是什么让这个点击通过？

Question

我想弄清楚这段代码是如何工作的，但我就是想不通是什么让它点击通过。

是的，这段代码不是我的，因为我正在尝试 learn/understand 它。

假设我想要透明度而不是点击需要更改的内容以及为什么？

我已经一遍又一遍地浏览 Windows styles 个页面，但仍然无法理解点击部分。

using System;
using System.Runtime.InteropServices;
using UnityEngine;

public class TransparentWindow : MonoBehaviour
{
    [SerializeField]
    private Material m_Material;

    private struct MARGINS
    {
        public int cxLeftWidth;
        public int cxRightWidth;
        public int cyTopHeight;
        public int cyBottomHeight;
    }

    [DllImport("user32.dll")]
    private static extern IntPtr GetActiveWindow();

    [DllImport("user32.dll")]
    private static extern int SetWindowLong(IntPtr hWnd, int nIndex, uint dwNewLong);

    [DllImport("user32.dll")]
    static extern bool ShowWindowAsync(IntPtr hWnd, int nCmdShow);

    [DllImport("user32.dll", EntryPoint = "SetLayeredWindowAttributes")]
    static extern int SetLayeredWindowAttributes(IntPtr hwnd, int crKey, byte bAlpha, int dwFlags);

    [DllImport("user32.dll", EntryPoint = "SetWindowPos")]
    private static extern int SetWindowPos(IntPtr hwnd, int hwndInsertAfter, int x, int y, int cx, int cy, int uFlags);

    [DllImport("Dwmapi.dll")]
    private static extern uint DwmExtendFrameIntoClientArea(IntPtr hWnd, ref MARGINS margins);

    const int GWL_STYLE = -16;
    const uint WS_POPUP = 0x80000000;
    const uint WS_VISIBLE = 0x10000000;
    const int HWND_TOPMOST = -1;

    void Start()
    {
        #if !UNITY_EDITOR // You really don't want to enable this in the editor..

        int fWidth = Screen.width;
        int fHeight = Screen.height;
        var margins = new MARGINS() { cxLeftWidth = -1 };
        var hwnd = GetActiveWindow();

        SetWindowLong(hwnd, GWL_STYLE, WS_POPUP | WS_VISIBLE);

        // Transparent windows with click through
        SetWindowLong(hwnd, -20, 524288 | 32);//GWL_EXSTYLE=-20; WS_EX_LAYERED=524288=&h80000, WS_EX_TRANSPARENT=32=0x00000020L        
        SetLayeredWindowAttributes(hwnd, 0, 255, 2);// Transparency=51=20%, LWA_ALPHA=2
        SetWindowPos(hwnd, HWND_TOPMOST, 0, 0, fWidth, fHeight, 32 | 64); //SWP_FRAMECHANGED = 0x0020 (32); //SWP_SHOWWINDOW = 0x0040 (64)
        DwmExtendFrameIntoClientArea(hwnd, ref margins);

        #endif
    }

    void OnRenderImage(RenderTexture from, RenderTexture to)
    {
        Graphics.Blit(from, to, m_Material);
    }
}

Answer 1

这个函数：

SetWindowLong(hwnd, -20, 524288 | 32);

成功了。 Windows 执行 Mircosoft 制定的规则，即对用户透明的 window 必须对鼠标透明。设置透明度位 WS_EX_TRANSPARENT 后，window 对鼠标也变得透明，点击传递到透明 window 后面的绘制层。

你不需要理解，但可以利用这个 'OS feature' ，它可能是为了掩盖其他东西而实现的。

阅读解释参数的article about the subject and this answer

是什么让这个点击通过？

What makes this click through?

c#

window

click-through