom;
 
    _rotozoomSurfaceSizeTrig(width, height, angle, zoom, zoom,
        dstwidth, dstheight, &dummy_sanglezoom, &dummy_canglezoom);
}

References _rotozoomSurfaceSizeTrig().

rotozoomSurfaceSizeXY()

void rotozoomSurfaceSizeXY	(	int	width,
		int	height,
		double	angle,
		double	zoomx,
		double	zoomy,
		int *	dstwidth,
		int *	dstheight
	)

Returns the size of the resulting target surface for a rotozoomSurfaceXY() call.

Parameters

width	The source surface width.
height	The source surface height.
angle	The angle to rotate in degrees.
zoomx	The horizontal scaling factor.
zoomy	The vertical scaling factor.
dstwidth	The calculated width of the rotozoomed destination surface.
dstheight	The calculated height of the rotozoomed destination surface.

Definition at line 1150 of file SDL2_rotozoom.cpp.

{
    double dummy_sanglezoom, dummy_canglezoom;
 
    _rotozoomSurfaceSizeTrig(width, height, angle, zoomx, zoomy,
        dstwidth, dstheight, &dummy_sanglezoom, &dummy_canglezoom);
}

References _rotozoomSurfaceSizeTrig().

rotozoomSurfaceXY()

SDL_Surface* rotozoomSurfaceXY	(	SDL_Surface *	src,
		double	angle,
		double	zoomx,
		double	zoomy,
		int	smooth
	)

Rotates and zooms a surface with different horizontal and vertival scaling factors and optional anti-aliasing.

Rotates and zooms a 32bit or 8bit 'src' surface to newly created 'dst' surface. 'angle' is the rotation in degrees, 'zoomx and 'zoomy' scaling factors. If 'smooth' is set then the destination 32bit surface is anti-aliased. If the surface is not 8bit or 32bit RGBA/ABGR it will be converted into a 32bit RGBA format on the fly.

Parameters

src	The surface to rotozoom.
angle	The angle to rotate in degrees.
zoomx	The horizontal scaling factor.
zoomy	The vertical scaling factor.
smooth	Antialiasing flag; set to SMOOTHING_ON to enable.

Returns

The new rotozoomed surface.

< Surface is in system memory

< Surface is in system memory

< Surface is in system memory

< Surface is in video memory

< Use asynchronous blits if possible

< Surface is RLE encoded

< Surface is in video memory

< Use asynchronous blits if possible

< Surface is RLE encoded

< Surface is in system memory

< Surface is in system memory

< Surface is in video memory

< Use asynchronous blits if possible

< Surface is RLE encoded

< Surface is in video memory

< Use asynchronous blits if possible

< Surface is RLE encoded

Definition at line 1230 of file SDL2_rotozoom.cpp.

{
    SDL_Surface *rz_src;
    SDL_Surface *rz_dst;
    double zoominv;
    double sanglezoom, canglezoom, sanglezoominv, canglezoominv;
    int dstwidthhalf, dstwidth, dstheighthalf, dstheight;
    int is32bit;
    int i, src_converted;
    int flipx,flipy;
 
    /*
    * Sanity check
    */
    if (src == nullptr)
    {
        return (nullptr);
    }
 
    /*
    * Determine if source surface is 32bit or 8bit
    */
    is32bit = (src->format->BitsPerPixel == 32);
    if ((is32bit) || (src->format->BitsPerPixel == 8))
    {
        /*
        * Use source surface 'as is'
        */
        rz_src = src;
        src_converted = 0;
    }
    else
    {
        /*
        * New source surface is 32bit with a defined RGBA ordering
        */
        rz_src =
            SDL_CreateRGBSurface(SDL_SWSURFACE, src->w, src->h, 32,
#if SDL_BYTEORDER == SDL_LIL_ENDIAN
            0x000000ff, 0x0000ff00, 0x00ff0000, 0xff000000
#else
            0xff000000,  0x00ff0000, 0x0000ff00, 0x000000ff
#endif
            );
 
