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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
// Description: A derived ComboBox with some extra functionality
// for the Zoom behaviours of DocumentApplicationUI.
#pragma warning disable 1634, 1691
using System;
using System.ComponentModel;
using System.Globalization;
using System.Windows;
using System.Windows.Automation;
using System.Windows.Automation.Peers;
using System.Windows.Automation.Provider;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Input; // For event args
using System.Windows.TrustUI; // For string resources
namespace MS.Internal.Documents.Application
{
/// <summary>
/// A derived ComboBox with some extra functionality for the Zoom behaviours of DocumentApplicationUI.
/// </summary>
internal sealed class ZoomComboBox : ComboBox
{
//------------------------------------------------------
//
// Constructors
//
//------------------------------------------------------
#region Constructors
/// <summary>
/// Static ZoomComboBox constructor
/// </summary>
static ZoomComboBox()
{
// Override this ComboBox property so that any zoom values that are found in the TextBox
// (either from user input, or databinding) are not looked up in the drop down list.
IsTextSearchEnabledProperty.OverrideMetadata(typeof(ZoomComboBox), new FrameworkPropertyMetadata(false));
}
/// <summary>
/// Default ZoomComboBox constructor.
/// </summary>
internal ZoomComboBox()
{
// Set any ComboBox properties.
SetDefaults();
// Setup any ComboBox event handlers.
SetHandlers();
}
#endregion Constructors
//------------------------------------------------------
//
// Public Properties
//
//------------------------------------------------------
#region Public Properties
/// <summary>
/// A reference to the TextBox contained within the ZoomComboBox.
/// </summary>
public TextBox TextBox
{
get
{
return _editableTextBox;
}
}
public static readonly DependencyProperty ZoomProperty =
DependencyProperty.Register(
"Zoom",
typeof(double),
typeof(ZoomComboBox),
new FrameworkPropertyMetadata(
_zoomDefault, //default value
FrameworkPropertyMetadataOptions.None, //MetaData flags
new PropertyChangedCallback(OnZoomChanged))); //changed callback
/// <summary>
/// Process returns true if selection events generated from the ZoomComboBox
/// should be used to update the actual zoom. This is usually not the case
/// since we want to ignore the user going through the combobox with the
/// arrow keys until they actually apply the selection.
/// </summary>
public bool ProcessSelections
{
get
{
return _processSelections;
}
}
#endregion Public Properties
//------------------------------------------------------
//
// Public Methods
//
//------------------------------------------------------
#region Public Methods
/// <summary>
/// OnApplyTemplate is called when the ComboBox's Template is applied,
/// at this point we can get the TextBox from the Template.
/// </summary>
public override void OnApplyTemplate()
{
base.OnApplyTemplate();
_editableTextBox = GetTemplateChild("PART_EditableTextBox") as TextBox;
if (_editableTextBox != null)
{
_editableTextBox.TextAlignment = TextAlignment.Right;
// Since ZoomComboBox primarily supports input as numbers, we should disable
// IME options so that we don't need multiple Enter presses to parse
// the input. This means that we don't handle the IME equivalent of %, but
// we'll still handle everything else.
InputMethod.SetIsInputMethodEnabled(_editableTextBox, false);
}
}
/// <summary>
/// Sets the current Zoom value being displayed in the ComboBox's TextBox.
/// </summary>
public void SetZoom(double zoom)
{
string zoomString;
if (ZoomValueToString(zoom, out zoomString))
{
this.Text = zoomString;
_isEditingText = false;
// If this is currently focused, refocus to reset text selection.
if ((_editableTextBox != null) && (_editableTextBox.IsFocused))
{
_editableTextBox.SelectAll();
}
}
}
#endregion Public Methods
//------------------------------------------------------
//
// Internal Events
//
//------------------------------------------------------
#region Internal Events
/// <summary>
/// This event will be fired anytime a user was editing the TextBox but applied
/// the new value (ie pressed enter, or tab).
