fix(incremental): Don't write files that have not changed

Author: jeromelaban

src/Resizetizer/src/CreatePartialInfoPlistTask.cs

@@ -34,18 +34,21 @@ public override bool Execute()
 
 				var plistFilename = Path.Combine(IntermediateOutputPath, PlistName ?? "PartialInfo.plist");
 
-				using (var f = File.CreateText(plistFilename))
-				{
-					f.WriteLine(plistHeader);
-
-					if (!string.IsNullOrEmpty(Storyboard))
+				FileHelper.WriteFileIfChanged(
+					plistFilename,
+					Log,
+					writer =>
 					{
-						f.WriteLine("  <key>UILaunchStoryboardName</key>");
-						f.WriteLine($"  <string>{Path.GetFileNameWithoutExtension(Storyboard)}</string>");
-					}
+						writer.WriteLine(plistHeader);
+
+						if (!string.IsNullOrEmpty(Storyboard))
+						{
+							writer.WriteLine("  <key>UILaunchStoryboardName</key>");
+							writer.WriteLine($"  <string>{Path.GetFileNameWithoutExtension(Storyboard)}</string>");
+						}
 
-					f.WriteLine(plistFooter);
-				}
+						writer.WriteLine(plistFooter);
+					});
 			}
 			catch (Exception ex)
 			{

src/Resizetizer/src/FileHelper.cs

@@ -0,0 +1,45 @@
+using Microsoft.Build.Framework;
+using Microsoft.Build.Utilities;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Text;
+
+namespace Uno.Resizetizer
+{
+    internal class FileHelper
+    {
+        public static void WriteFileIfChanged(string fileName, TaskLoggingHelper log, Action<StreamWriter> action)
+        {
+            var tempFile = Path.GetTempFileName();
+            try
+            {
+                using var writer = File.CreateText(tempFile);
+
+                action(writer);
+
+                if (!File.Exists(fileName)
+                    || !File.ReadAllText(fileName).Equals(File.ReadAllText(tempFile)))
+                {
+                    File.Move(tempFile, fileName);
+                }
+                else
+                {
+                    log.LogMessage(MessageImportance.Low, $"Skipping unchanged {fileName}");
+                }
+
+            }
+            finally
+            {
+                try
+                {
+                    File.Delete(tempFile);
+                }
+                catch
+                {
+                    // ignore errors
+                }
+            }
+        }
+    }
+}

src/Resizetizer/src/GenerateSplashStoryboard.cs

@@ -43,10 +43,10 @@ public override bool Execute()
 			var dir = Path.GetDirectoryName(OutputFile);
 			Directory.CreateDirectory(dir);
 
-			using (var writer = File.CreateText(OutputFile))
-			{
-				SubstituteStoryboard(writer, image, rStr, gStr, bStr, aStr);
-			}
+			FileHelper.WriteFileIfChanged(
+				OutputFile,
+				Log,
+				writer => SubstituteStoryboard(writer, image, rStr, gStr, bStr, aStr));
 
 			return !Log.HasLoggedErrors;
 		}

src/Resizetizer/src/GenerateWasmSplashAssets.cs

@@ -63,9 +63,10 @@ public override bool Execute()
 		var dir = Path.GetDirectoryName(OutputFile);
 		Directory.CreateDirectory(dir);
 
-		using var writer = File.CreateText(OutputFile);
-
-		ProcessAppManifestFile(UserAppManifest.ToString(), info, writer);
+		FileHelper.WriteFileIfChanged(
+			OutputFile,
+			Log,
+			writer => ProcessAppManifestFile(UserAppManifest.ToString(), info, writer));
 
 		return true;
 	}