Properly round the opacity percentages to an integer.

If the percentage ended up being a value like 57.99999... , this was being truncated to 57 instead of rounding to 58

Fixes: 2020596

CHANGELOG.md

@@ -20,6 +20,7 @@ Thanks to the following contributors who worked on this release:
 ### Fixed
 - Fixed an issue where the Pan tool's cursor could show up as a missing icon ([#2013047](https://bugs.launchpad.net/pinta/+bug/2013047))
 - Fixed errors when saving a file that was opened with a missing or incorrect extension ([#2013050](https://bugs.launchpad.net/pinta/+bug/2013050))
+- Fixed a bug where certain layer opacity settings could be incorrectly rounded ([#2020596](https://bugs.launchpad.net/pinta/+bug/2020596))
 
 ## [2.1.1](https://github.com/PintaProject/Pinta/releases/tag/2.1.1) - 2023/02/26
 

Pinta/Dialogs/LayerPropertiesDialog.cs

@@ -75,8 +75,8 @@ public LayerPropertiesDialog ()
 
 			layerNameEntry.SetText (initial_properties.Name);
 			visibilityCheckbox.Active = !initial_properties.Hidden;
-			opacitySpinner.Value = (int) (initial_properties.Opacity * 100);
-			opacitySlider.SetValue ((int) (initial_properties.Opacity * 100));
+			opacitySpinner.Value = Math.Round (initial_properties.Opacity * 100);
+			opacitySlider.SetValue (Math.Round (initial_properties.Opacity * 100));
 
 			var all_blendmodes = UserBlendOps.GetAllBlendModeNames ().ToList ();
 			var index = all_blendmodes.IndexOf (UserBlendOps.GetBlendModeName (blendmode));