/////////////////////////////////////////////////////////////////////////////
-// Name: imagepng.cpp
+// Name: src/common/imagepng.cpp
// Purpose: wxImage PNG handler
// Author: Robert Roebling
// RCS-ID: $Id$
// Licence: wxWindows licence
/////////////////////////////////////////////////////////////////////////////
+// ============================================================================
+// declarations
+// ============================================================================
+
#ifdef __GNUG__
#pragma implementation "imagpng.h"
#endif
+// ----------------------------------------------------------------------------
+// headers
+// ----------------------------------------------------------------------------
+
// For compilers that support precompilation, includes "wx.h".
#include "wx/wxprec.h"
#endif
#endif
-#ifdef __WXMSW__
-#include <windows.h>
-#endif
+// ----------------------------------------------------------------------------
+// constants
+// ----------------------------------------------------------------------------
+
+// image can not have any transparent pixels at all, have only 100% opaque
+// and/or 100% transparent pixels in which case a simple mask is enough to
+// store this information in wxImage or have a real alpha channel in which case
+// we need to have it in wxImage as well
+enum Transparency
+{
+ Transparency_None,
+ Transparency_Mask,
+ Transparency_Alpha
+};
+
+// ----------------------------------------------------------------------------
+// local functions
+// ----------------------------------------------------------------------------
+
+// return the kind of transparency needed for this image assuming that it does
+// have transparent pixels, i.e. either Transparency_Alpha or Transparency_Mask
+static Transparency
+CheckTransparency(const unsigned char *ptr,
+ png_uint_32 x, png_uint_32 y, png_uint_32 w, png_uint_32 h,
+ size_t numColBytes);
-//-----------------------------------------------------------------------------
-// wxPNGHandler
-//-----------------------------------------------------------------------------
+// init the alpha channel for the image and fill it with 1s up to (x, y)
+static unsigned char *InitAlpha(wxImage *image, png_uint_32 x, png_uint_32 y);
+
+// find a free colour for the mask in the PNG data array
+static void
+FindMaskColour(unsigned char **lines, png_uint_32 width, png_uint_32 height,
+ unsigned char& rMask, unsigned char& gMask, unsigned char& bMask);
+
+// is the pixel with this value of alpha a fully opaque one?
+static inline
+bool IsOpaque(unsigned char a)
+{
+ return a == 0xff;
+}
+
+// is the pixel with this value of alpha a fully transparent one?
+static inline
+bool IsTransparent(unsigned char a)
+{
+ return !a;
+}
+
+// ============================================================================
+// wxPNGHandler implementation
+// ============================================================================
IMPLEMENT_DYNAMIC_CLASS(wxPNGHandler,wxImageHandler)
// VS: wxPNGInfoStruct declared below is a hack that needs some explanation.
-// First, let me describe what's the problem: libpng uses jmp_buf in
-// its png_struct structure. Unfortunately, this structure is
-// compiler-specific and may vary in size, so if you use libpng compiled
+// First, let me describe what's the problem: libpng uses jmp_buf in
+// its png_struct structure. Unfortunately, this structure is
+// compiler-specific and may vary in size, so if you use libpng compiled
// as DLL with another compiler than the main executable, it may not work
-// (this is for example the case with wxMGL port and SciTech MGL library
+// (this is for example the case with wxMGL port and SciTech MGL library
// that provides custom runtime-loadable libpng implementation with jmpbuf
-// disabled altogether). Luckily, it is still possible to use setjmp() &
+// disabled altogether). Luckily, it is still possible to use setjmp() &
// longjmp() as long as the structure is not part of png_struct.
//
// Sadly, there's no clean way to attach user-defined data to png_struct.
// There is only one customizable place, png_struct.io_ptr, which is meant
-// only for I/O routines and is set with png_set_read_fn or
+// only for I/O routines and is set with png_set_read_fn or
// png_set_write_fn. The hacky part is that we use io_ptr to store
// a pointer to wxPNGInfoStruct that holds I/O structures _and_ jmp_buf.
