use wxWindows zlib.h instead of Mac OS X system zlib.h directly

[wxWidgets.git] / src / common / imagbmp.cpp

/////////////////////////////////////////////////////////////////////////////
// Name:        imagbmp.cpp
// Purpose:     wxImage BMP handler
// Author:      Robert Roebling
// RCS-ID:      $Id$
// Copyright:   (c) Robert Roebling
// Licence:     wxWindows licence
/////////////////////////////////////////////////////////////////////////////

#ifdef __GNUG__
#pragma implementation "imagbmp.h"
#endif

// For compilers that support precompilation, includes "wx.h".
#include "wx/wxprec.h"

#ifdef __BORLANDC__
#pragma hdrstop
#endif

#include "wx/defs.h"

#if wxUSE_IMAGE

#include "wx/imagbmp.h"
#include "wx/bitmap.h"
#include "wx/debug.h"
#include "wx/log.h"
#include "wx/app.h"
#include "wx/filefn.h"
#include "wx/wfstream.h"
#include "wx/intl.h"
#include "wx/module.h"
#include "wx/quantize.h"

// For memcpy
#include <string.h>

#ifdef __SALFORDC__
#ifdef FAR
#undef FAR
#endif
#endif

#ifdef __WXMSW__
#include <windows.h>
#endif

//-----------------------------------------------------------------------------
// wxBMPHandler
//-----------------------------------------------------------------------------

IMPLEMENT_DYNAMIC_CLASS(wxBMPHandler,wxImageHandler)


#if wxUSE_STREAMS


bool wxBMPHandler::SaveFile(wxImage *image,
                            wxOutputStream& stream,
                            bool verbose)
{
    wxCHECK_MSG( image, FALSE, _T("invalid pointer in wxBMPHandler::SaveFile") );

    if (!image->Ok())
    {
        if (verbose) wxLogError(_("BMP: Couldn't save invalid image."));
        return FALSE;
    }

    // get the format of the BMP file to save, else use 24bpp
    unsigned format = wxBMP_24BPP;
    if (image->HasOption(wxBMP_FORMAT))
        format = image->GetOptionInt(wxBMP_FORMAT);

    unsigned bpp;     // # of bits per pixel
    int palette_size; // # of color map entries, ie. 2^bpp colors

    // set the bpp and appropriate palette_size, and do additional checks
    if ((format == wxBMP_1BPP) || (format == wxBMP_1BPP_BW))
    {
        bpp = 1;
        palette_size = 2;
    }
    else if (format == wxBMP_4BPP)
    {
        bpp = 4;
        palette_size = 16;
    }
    else if ((format == wxBMP_8BPP) || (format == wxBMP_8BPP_GREY) ||
             (format == wxBMP_8BPP_RED) || (format == wxBMP_8BPP_PALETTE))
    {
        // need to set a wxPalette to use this, HOW TO CHECK IF VALID, SIZE?
        if ((format == wxBMP_8BPP_PALETTE)
#if wxUSE_PALETTE
                && !image->HasPalette()
#endif // wxUSE_PALETTE
            )
        {
            if (verbose)
                wxLogError(_("BMP: wImage doesn't have own wxPalette."));
            return FALSE;
        }
        bpp = 8;
        palette_size = 256;
    }
    else  // you get 24bpp
    {
        format = wxBMP_24BPP;
        bpp = 24;
        palette_size = 0;
    }

    unsigned width = image->GetWidth();
    unsigned row_padding = (4 - int(width*bpp/8.0) % 4) % 4; // # bytes to pad to dword
    unsigned row_width = int(width * bpp/8.0) + row_padding; // # of bytes per row

    struct
    {
        // BitmapHeader:
        wxUint16  magic;          // format magic, always 'BM'
        wxUint32  filesize;       // total file size, inc. headers
        wxUint32  reserved;       // for future use
        wxUint32  data_offset;    // image data offset in the file

