TextElementAutomationPeer.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Framework / System / Windows / Automation / Peers / TextElementAutomationPeer.cs / 1305600 / TextElementAutomationPeer.cs
                        
                        
                            //---------------------------------------------------------------------------- 
//
// Copyright (C) Microsoft Corporation.  All rights reserved.
//
// File: TextElementAutomationPeer.cs 
//
// Description: AutomationPeer associated with TextElements. 
// 
//---------------------------------------------------------------------------
 
using System.Collections;
using System.Collections.Generic;           // List
using System.Security;                      // SecurityCritical
using System.Windows.Documents;             // ITextContainer 
using System.Windows.Media;                 // Geometry
using System.Windows.Interop;               // HwndSource 
using MS.Internal.Automation;               // TextAdaptor 
using MS.Internal;
using MS.Internal.Documents;                // TextContainerHelper 

namespace System.Windows.Automation.Peers
{
    ///  
    /// AutomationPeer associated with TextElements.
    ///  
    public class TextElementAutomationPeer : ContentTextAutomationPeer 
    {
        ///  
        /// Constructor.
        /// 
        /// Owner of the AutomationPeer.
        public TextElementAutomationPeer(TextElement owner) 
            : base(owner)
        { } 
 
        /// 
        ///  
        /// 
        /// 
        /// Since DocumentAutomationPeer gives access to its content through
        /// TextPattern, this method always returns null. 
        /// 
        protected override List GetChildrenCore() 
        { 
            TextElement textElement = (TextElement)Owner;
            return TextContainerHelper.GetAutomationPeersFromRange(textElement.ContentStart, textElement.ContentEnd, null); 
        }

        /// 
        ///  
        /// 
        ///  
        ///     Critical    - Calls PresentationSource.CriticalFromVisual to get the source for this visual 
        ///     TreatAsSafe - The returned PresenationSource object is not exposed and is only used for converting
        ///                   co-ordinates to screen space. 
        /// 
        [SecurityCritical, SecurityTreatAsSafe]
        protected override Rect GetBoundingRectangleCore()
        { 
            TextElement textElement = (TextElement)Owner;
            ITextView textView = textElement.TextContainer.TextView; 
 
            if (textView == null || !textView.IsValid)
            { 
                return Rect.Empty;
            }

            Geometry geometry = textView.GetTightBoundingGeometryFromTextPositions(textElement.ContentStart, textElement.ContentEnd); 

            if (geometry != null) 
            { 
                PresentationSource presentationSource = PresentationSource.CriticalFromVisual(textView.RenderScope);
 
                if (presentationSource == null)
                {
                    return Rect.Empty;
                } 

                HwndSource hwndSource = presentationSource as HwndSource; 
 
                // If the source isn't an HwnSource, there's not much we can do, return empty rect
                if (hwndSource == null) 
                {
                    return Rect.Empty;
                }
 
                Rect rectElement = geometry.Bounds;
                Rect rectRoot = PointUtil.ElementToRoot(rectElement, textView.RenderScope, presentationSource); 
                Rect rectClient = PointUtil.RootToClient(rectRoot, presentationSource); 
                Rect rectScreen = PointUtil.ClientToScreen(rectClient, hwndSource);
 
                return rectScreen;
            }
            else
            { 
                return Rect.Empty;
            } 
        } 

        ///  
        /// 
        /// 
        /// 
        ///     Critical    - Calls PresentationSource.CriticalFromVisual to get the source for this visual 
        ///     TreatAsSafe - The returned PresenationSource object is not exposed and is only used for converting
        ///                   co-ordinates to screen space. 
        ///  
        [SecurityCritical, SecurityTreatAsSafe]
        protected override Point GetClickablePointCore() 
        {
            Point pt = new Point();

            TextElement textElement = (TextElement)Owner; 
            ITextView textView = textElement.TextContainer.TextView;
            if (textView == null || !textView.IsValid || (!textView.Contains(textElement.ContentStart) && !textView.Contains(textElement.ContentEnd))) 
            { 
                return pt;
            } 

            PresentationSource presentationSource = PresentationSource.CriticalFromVisual(textView.RenderScope);

            if (presentationSource == null) 
            {
                return pt; 
            } 

            HwndSource hwndSource = presentationSource as HwndSource; 

            // If the source isn't an HwnSource, there's not much we can do, return empty rect
            if (hwndSource == null)
            { 
                return pt;
            } 
 
            TextPointer endPosition = textElement.ContentStart.GetNextInsertionPosition(LogicalDirection.Forward);
            if (endPosition.CompareTo(textElement.ContentEnd) > 0) 
                endPosition = textElement.ContentEnd;

            Rect rectElement = CalculateVisibleRect(textView, textElement, textElement.ContentStart, endPosition);
            Rect rectRoot = PointUtil.ElementToRoot(rectElement, textView.RenderScope, presentationSource); 
            Rect rectClient = PointUtil.RootToClient(rectRoot, presentationSource);
            Rect rectScreen = PointUtil.ClientToScreen(rectClient, hwndSource); 
 
            pt = new Point(rectScreen.Left + rectScreen.Width * 0.5, rectScreen.Top + rectScreen.Height * 0.5);
 
            return pt;
        }

        ///  
        /// 
        ///  
        ///  
        protected override bool IsOffscreenCore()
        { 
            TextElement textElement = (TextElement)Owner;
            ITextView textView = textElement.TextContainer.TextView;
            if (textView == null || !textView.IsValid || (!textView.Contains(textElement.ContentStart) && !textView.Contains(textElement.ContentEnd)))
            { 
                return true;
            } 
 
            if (CalculateVisibleRect(textView, textElement, textElement.ContentStart, textElement.ContentEnd) == Rect.Empty)
            { 
                return true;
            }

            return false; 
        }
 
        ///  
        /// Compute visible rectangle.
        ///  
        private Rect CalculateVisibleRect(ITextView textView, TextElement textElement, TextPointer startPointer, TextPointer endPointer)
        {
            Geometry geometry = textView.GetTightBoundingGeometryFromTextPositions(startPointer, endPointer);
            Rect visibleRect = (geometry != null) ? geometry.Bounds : Rect.Empty; 
            Visual visual = textView.RenderScope;
            while (visual != null && visibleRect != Rect.Empty) 
            { 
                if (VisualTreeHelper.GetClip(visual) != null)
                { 
                    GeneralTransform transform = textView.RenderScope.TransformToAncestor(visual).Inverse;

                    // Safer version of transform to descendent (doing the inverse ourself),
                    // we want the rect inside of our space. (Which is always rectangular and much nicer to work with) 
                    if (transform != null)
                    { 
                        Rect rectBounds = VisualTreeHelper.GetClip(visual).Bounds; 
                        rectBounds = transform.TransformBounds(rectBounds);
 
                        visibleRect.Intersect(rectBounds);
                    }
                    else
                    { 
                        // No visibility if non-invertable transform exists.
                        return Rect.Empty; 
                    } 
                }
 
                visual = VisualTreeHelper.GetParent(visual) as Visual;
            }

            return visibleRect; 
        }
 
        ///  
        /// Gets collection of AutomationPeers for given text range.
        ///  
        internal override List GetAutomationPeersFromRange(ITextPointer start, ITextPointer end)
        {
            // Force children connection to automation tree.
            GetChildren(); 

            TextElement textElement = (TextElement)Owner; 
            return TextContainerHelper.GetAutomationPeersFromRange(start, end, textElement.ContentStart); 
        }
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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TextElementAutomationPeer.cs source code in C# .NET

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