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Added support for saving PNG files with palette.

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Based on (heavily modified) patch by troelsk.

Closes #12505.



git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66552 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Dimitri Schoolwerth
2011-01-03 22:22:16 +00:00
parent 41514cc474
commit 8ee313d2be
5 changed files with 294 additions and 43 deletions
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188
src/common/imagpng.cpp
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@@ -641,6 +641,26 @@ error:
return false;
}
// ----------------------------------------------------------------------------
// SaveFile() helpers
// ----------------------------------------------------------------------------
static int PaletteFind(const png_color& clr,
const png_color *pal, png_uint_16 palCount)
{
for (png_uint_16 i = 0; i < palCount; i++)
{
if ( (clr.red == pal[i].red)
&& (clr.green == pal[i].green)
&& (clr.blue == pal[i].blue))
{
return i;
}
}
return wxNOT_FOUND;
}
// ----------------------------------------------------------------------------
// writing PNGs
// ----------------------------------------------------------------------------
@@ -693,18 +713,81 @@ bool wxPNGHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbos
// explanation why this line is mandatory
png_set_write_fn( png_ptr, &wxinfo, wx_PNG_stream_writer, NULL);
const int iColorType = image->HasOption(wxIMAGE_OPTION_PNG_FORMAT)
const bool bHasPngFormatOption
= image->HasOption(wxIMAGE_OPTION_PNG_FORMAT);
int iColorType = bHasPngFormatOption
? image->GetOptionInt(wxIMAGE_OPTION_PNG_FORMAT)
: wxPNG_TYPE_COLOUR;
const int iBitDepth = image->HasOption(wxIMAGE_OPTION_PNG_BITDEPTH)
? image->GetOptionInt(wxIMAGE_OPTION_PNG_BITDEPTH)
: 8;
bool bHasAlpha = image->HasAlpha();
bool bHasMask = image->HasMask();
bool bUseAlpha = bHasAlpha || bHasMask;
#if wxUSE_PALETTE
/*
Only save as an indexed image if the number of palette entries does not
exceed libpng's limit (256).
We assume here that we will need an extra palette entry if there's an
alpha or mask, regardless of whether a possibly needed conversion from
alpha to a mask fails (unlikely), or whether the mask colour already
can be found in the palette (more likely). In the latter case an extra
palette entry would not be required later on and the image could actually
be saved as a palettised PNG (instead now it will be saved as true colour).
A little bit of precision is lost, but at the benefit of a lot more
simplified code.
*/
bool bUsePalette =
(!bHasPngFormatOption || iColorType == wxPNG_TYPE_PALETTE)
&& image->HasPalette()
&& image->GetPalette().GetColoursCount()
+ ((bHasAlpha || bHasMask) ? 1 : 0) <= PNG_MAX_PALETTE_LENGTH;
wxImage temp_image(*image);
if (bUsePalette && image->HasAlpha() && !bHasMask)
{
/*
Only convert alpha to mask if saving as a palettised image was
explicitly requested. We don't want to lose alpha's precision
by converting to a mask just to be able to save palettised.
*/
if (iColorType == wxPNG_TYPE_PALETTE
&& temp_image.ConvertAlphaToMask())
{
image = &temp_image;
bHasMask = true;
bHasAlpha = image->HasAlpha();
}
else
{
bUsePalette = false;
iColorType = wxPNG_TYPE_COLOUR;
}
}
#else
bool bUsePalette = false;
#endif // wxUSE_PALETTE
bool bUseAlpha = !bUsePalette && (bHasAlpha || bHasMask);
png_color mask;
if (bHasMask)
{
mask.red = image->GetMaskRed();
mask.green = image->GetMaskGreen();
mask.blue = image->GetMaskBlue();
}
int iPngColorType;
#if wxUSE_PALETTE
if (bUsePalette)
{
iPngColorType = PNG_COLOR_TYPE_PALETTE;
iColorType = wxPNG_TYPE_PALETTE;
}
else
#endif // wxUSE_PALETTE
if ( iColorType==wxPNG_TYPE_COLOUR )
{
iPngColorType = bUseAlpha ? PNG_COLOR_TYPE_RGB_ALPHA
