如何获取面板的可见边界

Question

我有一个面板，它可能在也可能不在其他面板中。我正在尝试确定该面板的可见边界。我认为GetWindowRect 或GetClientRect 可以解决问题，但没有乐趣。

为了测试这一点，我创建了一个带有面板和多行文本框的表单。面板比表单大（即它延伸到表单底部以下）

所以如果我的表格是 300 x 300。面板位于 10,10 并且是 100 x 500 我想要一些可以告诉我可见区域为 100、290 的东西（假设面板的 0,0 相对起点为 10,10。

有这样的方法吗？

我尝试了几种不同的方法，例如获取我感兴趣的面板的父句柄并对其进行测试，但我不能始终确定直接父句柄会决定可见性。

这是我为测试GetWindowRect 或GetClientRect 而编写的测试应用程序代码：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace clientRectTest
{
public partial class Form1 : Form
{
    [StructLayout(LayoutKind.Sequential)]
    public struct RECT
    {
        public Int32 left;
        public Int32 top;
        public Int32 right;
        public Int32 bottom;

        public static RECT FromRectangle(Rectangle rectangle)
        {
            RECT win32rect = new RECT();
            win32rect.top = rectangle.Top;
            win32rect.bottom = rectangle.Bottom;
            win32rect.left = rectangle.Left;
            win32rect.right = rectangle.Right;
            return win32rect;
        }
    }

    [DllImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static extern bool GetClientRect(IntPtr hWnd, out RECT lpRect);
    [DllImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static extern bool GetWindowRect(IntPtr hWnd, out RECT lpRect);
    [DllImport("user32.dll")]
    [return: MarshalAs(UnmanagedType.Bool)]
    public static extern bool SetWindowPos(IntPtr hWnd, IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags);
    [DllImport("user32.dll")]
    public static extern IntPtr GetWindowDC(IntPtr hWnd);


    public Form1()
    {
        InitializeComponent();
        this.AutoScrollMinSize = new Size(250, 500);

    }


    protected override void OnMouseClick(MouseEventArgs e)
    {
        NewLine("Click Location: " + e.Location.ToString());
        base.OnMouseClick(e);
    }

    protected override void OnResize(EventArgs e)
    {
        this.textBox1.Text = "Panel Size" + this.panel1.Size.ToString();

        NewLine( "Form Size" + this.Size.ToString());
        //  NewLine("Panel PARENT Client Rectangle: " + getPanelClientRectangle(this.panel1.Parent.Handle));


        NewLine("Panel Client Rectangle: " + getPanelClientRectangle(this.panel1.Handle));
        NewLine("Panel Window Rectangle: " + getPanelWindowRectangle(this.panel1.Handle));
        NewLine("Panel Window Bounts: " + this.panel1.Bounds.ToString());


        NewLine("Panel DC Client Rectangle: " + getPanelDCClientRectangle(this.panel1.Handle));
        NewLine("Panel DC Window Rectangle: " + getPanelDCWindowRectangle(this.panel1.Handle));

        NewLine("Panel Location: " + this.panel1.Location.ToString());


        base.OnResize(e);
    }

    private string getPanelDCClientRectangle(IntPtr handle)
    {
        string cr = string.Empty;

        RECT r1 = new RECT();
        IntPtr dc = GetWindowDC(handle);
        GetClientRect(dc, out r1);

        cr = r1.left.ToString() + ", " + r1.top.ToString() + ", " + r1.right.ToString()
         + ", " + r1.bottom.ToString();
        Point thisLocation = this.Location;

        return cr;
    }

    private string getPanelDCWindowRectangle(IntPtr handle)
    {
        string cr = string.Empty;

        RECT r1 = new RECT();
        IntPtr dc = GetWindowDC(handle);
        GetWindowRect(dc, out r1);

        cr = r1.left.ToString() + ", " + r1.top.ToString() + ", " + r1.right.ToString()
         + ", " + r1.bottom.ToString();
        Point thisLocation = this.Location;

        return cr;
    }

    private string getPanelWindowRectangle(IntPtr handle)
    {
        string cr = string.Empty;

        RECT r1 = new RECT();

        GetWindowRect(handle, out r1);

        cr = r1.left.ToString() + ", " + r1.top.ToString() + ", " + r1.right.ToString()
         + ", " + r1.bottom.ToString();
        Point thisLocation = this.Location;

        return cr;
    }

    private string getPanelClientRectangle(IntPtr handle)
    {
        string cr = string.Empty;

        RECT r1 = new RECT();

        GetClientRect(handle, out r1);

        cr = r1.left.ToString() + ", " + r1.top.ToString() + ", " + r1.right.ToString()
         + ", " + r1.bottom.ToString();
        Point thisLocation = this.Location;

        return cr;
    }

    private void NewLine(string p)
    {
        this.textBox1.Text += Environment.NewLine + p;
    }
}
}

编辑：找到更多信息：

我觉得行this.AutoScrollMinSize = new Size(250, 500); 搞砸了我的结果。这似乎使面板 500 即使它没有显示 500。将重做我的一些测试用例。我没想到这条线会引起问题。

Answer 1

您应该能够使用面板的 DisplayRectangle 属性来获取当前正在显示的矩形。此属性在 Control 中实现，但被 ScrollableControl（System.Windows.Forms.Panel 的父级）覆盖

Answer 2

这是我最后想到的：

WinSDK.RECT parentRect = new WinSDK.RECT();
            WinSDK.RECT intersectRect = new WinSDK.RECT();

            Rectangle parentRectangle = new Rectangle();
            Rectangle intersectRectangle = new Rectangle();

            // Get the current Handle.
            IntPtr currentHandle = this.Handle;

            // Get next Parent Handle.
            IntPtr parentHandle = WinSDK.GetParent(this.Handle);

            // Get the Rect for the current Window.
            WinSDK.GetWindowRect(this.Handle, out intersectRect);

            // Load Current Window Rect into a System.Drawing.Rectangle
            intersectRectangle = new Rectangle(intersectRect.left, intersectRect.top, intersectRect.right - intersectRect.left, intersectRect.bottom - intersectRect.top );

            // Itterate through all parent windows and get the overlap of the visible areas to find out what's actually visible.
            while (parentHandle != IntPtr.Zero)
            {
                // Get the Rect for the Parent Window.
                WinSDK.GetWindowRect(parentHandle, out parentRect);
                parentRectangle = new Rectangle(parentRect.left, parentRect.top, parentRect.right - parentRect.left, parentRect.bottom - parentRect.top);

                // Get the intersect between the current and parent window.
                intersectRectangle.Intersect(parentRectangle);

                // Set up for next loop.
                currentHandle = parentHandle;
                parentHandle = WinSDK.GetParent(currentHandle);
            }

            return intersectRectangle;