{
jmp_buf jmpbuf;
bool verbose;
-
+
union
{
wxInputStream *in;
#define WX_PNG_INFO(png_ptr) ((wxPNGInfoStruct*)png_get_io_ptr(png_ptr))
+// ----------------------------------------------------------------------------
+// helper functions
+// ----------------------------------------------------------------------------
extern "C"
{
} // extern "C"
+// ----------------------------------------------------------------------------
+// LoadFile() helpers
+// ----------------------------------------------------------------------------
+
+// determine the kind of transparency we need for this image: if the only alpha
+// values it has are 0 (transparent) and 0xff (opaque) then we can simply
+// create a mask for it, we should be ok with a simple mask but otherwise we
+// need a full blown alpha channel in wxImage
+//
+// parameters:
+// ptr the start of the data to examine
+// x, y starting position
+// w, h size of the image
+// numColBytes number of colour bytes (1 for grey scale, 3 for RGB)
+// (NB: alpha always follows the colour bytes)
+Transparency
+CheckTransparency(const unsigned char *ptr,
+ png_uint_32 x, png_uint_32 y, png_uint_32 w, png_uint_32 h,
+ size_t numColBytes)
+{
+ // we start from (x + 1, y)
+ x++;
+
+ // suppose that a mask will suffice and check all the remaining alpha
+ // values to see if it does
+ unsigned const char *ptr2 = ptr;
+ for ( png_uint_32 y2 = y; y2 < h; y2++ )
+ {
+ for ( png_uint_32 x2 = x; x2 < w; x2++ )
+ {
+ // skip the grey or colour byte(s)
+ ptr2 += numColBytes;
+
+ unsigned char a2 = *ptr2++;
+
+ if ( !IsTransparent(a2) && !IsOpaque(a2) )
+ {
+ // not fully opaque nor fully transparent, hence need alpha
+ return Transparency_Alpha;
+ }
+ }
+
+ // during the next loop iteration check all the pixels in the row
+ x = 0;
+ }
+
+ // mask will be enough
+ return Transparency_Mask;
+}
+
+unsigned char *InitAlpha(wxImage *image, png_uint_32 x, png_uint_32 y)
+{
+ // create alpha channel
+ image->SetAlpha();
+
+ unsigned char *alpha = image->GetAlpha();
+
+ // set alpha for the pixels we had so far
+ png_uint_32 end = y * image->GetWidth() + x;
+ for ( png_uint_32 i = 0; i < end; i++ )
+ {
+ // all the previous pixels were opaque
+ *alpha++ = 0xff;
+ }
+
+ return alpha;
+}
+
+void
+FindMaskColour(unsigned char **lines, png_uint_32 width, png_uint_32 height,
+ unsigned char& rMask, unsigned char& gMask, unsigned char& bMask)
+{
+ // choosing the colour for the mask is more
+ // difficult: we need to iterate over the entire
+ // image for this in order to choose an unused
+ // colour (this is not very efficient but what else
+ // can we do?)
+ wxImageHistogram h;
+ unsigned nentries = 0;
+ unsigned char r2, g2, b2;
+ for ( png_uint_32 y2 = 0; y2 < height; y2++ )
+ {
+ const unsigned char *p = lines[y2];
+ for ( png_uint_32 x2 = 0; x2 < width; x2++ )
+ {
+ r2 = *p++;
+ g2 = *p++;
+ b2 = *p++;
+
+ wxImageHistogramEntry&
+ entry = h[wxImageHistogram:: MakeKey(r2, g2, b2)];
+
+ if ( entry.value++ == 0 )
+ entry.index = nentries++;
+ }
+ }
+
+ if ( !h.FindFirstUnusedColour(&rMask, &gMask, &bMask) )
+ {
+ wxLogWarning(_("Too many colours in PNG, the image may be slightly blurred."));
+
+ // use a fixed mask colour and we'll fudge
+ // the real pixels with this colour (see
+ // below)
+ rMask = 0xfe;
+ gMask = 0;
+ bMask = 0xff;
+ }
+}
+
+// ----------------------------------------------------------------------------
+// reading PNGs
+// ----------------------------------------------------------------------------
+
+bool wxPNGHandler::DoCanRead( wxInputStream& stream )
+{
+ unsigned char hdr[4];
+
+ if ( !stream.Read(hdr, WXSIZEOF(hdr)) )
+ return FALSE;
+
+ return memcmp(hdr, "\211PNG", WXSIZEOF(hdr)) == 0;
+}
+
+// convert data from RGB to wxImage format
+static
+void CopyDataFromPNG(wxImage *image,
+ unsigned char **lines,
+ png_uint_32 width,
+ png_uint_32 height,
+ int color_type)
+{
+ Transparency transparency = Transparency_None;
+
+ // only non NULL if transparency == Transparency_Alpha
+ unsigned char *alpha = NULL;
+
+ // RGB of the mask colour if transparency == Transparency_Mask
