From 051798328c529cf6a3b5d8e1f391894b38359726 Mon Sep 17 00:00:00 2001
From: Alexander Marek <alexander.marek@outlook.com>
Date: Fri, 12 Jun 2026 13:39:48 +0200
Subject: [PATCH] TileGenerator stores scale factor of tiles (in relation to
 original svg dimensions) in dimensions.json

---
 Svg.Tests.Win/DeepZoom/TileGeneratorTests.cs | 33 ++++++++++++++++++++
 Svg/DeepZoom/TileGenerator.cs                | 12 ++++---
 Svg/Svg.csproj                               |  4 ++-
 3 files changed, 44 insertions(+), 5 deletions(-)

diff --git a/Svg.Tests.Win/DeepZoom/TileGeneratorTests.cs b/Svg.Tests.Win/DeepZoom/TileGeneratorTests.cs
index 13e50c3fc..10c9bf424 100644
--- a/Svg.Tests.Win/DeepZoom/TileGeneratorTests.cs
+++ b/Svg.Tests.Win/DeepZoom/TileGeneratorTests.cs
@@ -412,9 +412,42 @@ public async Task GenerateTilesFromSvgAsync_ProducesExpectedZoomLevels()
             var dims = System.Text.Json.JsonDocument.Parse(dimsJson).RootElement;
             Assert.AreEqual(pyramidW, dims.GetProperty("width").GetInt32(), "dimensions.json width mismatch.");
             Assert.AreEqual(pyramidH, dims.GetProperty("height").GetInt32(), "dimensions.json height mismatch.");
+            Assert.IsTrue(dims.TryGetProperty("scaleX", out _), "dimensions.json missing scaleX.");
+            Assert.IsTrue(dims.TryGetProperty("scaleY", out _), "dimensions.json missing scaleY.");
 #endif
         }
 
+#if !NETFRAMEWORK
+        [Test]
+        public async Task GenerateTilesFromSvgAsync_WritesScaleFactorsToDimensionsJson()
+        {
+            // Arrange — render the SVG into a pyramid 10× wider than the document so scaleX ≈ 10.
+            // Consumers (RenderOnPlanOptionsProvider) use these to re-map plan-item coordinates
+            // from the original SVG coordinate system into pyramid space and back.
+            var file = Path.Combine(TestContext.CurrentContext.WorkDirectory, "Assets\\plan_iss.svg");
+            var doc = SvgDocument.Open(file);
+            var docSize = doc.GetDimensions();
+            int targetWidth = (int)Math.Ceiling(docSize.Width * 10);
+            int pyramidH = (int)Math.Ceiling(targetWidth * docSize.Height / docSize.Width);
+            float expectedScaleX = targetWidth / docSize.Width;
+            float expectedScaleY = pyramidH / docSize.Height;
+
+            var tiles = new ConcurrentDictionary<string, MemoryStream>();
+
+            // Act
+            await new TileGenerator().GenerateTilesAsync(doc, targetWidth, CreateMemoryStreamProvider(tiles));
+
+            // Assert
+            Assert.IsTrue(tiles.ContainsKey("/dimensions.json"), "dimensions.json missing.");
+            var dimsJson = System.Text.Encoding.UTF8.GetString(tiles["/dimensions.json"].ToArray());
+            var dims = System.Text.Json.JsonDocument.Parse(dimsJson).RootElement;
+            Assert.AreEqual(expectedScaleX, (float)dims.GetProperty("scaleX").GetDouble(), 0.0001f,
+                "dimensions.json scaleX mismatch.");
+            Assert.AreEqual(expectedScaleY, (float)dims.GetProperty("scaleY").GetDouble(), 0.0001f,
+                "dimensions.json scaleY mismatch.");
+        }
+#endif
+
         [Test]
         public async Task GenerateTilesFromSvgAsync_TilesMatchCurrentPipeline_WithinTolerance()
         {
diff --git a/Svg/DeepZoom/TileGenerator.cs b/Svg/DeepZoom/TileGenerator.cs
index 060a6229f..b81619b9d 100644
--- a/Svg/DeepZoom/TileGenerator.cs
+++ b/Svg/DeepZoom/TileGenerator.cs
@@ -3,6 +3,7 @@
 using Svg.Platform;
 using System;
 using System.Collections.Generic;
+using System.Globalization;
 using System.IO;
 using System.Threading;
 using System.Threading.Tasks;
@@ -102,7 +103,7 @@ await GenerateZ0TilesScanlineAsync(codec, originalWidth, originalHeight,
                 kvp.Value.Dispose();
             }
             pending.Clear();
-            await WriteMetadataAsync(originalWidth, originalHeight, tileOutputStreamProvider);
+            await WriteMetadataAsync(originalWidth, originalHeight, 1.0, 1.0, tileOutputStreamProvider);
         }
 
         private async Task GenerateZ0TilesSubsetAsync(
@@ -431,7 +432,7 @@ await TryCascadeAsync(0, tx, ty, pending, pendingLock, levelTilesX, levelTilesY,
                 kvp.Value.Dispose();
             }
             pending.Clear();
-            await WriteMetadataAsync(pyramidW, pyramidH, tileOutputStreamProvider);
+            await WriteMetadataAsync(pyramidW, pyramidH, scaleX, scaleY, tileOutputStreamProvider);
         }
 
         private async Task WriteTileAndStorePendingAsync(
@@ -566,10 +567,13 @@ private static async Task WriteEncodedTileAsync(
         }
 
         private static async Task WriteMetadataAsync(
-            int width, int height,
+            int width, int height, double scaleX, double scaleY,
             Func<string, string, Task<Stream>> streamProvider)
         {
-            var json = System.Text.Encoding.UTF8.GetBytes($"{{\"width\":{width},\"height\":{height}}}");
+            var sx = scaleX.ToString("R", CultureInfo.InvariantCulture);
+            var sy = scaleY.ToString("R", CultureInfo.InvariantCulture);
+            var json = System.Text.Encoding.UTF8.GetBytes(
+                $"{{\"width\":{width},\"height\":{height},\"scaleX\":{sx},\"scaleY\":{sy}}}");
             using var outStream = await streamProvider("", "dimensions.json");
             await outStream.WriteAsync(json, 0, json.Length);
         }
diff --git a/Svg/Svg.csproj b/Svg/Svg.csproj
index a9b01bbdf..c030dc414 100644
--- a/Svg/Svg.csproj
+++ b/Svg/Svg.csproj
@@ -3,10 +3,12 @@
 	<PropertyGroup>
 		<TargetFrameworks>netstandard2.0;net48;net10.0</TargetFrameworks>
 		<RestoreProjectStyle>PackageReference</RestoreProjectStyle>
-		<Version>3.2.0-optiq01</Version>
+		<Version>3.2.0-optiq02</Version>
 		<Authors>gentledpp,zepr</Authors>
 		<Company>Opti-Q GmbH</Company>
 		<PackageReleaseNotes>
+			#3.2.0-optiq02
+			TileGenerator stores scale factor in dimensions.json (relative to svg dimensions)
 			#3.2.0-optiq01
 			Moved to avalonia 12
 			#3.1.4-optiq01