        // BitmapInfoHeader:
        wxUint32  bih_size;       // 2nd part's size
        wxUint32  width, height;  // bitmap's dimensions
        wxUint16  planes;         // num of planes
        wxUint16  bpp;            // bits per pixel
        wxUint32  compression;    // compression method
        wxUint32  size_of_bmp;    // size of the bitmap
        wxUint32  h_res, v_res;   // image resolution in dpi
        wxUint32  num_clrs;       // number of colors used
        wxUint32  num_signif_clrs;// number of significant colors
    } hdr;

    wxUint32 hdr_size = 14/*BitmapHeader*/ + 40/*BitmapInfoHeader*/;

    hdr.magic = wxUINT16_SWAP_ON_BE(0x4D42/*'BM'*/);
    hdr.filesize = wxUINT32_SWAP_ON_BE( hdr_size + palette_size*4 +
                                        row_width * image->GetHeight() );
    hdr.reserved = 0;
    hdr.data_offset = wxUINT32_SWAP_ON_BE(hdr_size + palette_size*4);

    hdr.bih_size = wxUINT32_SWAP_ON_BE(hdr_size - 14);
    hdr.width = wxUINT32_SWAP_ON_BE(image->GetWidth());
    hdr.height = wxUINT32_SWAP_ON_BE(image->GetHeight());
    hdr.planes = wxUINT16_SWAP_ON_BE(1); // always 1 plane
    hdr.bpp = wxUINT16_SWAP_ON_BE(bpp);
    hdr.compression = 0; // RGB uncompressed
    hdr.size_of_bmp = wxUINT32_SWAP_ON_BE(row_width * image->GetHeight());
    hdr.h_res = hdr.v_res = wxUINT32_SWAP_ON_BE(72);  // 72dpi is standard
    hdr.num_clrs = wxUINT32_SWAP_ON_BE(palette_size); // # colors in colormap
    hdr.num_signif_clrs = 0;     // all colors are significant

    if (// VS: looks ugly but compilers tend to do ugly things with structs,
        //     like aligning hdr.filesize's ofset to dword :(
        // VZ: we should add padding then...
        !stream.Write(&hdr.magic, 2) ||
        !stream.Write(&hdr.filesize, 4) ||
        !stream.Write(&hdr.reserved, 4) ||
        !stream.Write(&hdr.data_offset, 4) ||
        !stream.Write(&hdr.bih_size, 4) ||
        !stream.Write(&hdr.width, 4) ||
        !stream.Write(&hdr.height, 4) ||
        !stream.Write(&hdr.planes, 2) ||
        !stream.Write(&hdr.bpp, 2) ||
        !stream.Write(&hdr.compression, 4) ||
        !stream.Write(&hdr.size_of_bmp, 4) ||
        !stream.Write(&hdr.h_res, 4) ||
        !stream.Write(&hdr.v_res, 4) ||
        !stream.Write(&hdr.num_clrs, 4) ||
        !stream.Write(&hdr.num_signif_clrs, 4)
       )
    {
        if (verbose)
            wxLogError(_("BMP: Couldn't write the file header."));
        return FALSE;
    }

    wxPalette *palette = NULL; // entries for quantized images
    wxUint8 *rgbquad = NULL;   // for the RGBQUAD bytes for the colormap
    wxImage *q_image = NULL;   // destination for quantized image

    // if <24bpp use quantization to reduce colors for *some* of the formats
    if ( (format == wxBMP_1BPP) || (format == wxBMP_4BPP) ||
         (format == wxBMP_8BPP) || (format == wxBMP_8BPP_PALETTE))
    {
        // make a new palette and quantize the image
        if (format != wxBMP_8BPP_PALETTE)
        {
            q_image = new wxImage();

