dzsave: IIIF: use named region of 'full' when no crop takes place (#4578)

lovell · web-flow · commit 2e78894deba9 · 2025-07-06T14:02:52.000+01:00
Should improve conformance with IIIF v2 and v3, the specs of
which both mandate support for the 'full' region.

Also adds a couple of initial, basic IIIF layout tests
diff --git a/ChangeLog b/ChangeLog
@@ -9,6 +9,7 @@ master
 - text: prevent use of rgba subpixel anti-aliasing [lovell]
 - tiffsave: always apply resolution unit conversion [kleisauke]
 - cache: suppress invalidation errors in release builds [kleisauke]
+- dzsave: IIIF: use named region of 'full' when no crop takes place [lovell]
 
 5/6/25 8.17.0
 
diff --git a/libvips/foreign/dzsave.c b/libvips/foreign/dzsave.c
@@ -1212,6 +1212,9 @@ tile_name(Level *level, int x, int y)
 			save->ready->Xsize - left);
 		int height = VIPS_MIN(dz->tile_size * level->sub,
 			save->ready->Ysize - top);
+		gboolean is_region_full = left == 0 && top == 0 &&
+			width == save->ready->Xsize &&
+			height == save->ready->Ysize;
 
 		/* Rotation is always 0.
 		 */
@@ -1223,23 +1226,35 @@ tile_name(Level *level, int x, int y)
 			int ysize = VIPS_MIN(dz->tile_size,
 				level->height - y * dz->tile_size);
 
-			g_snprintf(subdir, VIPS_PATH_MAX,
-				"%d,%d,%d,%d" G_DIR_SEPARATOR_S "%d,%d" G_DIR_SEPARATOR_S "%d",
-				left, top, width, height,
-				xsize, ysize,
-				rotation);
+			if (is_region_full)
+				g_snprintf(subdir, VIPS_PATH_MAX,
+					"full" G_DIR_SEPARATOR_S "%d,%d" G_DIR_SEPARATOR_S "%d",
+					xsize, ysize,
+					rotation);
+			else
+				g_snprintf(subdir, VIPS_PATH_MAX,
+					"%d,%d,%d,%d" G_DIR_SEPARATOR_S "%d,%d" G_DIR_SEPARATOR_S "%d",
+					left, top, width, height,
+					xsize, ysize,
+					rotation);
 		}
 		else {
 			/* IIIF2 "size" is just real tile width, I think.
 			 */
 			int size = VIPS_MIN(dz->tile_size,
 				level->width - x * dz->tile_size);
 
-			g_snprintf(subdir, VIPS_PATH_MAX,
-				"%d,%d,%d,%d" G_DIR_SEPARATOR_S "%d," G_DIR_SEPARATOR_S "%d",
-				left, top, width, height,
-				size,
-				rotation);
+			if (is_region_full)
+				g_snprintf(subdir, VIPS_PATH_MAX,
+					"full" G_DIR_SEPARATOR_S "%d," G_DIR_SEPARATOR_S "%d",
+					size,
+					rotation);
+			else
+				g_snprintf(subdir, VIPS_PATH_MAX,
+					"%d,%d,%d,%d" G_DIR_SEPARATOR_S "%d," G_DIR_SEPARATOR_S "%d",
+					left, top, width, height,
+					size,
+					rotation);
 		}
 
 		g_snprintf(name, VIPS_PATH_MAX, "default%s", dz->file_suffix);
diff --git a/test/test-suite/test_foreign.py b/test/test-suite/test_foreign.py
@@ -1407,6 +1407,27 @@ def test_dzsave(self):
         assert x.width == 256
         assert x.height == 256
 
+        # IIIF v2
+        im = pyvips.Image.black(3509, 2506, bands=3)
+        filename = temp_filename(self.tempdir, '')
+        im.dzsave(filename, layout="iiif")
+        assert os.path.exists(filename + "/info.json")
+        assert os.path.exists(filename + "/0,0,512,512/512,/0/default.jpg")
+        assert os.path.exists(filename + "/2560,2048,512,458/512,/0/default.jpg")
+        x = pyvips.Image.new_from_file(filename + "/full/439,/0/default.jpg")
+        assert x.width == 439
+        assert x.height == 314
+
+        # IIIF v3
+        filename = temp_filename(self.tempdir, '')
+        im.dzsave(filename, layout="iiif3")
+        assert os.path.exists(filename + "/info.json")
+        assert os.path.exists(filename + "/0,0,512,512/512,512/0/default.jpg")
+        assert os.path.exists(filename + "/2560,2048,512,458/512,458/0/default.jpg")
+        x = pyvips.Image.new_from_file(filename + "/full/439,314/0/default.jpg")
+        assert x.width == 439
+        assert x.height == 314
+
         # test zip output
         filename = temp_filename(self.tempdir, '.zip')
         self.colour.dzsave(filename)
