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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.
using System.Collections.ObjectModel;
using System.Runtime.CompilerServices;
using System.Windows.Controls.Primitives;
using System.Windows.Data;
using System.Windows.Input;
using System.Windows.Media;
using MS.Internal;
namespace System.Windows.Controls
{
/// <summary>
/// Helper code for DataGrid.
/// </summary>
internal static class DataGridHelper
{
#region GridLines
// Common code for drawing GridLines. Shared by DataGridDetailsPresenter, DataGridCellsPresenter, and Cell
/// <summary>
/// Returns a size based on the given one with the given double subtracted out from the Width or Height.
/// Used to adjust for the thickness of grid lines.
/// </summary>
public static Size SubtractFromSize(Size size, double thickness, bool height)
{
if (height)
{
return new Size(size.Width, Math.Max(0.0, size.Height - thickness));
}
else
{
return new Size(Math.Max(0.0, size.Width - thickness), size.Height);
}
}
/// <summary>
/// Test if either the vertical or horizontal gridlines are visible.
/// </summary>
public static bool IsGridLineVisible(DataGrid dataGrid, bool isHorizontal)
{
if (dataGrid != null)
{
DataGridGridLinesVisibility visibility = dataGrid.GridLinesVisibility;
switch (visibility)
{
case DataGridGridLinesVisibility.All:
return true;
case DataGridGridLinesVisibility.Horizontal:
return isHorizontal;
case DataGridGridLinesVisibility.None:
return false;
case DataGridGridLinesVisibility.Vertical:
return !isHorizontal;
}
}
return false;
}
#endregion
#region Notification Propagation
public static bool ShouldNotifyCells(DataGridNotificationTarget target)
{
return TestTarget(target, DataGridNotificationTarget.Cells);
}
public static bool ShouldNotifyCellsPresenter(DataGridNotificationTarget target)
{
return TestTarget(target, DataGridNotificationTarget.CellsPresenter);
}
public static bool ShouldNotifyColumns(DataGridNotificationTarget target)
{
return TestTarget(target, DataGridNotificationTarget.Columns);
}
public static bool ShouldNotifyColumnHeaders(DataGridNotificationTarget target)
{
return TestTarget(target, DataGridNotificationTarget.ColumnHeaders);
}
public static bool ShouldNotifyColumnHeadersPresenter(DataGridNotificationTarget target)
{
return TestTarget(target, DataGridNotificationTarget.ColumnHeadersPresenter);
}
public static bool ShouldNotifyColumnCollection(DataGridNotificationTarget target)
{
return TestTarget(target, DataGridNotificationTarget.ColumnCollection);
}
public static bool ShouldNotifyDataGrid(DataGridNotificationTarget target)
{
return TestTarget(target, DataGridNotificationTarget.DataGrid);
}
public static bool ShouldNotifyDetailsPresenter(DataGridNotificationTarget target)
{
return TestTarget(target, DataGridNotificationTarget.DetailsPresenter);
}
public static bool ShouldRefreshCellContent(DataGridNotificationTarget target)
{
return TestTarget(target, DataGridNotificationTarget.RefreshCellContent);
}
public static bool ShouldNotifyRowHeaders(DataGridNotificationTarget target)
{
return TestTarget(target, DataGridNotificationTarget.RowHeaders);
}
public static bool ShouldNotifyRows(DataGridNotificationTarget target)
{
return TestTarget(target, DataGridNotificationTarget.Rows);
}
public static bool ShouldNotifyRowSubtree(DataGridNotificationTarget target)
{
DataGridNotificationTarget value =
DataGridNotificationTarget.Rows |
DataGridNotificationTarget.RowHeaders |
DataGridNotificationTarget.CellsPresenter |
DataGridNotificationTarget.Cells |
DataGridNotificationTarget.RefreshCellContent |
DataGridNotificationTarget.DetailsPresenter;
return TestTarget(target, value);
}
private static bool TestTarget(DataGridNotificationTarget target, DataGridNotificationTarget value)
{
return (target & value) != 0;
}
#endregion
#region Tree Helpers
/// <summary>
/// Walks up the templated parent tree looking for a parent type.