            // I get a delete error using Quantize when desired colors > 236
            int quantize = ((palette_size > 236) ? 236 : palette_size);
            // fill the destination too, it gives much nicer 4bpp images
            wxQuantize::Quantize( *image, *q_image, &palette, quantize, 0,
                                  wxQUANTIZE_FILL_DESTINATION_IMAGE );
        }
        else
        {
#if wxUSE_PALETTE
            palette = new wxPalette(image->GetPalette());
#endif // wxUSE_PALETTE
        }

        int i;
        unsigned char r, g, b;
        rgbquad = new wxUint8 [palette_size*4];

        for (i=0; i<palette_size; i++)
        {
#if wxUSE_PALETTE
            if (!palette->GetRGB( i, &r, &g, &b ))
#endif // wxUSE_PALETTE
                r = g = b = 0;

            rgbquad[i*4] = b;
            rgbquad[i*4+1] = g;
            rgbquad[i*4+2] = r;
            rgbquad[i*4+3] = 0;
        }
    }
    // make a 256 entry greyscale colormap or 2 entry black & white
    else if ((format == wxBMP_8BPP_GREY) || (format == wxBMP_8BPP_RED) ||
             (format == wxBMP_1BPP_BW))
    {
        int i;
        rgbquad = new wxUint8 [palette_size*4];

        for (i=0; i<palette_size; i++)
        {
            // if 1BPP_BW then just 0 and 255 then exit
            if (( i > 0) && (format == wxBMP_1BPP_BW)) i = 255;
            rgbquad[i*4] = i;
            rgbquad[i*4+1] = i;
            rgbquad[i*4+2] = i;
            rgbquad[i*4+3] = 0;
        }
    }

    // if the colormap was made, then it needs to be written
    if (rgbquad)
    {
        if (!stream.Write(rgbquad, palette_size*4))
        {
            if (verbose)
                wxLogError(_("BMP: Couldn't write RGB color map."));
            delete [] rgbquad;
#if wxUSE_PALETTE
            delete palette;
#endif // wxUSE_PALETTE
            delete q_image;
            return FALSE;
        }
        delete []rgbquad;
    }

    // pointer to the image data, use quantized if available
    wxUint8 *data = (wxUint8*) image->GetData();
    if (q_image) if (q_image->Ok()) data = (wxUint8*) q_image->GetData();

    wxUint8 *buffer = new wxUint8[row_width];
    memset(buffer, 0, row_width);
    int y; unsigned x;
    long int pixel;

    for (y = image->GetHeight() -1 ; y >= 0; y--)
    {
        if (format == wxBMP_24BPP)  // 3 bytes per pixel red,green,blue
        {
            for (x = 0; x < width; x++)
            {
                pixel = 3*(y*width + x);

                buffer[3*x    ] = data[pixel+2];
                buffer[3*x + 1] = data[pixel+1];
                buffer[3*x + 2] = data[pixel];
            }
        }
        else if ((format == wxBMP_8BPP) ||       // 1 byte per pixel in color
                 (format == wxBMP_8BPP_PALETTE))
        {
            for (x = 0; x < width; x++)
            {
                pixel = 3*(y*width + x);
#if wxUSE_PALETTE
                buffer[x] = palette->GetPixel( data[pixel],
                                               data[pixel+1],
                                               data[pixel+2] );
#else
                // FIXME: what should this be? use some std palette maybe?
                buffer[x] = 0;
#endif // wxUSE_PALETTE
            }
        }
        else if (format == wxBMP_8BPP_GREY) // 1 byte per pix, rgb ave to grey
        {
            for (x = 0; x < width; x++)
            {
                pixel = 3*(y*width + x);
                buffer[x] = (wxUint8)(.299*data[pixel] +
                                      .587*data[pixel+1] +
                                      .114*data[pixel+2]);
            }
        }
        else if (format == wxBMP_8BPP_RED) // 1 byte per pixel, red as greys
        {
            for (x = 0; x < width; x++)
            {
                buffer[x] = (wxUint8)data[3*(y*width + x)];
            }
        }
        else if (format == wxBMP_4BPP) // 4 bpp in color
        {
            for (x = 0; x < width; x+=2)
            {
                pixel = 3*(y*width + x);

