fix tile edges

see libvips/vipsdisp#47

thanks @kleisauke!

Author: jcupitt

CHANGELOG.md

@@ -1,6 +1,7 @@
 ## master
 
 - better power of two detection in openslideload
+- fix tile edges with gtk_snapshot_set_snap() [kleisauke]
 
 ## 9.0.11 2025/07/21
 

meson.build

@@ -71,6 +71,10 @@ config_h.set('HAVE_SYS_RESOURCE_H', cc.has_header('sys/resource.h'))
 config_h.set('HAVE_GETRLIMIT', cc.has_function('getrlimit'))
 config_h.set('HAVE_REALLOCARRAY', cc.has_function('reallocarray', prefix: '#include <stdlib.h>', args: default_source_flag))
 
+gtk_dep = dependency('gtk4', version: '>=4.14')
+# use this to fix tile alignment, not yet merged
+config_h.set('HAVE_GTK_SNAPSHOT_SET_SNAP', cc.has_header_symbol('gtk.h', 'gtk_snapshot_set_snap', dependencies : gtk_dep))
+
 config_file = configure_file(
   output: 'config.h',
   configuration: config_h,
@@ -84,7 +88,7 @@ nip4_deps += declare_dependency(
 
 # need vips_thread_execute()
 nip4_deps += dependency('vips', version: '>=8.16')
-nip4_deps += dependency('gtk4', version: '>=4.14')
+nip4_deps += gtk_dep
 nip4_deps += dependency('gsl')
 nip4_deps += dependency('libxml-2.0')
 

src/imagedisplay.c

@@ -649,6 +649,10 @@ imagedisplay_snapshot(GtkWidget *widget, GtkSnapshot *snapshot)
 
 	GTK_WIDGET_CLASS(imagedisplay_parent_class)->snapshot(widget, snapshot);
 
+#ifdef HAVE_GTK_SNAPSHOT_SET_SNAP
+	gtk_snapshot_set_snap(snapshot, GSK_RECT_SNAP_ROUND);
+#endif /*HAVE_GTK_SNAPSHOT_SET_SNAP*/
+
 	/* Clip to the widget area, or we may paint over the display control
 	 * bar.
 	 */

src/nip4.h

@@ -130,11 +130,6 @@
  */
 #define MAX_LINELENGTH (120)
 
-/* We use various gtk4 features (GtkInfoBar, GtkDialog) which are going away
- * in gtk5.
- */
-G_GNUC_BEGIN_IGNORE_DEPRECATIONS
-
 // various forward typdefs
 
 typedef struct _BuiltinInfo BuiltinInfo;

src/tilecache.c

@@ -944,8 +944,16 @@ tilecache_snapshot(Tilecache *tilecache, GtkSnapshot *snapshot,
 			// +1 to hide tile boundaries
 			bounds.origin.x = tile->bounds0.left * scale - x + paint->origin.x;
 			bounds.origin.y = tile->bounds0.top * scale - y + paint->origin.y;
-			bounds.size.width = tile->bounds0.width * scale + 1;
-			bounds.size.height = tile->bounds0.height * scale + 1;
+			bounds.size.width = tile->bounds0.width * scale;
+			bounds.size.height = tile->bounds0.height * scale;
+
+#ifdef HAVE_GTK_SNAPSHOT_SET_SNAP
+			/* Without set snap, we have to hide tile edges by expanding the
+			 * tile.
+			 */
+			bounds.size.width += 1;
+			bounds.size.height = += 1;
+#endif /*HAVE_GTK_SNAPSHOT_SET_SNAP*/
 
 			gtk_snapshot_append_scaled_texture(snapshot,
 				tile_get_texture(tile), filter, &bounds);

src/tilesource.c

@@ -30,8 +30,8 @@
 /*
 #define DEBUG_VERBOSE
 #define DEBUG_MAKE
- */
 #define DEBUG
+ */
 
 #include "nip4.h"