+ // (but init them anyhow to avoid compiler warnings)
+ unsigned char rMask = 0,
+ gMask = 0,
+ bMask = 0;
+
+ unsigned char *ptrDst = image->GetData();
+ if ( !(color_type & PNG_COLOR_MASK_COLOR) )
+ {
+ // grey image: GAGAGA... where G == grey component and A == alpha
+ for ( png_uint_32 y = 0; y < height; y++ )
+ {
+ const unsigned char *ptrSrc = lines[y];
+ for ( png_uint_32 x = 0; x < width; x++ )
+ {
+ unsigned char g = *ptrSrc++;
+ unsigned char a = *ptrSrc++;
+
+ // the first time we encounter a transparent pixel we must
+ // decide about what to do about them
+ if ( !IsOpaque(a) && transparency == Transparency_None )
+ {
+ // we'll need at least the mask for this image and
+ // maybe even full alpha channel info: the former is
+ // only enough if we have alpha values of 0 and 0xff
+ // only, otherwisewe need the latter
+ transparency = CheckTransparency
+ (
+ ptrSrc,
+ x, y,
+ width, height,
+ 1
+ );
+
+ if ( transparency == Transparency_Mask )
+ {
+ // let's choose this colour for the mask: this is
+ // not a problem here as all the other pixels are
+ // grey, i.e. R == G == B which is not the case for
+ // this one so no confusion is possible
+ rMask = 0xff;
+ gMask = 0;
+ bMask = 0xff;
+ }
+ else // transparency == Transparency_Alpha
+ {
+ alpha = InitAlpha(image, x, y);
+ }
+ }
+
+ switch ( transparency )
+ {
+ case Transparency_Mask:
+ if ( IsTransparent(a) )
+ {
+ *ptrDst++ = rMask;
+ *ptrDst++ = bMask;
+ *ptrDst++ = gMask;
+ break;
+ }
+ // else: !transparent
+
+ // must be opaque then as otherwise we shouldn't be
+ // using the mask at all
+ wxASSERT_MSG( IsOpaque(a), _T("logic error") );
+
+ // fall through
+
+ case Transparency_Alpha:
+ if ( alpha )
+ *alpha++ = a;
+ // fall through
+
+ case Transparency_None:
+ *ptrDst++ = g;
+ *ptrDst++ = g;
+ *ptrDst++ = g;
+ break;
+ }
+ }
+ }
+ }
+ else // colour image: RGBRGB...
+ {
+ for ( png_uint_32 y = 0; y < height; y++ )
+ {
+ const unsigned char *ptrSrc = lines[y];
+ for ( png_uint_32 x = 0; x < width; x++ )
+ {
+ unsigned char r = *ptrSrc++;
+ unsigned char g = *ptrSrc++;
+ unsigned char b = *ptrSrc++;
+ unsigned char a = *ptrSrc++;
+
+ // the logic here is the same as for the grey case except
+ // where noted
+ if ( !IsOpaque(a) && transparency == Transparency_None )
+ {
+ transparency = CheckTransparency
+ (
+ ptrSrc,
+ x, y,
+ width, height,
+ 3
+ );
+
+ if ( transparency == Transparency_Mask )
+ {
+ FindMaskColour(lines, width, height,
+ rMask, gMask, bMask);
+ }
+ else // transparency == Transparency_Alpha
+ {
+ alpha = InitAlpha(image, x, y);
+ }
+
+ }
+
+ switch ( transparency )
+ {
+ case Transparency_Mask:
+ if ( IsTransparent(a) )
+ {
+ // if we couldn't find a unique colour for the mask, we
+ // can have real pixels with the same value as the mask
+ // and it's better to slightly change their colour than
+ // to make them transparent
+ if ( r == rMask && g == gMask && b == bMask )
+ {
+ r++;
+ }
+
+ *ptrDst++ = rMask;
+ *ptrDst++ = bMask;
+ *ptrDst++ = gMask;
+ break;
+ }
+ // else: !transparent
+
+ // must be opaque then as otherwise we shouldn't be
+ // using the mask at all
+ wxASSERT_MSG( IsOpaque(a), _T("logic error") );
+
+ // fall through
+
+ case Transparency_Alpha:
+ if ( alpha )
+ *alpha++ = a;
+ // fall through
+
+ case Transparency_None:
+ *ptrDst++ = r;
+ *ptrDst++ = g;
+ *ptrDst++ = b;
+ break;
+ }
+ }
+ }
+ }
+
+ if ( transparency == Transparency_Mask )
+ {
+ image->SetMaskColour(rMask, gMask, bMask);
+ }
+}
+
// temporarily disable the warning C4611 (interaction between '_setjmp' and
// C++ object destruction is non-portable) - I don't see any dtors here
#ifdef __VISUALC__
#pragma warning(disable:4611)
#endif /* VC++ */
-bool wxPNGHandler::LoadFile( wxImage *image, wxInputStream& stream, bool verbose, int WXUNUSED(index) )
+bool
+wxPNGHandler::LoadFile(wxImage *image,
+ wxInputStream& stream,
+ bool verbose,
+ int WXUNUSED(index))
{
// VZ: as this function uses setjmp() the only fool proof error handling
// method is to use goto (setjmp is not really C++ dtors friendly...)