/// </summary>
internal event EventHandler ZoomValueEdited;
/// <summary>
/// This will fire a ZoomValueEdited event if required.
/// </summary>
internal void OnZoomValueEdited()
{
// Check if the TextBox is being edited
if (_isEditingText)
{
_isEditingText = false;
// Since the TextBox was being edited, fire a cancelled event so that the value
// may be applied (if desired by the UI).
ZoomValueEdited(this, EventArgs.Empty);
}
}
/// <summary>
/// This event will be fired anytime a user was editing the TextBox but chose not to apply
/// the new value (ie change of focus, or escape pressed).
/// </summary>
internal event EventHandler ZoomValueEditCancelled;
/// <summary>
/// This will fire a ZoomValueEditCancelled event if required.
/// </summary>
internal void OnZoomValueEditCancelled()
{
// Check if the TextBox is being edited
if (_isEditingText)
{
_isEditingText = false;
// Since the TextBox was being edited, fire a cancelled event so that the value
// may be reset (if desired by the UI).
ZoomValueEditCancelled(this, EventArgs.Empty);
}
}
#endregion Internal Events
//------------------------------------------------------
//
// Protected Methods
//
//------------------------------------------------------
/// <summary>
/// This will be fired anytime a selection has been made from the list
/// or a new value has been entered into the TextBox
/// </summary>
/// <param name="e">Event args.</param>
protected override void OnSelectionChanged(SelectionChangedEventArgs e)
{
// Only process selections when responding to a mouse click
if (ProcessSelections)
{
// If we were in edit mode, cancel it
if (_isEditingText)
{
_isEditingText = false;
}
// Since an item has been selected from the list, update the ComboBox
base.OnSelectionChanged(e);
// Reset the focus to highlight the new value.
Focus();
}
}
/// <summary>
/// Clears the current selection whenever the dropdown is opened.
/// </summary>
/// <param name="e"></param>
protected override void OnDropDownOpened(EventArgs e)
{
SelectedIndex = -1;
}
/// <summary>
/// Creates AutomationPeer (<see cref="UIElement.OnCreateAutomationPeer"/>)
/// </summary>
protected override AutomationPeer OnCreateAutomationPeer()
{
return new ZoomComboBoxBoxAutomationPeer(this);
}
/// <summary>
/// This will check incoming key presses for 'enter', 'escape', and 'tab' and take the
/// appropriate action.
/// </summary>
/// <param name="sender">A reference to the sender of the event.</param>
/// <param name="e">Arguments to the event, used for the key reference.</param>
protected override void OnPreviewKeyDown(KeyEventArgs e)
{
// This will check for the use of 'enter', 'escape' and 'tab' and take the appropriate action
// Ensure the arguments are not null.
if (e != null)
{
// Check which Key was pressed.
switch (e.Key)
{
// Erasure keys -- these don't trigger OnPreviewTextInput but should
// set _isEditingText nonetheless
case Key.Delete:
case Key.Back:
_isEditingText = true;
break;
// Submission Keys
case Key.Return: // This also covers: case Key.Enter
case Key.Tab:
case Key.Execute:
if (IsDropDownOpen)
{
// If the user presses the enter key while the drop down is
// open, this is the final selection from the dropdown and
// should be applied. Since the selection of this item
// (via up/down) was ignored, first we must copy the selected
// value into the TextBox. Then we process it as if the user
// had typed it in.
if (SelectedItem != null)
{
Text = ((ComboBoxItem)SelectedItem).Content.ToString();
}
_isEditingText = true;
}
// Enter pressed, issue submit, mark input as handled.
OnZoomValueEdited();
break;
// Rejection Keys
case Key.Cancel:
case Key.Escape:
// Escape pressed, issue cancel, mark input as handled.
