GetWindowRect与Window.Left不同

Question

我创建了一个小样本应用程序来说明我在使用时遇到的问题GetWindowRect.当我单击Foo按钮时,它显示Left返回的值GetWindowRect不同于Window.Left.

看来返回的值Window.Left是相对的,但我不确定是什么.同样奇怪的是,我不能在每台机器上重现这一点,在我的家用笔记本电脑上有或没有额外的显示器我​​可以重现这个问题,在我的工作电脑上问题不会发生.两个系统都运行Windows 7

为什么这些值不同,我该如何解决这个问题呢？

MainWindow.xaml.cs

using System;
using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Interop;

namespace PositionTest
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        private IntPtr thisHandle;
        public MainWindow()
        {
            InitializeComponent();
        }

        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            thisHandle = new WindowInteropHelper(this).Handle;
        }

        [DllImport("user32.dll", SetLastError = true)]
        [return: MarshalAs(UnmanagedType.Bool)]
        public static extern bool GetWindowRect(IntPtr hWnd, ref RECT lpRect);

        [StructLayout(LayoutKind.Sequential)]
        public struct RECT
        {
            public int Left;
            public int Top;
            public int Right;
            public int Bottom;
        }

        private void ReportLocation(object sender, RoutedEventArgs e)
        {
            var rct = new RECT();
            GetWindowRect(thisHandle, ref rct);

            MessageBox.Show(Left.ToString() + " " + rct.Left);
        }
    }
}

MainWindow.xaml

<Window x:Class="PositionTest.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Loaded="Window_Loaded" WindowStartupLocation="Manual" Height="150" Width="150" WindowStyle="SingleBorderWindow" ResizeMode="NoResize" BorderThickness="0,1,0,0" >
    <Grid>
        <Button Content="Foo" HorizontalAlignment="Left" Margin="35,50,0,0" VerticalAlignment="Top" Width="75" Click="ReportLocation"/>
    </Grid>
</Window>

Answer 1

你没有量化差异,有几种解释,但有一个明显的不匹配.Windows和WPF使用不同的单位.GetWindowRect()以像素为单位返回窗口位置,Window.Left以1/96英寸返回位置.当视频适配器没有以每英寸96点的速度运行时,它们将不匹配.96 dpi是传统设置,在更高版本的Windows上更改非常容易.WPF使得获取dpi设置有点困难,请查看此博客文章以获取代码.