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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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66
src/common/imagtiff.cpp
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@@ -402,11 +402,32 @@ bool wxTIFFHandler::LoadFile( wxImage *image, wxInputStream& stream, bool verbos
alpha -= 2*w; alpha -= 2*w;
} }
// set the image resolution if it's available
uint16 tiffRes; uint16 spp, bpp, compression;
if ( TIFFGetField(tif, TIFFTAG_RESOLUTIONUNIT, &tiffRes) ) /*
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) )
{
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) )
{ {
wxImageResolution res;
switch (tiffRes) switch (tiffRes)
{ {
default: default:
@@ -415,29 +436,44 @@ bool wxTIFFHandler::LoadFile( wxImage *image, wxInputStream& stream, bool verbos
// fall through // fall through
case RESUNIT_NONE: case RESUNIT_NONE:
res = wxIMAGE_RESOLUTION_NONE; resUnit = wxIMAGE_RESOLUTION_NONE;
break; break;
case RESUNIT_INCH: case RESUNIT_INCH:
res = wxIMAGE_RESOLUTION_INCHES; resUnit = wxIMAGE_RESOLUTION_INCHES;
break; break;
case RESUNIT_CENTIMETER: case RESUNIT_CENTIMETER:
res = wxIMAGE_RESOLUTION_CM; resUnit = wxIMAGE_RESOLUTION_CM;
break; break;
} }
}
if ( res != wxIMAGE_RESOLUTION_NONE ) 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) )
{ {
float xres, yres; /*
if ( TIFFGetField(tif, TIFFTAG_XRESOLUTION, &xres) ) Use a string value to not lose precision.
image->SetOption(wxIMAGE_OPTION_RESOLUTIONX, wxRound(xres)); rounding to int as cm and then converting to inch may
result in whole integer rounding error, eg. 201 instead of 200 dpi.
if ( TIFFGetField(tif, TIFFTAG_YRESOLUTION, &yres) ) If an app wants an int, GetOptionInt will convert and round down.
image->SetOption(wxIMAGE_OPTION_RESOLUTIONY, wxRound(yres)); */
} 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 ); _TIFFfree( raster );