OnZoomValueEditCancelled();
break;
case Key.Up:
case Key.Down:
// Open the drop down when up or down is pressed
if (!IsDropDownOpen)
{
IsDropDownOpen = true;
e.Handled = true;
// Always open with the first item (400%) selected
SelectedIndex = 0;
}
break;
}
if (!e.Handled)
{
base.OnPreviewKeyDown(e);
}
}
}
//------------------------------------------------------
//
// Private Methods
//
//------------------------------------------------------
#region Private Methods
/// <summary>
/// When the left mouse button is released, the resulting selection (if any) should
/// be processed.
/// </summary>
/// <param name="sender">A reference to the sender of the event (not used)</param>
/// <param name="e">Arguments to the event, used for the input text (not used)</param>
private void OnPreviewMouseLeftButtonUp(object sender, EventArgs e)
{
_processSelections = true;
}
/// <summary>
/// When the left mouse button press bubbles back up, we're done with it, so we
/// won't process further selections.
/// </summary>
/// <param name="sender">A reference to the sender of the event (not used)</param>
/// <param name="e">Arguments to the event, used for the input text (not used)</param>
private void OnMouseLeftButtonUp(object sender, EventArgs e)
{
_processSelections = false;
}
/// <summary>
/// This will check the characters that have been entered into the TextBox, and restrict it
/// to only the valid set.
/// </summary>
/// <param name="sender">A reference to the sender of the event.</param>
/// <param name="e">Arguments to the event, used for the input text.</param>
private void OnPreviewTextInput(object sender, TextCompositionEventArgs e)
{
// This will limit which characters are allowed to be entered into the TextBox
// Currently this is limited to 0-9, ',', '.', '%'
if ((e != null) && (!String.IsNullOrEmpty(e.Text)))
{
if (IsValidInputChar(e.Text[0]))
{
// Set editing mode and allow the ComboBox to handle it.
_isEditingText = true;
}
else
{
// Do not allow any remaining characters for text input.
e.Handled = true;
}
}
}
/// <summary>
/// This will validate incoming strings pasted into the textbox, only pasting
/// valid (all digit) strings.
/// </summary>
/// <param name="sender">A reference to the sender of the event.</param>
/// <param name="e">Arguments to the event, used to determine the input.</param>
private void OnPaste(object sender, DataObjectPastingEventArgs e)
{
// Validate the parameters, return if data is null.
if ((e == null) || (e.DataObject == null) || (String.IsNullOrEmpty(e.FormatToApply)))
{
return;
}
// Acquire a reference to the new string.
string incomingString = e.DataObject.GetData(e.FormatToApply) as string;
if (IsValidInputString(incomingString))
{
// Since the new content is valid set the ZoomComboBox as in edit mode
// and allow the text to be processed normally (ie don't CancelCommand).
_isEditingText = true;
}
else
{
// Cancel the paste if the string is null, empty, or otherwise invalid.
e.Handled = true;
e.CancelCommand();
}
}
/// <summary>
/// Checks if the given string contains valid characters for this control. Used for pasting
/// and UI Automation.
/// </summary>
/// <param name="value">The string to test.</param>
private bool IsValidInputString(string incomingString)
{
if (String.IsNullOrEmpty(incomingString))
{
return false;
}
// Check that each character is valid
foreach (char c in incomingString.ToCharArray())
{
// If the character is not a digit or acceptable symbol then refuse new content.
if (!(IsValidInputChar(c)))
{
return false;
}
}
return true;
}
/// <summary>
/// Returns true if the character is valid for input to this control.
/// </summary>
/// <param name="c">The character to test.</param>
private bool IsValidInputChar(char c)
{
// After discussing this with localization this is an approved method for
// checking for digit input, as it works regardless of the keyboard mapping.
// The ',' '.' and '%' are allowed, as they are the only other characters that
// can be displayed (or input) in a percentage. Localization informed me that
// although not every culture uses them (ie North America might not use ',' in
// a percentage) they are the only required characters, and as such we filter
// to only allow them to be input.
return (Char.IsDigit(c)) || (c == ',') || (c == '.') || (c == '%');
}
/// <summary>
/// Callback for the Zoom DependencyProperty.