/// </summary>
public static T FindParent<T>(FrameworkElement element) where T : FrameworkElement
{
FrameworkElement parent = element.TemplatedParent as FrameworkElement;
while (parent != null)
{
T correctlyTyped = parent as T;
if (correctlyTyped != null)
{
return correctlyTyped;
}
parent = parent.TemplatedParent as FrameworkElement;
}
return null;
}
public static T FindVisualParent<T>(UIElement element) where T : UIElement
{
UIElement parent = element;
while (parent != null)
{
T correctlyTyped = parent as T;
if (correctlyTyped != null)
{
return correctlyTyped;
}
parent = VisualTreeHelper.GetParent(parent) as UIElement;
}
return null;
}
/// <summary>
/// Helper method which determines if any of the elements of
/// the tree is focusable and has tab stop
/// </summary>
public static bool TreeHasFocusAndTabStop(DependencyObject element)
{
if (element == null)
{
return false;
}
UIElement uielement = element as UIElement;
if (uielement != null)
{
if (uielement.Focusable && KeyboardNavigation.GetIsTabStop(uielement))
{
return true;
}
}
else
{
ContentElement contentElement = element as ContentElement;
if (contentElement != null && contentElement.Focusable && KeyboardNavigation.GetIsTabStop(contentElement))
{
return true;
}
}
int childCount = VisualTreeHelper.GetChildrenCount(element);
for (int i = 0; i < childCount; i++)
{
DependencyObject child = VisualTreeHelper.GetChild(element, i) as DependencyObject;
if (TreeHasFocusAndTabStop(child))
{
return true;
}
}
return false;
}
#endregion
#region Cells Panel Helper
/// <summary>
/// Invalidates a cell's panel if its column's width changes sufficiently.
/// </summary>
/// <param name="cell">The cell or header.</param>
/// <param name="e"></param>
public static void OnColumnWidthChanged(IProvideDataGridColumn cell, DependencyPropertyChangedEventArgs e)
{
Debug.Assert((cell is DataGridCell) || (cell is DataGridColumnHeader), "provideColumn should be one of the cell or header containers.");
UIElement element = (UIElement)cell;
DataGridColumn column = cell.Column;
bool isColumnHeader = (cell is DataGridColumnHeader);
if (column != null)
{
// determine the desired value of width for auto kind columns
DataGridLength width = column.Width;
if (width.IsAuto ||
(!isColumnHeader && width.IsSizeToCells) ||
(isColumnHeader && width.IsSizeToHeader))
{
DataGridLength oldWidth = (DataGridLength)e.OldValue;
double desiredWidth = 0.0;
if (oldWidth.UnitType != width.UnitType)
{
double constraintWidth = column.GetConstraintWidth(isColumnHeader);
if (!DoubleUtil.AreClose(element.DesiredSize.Width, constraintWidth))
{
element.InvalidateMeasure();
element.Measure(new Size(constraintWidth, double.PositiveInfinity));
}
desiredWidth = element.DesiredSize.Width;
}
else
{
desiredWidth = oldWidth.DesiredValue;
}
if (double.IsNaN(width.DesiredValue) ||
DoubleUtil.LessThan(width.DesiredValue, desiredWidth))
{
column.SetWidthInternal(new DataGridLength(width.Value, width.UnitType, desiredWidth, width.DisplayValue));
}
}
}
}
/// <summary>
/// Helper method which returns the clip for the cell based on whether it overlaps with frozen columns or not
/// </summary>
/// <param name="cell">The cell or header.</param>
/// <returns></returns>
public static Geometry GetFrozenClipForCell(IProvideDataGridColumn cell)
{
DataGridCellsPanel panel = GetParentPanelForCell(cell);
if (panel != null)
{
return panel.GetFrozenClipForChild((UIElement)cell);
}
return null;
}
/// <summary>
/// Helper method which returns the parent DataGridCellsPanel for a cell
/// </summary>
/// <param name="cell">The cell or header.</param>
/// <returns>Parent panel of the given cell or header</returns>
public static DataGridCellsPanel GetParentPanelForCell(IProvideDataGridColumn cell)
{
Debug.Assert((cell is DataGridCell) || (cell is DataGridColumnHeader), "provideColumn should be one of the cell or header containers.");
UIElement element = (UIElement)cell;
return VisualTreeHelper.GetParent(element) as DataGridCellsPanel;
}
/// <summary>
/// Helper method which returns the parent DataGridCellPanel's offset from the scroll viewer
/// for a cell or Header
/// </summary>
/// <param name="cell">The cell or header.</param>
/// <returns>Parent Panel's offset with respect to scroll viewer</returns>
public static double GetParentCellsPanelHorizontalOffset(IProvideDataGridColumn cell)
{
DataGridCellsPanel panel = GetParentPanelForCell(cell);
if (panel != null)
{
return panel.ComputeCellsPanelHorizontalOffset();
}
return 0.0;
}
#endregion
#region Property Helpers
public static bool IsDefaultValue(DependencyObject d, DependencyProperty dp)
{
return DependencyPropertyHelper.GetValueSource(d, dp).BaseValueSource == BaseValueSource.Default;
}
public static object GetCoercedTransferPropertyValue(
DependencyObject baseObject,
object baseValue,
DependencyProperty baseProperty,
DependencyObject parentObject,
DependencyProperty parentProperty)
{
return GetCoercedTransferPropertyValue(
baseObject,
baseValue,
baseProperty,
parentObject,
parentProperty,
null,
null);
}
/// <summary>
/// Computes the value of a given property based on the DataGrid property transfer rules.
