Add telemetry for Svg preview handler (microsoft#1314)

* Added telemetry events for Svg Preview Handler

* Added unit test in case preview handler throws

* Updated the Error event name

* Remove the not required return statement

src/modules/previewpane/SvgPreviewHandler/Resource.resx

@@ -120,4 +120,7 @@
   <data name="BlockedElementInfoText" xml:space="preserve">
     <value>Some elements have been blocked to help prevent the sender from identifying your computer. Open this item to view all elements.</value>
   </data>
+  <data name="SvgNotPreviewedError" xml:space="preserve">
+    <value>The Svg could not be preview due to an internal error in Svg Preview Handler.</value>
+  </data>
 </root>

src/modules/previewpane/SvgPreviewHandler/SvgPreviewControl.cs

@@ -8,6 +8,7 @@
 using System.IO;
 using System.Linq;
 using System.Runtime.InteropServices.ComTypes;
+using System.Runtime.Versioning;
 using System.Windows.Forms;
 using System.Xml;
 using System.Xml.Linq;
@@ -33,9 +34,9 @@ public class SvgPreviewControl : FormHandlerControl
         private RichTextBox textBox;
 
         /// <summary>
-        /// Represent if any blocked element is found in the Svg.
+        /// Represent if an text box info bar is added for showing message.
         /// </summary>
-        private bool foundFilteredElements = false;
+        private bool infoBarAdded = false;
 
         /// <summary>
         /// Start the preview on the Control.
@@ -45,25 +46,37 @@ public override void DoPreview<T>(T dataSource)
         {
             this.InvokeOnControlThread(() =>
             {
-                this.foundFilteredElements = false;
-                string svgData = null;
-                using (var stream = new StreamWrapper(dataSource as IStream))
+                try
                 {
-                    using (var reader = new StreamReader(stream))
+                    this.infoBarAdded = false;
+                    string svgData = null;
+                    using (var stream = new StreamWrapper(dataSource as IStream))
                     {
-                        svgData = reader.ReadToEnd();
+                        using (var reader = new StreamReader(stream))
+                        {
+                            svgData = reader.ReadToEnd();
+                        }
+                    }
+
+                    svgData = string.IsNullOrWhiteSpace(svgData) ? svgData : SvgPreviewHandlerHelper.RemoveElements(svgData, out this.infoBarAdded);
+                    if (this.infoBarAdded)
+                    {
+                        this.AddTextBoxControl(Resource.BlockedElementInfoText);
                     }
-                }
 
-                svgData = string.IsNullOrWhiteSpace(svgData) ? svgData : SvgPreviewHandlerHelper.RemoveElements(svgData, out this.foundFilteredElements);
-                if (this.foundFilteredElements)
+                    this.AddBrowserControl(svgData);
+                    this.Resize += this.FormResized;
+                    base.DoPreview(dataSource);
+                    SvgTelemetry.Log.SvgFilePreviewed();
+                }
+                catch (Exception ex)
                 {
-                    this.AddTextBoxControl();
+                    SvgTelemetry.Log.SvgFilePreviewError(ex.Message);
+                    this.Controls.Clear();
+                    this.infoBarAdded = true;
+                    this.AddTextBoxControl(Resource.SvgNotPreviewedError);
+                    base.DoPreview(dataSource);
                 }
-
-                this.AddBrowserControl(svgData);
-                this.Resize += this.FormResized;
-                base.DoPreview(dataSource);
             });
         }
 
@@ -85,7 +98,7 @@ private void RTBContentsResized(object sender, ContentsResizedEventArgs e)
         /// <param name="e">Provides data for the resize event.</param>
         private void FormResized(object sender, EventArgs e)
         {
-            if (this.foundFilteredElements)
+            if (this.infoBarAdded)
             {
                 this.textBox.Width = this.Width;
             }
@@ -109,10 +122,11 @@ private void AddBrowserControl(string svgData)
         /// <summary>
         /// Adds a Text Box in Controls for showing information about blocked elements.
         /// </summary>
-        private void AddTextBoxControl()
+        /// <param name="message">Message to be displayed in textbox.</param>
+        private void AddTextBoxControl(string message)
         {
             this.textBox = new RichTextBox();
-            this.textBox.Text = Resource.BlockedElementInfoText;
+            this.textBox.Text = message;
             this.textBox.BackColor = Color.LightYellow;
             this.textBox.Multiline = true;
             this.textBox.Dock = DockStyle.Top;