        SDL_BlitSurface(src, nullptr, rz_src, nullptr);
 
        src_converted = 1;
        is32bit = 1;
    }
 
    /*
    * Sanity check zoom factor
    */
    flipx = (zoomx<0.0);
    if (flipx) zoomx=-zoomx;
    flipy = (zoomy<0.0);
    if (flipy) zoomy=-zoomy;
    if (zoomx < VALUE_LIMIT) zoomx = VALUE_LIMIT;
    if (zoomy < VALUE_LIMIT) zoomy = VALUE_LIMIT;
    zoominv = 65536.0 / (zoomx * zoomx);
 
    /*
    * Check if we have a rotozoom or just a zoom
    */
    if (fabs(angle) > VALUE_LIMIT)
    {
 
        /*
        * Angle!=0: full rotozoom
        */
        /*
        * -----------------------
        */
 
        /* Determine target size */
        _rotozoomSurfaceSizeTrig(rz_src->w, rz_src->h, angle, zoomx, zoomy,
            &dstwidth, &dstheight, &canglezoom, &sanglezoom);
 
        /*
        * Calculate target factors from sin/cos and zoom
        */
        sanglezoominv = sanglezoom;
        canglezoominv = canglezoom;
        sanglezoominv *= zoominv;
        canglezoominv *= zoominv;
 
        /* Calculate half size */
        dstwidthhalf = dstwidth / 2;
        dstheighthalf = dstheight / 2;
 
        /*
        * Alloc space to completely contain the rotated surface
        */
        rz_dst = nullptr;
        if (is32bit)
        {
            /*
            * Target surface is 32bit with source RGBA/ABGR ordering
            */
            rz_dst =
                SDL_CreateRGBSurface(SDL_SWSURFACE,
                dstwidth, dstheight + GUARD_ROWS, 32,
                rz_src->format->Rmask, rz_src->format->Gmask,
                rz_src->format->Bmask, rz_src->format->Amask);
        }
        else
        {
            /*
            * Target surface is 8bit
            */
            rz_dst = SDL_CreateRGBSurface(SDL_SWSURFACE, dstwidth,
                dstheight + GUARD_ROWS, 8, 0, 0, 0, 0);
        }
 
        /* Check target */
        if (rz_dst == nullptr)
            return nullptr;
 
        /* Adjust for guard rows */
        rz_dst->h = dstheight;
 
        /*
        * Lock source surface
        */
        if (SDL_MUSTLOCK(rz_src))
        {
            SDL_LockSurface(rz_src);
        }
 
        /*
        * Check which kind of surface we have
        */
        if (is32bit)
        {
            /*
            * Call the 32bit transformation routine to do the rotation
            * (using alpha)
            */
            _transformSurfaceRGBA(rz_src, rz_dst, dstwidthhalf, dstheighthalf,
                static_cast<int>(sanglezoominv),
                static_cast<int>(canglezoominv),
                flipx, flipy,
                smooth);
        }
        else
        {
            /*
            * Copy palette and colorkey info
            */
            for (i = 0; i < rz_src->format->palette->ncolors; i++)
            {
                rz_dst->format->palette->colors[i] =
                    rz_src->format->palette->colors[i];
            }
            rz_dst->format->palette->ncolors =
                rz_src->format->palette->ncolors;
            /*
            * Call the 8bit transformation routine to do the rotation
            */
            transformSurfaceY(rz_src, rz_dst, dstwidthhalf, dstheighthalf,
                static_cast<int>(sanglezoominv),
                static_cast<int>(canglezoominv),
                flipx, flipy);
        }
        /*
        * Unlock source surface
        */
        if (SDL_MUSTLOCK(rz_src))
        {
            SDL_UnlockSurface(rz_src);
        }
 
    }
    else
    {
        /*
        * Angle=0: Just a zoom
        */
        /*
        * --------------------
        */
 
