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Made some TIFF reading adjustments.

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Read a few TIFF tags that assist with having a similar TIFF file when saving the image again, instead of (by default) always saving as a 24-bit RGB image. Also, in accordance with libtiff, allow reading X and Y resolution values even if the resolution unit tag is not set.

Applied (modified) patch by scottb. Closes #13015.


git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@67264 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Dimitri Schoolwerth 2011-03-20 19:48:03 +00:00
parent 035fa7f78c
commit 4d37f425ff
1 changed files with 55 additions and 19 deletions
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74
src/common/imagtiff.cpp
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@ -402,42 +402,78 @@ bool wxTIFFHandler::LoadFile( wxImage *image, wxInputStream& stream, bool verbos
alpha -= 2*w;
}
// set the image resolution if it's available
uint16 tiffRes;
if ( TIFFGetField(tif, TIFFTAG_RESOLUTIONUNIT, &tiffRes) )
uint16 spp, bpp, compression;
/*
Read some baseline TIFF tags which helps when re-saving a TIFF
to be similar to the original image.
*/
if ( TIFFGetFieldDefaulted(tif, TIFFTAG_SAMPLESPERPIXEL, &spp) )
{
wxImageResolution res;
switch ( tiffRes )
image->SetOption(wxIMAGE_OPTION_SAMPLESPERPIXEL, spp);
}
if ( TIFFGetFieldDefaulted(tif, TIFFTAG_BITSPERSAMPLE, &bpp) )
{
image->SetOption(wxIMAGE_OPTION_BITSPERSAMPLE, bpp);
}
if ( TIFFGetFieldDefaulted(tif, TIFFTAG_COMPRESSION, &compression) )
{
image->SetOption(wxIMAGE_OPTION_COMPRESSION, compression);
}
// Set the resolution unit.
wxImageResolution resUnit = wxIMAGE_RESOLUTION_NONE;
uint16 tiffRes;
if ( TIFFGetFieldDefaulted(tif, TIFFTAG_RESOLUTIONUNIT, &tiffRes) )
{
switch (tiffRes)
{
default:
wxLogWarning(_("Unknown TIFF resolution unit %d ignored"),
tiffRes);
tiffRes);
// fall through
case RESUNIT_NONE:
res = wxIMAGE_RESOLUTION_NONE;
resUnit = wxIMAGE_RESOLUTION_NONE;
break;
case RESUNIT_INCH:
res = wxIMAGE_RESOLUTION_INCHES;
resUnit = wxIMAGE_RESOLUTION_INCHES;
break;
case RESUNIT_CENTIMETER:
res = wxIMAGE_RESOLUTION_CM;
resUnit = wxIMAGE_RESOLUTION_CM;
break;
}
if ( res != wxIMAGE_RESOLUTION_NONE )
{
float xres, yres;
if ( TIFFGetField(tif, TIFFTAG_XRESOLUTION, &xres) )
image->SetOption(wxIMAGE_OPTION_RESOLUTIONX, wxRound(xres));
if ( TIFFGetField(tif, TIFFTAG_YRESOLUTION, &yres) )
image->SetOption(wxIMAGE_OPTION_RESOLUTIONY, wxRound(yres));
}
}
image->SetOption(wxIMAGE_OPTION_RESOLUTIONUNIT, resUnit);
/*
Set the image resolution if it's available. Resolution tag is not
dependant on RESOLUTIONUNIT != RESUNIT_NONE (according to TIFF spec).
*/
float resX, resY;
if ( TIFFGetField(tif, TIFFTAG_XRESOLUTION, &resX) )
{
/*
Use a string value to not lose precision.
rounding to int as cm and then converting to inch may
result in whole integer rounding error, eg. 201 instead of 200 dpi.
If an app wants an int, GetOptionInt will convert and round down.
*/
image->SetOption(wxIMAGE_OPTION_RESOLUTIONX,
wxString::FromCDouble((double) resX));
}
if ( TIFFGetField(tif, TIFFTAG_YRESOLUTION, &resY) )
{
image->SetOption(wxIMAGE_OPTION_RESOLUTIONY,
wxString::FromCDouble((double) resY));
}
_TIFFfree( raster );