src/modules/previewpane/SvgPreviewHandler/SvgPreviewHandler.csproj

@@ -67,6 +67,7 @@
     </Compile>
     <Compile Include="SvgPreviewHandler.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
+    <Compile Include="SvgTelemetry.cs" />
     <Compile Include="Utilities\SvgPreviewHandlerHelper.cs" />
   </ItemGroup>
   <ItemGroup>

src/modules/previewpane/SvgPreviewHandler/SvgTelemetry.cs

@@ -0,0 +1,70 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Diagnostics.Tracing;
+using PreviewHandlerCommon.Telemetry;
+
+namespace SvgPreviewHandler
+{
+    /// <summary>
+    /// Telemetry helper class for Svg renderer.
+    /// </summary>
+    public class SvgTelemetry : TelemetryBase
+    {
+        /// <summary>
+        /// Name for ETW event.
+        /// </summary>
+        private const string EventSourceName = "Microsoft.PowerToys";
+
+        /// <summary>
+        /// ETW event name when Svg is previewed.
+        /// </summary>
+        private const string SvgFilePreviewedEventName = "PowerPreview_SVGRenderer_Previewed";
+
+        /// <summary>
+        /// ETW event name when error is thrown during Svg preview.
+        /// </summary>
+        private const string SvgFilePreviewErrorEventName = "PowerPreview_SVGRenderer_Error";
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="SvgTelemetry"/> class.
+        /// </summary>
+        public SvgTelemetry()
+            : base(EventSourceName)
+        {
+        }
+
+        /// <summary>
+        /// Gets an instance of the <see cref="SvgTelemetry"/> class.
+        /// </summary>
+        public static SvgTelemetry Log { get; } = new SvgTelemetry();
+
+        /// <summary>
+        /// Publishes ETW event when svg is previewed successfully.
+        /// </summary>
+        public void SvgFilePreviewed()
+        {
+            this.Write(SvgFilePreviewedEventName, new EventSourceOptions()
+            {
+                Keywords = ProjectKeywordMeasure,
+                Tags = ProjectTelemetryTagProductAndServicePerformance,
+            });
+        }
+
+        /// <summary>
+        /// Publishes ETW event when svg could not be previewed.
+        /// </summary>
+        public void SvgFilePreviewError(string message)
+        {
+            this.Write(
+                SvgFilePreviewErrorEventName,
+                new EventSourceOptions()
+                {
+                    Keywords = ProjectKeywordMeasure,
+                    Tags = ProjectTelemetryTagProductAndServicePerformance,
+                },
+                new { Message = message, });
+        }
+    }
+}

src/modules/previewpane/UnitTests-SvgPreviewHandler/SvgPreviewControlTests.cs

@@ -162,6 +162,31 @@ public void SvgPreviewControl_RichTextBoxWidthShouldAdjust_IfParentControlWidthC
             Assert.AreEqual(finalParentWidth, textBox.Width);
         }
 
+        [TestMethod]
+        public void SvgPreviewControl_ShouldAddValidTextBox_IfSvgPreviewThrows()
+        {
+            // Arrange
+            var svgPreviewControl = new SvgPreviewControl();
+            var mockStream = new Mock<IStream>();
+            mockStream
+                .Setup(x => x.Read(It.IsAny<byte[]>(), It.IsAny<int>(), It.IsAny<IntPtr>()))
+                .Throws(new Exception());
+
+            // Act
+            svgPreviewControl.DoPreview(mockStream.Object);
+            var textBox = svgPreviewControl.Controls[0] as RichTextBox;
+
+            // Assert
+            Assert.IsFalse(string.IsNullOrWhiteSpace(textBox.Text));
+            Assert.AreEqual(svgPreviewControl.Controls.Count, 1);
+            Assert.AreEqual(textBox.Dock, DockStyle.Top);
+            Assert.AreEqual(textBox.BackColor, Color.LightYellow);
+            Assert.IsTrue(textBox.Multiline);
+            Assert.IsTrue(textBox.ReadOnly);
+            Assert.AreEqual(textBox.ScrollBars, RichTextBoxScrollBars.None);
+            Assert.AreEqual(textBox.BorderStyle, BorderStyle.None);
+        }
+
         private IStream GetMockStream(string streamData) 
         {
             var mockStream = new Mock<IStream>();