@@ -731,11 +814,65 @@ bool wxPNGHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbos
if (image->HasOption(wxIMAGE_OPTION_PNG_COMPRESSION_BUFFER_SIZE))
png_set_compression_buffer_size( png_ptr, image->GetOptionInt(wxIMAGE_OPTION_PNG_COMPRESSION_BUFFER_SIZE) );
int iBitDepth = !bUsePalette && image->HasOption(wxIMAGE_OPTION_PNG_BITDEPTH)
? image->GetOptionInt(wxIMAGE_OPTION_PNG_BITDEPTH)
: 8;
png_set_IHDR( png_ptr, info_ptr, image->GetWidth(), image->GetHeight(),
iBitDepth, iPngColorType,
PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_BASE,
PNG_FILTER_TYPE_BASE);
#if wxUSE_PALETTE
if (bUsePalette)
{
const wxPalette& pal = image->GetPalette();
const int palCount = pal.GetColoursCount();
png_colorp palette = (png_colorp) malloc(
(palCount + 1 /*headroom for trans */) * sizeof(png_color));
if (!palette)
{
png_destroy_write_struct( &png_ptr, (png_infopp)NULL );
if (verbose)
{
wxLogError(_("Couldn't save PNG image."));
}
return false;
}
png_uint_16 i;
for (i = 0; i < palCount; ++i)
{
pal.GetRGB(i, &palette[i].red, &palette[i].green, &palette[i].blue);
}
png_uint_16 numPalette = palCount;
if (bHasMask)
{
int index = PaletteFind(mask, palette, numPalette);
if (index)
{
if (index == wxNOT_FOUND)
{
numPalette++;
index = palCount;
palette[index] = mask;
}
wxSwap(palette[0], palette[index]);
}
png_byte trans = 0;
png_set_tRNS(png_ptr, info_ptr, &trans, 1, NULL);
}
png_set_PLTE(png_ptr, info_ptr, palette, numPalette);
free (palette);
}
#endif // wxUSE_PALETTE
int iElements;
png_color_8 sig_bit;
@@ -806,15 +943,6 @@ bool wxPNGHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbos
int iHeight = image->GetHeight();
int iWidth = image->GetWidth();
unsigned char uchMaskRed = 0, uchMaskGreen = 0, uchMaskBlue = 0;
if ( bHasMask )
{
uchMaskRed = image->GetMaskRed();
uchMaskGreen = image->GetMaskGreen();
uchMaskBlue = image->GetMaskBlue();
}
unsigned char *pColors = image->GetData();
for (int y = 0; y != iHeight; ++y)
@@ -822,9 +950,10 @@ bool wxPNGHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbos
unsigned char *pData = data;
for (int x = 0; x != iWidth; x++)
{
unsigned char uchRed = *pColors++;
unsigned char uchGreen = *pColors++;
unsigned char uchBlue = *pColors++;
png_color clr;
clr.red = *pColors++;
clr.green = *pColors++;
clr.blue = *pColors++;
switch ( iColorType )
{
@@ -833,13 +962,13 @@ bool wxPNGHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbos
// fall through
case wxPNG_TYPE_COLOUR:
*pData++ = uchRed;
*pData++ = clr.red;
if ( iBitDepth == 16 )
*pData++ = 0;
*pData++ = uchGreen;
*pData++ = clr.green;
if ( iBitDepth == 16 )
*pData++ = 0;
*pData++ = uchBlue;
*pData++ = clr.blue;
if ( iBitDepth == 16 )
*pData++ = 0;
break;
@@ -849,9 +978,9 @@ bool wxPNGHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbos
// where do these coefficients come from? maybe we
// should have image options for them as well?
unsigned uiColor =
(unsigned) (76.544*(unsigned)uchRed +
150.272*(unsigned)uchGreen +
36.864*(unsigned)uchBlue);
(unsigned) (76.544*(unsigned)clr.red +
150.272*(unsigned)clr.green +
36.864*(unsigned)clr.blue);
*pData++ = (unsigned char)((uiColor >> 8) & 0xFF);
if ( iBitDepth == 16 )
@@ -860,10 +989,15 @@ bool wxPNGHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbos
break;
case wxPNG_TYPE_GREY_RED:
*pData++ = uchRed;
*pData++ = clr.red;
if ( iBitDepth == 16 )
*pData++ = 0;
break;
case wxPNG_TYPE_PALETTE:
*pData++ = (unsigned char) PaletteFind(clr,
info_ptr->palette, info_ptr->num_palette);
break;
}
if ( bUseAlpha )
@@ -874,9 +1008,9 @@ bool wxPNGHandler::SaveFile( wxImage *image, wxOutputStream& stream, bool verbos
if ( bHasMask )
{
if ( (uchRed == uchMaskRed)
&& (uchGreen == uchMaskGreen)
&& (uchBlue == uchMaskBlue) )
if ( (clr.red == mask.red)
&& (clr.green == mask.green)
&& (clr.blue == mask.blue) )
uchAlpha = 0;
}