        /*
        * Calculate target size
        */
        zoomSurfaceSize(rz_src->w, rz_src->h, zoomx, zoomy,
            &dstwidth, &dstheight);
 
        /*
        * Alloc space to completely contain the zoomed surface
        */
        rz_dst = nullptr;
        if (is32bit)
        {
            /*
            * Target surface is 32bit with source RGBA/ABGR ordering
            */
            rz_dst =
                SDL_CreateRGBSurface(SDL_SWSURFACE,
                dstwidth, dstheight + GUARD_ROWS, 32,
                rz_src->format->Rmask, rz_src->format->Gmask,
                rz_src->format->Bmask, rz_src->format->Amask);
        }
        else
        {
            /*
            * Target surface is 8bit
            */
            rz_dst = SDL_CreateRGBSurface(SDL_SWSURFACE,
                dstwidth, dstheight + GUARD_ROWS, 8, 0, 0, 0, 0);
        }
 
        /* Check target */
        if (rz_dst == nullptr)
            return nullptr;
 
        /* Adjust for guard rows */
        rz_dst->h = dstheight;
 
        /*
        * Lock source surface
        */
        if (SDL_MUSTLOCK(rz_src))
        {
            SDL_LockSurface(rz_src);
        }
 
        /*
        * Check which kind of surface we have
        */
        if (is32bit)
        {
            /*
            * Call the 32bit transformation routine to do the zooming
            * (using alpha)
            */
            _zoomSurfaceRGBA(rz_src, rz_dst, flipx, flipy, smooth);
 
        }
        else
        {
            /*
            * Copy palette and colorkey info
            */
            for (i = 0; i < rz_src->format->palette->ncolors; i++)
            {
                rz_dst->format->palette->colors[i] =
                    rz_src->format->palette->colors[i];
            }
            rz_dst->format->palette->ncolors =
                rz_src->format->palette->ncolors;
 
            /*
            * Call the 8bit transformation routine to do the zooming
            */
            _zoomSurfaceY(rz_src, rz_dst, flipx, flipy);
        }
 
        /*
        * Unlock source surface
        */
        if (SDL_MUSTLOCK(rz_src))
        {
            SDL_UnlockSurface(rz_src);
        }
    }
 
    /*
    * Cleanup temp surface
    */
    if (src_converted)
    {
        SDL_FreeSurface(rz_src);
    }
 
    /*
    * Return destination surface
    */
    return (rz_dst);
}

References _rotozoomSurfaceSizeTrig(), _transformSurfaceRGBA(), _zoomSurfaceRGBA(), _zoomSurfaceY(), GUARD_ROWS, transformSurfaceY(), VALUE_LIMIT, and zoomSurfaceSize().

Referenced by rotozoomSurface().

shrinkSurface()

SDL_Surface* shrinkSurface	(	SDL_Surface *	src,
		int	factorx,
		int	factory
	)

Shrink a surface by an integer ratio using averaging.

Shrinks a 32bit or 8bit 'src' surface to a newly created 'dst' surface. 'factorx' and 'factory' are the shrinking ratios (i.e. 2=1/2 the size, 3=1/3 the size, etc.) The destination surface is antialiased by averaging the source box RGBA or Y information. If the surface is not 8bit or 32bit RGBA/ABGR it will be converted into a 32bit RGBA format on the fly. The input surface is not modified. The output surface is newly allocated.

Parameters

src	The surface to shrink.
factorx	The horizontal shrinking ratio.
factory	The vertical shrinking ratio.

Returns

The new, shrunken surface.

< Surface is in system memory

< Surface is in video memory

< Use asynchronous blits if possible

< Surface is RLE encoded

< Surface is in system memory

< Surface is in system memory

< Surface is in video memory

< Use asynchronous blits if possible

< Surface is RLE encoded

Definition at line 1762 of file SDL2_rotozoom.cpp.

