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实现类似iPhone效果的选择器，以便在x86平台做平板应用
using System;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.ComponentModel;
namespace WpfUIPickerLib
{
/// <summary>
/// Interaction logic for UserControl1.xaml
/// </summary>
public partial class WpfUIPickerControl : UserControl, INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public WpfUIPickerControl()
{
InitializeComponent();
}
public List<object> SelectedValues
{
get
{
List<object> retVal = new List<object>();
foreach (var tumbler in this.Tumblers)
{
retVal.Add(tumbler.SelectedValue);
}
return retVal;
}
private set
{
SelectedValues = value;
if (this.PropertyChanged != null)
this.PropertyChanged(this, new PropertyChangedEventArgs("SelectedValues"));
}
}
private bool open = false;
/// <summary>
/// Flag to indicate whether the user control is "open" (i.e. displaying tumblers).
/// </summary>
public bool IsOpen
{
get
{
return this.open || this.AlwaysOpen;
}
set
{
bool newVal = value || this.AlwaysOpen;
if (this.open != newVal)
{
this.open = newVal;
if (this.PropertyChanged != null)
this.PropertyChanged(this, new PropertyChangedEventArgs("IsOpen"));
}
}
}
#region Tumblers Dependency Property
/// <summary>
/// Dependency property for List of Tumblers
/// </summary>
public List<TumblerData> Tumblers
{
get { return (List<TumblerData>)GetValue(TumblersProperty); }
set { SetValue(TumblersProperty, value); }
}
// Using a DependencyProperty as the backing store for Tumblers. This enables animation, styling, binding, etc...
public static readonly DependencyProperty TumblersProperty =
DependencyProperty.Register("Tumblers", typeof(List<TumblerData>), typeof(WpfUIPickerControl), new UIPropertyMetadata(null, OnTumblersPropertyChanged));
private static void OnTumblersPropertyChanged(DependencyObject source, DependencyPropertyChangedEventArgs e)
{
WpfUIPickerControl thisCtrl = source as WpfUIPickerControl;
// TODO: update display
}
#endregion
#region AlwaysOpen Dependency Property
public bool AlwaysOpen
{
get { return (bool)GetValue(AlwaysOpenProperty); }
set { SetValue(AlwaysOpenProperty, value); }
}
// Using a DependencyProperty as the backing store for AlwaysOpen. This enables animation, styling, binding, etc...
public static readonly DependencyProperty AlwaysOpenProperty =
DependencyProperty.Register("AlwaysOpen", typeof(bool), typeof(WpfUIPickerControl), new UIPropertyMetadata(false));
#endregion
/// <summary>
/// Mouse wheel handler for tumblers. This is not a fired event because we need to mouse capture on the main grid
/// so we can know when to close the control. Instead this event gets called via the MouseWheel event on the main grid.
/// </summary>
/// <param name="tumbler">The tumbler (grid) that should receive the mouse wheel event</param>
/// <param name="e">the MouseWheelEventArgs forwarded from the main grid MouseWheel event</param>
private void Tumbler_PreviewMouseWheel(Grid tumbler, MouseWheelEventArgs e)
{
if (tumbler != null)
{
TumblerData td = tumbler.Tag as TumblerData;
// Each click in the mouse will increment or decrement the tumbler value by one
int newIdx = td.SelectedValueIndex (e.Delta > 0 ? 1 : -1);
if (newIdx >= 0 && newIdx < td.Values.Count)
{
// Set the new index which will cause NotifyPropertyChanged to fire, which in turn will cause
// the binding/converter to re-evaluate, which will result in the tumbler animating to the correct
// canvas offset.
td.SelectedValueIndex = newIdx;
}
}
}
private Grid dragTumbler = null;
private Point dragPt = new Point(0, 0);
private double originalDragOffset = 0;
private void mainGrid_PreviewMouseDown(object sender, MouseButtonEventArgs e)
{
if (this.mainGrid.IsMouseCaptured == false)
{
this.IsOpen = true;
this.mainGrid.CaptureMouse();
StartDrag();
}
else if (this.mainGrid.ContainsMouse())
{
StartDrag();
}
else
{
// close ui picker
this.mainGrid.ReleaseMouseCapture();
this.IsOpen = false;
}
}
private void StartDrag()
{
this.dragTumbler = getTargetTumbler();
this.dragPt = Mouse.GetPosition(this.mainGrid);
this.originalDragOffset = Canvas.GetTop(this.dragTumbler);
}
private void mainGrid_PreviewMouseWheel(object sender, MouseWheelEventArgs e)
{
// figure out which tumbler should get the mouse wheel
Grid targetTumbler = this.getTargetTumbler();
if (targetTumbler != null && this.IsOpen)
{
Tumbler_PreviewMouseWheel(targetTumbler, e);
}
}
private void mainGrid_PreviewMouseUp(object sender, MouseButtonEventArgs e)
{
// is this the end of a drag operation?
if (this.dragTumbler != null)
{
double offset = -Canvas.GetTop(this.dragTumbler);
Point mousePt = Mouse.GetPosition(this.mainGrid);
if (mousePt.Equals(this.dragPt))
{
// user clicked on tumbler without dragging, select the clicked-on value
offset = mousePt.Y - (this.mainGrid.ActualHeight / 2);
}
// find the Canvas offset for the value closest to where the drag ended
TumblerData td = this.dragTumbler.Tag as TumblerData;
double itemHeight = this.dragTumbler.ActualHeight / (td.Values.Count);
double newVal = offset / itemHeight 2;
int iVal = (int)Math.Round(newVal);
// update index, limit to valid values. The update will cause NotifyPropertyChanged which
// will animate the tumbler into the appropriate position for the selected value
td.SelectedValueIndex = Math.Min(Math.Max(0, iVal), td.Values.Count-1);
this.dragTumbler = null;
}
if (this.mainGrid.IsMouseCaptured && this.AlwaysOpen)
this.mainGrid.ReleaseMouseCapture();
}
private void mainGrid_PreviewMouseMove(object sender, MouseEventArgs e)
{
// are we dragging a tumbler?
if (Mouse.LeftButton == MouseButtonState.Pressed && this.dragTumbler != null)
{
Point pt = Mouse.GetPosition(this.mainGrid);
double diff = pt.Y - this.dragPt.Y;
// have to remove the animation before setting it manually (otherwise nothing happens because
// the animation fill behavior is set to HoldEnd)
this.dragTumbler.BeginAnimation(Canvas.TopProperty, null);
Canvas.SetTop(this.dragTumbler, this.originalDragOffset diff);
}
}
/// <summary>
/// Gets the Tumbler (grid) that currently contains the mouse. Useful for forwarding mouse events to the specific tumbler.
/// </summary>
/// <returns>the Grid (itemsGrid) that contains the mouse pointer</returns>
private Grid getTargetTumbler()
{
Grid targetTumbler = null;
for (int i = 0; i < this.Tumblers.Count; i)
{
Border foundTumbler = this.mainGrid.FindChild<Border>("tumblerBorder", i);
if (foundTumbler != null && foundTumbler.ContainsMouse())
{
targetTumbler = foundTumbler.FindChild<Grid>("itemsGrid", 0);
break;
}
}
return targetTumbler;
}
private void thisCtrl_Loaded(object sender, RoutedEventArgs e)
{
this.IsOpen = this.AlwaysOpen;
// Trigger an update on each tumbler so its canvas offset is set properly for displaying the selected value
foreach (var td in this.Tumblers)
td.TriggerUpdate();
}
}
}