为什么 GetWindowRect 在我的 WPF 窗口中包含标题栏？

Question

我正在尝试使用GetWindowRect()（和GetGUIThreadInfo()）获得插入符号位置：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Runtime.InteropServices;

namespace WpfApplication1
{
    public class CaretInfo
    {
        public double Width { get; private set; }
        public double Height { get; private set; }
        public double Left { get; private set; }
        public double Top { get; private set; }

        public CaretInfo(double width, double height, double left, double top)
        {
            Width = width;
            Height = height;
            Left = left;
            Top = top;
        }
    }

    public class CaretHelper
    {

        public static CaretInfo GetCaretPosition()
        {
            // Get GUI info containing caret poisition
            var guiInfo = new GUITHREADINFO();
            guiInfo.cbSize = (uint)Marshal.SizeOf(guiInfo);
            GetGUIThreadInfo(0, out guiInfo);

            // Get width/height
            double width = guiInfo.rcCaret.right - guiInfo.rcCaret.left;
            double height = guiInfo.rcCaret.bottom - guiInfo.rcCaret.top;

            // Get left/top relative to screen
            RECT rect;
            GetWindowRect(guiInfo.hwndFocus, out rect);

            double left = guiInfo.rcCaret.left + rect.left + 2;
            double top = guiInfo.rcCaret.top + rect.top + 2;


            int capacity = GetWindowTextLength(guiInfo.hwndFocus) * 2;
            StringBuilder stringBuilder = new StringBuilder(capacity);
            GetWindowText(guiInfo.hwndFocus, stringBuilder, stringBuilder.Capacity);
            Console.WriteLine("Window: " + stringBuilder);
            Console.WriteLine("Caret: " + guiInfo.rcCaret.left + ", " + guiInfo.rcCaret.top);
            Console.WriteLine("Rect : " + rect.left + ", " + rect.top);

            return new CaretInfo(width, height, left, top);
        }

        [DllImport("user32.dll", EntryPoint = "GetGUIThreadInfo")]
        public static extern bool GetGUIThreadInfo(uint tId, out GUITHREADINFO threadInfo);

        [DllImport("user32.dll")]
        public static extern bool ClientToScreen(IntPtr hWnd, out Point position);

        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        public static extern bool GetWindowRect(IntPtr handle, out RECT lpRect);

        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern bool GetClientRect(IntPtr hWnd, ref Rect rect);

        [StructLayout(LayoutKind.Sequential)]
        public struct GUITHREADINFO
        {
            public uint cbSize;
            public uint flags;
            public IntPtr hwndActive;
            public IntPtr hwndFocus;
            public IntPtr hwndCapture;
            public IntPtr hwndMenuOwner;
            public IntPtr hwndMoveSize;
            public IntPtr hwndCaret;
            public RECT rcCaret;
        };

        [StructLayout(LayoutKind.Sequential)]
        public struct RECT
        {
            public int left;
            public int top;
            public int right;
            public int bottom;
        }

        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        public static extern int GetWindowTextLe

对于记事本和几乎其他任何地方，坐标都可以正确获取：

然而，在我的 WPF（和任何其他 WPF）窗口中，GetWindowRect() 决定包含标题栏并将插入符号的顶部位置偏移标题栏的高度：

知道为什么吗？

我也尝试使用DwmGetWindowAttribute()，但它在 WPF 窗口中的坐标与GetWindowRect() 相同。

编辑：

通过Brian Reichle 的回答，我已经能够确定一种获取客户区坐标的方法：

[DllImport("user32.dll")]
public static extern bool ClientToScreen(IntPtr hWnd, ref System.Drawing.Point lpPoint);

System.Drawing.Point point = new System.Drawing.Point(0, 0);
ClientToScreen(guiInfo.hwndFocus, ref point)

0,0 是guiInfo.hwndFocus 指定的窗口客户区的左上角坐标，它始终是0,0，因为它是相对于窗口的客户区的。 ClientToScreen() 将坐标转换为相对于屏幕的坐标（必须为 System.Drawing.Point，System.Windows.Point 将不起作用）。

Answer 1

包含标题栏是因为它是窗口的一部分，如果您不想要非客户区，那么您需要请求客户区 rect (GetClientRect)。

记事本的混乱可能是因为您使用的是文本框的窗口句柄而不是窗口本身。请记住，WPF 为整个窗口使用单个句柄，而 win32 经常（但不总是）为窗口中的每个控件使用单独的句柄。

在你提到GetClientRect'returned'0,0的评论中，你检查它是返回true（成功）还是false（失败）？如果返回false，你检查GetLastError()的结果了吗？