{
    int result;
    SDL_Surface *rz_src;
    SDL_Surface *rz_dst = nullptr;
    int dstwidth, dstheight;
    int is32bit;
    int i, src_converted = 0;
    int haveError = 0;
 
    /*
    * Sanity check
    */
    if (src == nullptr)
    {
        return (nullptr);
    }
 
    /*
    * Determine if source surface is 32bit or 8bit
    */
    is32bit = (src->format->BitsPerPixel == 32);
    if ((is32bit) || (src->format->BitsPerPixel == 8))
    {
        /*
        * Use source surface 'as is'
        */
        rz_src = src;
        src_converted = 0;
    }
    else
    {
        /*
        * New source surface is 32bit with a defined RGBA ordering
        */
        rz_src = SDL_CreateRGBSurface(SDL_SWSURFACE, src->w, src->h, 32,
#if SDL_BYTEORDER == SDL_LIL_ENDIAN
            0x000000ff, 0x0000ff00, 0x00ff0000, 0xff000000
#else
            0xff000000,  0x00ff0000, 0x0000ff00, 0x000000ff
#endif
            );
        if (rz_src==nullptr)
        {
            haveError = 1;
            goto exitShrinkSurface;
        }
 
        SDL_BlitSurface(src, nullptr, rz_src, nullptr);
        src_converted = 1;
        is32bit = 1;
    }
 
    /*
    * Lock the surface
    */
    if (SDL_MUSTLOCK(rz_src))
    {
        if (SDL_LockSurface(rz_src) < 0)
        {
            haveError = 1;
            goto exitShrinkSurface;
        }
    }
 
    /* Get size for target */
    dstwidth=rz_src->w/factorx;
    while (dstwidth*factorx>rz_src->w)
    {
        dstwidth--;
    }
    dstheight=rz_src->h/factory;
    while (dstheight*factory>rz_src->h)
    {
        dstheight--;
    }
 
    /*
    * Alloc space to completely contain the shrunken surface
    * (with added guard rows)
    */
    if (is32bit==1)
    {
        /*
        * Target surface is 32bit with source RGBA/ABGR ordering
        */
        rz_dst = SDL_CreateRGBSurface(
            SDL_SWSURFACE, dstwidth, dstheight + GUARD_ROWS, 32,
            rz_src->format->Rmask, rz_src->format->Gmask,
            rz_src->format->Bmask, rz_src->format->Amask);
    }
    else
    {
        /*
        * Target surface is 8bit
        */
        rz_dst = SDL_CreateRGBSurface(SDL_SWSURFACE,
            dstwidth, dstheight + GUARD_ROWS, 8, 0, 0, 0, 0);
    }
 
    /* Check target */
    if (rz_dst == nullptr)
    {
        haveError = 1;
        goto exitShrinkSurface;
    }
 
    /* Adjust for guard rows */
    rz_dst->h = dstheight;
 
    /*
    * Check which kind of surface we have
    */
    if (is32bit==1)
    {
        /*
        * Call the 32bit transformation routine to do the shrinking (using alpha)
        */
        result = _shrinkSurfaceRGBA(rz_src, rz_dst, factorx, factory);
        if ((result!=0) || (rz_dst==nullptr))
        {
            haveError = 1;
            goto exitShrinkSurface;
        }
    }
    else
    {
        /*
        * Copy palette and colorkey info
        */
        for (i = 0; i < rz_src->format->palette->ncolors; i++)
        {
            rz_dst->format->palette->colors[i] = rz_src->format->palette->colors[i];
        }
        rz_dst->format->palette->ncolors = rz_src->format->palette->ncolors;
        /*
        * Call the 8bit transformation routine to do the shrinking
        */
        result = _shrinkSurfaceY(rz_src, rz_dst, factorx, factory);
        if (result!=0)
        {
            haveError = 1;
            goto exitShrinkSurface;
        }
    }
 
exitShrinkSurface:
    if (rz_src!=nullptr)
    {
        /*
        * Unlock source surface
        */
        if (SDL_MUSTLOCK(rz_src))
        {
            SDL_UnlockSurface(rz_src);
        }
 
