From 7024deccab987d53bddc2a78cfaa00869dc9f1a5 Mon Sep 17 00:00:00 2001
From: Dirk Lemstra <dirk@git.imagemagick.org>
Date: Sun, 5 Feb 2017 13:14:35 +0100
Subject: [PATCH] Added method to update the profile data (based on #96)

---
 .../JpegEncoderCore.cs                        |  1 +
 src/ImageSharp/MetaData/ImageMetaData.cs      | 29 ++++++++++++++++
 .../MetaData/ImageMetaDataTests.cs            | 33 +++++++++++++++++++
 .../Profiles/Exif/ExifProfileTests.cs         |  3 ++
 4 files changed, 66 insertions(+)

diff --git a/src/ImageSharp.Formats.Jpeg/JpegEncoderCore.cs b/src/ImageSharp.Formats.Jpeg/JpegEncoderCore.cs
index 9cc51c7772..657470f5cf 100644
--- a/src/ImageSharp.Formats.Jpeg/JpegEncoderCore.cs
+++ b/src/ImageSharp.Formats.Jpeg/JpegEncoderCore.cs
@@ -706,6 +706,7 @@ namespace ImageSharp.Formats
         private void WriteProfiles<TColor>(Image<TColor> image)
             where TColor : struct, IPackedPixel, IEquatable<TColor>
         {
+            image.MetaData.SyncProfiles();
             this.WriteProfile(image.MetaData.ExifProfile);
         }
 
diff --git a/src/ImageSharp/MetaData/ImageMetaData.cs b/src/ImageSharp/MetaData/ImageMetaData.cs
index a38899840e..0bd0d0f789 100644
--- a/src/ImageSharp/MetaData/ImageMetaData.cs
+++ b/src/ImageSharp/MetaData/ImageMetaData.cs
@@ -136,5 +136,34 @@ namespace ImageSharp
         /// <remarks>0 means to repeat indefinitely.</remarks>
         /// </summary>
         public ushort RepeatCount { get; set; }
+
+        /// <summary>
+        /// Synchronizes the profiles with the current meta data.
+        /// </summary>
+        internal void SyncProfiles()
+        {
+            this.SyncExifProfile();
+        }
+
+        private void SyncExifProfile()
+        {
+            if (this.ExifProfile == null)
+            {
+                return;
+            }
+
+            this.SyncExifResolution(ExifTag.XResolution, this.HorizontalResolution);
+            this.SyncExifResolution(ExifTag.YResolution, this.VerticalResolution);
+        }
+
+        private void SyncExifResolution(ExifTag tag, double resolution)
+        {
+            ExifValue value = this.ExifProfile.GetValue(tag);
+            if (value != null)
+            {
+                Rational newResolution = new Rational(resolution, false);
+                this.ExifProfile.SetValue(tag, newResolution);
+            }
+        }
     }
 }
diff --git a/tests/ImageSharp.Tests/MetaData/ImageMetaDataTests.cs b/tests/ImageSharp.Tests/MetaData/ImageMetaDataTests.cs
index 9034b88c09..d9bd52c730 100644
--- a/tests/ImageSharp.Tests/MetaData/ImageMetaDataTests.cs
+++ b/tests/ImageSharp.Tests/MetaData/ImageMetaDataTests.cs
@@ -38,5 +38,38 @@ namespace ImageSharp.Tests
             Assert.Equal(24, clone.Quality);
             Assert.Equal(1, clone.RepeatCount);
         }
+
+        [Fact]
+        public void SyncProfiles()
+        {
+            ExifProfile exifProfile = new ExifProfile();
+            exifProfile.SetValue(ExifTag.XResolution, new Rational(200));
+            exifProfile.SetValue(ExifTag.YResolution, new Rational(300));
+
+            Image image = new Image(1, 1);
+            image.MetaData.ExifProfile = exifProfile;
+            image.MetaData.HorizontalResolution = 200;
+            image.MetaData.VerticalResolution = 300;
+
+            image.MetaData.HorizontalResolution = 100;
+
+            Assert.Equal(200, ((Rational)image.MetaData.ExifProfile.GetValue(ExifTag.XResolution).Value).ToDouble());
+            Assert.Equal(300, ((Rational)image.MetaData.ExifProfile.GetValue(ExifTag.YResolution).Value).ToDouble());
+
+            image.MetaData.SyncProfiles();
+
+            Assert.Equal(100, ((Rational)image.MetaData.ExifProfile.GetValue(ExifTag.XResolution).Value).ToDouble());
+            Assert.Equal(300, ((Rational)image.MetaData.ExifProfile.GetValue(ExifTag.YResolution).Value).ToDouble());
+
+            image.MetaData.VerticalResolution = 150;
+
+            Assert.Equal(100, ((Rational)image.MetaData.ExifProfile.GetValue(ExifTag.XResolution).Value).ToDouble());
+            Assert.Equal(300, ((Rational)image.MetaData.ExifProfile.GetValue(ExifTag.YResolution).Value).ToDouble());
+
+            image.MetaData.SyncProfiles();
+
+            Assert.Equal(100, ((Rational)image.MetaData.ExifProfile.GetValue(ExifTag.XResolution).Value).ToDouble());
+            Assert.Equal(150, ((Rational)image.MetaData.ExifProfile.GetValue(ExifTag.YResolution).Value).ToDouble());
+        }
     }
 }
diff --git a/tests/ImageSharp.Tests/MetaData/Profiles/Exif/ExifProfileTests.cs b/tests/ImageSharp.Tests/MetaData/Profiles/Exif/ExifProfileTests.cs
index 61307da205..f4a2bcf401 100644
--- a/tests/ImageSharp.Tests/MetaData/Profiles/Exif/ExifProfileTests.cs
+++ b/tests/ImageSharp.Tests/MetaData/Profiles/Exif/ExifProfileTests.cs
@@ -150,6 +150,9 @@ namespace ImageSharp.Tests
 
             image.MetaData.ExifProfile.SetValue(ExifTag.XResolution, new Rational(150.0));
 
+            // We also need to change this value because this overrides XResolution when the image is written.
+            image.MetaData.HorizontalResolution = 150.0;
+
             value = image.MetaData.ExifProfile.GetValue(ExifTag.XResolution);
             TestValue(value, new Rational(150, 1));