kimgio: Support TIFF transparency

See: https://mirror.git.trinitydesktop.org/gitea/TDE/tdelibs/issues/282
Signed-off-by: mio <stigma@disroot.org>
(cherry picked from commit 6adcd87798)

kimgio/tiffr.cpp

@@ -6,6 +6,7 @@
 
 #include <tiffio.h>
 
+#include <kdebug.h>
 #include <tqimage.h>
 #include <tqfile.h>
 #include <tdelibs_export.h>
@@ -66,6 +67,9 @@ TDE_EXPORT void kimgio_tiff_read( TQImageIO *io )
 	uint32 width, height;
 	uint32 *data;
 
+	uint16_t  extra_samples_count;
+	uint16_t *extra_samples;
+
 	// FIXME: use qdatastream
 
 	// open file
@@ -79,9 +83,12 @@ TDE_EXPORT void kimgio_tiff_read( TQImageIO *io )
 	}
 
 	// create image with loaded dimensions
-	if( TIFFGetField( tiff, TIFFTAG_IMAGEWIDTH, &width ) != 1
-            || TIFFGetField( tiff, TIFFTAG_IMAGELENGTH, &height ) != 1 )
-            return;
+	if ((TIFFGetField(tiff, TIFFTAG_IMAGEWIDTH, &width) != 1) ||
+		(TIFFGetField(tiff, TIFFTAG_IMAGELENGTH, &height) != 1))
+	{
+		TIFFClose(tiff);
+		return;
+	}
 
 	TQImage image( width, height, 32 );
 	if( image.isNull()) {
@@ -128,6 +135,21 @@ TDE_EXPORT void kimgio_tiff_read( TQImageIO *io )
 		// swap rows
 	}
 
+	// Extra Samples
+	if (TIFFGetField(tiff, TIFFTAG_EXTRASAMPLES, &extra_samples_count, &extra_samples) == 1)
+	{
+		kdDebug(399) << "TIFF image has " << extra_samples_count << " extra sample(s)." << endl;
+		for (uint16_t i = 0; i < extra_samples_count; i++)
+		{
+			if ((extra_samples[i] == EXTRASAMPLE_ASSOCALPHA) ||
+				(extra_samples[i] == EXTRASAMPLE_UNASSALPHA))
+			{
+				image.setAlphaBuffer(true);
+				break;
+			}
+		}
+	}
+
 	// set channel order to Qt order
 	// FIXME: Right now they are the same, but will it change?