/// </summary>
/// <param name="d">The ZoomComboBox to update</param>
/// <param name="e">The associated arguments.</param>
private static void OnZoomChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
ZoomComboBox zoomComboBox = (ZoomComboBox)d;
zoomComboBox.SetZoom((double)e.NewValue);
}
/// <summary>
/// Converts a double Zoom value to a corresponding string (with % sign)
/// </summary>
/// <param name="zoomValue">The zoom value to convert</param>
/// <param name="zoomString">The converted string value</param>
/// <returns></returns>
private static bool ZoomValueToString(double zoomValue, out string zoomString)
{
// Check that value is a valid double.
if (!(double.IsNaN(zoomValue)) && !(double.IsInfinity(zoomValue)))
{
try
{
// Ensure output string is formatted to current globalization standards.
zoomString = String.Format(CultureInfo.CurrentCulture,
SR.ZoomPercentageConverterStringFormat, zoomValue);
return true;
}
// Allow empty catch statements.
#pragma warning disable 56502
catch (ArgumentNullException) { }
catch (FormatException) { }
// Disallow empty catch statements.
#pragma warning restore 56502
}
// Invalid zoom value encountered.
zoomString = String.Empty;
return false;
}
/// <summary>
/// Set the default ComboBox properties
/// </summary>
private void SetDefaults()
{
ToolTip = SR.ZoomComboBoxToolTip;
IsReadOnly = false;
IsEditable = true;
IsTabStop = false;
IsTextSearchEnabled = false;
}
/// <summary>
/// Attach any needed ComboBox event handlers.
/// </summary>
private void SetHandlers()
{
PreviewTextInput += OnPreviewTextInput;
PreviewMouseLeftButtonUp += OnPreviewMouseLeftButtonUp;
AddHandler(ComboBox.MouseLeftButtonUpEvent, new RoutedEventHandler(OnMouseLeftButtonUp), true);
DataObject.AddPastingHandler(this, new DataObjectPastingEventHandler(OnPaste));
}
#endregion Private Methods
#region Nested Classes
/// <summary>
/// AutomationPeer associated with ZoomComboBox
/// </summary>
private class ZoomComboBoxBoxAutomationPeer : ComboBoxAutomationPeer, IValueProvider
{
/// <summary>
/// Constructor
/// </summary>
/// <param name="owner">Owner of the AutomationPeer.</param>
public ZoomComboBoxBoxAutomationPeer(ZoomComboBox owner)
: base(owner)
{ }
/// <summary>
/// <see cref="AutomationPeer.GetClassNameCore"/>
/// </summary>
override protected string GetClassNameCore()
{
return "ZoomComboBox";
}
/// <summary>
/// <see cref="AutomationPeer.GetPattern"/>
/// </summary>
override public object GetPattern(PatternInterface patternInterface)
{
if (patternInterface == PatternInterface.Value)
{
return this;
}
else
{
return base.GetPattern(patternInterface);
}
}
void IValueProvider.SetValue(string value)
{
ArgumentNullException.ThrowIfNull(value);
if (!IsEnabled())
{
throw new ElementNotEnabledException();
}
ZoomComboBox owner = (ZoomComboBox)Owner;
if (owner.IsReadOnly)
{
throw new ElementNotEnabledException();
}
if (owner.IsValidInputString(value))
{
owner.Text = value;
owner._isEditingText = true;
owner.OnZoomValueEdited();
}
}
}
#endregion
//------------------------------------------------------
//
// Private Fields
//
//------------------------------------------------------
private bool _isEditingText;
private bool _processSelections = false;
private TextBox _editableTextBox;
private const string _editableTextBoxName = "PART_EditableTextBox";
private const double _zoomDefault = 0.0;
}
}
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