/// </summary>
/// <remarks>
/// This is intended to be called from within the coercion of the baseProperty.
/// </remarks>
/// <param name="baseObject">The target object which recieves the transferred property</param>
/// <param name="baseValue">The baseValue that was passed into the coercion delegate</param>
/// <param name="baseProperty">The property that is being coerced</param>
/// <param name="parentObject">The object that contains the parentProperty</param>
/// <param name="parentProperty">A property who's value should be transfered (via coercion) to the baseObject if it has a higher precedence.</param>
/// <param name="grandParentObject">Same as parentObject but evaluated at a lower presedece for a given BaseValueSource</param>
/// <param name="grandParentProperty">Same as parentProperty but evaluated at a lower presedece for a given BaseValueSource</param>
/// <returns></returns>
public static object GetCoercedTransferPropertyValue(
DependencyObject baseObject,
object baseValue,
DependencyProperty baseProperty,
DependencyObject parentObject,
DependencyProperty parentProperty,
DependencyObject grandParentObject,
DependencyProperty grandParentProperty)
{
// Transfer Property Coercion rules:
//
// Determine if this is a 'Transfer Property Coercion'. If so:
// We can safely get the BaseValueSource because the property change originated from another
// property, and thus this BaseValueSource wont be stale.
// Pick a value to use based on who has the greatest BaseValueSource
// If not a 'Transfer Property Coercion', simply return baseValue. This will cause a property change if the value changes, which
// will trigger a 'Transfer Property Coercion', and we will no longer have a stale BaseValueSource
var coercedValue = baseValue;
if (IsPropertyTransferEnabled(baseObject, baseProperty))
{
var propertySource = DependencyPropertyHelper.GetValueSource(baseObject, baseProperty);
var maxBaseValueSource = propertySource.BaseValueSource;
if (parentObject != null)
{
var parentPropertySource = DependencyPropertyHelper.GetValueSource(parentObject, parentProperty);
if (parentPropertySource.BaseValueSource > maxBaseValueSource)
{
coercedValue = parentObject.GetValue(parentProperty);
maxBaseValueSource = parentPropertySource.BaseValueSource;
}
}
if (grandParentObject != null)
{
var grandParentPropertySource = DependencyPropertyHelper.GetValueSource(grandParentObject, grandParentProperty);
if (grandParentPropertySource.BaseValueSource > maxBaseValueSource)
{
coercedValue = grandParentObject.GetValue(grandParentProperty);
maxBaseValueSource = grandParentPropertySource.BaseValueSource;
}
}
}
return coercedValue;
}
/// <summary>
/// Causes the given DependencyProperty to be coerced in transfer mode.
/// </summary>
/// <remarks>
/// This should be called from within the target object's NotifyPropertyChanged. It MUST be called in
/// response to a change in the target property.
/// </remarks>
/// <param name="d">The DependencyObject which contains the property that needs to be transfered.</param>
/// <param name="p">The DependencyProperty that is the target of the property transfer.</param>
public static void TransferProperty(DependencyObject d, DependencyProperty p)
{
var transferEnabledMap = GetPropertyTransferEnabledMapForObject(d);
transferEnabledMap[p] = true;
d.CoerceValue(p);
transferEnabledMap[p] = false;
}
private static Dictionary<DependencyProperty, bool> GetPropertyTransferEnabledMapForObject(DependencyObject d)
{
Dictionary<DependencyProperty, bool> propertyTransferEnabledForObject;
if (!_propertyTransferEnabledMap.TryGetValue(d, out propertyTransferEnabledForObject))
{
propertyTransferEnabledForObject = new Dictionary<DependencyProperty, bool>();
_propertyTransferEnabledMap.Add(d, propertyTransferEnabledForObject);
}
return propertyTransferEnabledForObject;
}
internal static bool IsPropertyTransferEnabled(DependencyObject d, DependencyProperty p)
{
Dictionary<DependencyProperty, bool> propertyTransferEnabledForObject;
if ( _propertyTransferEnabledMap.TryGetValue(d, out propertyTransferEnabledForObject))
{
bool isPropertyTransferEnabled;
if (propertyTransferEnabledForObject.TryGetValue(p, out isPropertyTransferEnabled))
{
return isPropertyTransferEnabled;
}
}
return false;
}
/// <summary>
/// Tracks which properties are currently being transfered. This information is needed when GetPropertyTransferEnabledMapForObject
/// is called inside of Coercion.
