Add Support for Selecting Process Trees (#2195)

* Add support for selecting process trees

* Child --> Descendant

Update checkbox text.

Co-authored-by: Drew Noakes <git@drewnoakes.com>

---------

Co-authored-by: Drew Noakes <git@drewnoakes.com>

Author: brianrob

build.cmd

@@ -41,6 +41,7 @@
         </Grid>
         <Grid DockPanel.Dock="Bottom" Background="{DynamicResource BackgroundColour}" >
             <Grid.ColumnDefinitions>
+                <ColumnDefinition Width="Auto"/>
                 <ColumnDefinition Width="*"/>
                 <ColumnDefinition Width="Auto"/>
                 <ColumnDefinition Width="*"/>
@@ -50,10 +51,12 @@
                 <ColumnDefinition Width="*"/>
                 <ColumnDefinition Width="Auto"/>
             </Grid.ColumnDefinitions>
-            <Button Name="OKButton" Margin="5,4" Grid.Column="1" MinWidth="80" Content="OK" Click="OKClicked" IsDefault="True" />
-            <Button Name="AllProcsButton" Margin="5,4" Grid.Column="3" MinWidth="80" Content="All Procs" Click="AllProcsClicked"
+            <CheckBox Name="IncludeChildProcessesCheckBox" Grid.Column="0" Margin="5,0,0,0" VerticalAlignment="Center" 
+                     ToolTip="Include all descendant processes of selected processes">Include descendant processes</CheckBox>
+            <Button Name="OKButton" Margin="5,4" Grid.Column="2" MinWidth="80" Content="OK" Click="OKClicked" IsDefault="True" />
+            <Button Name="AllProcsButton" Margin="5,4" Grid.Column="4" MinWidth="80" Content="All Procs" Click="AllProcsClicked"
                     ToolTip="Investigate all processes"/>
-            <Button Margin="5,4" Grid.Column="5" MinWidth="80" Content="Cancel" Click="CancelClicked" IsCancel="True" />
+            <Button Margin="5,4" Grid.Column="6" MinWidth="80" Content="Cancel" Click="CancelClicked" IsCancel="True" />
         </Grid>
         <Grid PreviewKeyDown="GridKeyDownHander">
             <WPFToolKit:DataGrid Name="Grid"

src/PerfView/Dialogs/SelectProcess.xaml

@@ -132,15 +132,95 @@ internal void OKClicked(object sender, RoutedEventArgs e)
                 SystemSounds.Beep.Play();
                 return;
             }
+            
             var ret = new List<IProcess>();
+            var selectedProcesses = new List<IProcess>();
+            
+            // Add explicitly selected processes
             foreach (var item in items)
             {
-                ret.Add((IProcess)item);
+                var process = (IProcess)item;
+                selectedProcesses.Add(process);
+                ret.Add(process);
+            }
+            
+            // If checkbox is checked, add child processes
+            if (IncludeChildProcessesCheckBox.IsChecked == true)
+            {
+                // Build dictionaries for process lookup
+                Dictionary<int, IProcess> processById = new Dictionary<int, IProcess>();
+                Dictionary<int, List<int>> childrenByParentId = new Dictionary<int, List<int>>();
+                
+                // First pass: build process ID mapping
+                foreach (var process in m_processes)
+                {
+                    processById[process.ProcessID] = process;
+                    
+                    // Initialize empty children list for each parent
+                    if (!childrenByParentId.ContainsKey(process.ParentID))
+                    {
+                        childrenByParentId[process.ParentID] = new List<int>();
+                    }
+                    
+                    // Add this process as a child of its parent
+                    childrenByParentId[process.ParentID].Add(process.ProcessID);
+                }
+                
+                // Add all transitive children of selected processes
+                HashSet<int> addedProcessIds = new HashSet<int>();
+                foreach (var process in selectedProcesses)
+                {
+                    addedProcessIds.Add(process.ProcessID); // Mark selected processes as already added
+                }
+                
+                // For each selected process, add all its descendants
+                foreach (var process in selectedProcesses)
+                {
+                    AddChildProcesses(process.ProcessID, processById, childrenByParentId, ret, addedProcessIds);
+                }
             }
 
             m_action(ret);
             Close();
         }
+        
+        private void AddChildProcesses(
+            int processId, 
+            Dictionary<int, IProcess> processById, 
+            Dictionary<int, List<int>> childrenByParentId,
+            List<IProcess> resultList,
+            HashSet<int> addedProcessIds)
+        {
+            // Check if this parent has any children
+            if (!childrenByParentId.ContainsKey(processId))
+            {
+                return;
+            }
+            
+            // For each child process
+            foreach (var childId in childrenByParentId[processId])
+            {
+                // Skip if already added (prevents potential infinite recursion if process tree has cycles)
+                if (addedProcessIds.Contains(childId))
+                {
+                    continue;
+                }
+                
+                // Skip if the process doesn't exist in our dictionary (shouldn't happen)
+                if (!processById.ContainsKey(childId))
+                {
+                    continue;
+                }
+                
+                // Add the child process to the result list
+                var childProcess = processById[childId];
+                resultList.Add(childProcess);
+                addedProcessIds.Add(childId);
+                
+                // Recursively add its children
+                AddChildProcesses(childId, processById, childrenByParentId, resultList, addedProcessIds);
+            }
+        }
         private void DoHyperlinkHelp(object sender, ExecutedRoutedEventArgs e)
         {
             MainWindow.DisplayUsersGuide(e.Parameter as string);