        /*
        * Cleanup temp surface
        */
        if (src_converted==1)
        {
            SDL_FreeSurface(rz_src);
        }
    }
 
    /* Check error state; maybe need to cleanup destination */
    if (haveError==1)
    {
        if (rz_dst!=nullptr)
        {
            SDL_FreeSurface(rz_dst);
        }
        rz_dst=nullptr;
    }
 
    /*
    * Return destination surface
    */
    return (rz_dst);
}

References _shrinkSurfaceRGBA(), _shrinkSurfaceY(), and GUARD_ROWS.

zoomSurface()

SDL_Surface* zoomSurface	(	SDL_Surface *	src,
		double	zoomx,
		double	zoomy,
		int	smooth
	)

Zoom a surface by independent horizontal and vertical factors with optional smoothing.

Zooms a 32bit or 8bit 'src' surface to newly created 'dst' surface. 'zoomx' and 'zoomy' are scaling factors for width and height. If 'smooth' is on then the destination 32bit surface is anti-aliased. If the surface is not 8bit or 32bit RGBA/ABGR it will be converted into a 32bit RGBA format on the fly. If zoom factors are negative, the image is flipped on the axes.

Parameters

src	The surface to zoom.
zoomx	The horizontal zoom factor.
zoomy	The vertical zoom factor.
smooth	Antialiasing flag; set to SMOOTHING_ON to enable.

Returns

The new, zoomed surface.

< Surface is in system memory

< Surface is in system memory

< Surface is in system memory

< Surface is in video memory

< Use asynchronous blits if possible

< Surface is RLE encoded

< Surface is in video memory

< Use asynchronous blits if possible

< Surface is RLE encoded

Definition at line 1590 of file SDL2_rotozoom.cpp.

{
    SDL_Surface *rz_src;
    SDL_Surface *rz_dst;
    int dstwidth, dstheight;
    int is32bit;
    int i, src_converted;
    int flipx, flipy;
 
    /*
    * Sanity check
    */
    if (src == nullptr)
        return (nullptr);
 
    /*
    * Determine if source surface is 32bit or 8bit
    */
    is32bit = (src->format->BitsPerPixel == 32);
    if ((is32bit) || (src->format->BitsPerPixel == 8))
    {
        /*
        * Use source surface 'as is'
        */
        rz_src = src;
        src_converted = 0;
    }
    else
    {
        /*
        * New source surface is 32bit with a defined RGBA ordering
        */
        rz_src =
            SDL_CreateRGBSurface(SDL_SWSURFACE, src->w, src->h, 32,
#if SDL_BYTEORDER == SDL_LIL_ENDIAN
            0x000000ff, 0x0000ff00, 0x00ff0000, 0xff000000
#else
            0xff000000,  0x00ff0000, 0x0000ff00, 0x000000ff
#endif
            );
        if (rz_src == nullptr)
        {
            return nullptr;
        }
        SDL_BlitSurface(src, nullptr, rz_src, nullptr);
        src_converted = 1;
        is32bit = 1;
    }
 
    flipx = (zoomx<0.0);
    if (flipx) zoomx = -zoomx;
    flipy = (zoomy<0.0);
    if (flipy) zoomy = -zoomy;
 
    /* Get size if target */
    zoomSurfaceSize(rz_src->w, rz_src->h, zoomx, zoomy, &dstwidth, &dstheight);
 
