MouseEventArgs.GetPosition 在 WPF 中无法按预期工作
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/20098435/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
MouseEventArgs.GetPosition not working as expected in WPF
提问by GreenEyedAndy
I would try a little Shapemoving and wrote the following Application:
我会尝试一点 Shapemoving 并编写以下应用程序：
<Window x:Class="WpfApplication7.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="27" />
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<ToolBar Grid.Row="0"/>
<Canvas Grid.Row="1" MouseDown="OnMouseDown" MouseUp="OnMouseUp" MouseMove="OnMouseMove">
<Ellipse Width="100" Height="100" Fill="Red" Canvas.Left="50" Canvas.Top="50" />
<Ellipse Width="100" Height="100" Fill="Red" Canvas.Left="180" Canvas.Top="50" />
<Rectangle Width="100" Height="100" Fill="Blue" Canvas.Left="220" Canvas.Top="160" />
</Canvas>
</Grid>
</Window>
and the Code behind:
以及背后的代码：
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
namespace WpfApplication7
{
public partial class MainWindow
{
private UIElement SelectedObject { get; set; }
private bool captureMouse;
private Point diffPosition;
public MainWindow()
{
InitializeComponent();
}
private void OnMouseDown(object sender, MouseButtonEventArgs e)
{
SelectedObject = e.Source as UIElement;
if (SelectedObject != null)
{
captureMouse = SelectedObject.CaptureMouse();
diffPosition = e.GetPosition(SelectedObject);
}
}
private void OnMouseUp(object sender, MouseButtonEventArgs e)
{
if (captureMouse)
{
SelectedObject.ReleaseMouseCapture();
}
SelectedObject = null;
}
private void OnMouseMove(object sender, MouseEventArgs e)
{
if (SelectedObject != null)
{
Canvas.SetLeft(SelectedObject, e.GetPosition(this).X - diffPosition.X);
Canvas.SetTop(SelectedObject, e.GetPosition(this).Y - diffPosition.Y);
}
}
}
}
I thought getting the diffPositionof the Click-Point in OnMouseDownwith GetPositionrelative to SelectedObjectsave me a few lines of code, but the height of the Toolbar is added. So my Y-Coordinate is 27 pixel more than I expected. If I delete the Toolbar, all works well.
What do I have to do to get the correct offset with the Toolbar in the Form?
我以为获得diffPosition的点击点在OnMouseDown与GetPosition相对于SelectedObject我保存的几行代码，但添加了工具栏的高度。所以我的 Y 坐标比我预期的多 27 像素。如果我删除工具栏，一切正常。我该怎么做才能使用表单中的工具栏获得正确的偏移量？
I know it's just a little mistake, but I can't find it.
我知道这只是一个小错误，但我找不到它。
采纳答案by Bizhan
Name your drawing area:
命名您的绘图区域：
<Canvas Grid.Row="1" x:Name="drawingArea" ...>
...
</Canvas>
and compare positions with drawingArea's.
并与drawingArea 的位置进行比较。
e.GetPosition(this.drawingArea)
This way you don't need to worry about layout changes and etc.
这样您就无需担心布局更改等。
