fix TIFF thumbnail of buffer and source

We had dropped a couple of patches.

see https://github.com/libvips/libvips/issues/1815

ChangeLog

@@ -1,6 +1,7 @@
 6/9/20 started 8.10.2
 - update magicksave/load profile handling [kelilevi]
 - better demand hint rules [kaas3000]
+- fix tiff thumbnail from buffer and source [vansante]
 
 9/8/20 started 8.10.1
 - fix markdown -> xml conversion in doc generation

libvips/resample/thumbnail.c

@@ -1057,6 +1057,7 @@ vips_thumbnail_file_open( VipsThumbnail *thumbnail, double factor )
 			"scale", 1.0 / factor,
 			NULL ) );
 	}
+
 	else if( vips_isprefix( "VipsForeignLoadTiff", thumbnail->loader ) ) {
 		/* We support three modes: subifd pyramids, page-based
 		 * pyramids, and simple multi-page TIFFs (no pyramid).
@@ -1075,8 +1076,8 @@ vips_thumbnail_file_open( VipsThumbnail *thumbnail, double factor )
 			return( vips_image_new_from_file( file->filename, 
 				"access", VIPS_ACCESS_SEQUENTIAL,
 				NULL ) );
-
 	}
+
 	else if( vips_isprefix( "VipsForeignLoadHeif", thumbnail->loader ) ) {
 		return( vips_image_new_from_file( file->filename, 
 			"access", VIPS_ACCESS_SEQUENTIAL,
@@ -1270,12 +1271,29 @@ vips_thumbnail_buffer_open( VipsThumbnail *thumbnail, double factor )
 			NULL ) );
 	}
 	else if( vips_isprefix( "VipsForeignLoadTiff", thumbnail->loader ) ) {
+		/* We support three modes: subifd pyramids, page-based
+		 * pyramids, and simple multi-page TIFFs (no pyramid).
+		 */
+		if( thumbnail->subifd_pyramid )
+			return( vips_image_new_from_buffer( 
+				buffer->buf->data, buffer->buf->length, 
+				buffer->option_string,
+				"access", VIPS_ACCESS_SEQUENTIAL,
+				"subifd", (int) factor,
+				NULL ) );
+		else if( thumbnail->page_pyramid )
 			return( vips_image_new_from_buffer( 
 				buffer->buf->data, buffer->buf->length, 
 				buffer->option_string,
 				"access", VIPS_ACCESS_SEQUENTIAL,
 				"page", (int) factor,
 				NULL ) );
+		else
+			return( vips_image_new_from_buffer( 
+				buffer->buf->data, buffer->buf->length, 
+				buffer->option_string,
+				"access", VIPS_ACCESS_SEQUENTIAL,
+				NULL ) );
 	}
 	else if( vips_isprefix( "VipsForeignLoadHeif", thumbnail->loader ) ) {
 		return( vips_image_new_from_buffer( 
@@ -1449,12 +1467,29 @@ vips_thumbnail_source_open( VipsThumbnail *thumbnail, double factor )
 			NULL ) );
 	}
 	else if( vips_isprefix( "VipsForeignLoadTiff", thumbnail->loader ) ) {
+		/* We support three modes: subifd pyramids, page-based
+		 * pyramids, and simple multi-page TIFFs (no pyramid).
+		 */
+		if( thumbnail->subifd_pyramid )
+			return( vips_image_new_from_source(
+				source->source, 
+				source->option_string,
+				"access", VIPS_ACCESS_SEQUENTIAL,
+				"subifd", (int) factor,
+				NULL ) );
+		else if( thumbnail->page_pyramid )
 			return( vips_image_new_from_source(
 				source->source, 
 				source->option_string,
 				"access", VIPS_ACCESS_SEQUENTIAL,
 				"page", (int) factor,
 				NULL ) );
+		else
+			return( vips_image_new_from_source(
+				source->source, 
+				source->option_string,
+				"access", VIPS_ACCESS_SEQUENTIAL,
+				NULL ) );
 	}
 	else if( vips_isprefix( "VipsForeignLoadHeif", thumbnail->loader ) ) {
 		return( vips_image_new_from_source( 

test/test-suite/test_resample.py

@@ -2,7 +2,7 @@
 import pytest
 
 import pyvips
-from helpers import JPEG_FILE, OME_FILE, HEIC_FILE, all_formats, have
+from helpers import JPEG_FILE, OME_FILE, HEIC_FILE, TIF_FILE, all_formats, have
 
 
 # Run a function expecting a complex image on a two-band image
@@ -186,6 +186,13 @@ class TestResample:
         assert im.width == 100
         assert im.height == 570
 
+        # should be able to thumbnail a single-page tiff in a buffer
+        im1 = pyvips.Image.thumbnail(TIF_FILE, 100)
+        with open(TIF_FILE, 'rb') as f:
+            buf = f.read()
+        im2 = pyvips.Image.thumbnail_buffer(buf, 100)
+        assert abs(im1.avg() - im2.avg()) < 1
+
         if have("heifload"):
             # this image is orientation 6 ... thumbnail should flip it
             im = pyvips.Image.new_from_file(HEIC_FILE)