- unsigned char **lines;
- unsigned int i;
- png_infop info_ptr = (png_infop) NULL;
+ unsigned char **lines = NULL;
+ png_infop info_ptr = (png_infop) NULL;
wxPNGInfoStruct wxinfo;
wxinfo.verbose = verbose;
(png_error_ptr) NULL,
(png_error_ptr) NULL );
if (!png_ptr)
- goto error_nolines;
+ goto error;
png_set_error_fn(png_ptr, (png_voidp)NULL, wx_png_error, wx_png_warning);
info_ptr = png_create_info_struct( png_ptr );
if (!info_ptr)
- goto error_nolines;
+ goto error;
if (setjmp(wxinfo.jmpbuf))
- goto error_nolines;
-
- if (info_ptr->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
- goto error_nolines;
+ goto error;
- png_uint_32 width,height;
- int bit_depth,color_type,interlace_type;
+ png_uint_32 i, width, height;
+ int bit_depth, color_type, interlace_type;
png_read_info( png_ptr, info_ptr );
png_get_IHDR( png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, &interlace_type, (int*) NULL, (int*) NULL );
image->Create( (int)width, (int)height );
if (!image->Ok())
- goto error_nolines;
+ goto error;
lines = (unsigned char **)malloc( (size_t)(height * sizeof(unsigned char *)) );
- if (lines == NULL)
- goto error_nolines;
+ if ( !lines )
+ goto error;
for (i = 0; i < height; i++)
{
}
}
- // loaded successfully!
- {
- int transp = 0;
- png_read_image( png_ptr, lines );
- png_read_end( png_ptr, info_ptr );
- png_destroy_read_struct( &png_ptr, &info_ptr, (png_infopp) NULL );
- unsigned char *ptr = image->GetData();
- if ((color_type == PNG_COLOR_TYPE_GRAY) ||
- (color_type == PNG_COLOR_TYPE_GRAY_ALPHA))
- {
- for (unsigned int y = 0; y < height; y++)
- {
- unsigned char *ptr2 = lines[y];
- for (unsigned int x = 0; x < width; x++)
- {
- unsigned char r = *ptr2++;
- unsigned char a = *ptr2++;
- if (a < 128)
- {
- *ptr++ = 255;
- *ptr++ = 0;
- *ptr++ = 255;
- transp = 1;
- }
- else
- {
- *ptr++ = r;
- *ptr++ = r;
- *ptr++ = r;
- }
- }
- }
- }
- else
- {
- for (unsigned int y = 0; y < height; y++)
- {
- unsigned char *ptr2 = lines[y];
- for (unsigned int x = 0; x < width; x++)
- {
- unsigned char r = *ptr2++;
- unsigned char g = *ptr2++;
- unsigned char b = *ptr2++;
- unsigned char a = *ptr2++;
- if (a < 128)
- {
- *ptr++ = 255;
- *ptr++ = 0;
- *ptr++ = 255;
- transp = 1;
- }
- else
- {
- if ((r == 255) && (g == 0) && (b == 255)) r = 254;
- *ptr++ = r;
- *ptr++ = g;
- *ptr++ = b;
- }
- }
- }
- }
+ png_read_image( png_ptr, lines );
+ png_read_end( png_ptr, info_ptr );
+ png_destroy_read_struct( &png_ptr, &info_ptr, (png_infopp) NULL );
- for ( unsigned int j = 0; j < height; j++ )
- free( lines[j] );
- free( lines );
+ // loaded successfully, now init wxImage with this data
+ CopyDataFromPNG(image, lines, width, height, color_type);
- if (transp)
- {
- image->SetMaskColour( 255, 0, 255 );
- }
- else
- {
- image->SetMask( FALSE );
- }
- }
+ for ( i = 0; i < height; i++ )
+ free( lines[i] );
+ free( lines );
return TRUE;
- error_nolines:
- lines = NULL; // called from before it was set
- error:
+error:
if (verbose)
wxLogError(_("Couldn't load a PNG image - file is corrupted or not enough memory."));
return FALSE;
}
+// ----------------------------------------------------------------------------
+// writing PNGs
+// ----------------------------------------------------------------------------
+
bool wxPNGHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbose )
{
wxPNGInfoStruct wxinfo;
#pragma warning(default:4611)
#endif /* VC++ */
-bool wxPNGHandler::DoCanRead( wxInputStream& stream )
-{
- unsigned char hdr[4];
-
- if ( !stream.Read(hdr, WXSIZEOF(hdr)) )
- return FALSE;
-
- return memcmp(hdr, "\211PNG", WXSIZEOF(hdr)) == 0;
-}
-
#endif // wxUSE_STREAMS
#endif // wxUSE_LIBPNG
projects / wxWidgets.git / blobdiff