/// </summary>
private static ConditionalWeakTable<DependencyObject, Dictionary<DependencyProperty, bool>> _propertyTransferEnabledMap = new ConditionalWeakTable<DependencyObject, Dictionary<DependencyProperty, bool>>();
#endregion
#region Binding
/// <summary>
/// Returns true if the binding (or any part of it) is OneWay.
/// </summary>
internal static bool IsOneWay(BindingBase bindingBase)
{
if (bindingBase == null)
{
return false;
}
// If it is a standard Binding, then check if it's Mode is OneWay
Binding binding = bindingBase as Binding;
if (binding != null)
{
return binding.Mode == BindingMode.OneWay;
}
// A multi-binding can be OneWay as well
MultiBinding multiBinding = bindingBase as MultiBinding;
if (multiBinding != null)
{
return multiBinding.Mode == BindingMode.OneWay;
}
// A priority binding is a list of bindings, if any are OneWay, we'll call it OneWay
PriorityBinding priBinding = bindingBase as PriorityBinding;
if (priBinding != null)
{
Collection<BindingBase> subBindings = priBinding.Bindings;
int count = subBindings.Count;
for (int i = 0; i < count; i++)
{
if (IsOneWay(subBindings[i]))
{
return true;
}
}
}
return false;
}
internal static BindingExpression GetBindingExpression(FrameworkElement element, DependencyProperty dp)
{
if (element != null)
{
return element.GetBindingExpression(dp);
}
return null;
}
internal static bool ValidateWithoutUpdate(FrameworkElement element)
{
bool result = true;
BindingGroup bindingGroup = element.BindingGroup;
DataGridCell cell = (element != null) ? element.Parent as DataGridCell : null;
if (bindingGroup != null && cell != null)
{
Collection<BindingExpressionBase> expressions = bindingGroup.BindingExpressions;
BindingExpressionBase[] bindingExpressionsCopy = new BindingExpressionBase[expressions.Count];
expressions.CopyTo(bindingExpressionsCopy, 0);
for (int i = 0; i < bindingExpressionsCopy.Length; i++)
{
// Check the binding's target element - it might have been GC'd
// (this can happen when column-virtualization is enabled, for e.g.
// ArgumentNullException when calling VisualTreeHelper.IsAncestor
// during DataGrid edit)
// If so, fetching TargetElement will detach the binding and remove it
// from the binding group's collection. This side-effect is why we
// loop through a copy of the original collection, and don't rely
// on i to be a valid index into the original collection.