                // fill buffer, ignore if > width
#if wxUSE_PALETTE
                buffer[x/2] =
                    ((wxUint8)palette->GetPixel(data[pixel],
                                                data[pixel+1],
                                                data[pixel+2]) << 4) |
                    (((x+1) > width)
                     ? 0
                     : ((wxUint8)palette->GetPixel(data[pixel+3],
                                                   data[pixel+4],
                                                   data[pixel+5]) ));
#else
                // FIXME: what should this be? use some std palette maybe?
                buffer[x/2] = 0;
#endif // wxUSE_PALETTE
            }
        }
        else if (format == wxBMP_1BPP) // 1 bpp in "color"
        {
            for (x = 0; x < width; x+=8)
            {
                pixel = 3*(y*width + x);

#if wxUSE_PALETTE
                buffer[x/8] = ((wxUint8)palette->GetPixel(data[pixel], data[pixel+1], data[pixel+2]) << 7) |
                    (((x+1) > width) ? 0 : ((wxUint8)palette->GetPixel(data[pixel+3], data[pixel+4], data[pixel+5]) << 6)) |
                    (((x+2) > width) ? 0 : ((wxUint8)palette->GetPixel(data[pixel+6], data[pixel+7], data[pixel+8]) << 5)) |
                    (((x+3) > width) ? 0 : ((wxUint8)palette->GetPixel(data[pixel+9], data[pixel+10], data[pixel+11]) << 4)) |
                    (((x+4) > width) ? 0 : ((wxUint8)palette->GetPixel(data[pixel+12], data[pixel+13], data[pixel+14]) << 3)) |
                    (((x+5) > width) ? 0 : ((wxUint8)palette->GetPixel(data[pixel+15], data[pixel+16], data[pixel+17]) << 2)) |
                    (((x+6) > width) ? 0 : ((wxUint8)palette->GetPixel(data[pixel+18], data[pixel+19], data[pixel+20]) << 1)) |
                    (((x+7) > width) ? 0 : ((wxUint8)palette->GetPixel(data[pixel+21], data[pixel+22], data[pixel+23])     ));
#else
                // FIXME: what should this be? use some std palette maybe?
                buffer[x/8] = 0;
#endif // wxUSE_PALETTE
            }
        }
        else if (format == wxBMP_1BPP_BW) // 1 bpp B&W colormap from red color ONLY
        {
            for (x = 0; x < width; x+=8)
            {
                pixel = 3*(y*width + x);

                buffer[x/8] =
                                            (((wxUint8)(data[pixel]   /128.)) << 7) |
                    ( ((x+1) > width) ? 0 : (((wxUint8)(data[pixel+3] /128.)) << 6)) |
                    ( ((x+2) > width) ? 0 : (((wxUint8)(data[pixel+6] /128.)) << 5)) |
                    ( ((x+3) > width) ? 0 : (((wxUint8)(data[pixel+9] /128.)) << 4)) |
                    ( ((x+4) > width) ? 0 : (((wxUint8)(data[pixel+12]/128.)) << 3)) |
                    ( ((x+5) > width) ? 0 : (((wxUint8)(data[pixel+15]/128.)) << 2)) |
                    ( ((x+6) > width) ? 0 : (((wxUint8)(data[pixel+18]/128.)) << 1)) |
                    ( ((x+7) > width) ? 0 : (((wxUint8)(data[pixel+21]/128.))     ));
            }
        }

        if (!stream.Write(buffer, row_width))
        {
            if (verbose)
                wxLogError(_("BMP: Couldn't write data."));
            delete[] buffer;
#if wxUSE_PALETTE
            delete palette;
#endif // wxUSE_PALETTE
            delete q_image;
            return FALSE;
        }
    }
    delete[] buffer;
#if wxUSE_PALETTE
    delete palette;
#endif // wxUSE_PALETTE
    delete q_image;

    return TRUE;
}



#ifndef BI_RGB
#define BI_RGB       0
#define BI_RLE8      1
#define BI_RLE4      2
#endif

