improve power of two detection in openslideload

Author: jcupitt

CHANGELOG.md

@@ -1,5 +1,9 @@
 ## master
 
+- better power of two detection in openslideload
+
+## 9.0.11 2025/07/21
+
 - fix path for Widget_pathname_item.action [MvGulik]
 - add more draw compat definitions [MvGulik]
 - better error / alert system

TODO

@@ -2,6 +2,8 @@
 
 - About should show the linked libvips version
 
+- "merge column" in tab menu should show column captions
+
 
 - get judder with rotate and images smaller than the window
 

meson.build

@@ -1,6 +1,6 @@
 project('nip4', 'c',
   # ie. a major after nip2 8.9 for workspace save file versioning
-  version: '9.0.11',
+  version: '9.0.12',
   license: 'GPL',
   meson_version: '>=0.64',
   default_options: [

src/tilesource.c

@@ -30,8 +30,8 @@
 /*
 #define DEBUG_VERBOSE
 #define DEBUG_MAKE
-#define DEBUG
  */
+#define DEBUG
 
 #include "nip4.h"
 
@@ -1800,7 +1800,7 @@ tilesource_new_from_file(const char *filename)
 				tilesource->level_width[level];
 			double power = log(downsample) / log(2);
 
-			if (fabs(power - floor(power)) > 0.01) {
+			if (fabs(power - rint(power)) > 0.01) {
 				// too far away from a power of two, ignore any remaining
 				// frames
 				tilesource->level_count = level;