BindingExpressionBase beb = bindingExpressionsCopy[i];
if (BindingExpressionBelongsToElement<DataGridCell>(beb, cell))
{
result = beb.ValidateWithoutUpdate() && result;
}
}
}
return result;
}
internal static bool BindingExpressionBelongsToElement<T>(BindingExpressionBase beb, T element) where T : FrameworkElement
{
DependencyObject targetElement = beb.TargetElement;
if (targetElement != null)
{
DependencyObject contextElement = FindContextElement(beb);
if (contextElement == null)
{
contextElement = targetElement;
}
if (contextElement is Visual || contextElement is System.Windows.Media.Media3D.Visual3D)
{
return VisualTreeHelper.IsAncestorOf(element, contextElement, typeof(T));
}
}
return false;
}
private static DependencyObject FindContextElement(BindingExpressionBase beb)
{
BindingExpression be;
MultiBindingExpression mbe;
PriorityBindingExpression pbe;
if ((be = beb as BindingExpression) != null)
{
// leaf binding - return its context element
return be.ContextElement;
}
// otherwise, depth-first search through tree of bindings
ReadOnlyCollection<BindingExpressionBase> childBindings = null;
if ((mbe = beb as MultiBindingExpression) != null)
{
childBindings = mbe.BindingExpressions;
}
else if ((pbe = beb as PriorityBindingExpression) != null)
{
childBindings = pbe.BindingExpressions;
}
if (childBindings != null)
{
foreach (BindingExpressionBase childBEB in childBindings)
{
DependencyObject result = FindContextElement(childBEB);
if (result != null)
{
return result;
}
}
}
return null;
}
private static readonly DependencyProperty FlowDirectionCacheProperty = DependencyProperty.Register("FlowDirectionCache", typeof(FlowDirection), typeof(DataGridHelper));
internal static void CacheFlowDirection(FrameworkElement element, DataGridCell cell)
{
if (element != null && cell != null)
{
object flowDirectionObj = element.ReadLocalValue(FrameworkElement.FlowDirectionProperty);
if (flowDirectionObj != DependencyProperty.UnsetValue)
{
cell.SetValue(FlowDirectionCacheProperty, flowDirectionObj);
}
}
}
internal static void RestoreFlowDirection(FrameworkElement element, DataGridCell cell)
{
if (element != null && cell != null)
{
object flowDirectionObj = cell.ReadLocalValue(DataGridHelper.FlowDirectionCacheProperty);
if (flowDirectionObj != DependencyProperty.UnsetValue)
{
element.SetValue(FrameworkElement.FlowDirectionProperty, flowDirectionObj);
}
}
}
internal static void UpdateTarget(FrameworkElement element)
{
BindingGroup bindingGroup = element.BindingGroup;
DataGridCell cell = (element != null) ? element.Parent as DataGridCell : null;
if (bindingGroup != null && cell != null)
{
Collection<BindingExpressionBase> expressions = bindingGroup.BindingExpressions;
BindingExpressionBase[] bindingExpressionsCopy = new BindingExpressionBase[expressions.Count];
expressions.CopyTo(bindingExpressionsCopy, 0);
for (int i = 0; i < bindingExpressionsCopy.Length; i++)
{
// Check the binding's target element - it might have been GC'd
// (this can happen when column-virtualization is enabled).
// If so, fetching TargetElement will detach the binding and remove it
// from the binding group's collection. This side-effect is why we
// loop through a copy of the original collection, and don't rely
// on i to be a valid index into the original collection.
BindingExpressionBase beb = bindingExpressionsCopy[i];
DependencyObject targetElement = beb.TargetElement;
if (targetElement != null &&
VisualTreeHelper.IsAncestorOf(cell, targetElement, typeof(DataGridCell)))
{
beb.UpdateTarget();
}
}
}
}
internal static void SyncColumnProperty(DependencyObject column, DependencyObject content, DependencyProperty contentProperty, DependencyProperty columnProperty)
{
if (IsDefaultValue(column, columnProperty))
{
content.ClearValue(contentProperty);
}
else
{
content.SetValue(contentProperty, column.GetValue(columnProperty));
}
}
internal static string GetPathFromBinding(Binding binding)
{
if (binding != null)
{
if (!string.IsNullOrEmpty(binding.XPath))
{
return binding.XPath;
}
else if (binding.Path != null)
{
return binding.Path.Path;
}
}
return null;
}
#endregion
#region Other Helpers
/// <summary>
/// Method which takes in DataGridHeadersVisibility parameter
/// and determines if row headers are visible.
/// </summary>
public static bool AreRowHeadersVisible(DataGridHeadersVisibility headersVisibility)
{
return (headersVisibility & DataGridHeadersVisibility.Row) == DataGridHeadersVisibility.Row;
}
/// <summary>
/// Helper method which coerces a value such that it satisfies min and max restrictions
/// </summary>
public static double CoerceToMinMax(double value, double minValue, double maxValue)
{
value = Math.Max(value, minValue);
value = Math.Min(value, maxValue);
return value;
}
/// <summary>
/// Helper to check if TextCompositionEventArgs.Text has any non
/// escape characters.
/// </summary>
public static bool HasNonEscapeCharacters(TextCompositionEventArgs textArgs)
{
if (textArgs != null)
{
string text = textArgs.Text;
for (int i = 0, count = text.Length; i < count; i++)
{
if (text[i] != _escapeChar)
{
return true;
}
}
}
return false;
}
/// <summary>
/// Helper to check if KeyEventArgs.Key is ImeProcessed.
/// </summary>
public static bool IsImeProcessed(KeyEventArgs keyArgs)
{
if (keyArgs != null)
{
return keyArgs.Key == Key.ImeProcessed;
}
return false;
}
private const char _escapeChar = '\u001b';
#endregion
}
}
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