#ifndef BI_BITFIELDS
#define BI_BITFIELDS 3
#endif

#define poffset (line * width * 3 + column * 3)

bool wxBMPHandler::LoadFile( wxImage *image, wxInputStream& stream, bool verbose, int WXUNUSED(index) )
{
    int             rshift = 0, gshift = 0, bshift = 0;
    wxUint8         aByte;
    wxUint16        aWord;
    wxInt32         dbuf[4];
	wxInt32         aDword, rmask = 0, gmask = 0, bmask = 0;
    wxInt8          bbuf[4];
    struct _cmap {
        unsigned char r, g, b;
    } *cmap = NULL;

    off_t start_offset = stream.TellI();
    if (start_offset == wxInvalidOffset) start_offset = 0;

    image->Destroy();

    /*
     * Read the BMP header
     */

    stream.Read( bbuf, 2 );
    stream.Read( dbuf, 4 * 4 );

#if 0 // unused
    wxInt32 size = wxINT32_SWAP_ON_BE( dbuf[0] );
#endif
    wxInt32 offset = wxINT32_SWAP_ON_BE( dbuf[2] );

    stream.Read(dbuf, 4 * 2);
    int width = (int)wxINT32_SWAP_ON_BE( dbuf[0] );
    int height = (int)wxINT32_SWAP_ON_BE( dbuf[1] );
    if (width > 32767)
    {
        if (verbose)
            wxLogError( _("BMP: Image width > 32767 pixels for file.") );
        return FALSE;
    }
    if (height > 32767)
    {
        if (verbose)
            wxLogError( _("BMP: Image height > 32767 pixels for file.") );
        return FALSE;
    }

    stream.Read( &aWord, 2 );
/*
    TODO
    int planes = (int)wxUINT16_SWAP_ON_BE( aWord );
*/
    stream.Read( &aWord, 2 );
    int bpp = (int)wxUINT16_SWAP_ON_BE( aWord );
    if (bpp != 1 && bpp != 4 && bpp != 8 && bpp != 16 && bpp != 24 && bpp != 32)
    {
        if (verbose)
            wxLogError( _("BMP: Unknown bitdepth in file.") );
        return FALSE;
    }

    stream.Read( dbuf, 4 * 4 );
    int comp = (int)wxINT32_SWAP_ON_BE( dbuf[0] );
    if (comp != BI_RGB && comp != BI_RLE4 && comp != BI_RLE8 && comp != BI_BITFIELDS)
    {
        if (verbose)
            wxLogError( _("BMP: Unknown encoding in file.") );
        return FALSE;
    }

    stream.Read( dbuf, 4 * 2 );
    int ncolors = (int)wxINT32_SWAP_ON_BE( dbuf[0] );
    if (ncolors == 0)
        ncolors = 1 << bpp;
    /* some more sanity checks */
    if (((comp == BI_RLE4) && (bpp != 4)) ||
        ((comp == BI_RLE8) && (bpp != 8)) ||
        ((comp == BI_BITFIELDS) && (bpp != 16 && bpp != 32)))
    {
        if (verbose)
            wxLogError( _("BMP: Encoding doesn't match bitdepth.") );
        return FALSE;
    }
    if (bpp < 16)
    {
        cmap = (struct _cmap *)malloc(sizeof(struct _cmap) * ncolors);
        if (!cmap)
        {
            if (verbose)
                wxLogError( _("BMP: Couldn't allocate memory.") );
            return FALSE;
        }
    }
    else
        cmap = NULL;

    image->Create( width, height );
    unsigned char *ptr = image->GetData();
    if (!ptr)
    {
        if (verbose)
            wxLogError( _("BMP: Couldn't allocate memory.") );
        if (cmap)
            free(cmap);
        return FALSE;
    }

