X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/9c1f960facd309385710af076b1f579aad9a28ef..74a8f67d96591cec101def2a7d47c64072aff7fd:/src/common/imagtiff.cpp

diff --git a/src/common/imagtiff.cpp b/src/common/imagtiff.cpp
index 5d8476daec..2501e91f3e 100644
--- a/src/common/imagtiff.cpp
+++ b/src/common/imagtiff.cpp
@@ -296,13 +296,23 @@ bool wxTIFFHandler::LoadFile( wxImage *image, wxInputStream& stream, bool verbos
     TIFFGetField( tif, TIFFTAG_IMAGEWIDTH, &w );
     TIFFGetField( tif, TIFFTAG_IMAGELENGTH, &h );
 
+    uint16 photometric;
+    uint16 samplesPerPixel;
     uint16 extraSamples;
     uint16* samplesInfo;
+    TIFFGetFieldDefaulted(tif, TIFFTAG_SAMPLESPERPIXEL, &samplesPerPixel);
     TIFFGetFieldDefaulted(tif, TIFFTAG_EXTRASAMPLES,
                           &extraSamples, &samplesInfo);
-    const bool hasAlpha = (extraSamples == 1 &&
-                           (samplesInfo[0] == EXTRASAMPLE_ASSOCALPHA ||
-                            samplesInfo[0] == EXTRASAMPLE_UNASSALPHA));
+    if (!TIFFGetField(tif, TIFFTAG_PHOTOMETRIC, &photometric))
+    {
+        photometric = PHOTOMETRIC_MINISWHITE;
+    }
+    const bool hasAlpha = (extraSamples >= 1
+        && ((samplesInfo[0] == EXTRASAMPLE_UNSPECIFIED && samplesPerPixel > 3)
+            || samplesInfo[0] == EXTRASAMPLE_ASSOCALPHA
+            || samplesInfo[0] == EXTRASAMPLE_UNASSALPHA))
+        || (extraSamples == 0 && samplesPerPixel == 4
+            && photometric == PHOTOMETRIC_RGB);
 
     // guard against integer overflow during multiplication which could result
     // in allocating a too small buffer and then overflowing it
@@ -334,7 +344,7 @@ bool wxTIFFHandler::LoadFile( wxImage *image, wxInputStream& stream, bool verbos
     }
 
     image->Create( (int)w, (int)h );
-    if (!image->Ok())
+    if (!image->IsOk())
     {
         if (verbose)
         {
@@ -392,42 +402,78 @@ bool wxTIFFHandler::LoadFile( wxImage *image, wxInputStream& stream, bool verbos
             alpha -= 2*w;
     }
 
-    // set the image resolution if it's available
+
+    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) )
+    {
+        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 ( TIFFGetField(tif, TIFFTAG_RESOLUTIONUNIT, &tiffRes) )
+    if ( TIFFGetFieldDefaulted(tif, TIFFTAG_RESOLUTIONUNIT, &tiffRes) )
     {
-        wxImageResolution res;
-        switch ( 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));
+    image->SetOption(wxIMAGE_OPTION_RESOLUTIONUNIT, resUnit);
 
-            if ( TIFFGetField(tif, TIFFTAG_YRESOLUTION, &yres) )
-                image->SetOption(wxIMAGE_OPTION_RESOLUTIONY, wxRound(yres));
-        }
+    /*
+    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 );