    /*
    * Alloc space to completely contain the zoomed surface
    */
    rz_dst = nullptr;
    if (is32bit)
    {
        /*
        * Target surface is 32bit with source RGBA/ABGR ordering
        */
        rz_dst = SDL_CreateRGBSurface(SDL_SWSURFACE,
            dstwidth, dstheight + GUARD_ROWS, 32,
            rz_src->format->Rmask, rz_src->format->Gmask,
            rz_src->format->Bmask, rz_src->format->Amask);
    }
    else
    {
        /*
        * Target surface is 8bit
        */
        rz_dst = SDL_CreateRGBSurface(SDL_SWSURFACE,
            dstwidth, dstheight + GUARD_ROWS, 8, 0, 0, 0, 0);
    }
 
    /* Check target */
    if (rz_dst == nullptr)
    {
        /*
        * Cleanup temp surface
        */
        if (src_converted)
        {
            SDL_FreeSurface(rz_src);
        }
        return nullptr;
    }
 
    /* Adjust for guard rows */
    rz_dst->h = dstheight;
 
    /*
    * Lock source surface
    */
    if (SDL_MUSTLOCK(rz_src))
    {
        SDL_LockSurface(rz_src);
    }
 
    /*
    * Check which kind of surface we have
    */
    if (is32bit)
    {
        /*
        * Call the 32bit transformation routine to do the zooming (using alpha)
        */
        _zoomSurfaceRGBA(rz_src, rz_dst, flipx, flipy, smooth);
    }
    else
    {
        /*
        * Copy palette and colorkey info
        */
        for (i = 0; i < rz_src->format->palette->ncolors; i++)
        {
            rz_dst->format->palette->colors[i] =
                rz_src->format->palette->colors[i];
        }
        rz_dst->format->palette->ncolors = rz_src->format->palette->ncolors;
        /*
        * Call the 8bit transformation routine to do the zooming
        */
        _zoomSurfaceY(rz_src, rz_dst, flipx, flipy);
    }
    /*
    * Unlock source surface
    */
    if (SDL_MUSTLOCK(rz_src))
    {
        SDL_UnlockSurface(rz_src);
    }
 
    /*
    * Cleanup temp surface
    */
    if (src_converted)
    {
        SDL_FreeSurface(rz_src);
    }
 
    /*
    * Return destination surface
    */
    return (rz_dst);
}

References _zoomSurfaceRGBA(), _zoomSurfaceY(), GUARD_ROWS, and zoomSurfaceSize().

zoomSurfaceSize()

void zoomSurfaceSize	(	int	width,
		int	height,
		double	zoomx,
		double	zoomy,
		int *	dstwidth,
		int *	dstheight
	)

Calculates the size of the target surface for a zoomSurface() call.

The minimum size of the target surface is 1. The input factors can be positive or negative.

Parameters

width	The width of the source surface to zoom.
height	The height of the source surface to zoom.
zoomx	The horizontal zoom factor.
zoomy	The vertical zoom factor.
dstwidth	Pointer to an integer to store the calculated width of the zoomed target surface.
dstheight	Pointer to an integer to store the calculated height of the zoomed target surface.

Definition at line 1531 of file SDL2_rotozoom.cpp.

{
    /*
    * Make zoom factors positive
    */
    int flipx, flipy;
    flipx = (zoomx<0.0);
    if (flipx) zoomx = -zoomx;
    flipy = (zoomy<0.0);
    if (flipy) zoomy = -zoomy;
 
    /*
    * Sanity check zoom factors
    */
    if (zoomx < VALUE_LIMIT)
    {
        zoomx = VALUE_LIMIT;
    }
    if (zoomy < VALUE_LIMIT)
    {
        zoomy = VALUE_LIMIT;
    }
 
    /*
    * Calculate target size
    */
    *dstwidth = static_cast<int>(floor((static_cast<double>(
        width) * zoomx) + 0.5));
    *dstheight = static_cast<int>(floor((static_cast<double>(
        height) * zoomy) + 0.5));
    if (*dstwidth < 1)
    {
        *dstwidth = 1;
    }
    if (*dstheight < 1)
    {
        *dstheight = 1;
    }
}

References VALUE_LIMIT.

Referenced by rotozoomSurfaceXY(), and zoomSurface().