    /*
     * Reading the palette, if it exists.
     */
    if (bpp < 16 && ncolors != 0)
    {
        unsigned char* r = new unsigned char[ncolors];
        unsigned char* g = new unsigned char[ncolors];
        unsigned char* b = new unsigned char[ncolors];
        for (int j = 0; j < ncolors; j++)
        {
            stream.Read( bbuf, 4 );
            cmap[j].b = bbuf[0];
            cmap[j].g = bbuf[1];
            cmap[j].r = bbuf[2];

            r[j] = cmap[j].r;
            g[j] = cmap[j].g;
            b[j] = cmap[j].b;
        }

#if wxUSE_PALETTE
        // Set the palette for the wxImage
        image->SetPalette(wxPalette(ncolors, r, g, b));
#endif // wxUSE_PALETTE

        delete[] r;
        delete[] g;
        delete[] b;
    }
    else if (bpp == 16 || bpp == 32)
    {
        if (comp == BI_BITFIELDS)
        {
            int bit = 0;
            stream.Read( dbuf, 4 * 3 );
            bmask = wxINT32_SWAP_ON_BE( dbuf[0] );
            gmask = wxINT32_SWAP_ON_BE( dbuf[1] );
            rmask = wxINT32_SWAP_ON_BE( dbuf[2] );
            /* find shift amount.. ugly, but i can't think of a better way */
            for (bit = 0; bit < bpp; bit++)
            {
                if (bmask & (1 << bit))
                    bshift = bit;
                if (gmask & (1 << bit))
                    gshift = bit;
                if (rmask & (1 << bit))
                    rshift = bit;
            }
        }
        else if (bpp == 16)
        {
            rmask = 0x7C00;
            gmask = 0x03E0;
            bmask = 0x001F;
            rshift = 10;
            gshift = 5;
            bshift = 0;
        }
        else if (bpp == 32)
        {
            rmask = 0x00FF0000;
            gmask = 0x0000FF00;
            bmask = 0x000000FF;
            rshift = 16;
            gshift = 8;
            bshift = 0;
        }
    }

    /*
     * Reading the image data
     */
    stream.SeekI( start_offset + offset );
    unsigned char *data = ptr;

    /* set the whole image to the background color */
    if (bpp < 16 && (comp == BI_RLE4 || comp == BI_RLE8))
    {
        for (int i = 0; i < width * height; i++)
        {
            *ptr++ = cmap[0].r;
            *ptr++ = cmap[0].g;
            *ptr++ = cmap[0].b;
        }
        ptr = data;
    }

    int line = 0;
    int column = 0;
    int linesize = ((width * bpp + 31) / 32) * 4;

    /* BMPs are stored upside down */
    for (line = (height - 1); line >= 0; line--)
    {
        int linepos = 0;
        for (column = 0; column < width;)
        {
            if (bpp < 16)
            {
                int index = 0;
                linepos++;
                aByte = stream.GetC();
                if (bpp == 1)
                {
                    int bit = 0;
                    for (bit = 0; bit < 8 && column < width; bit++)
                    {
                        index = ((aByte & (0x80 >> bit)) ? 1 : 0);
                        ptr[poffset] = cmap[index].r;
                        ptr[poffset + 1] = cmap[index].g;
                        ptr[poffset + 2] = cmap[index].b;
                        column++;
                    }
                }
                else if (bpp == 4)
                {
                    if (comp == BI_RLE4)
                    {
                        if (verbose)
                            wxLogError( _("BMP: Cannot deal with 4bit encoded yet.") );
                        image->Destroy();
                        free(cmap);
                        return FALSE;
                    }
                    else
                    {
                        int nibble = 0;
                        for (nibble = 0; nibble < 2 && column < width; nibble++)
                        {
                            index = ((aByte & (0xF0 >> nibble * 4)) >> (!nibble * 4));
                            if (index >= 16)
                                index = 15;
                            ptr[poffset] = cmap[index].r;
                            ptr[poffset + 1] = cmap[index].g;
                            ptr[poffset + 2] = cmap[index].b;
                            column++;
                        }
                    }
                }
                else if (bpp == 8)
                {
                    if (comp == BI_RLE8)
                    {
                        unsigned char first;
                        first = aByte;
                        aByte = stream.GetC();
                        if (first == 0)
                        {
                            if (aByte == 0)
                            {
                                /* column = width; */
                            }
                            else if (aByte == 1)
                            {
                                column = width;
                                line = -1;
                            }
                            else if (aByte == 2)
                            {
                                aByte = stream.GetC();
                                column += aByte;
                                linepos = column * bpp / 8;
                                aByte = stream.GetC();
                                line += aByte;
                            }
                            else
                            {
                                int absolute = aByte;
                                for (int k = 0; k < absolute; k++)
                                {
                                    linepos++;
                                    aByte = stream.GetC();
                                    ptr[poffset    ] = cmap[aByte].r;
                                    ptr[poffset + 1] = cmap[aByte].g;
                                    ptr[poffset + 2] = cmap[aByte].b;
                                    column++;
                                }
                                if (absolute & 0x01)
                                    aByte = stream.GetC();
                            }
                        }
                        else
                        {
                            for (int l = 0; l < first && column < width; l++)
                            {
                                ptr[poffset    ] = cmap[aByte].r;
                                ptr[poffset + 1] = cmap[aByte].g;
                                ptr[poffset + 2] = cmap[aByte].b;
                                column++;
                                linepos++;
                            }
                        }
                    }
                    else
                    {
                        ptr[poffset    ] = cmap[aByte].r;
                        ptr[poffset + 1] = cmap[aByte].g;
                        ptr[poffset + 2] = cmap[aByte].b;
                        column++;
                        // linepos += size;    seems to be wrong, RR
                    }
                }
               }
               else if (bpp == 24)
               {
                   stream.Read( bbuf, 3 );
                   linepos += 3;
                   ptr[poffset    ] = (unsigned char)bbuf[2];
                   ptr[poffset + 1] = (unsigned char)bbuf[1];
                   ptr[poffset + 2] = (unsigned char)bbuf[0];
                   column++;
               }
               else if (bpp == 16)
               {
                   unsigned char temp;
                   stream.Read( &aWord, 2 );
                   aWord = wxUINT16_SWAP_ON_BE( aWord );
                   linepos += 2;
                   temp = (aWord & rmask) >> rshift;
                   ptr[poffset] = temp;
                   temp = (aWord & gmask) >> gshift;
                   ptr[poffset + 1] = temp;
                   temp = (aWord & bmask) >> bshift;
                   ptr[poffset + 2] = temp;
                   column++;
               }
               else
               {
                   unsigned char temp;
                   stream.Read( &aDword, 4 );
                   aDword = wxINT32_SWAP_ON_BE( aDword );
                   linepos += 4;
                   temp = (aDword & rmask) >> rshift;
                   ptr[poffset] = temp;
                   temp = (aDword & gmask) >> gshift;
                   ptr[poffset + 1] = temp;
                   temp = (aDword & bmask) >> bshift;
                   ptr[poffset + 2] = temp;
                   column++;
               }
          }
          while ((linepos < linesize) && (comp != 1) && (comp != 2))
          {
              stream.Read( &aByte, 1 );
              linepos += 1;
              if (stream.LastError() != wxStream_NOERROR)
                  break;
          }
     }
     if (cmap)
       free(cmap);

     image->SetMask( FALSE );

     return TRUE;
}

bool wxBMPHandler::DoCanRead( wxInputStream& stream )
{
    unsigned char hdr[2];

    stream.Read(hdr, 2);
    stream.SeekI(-2, wxFromCurrent);
    return (hdr[0] == 'B' && hdr[1] == 'M');
}

#endif // wxUSE_STREAMS

#endif // wxUSE_IMAGE