和Snipaste开发交流之后，觉得还是不死心，心里过不去，于是乎又拿MSAA ()

非常有用的文章：

官方doc:

主要使用的方法：

注意：这块VS的代码提示可能会有缺失，一切以demo code和API为准。

这里我找到了一个九年前的项目，其中包含了相关的代码，可以借鉴：

我怕没了所以又fork了一份🤣：

注意：这个项目有些部分代码是有问题的，比方说if (xxxObject != null && xxxObject.Trim() != "")，这种写法明显如果出了NullPointerException就挂。所以大家还是要有分辨能力。

最终，下面是我的Win32API P/Invoke (有些没用到)：

[DllImport("oleacc.dll")]
public static extern uint GetRoleText(uint dwRole, [Out] StringBuilder lpszRole, uint cchRoleMax);

[DllImport("oleacc.dll")]
public static extern uint GetStateText(uint dwStateBit, [Out] StringBuilder lpszStateBit, uint cchStateBitMax);

[DllImport("oleacc.dll")]
public static extern uint WindowFromAccessibleObject(IAccessible pacc, ref IntPtr phwnd);

[DllImport("oleacc.dll", PreserveSig = false)]
[return: MarshalAs(UnmanagedType.Interface)]
public static extern object AccessibleObjectFromWindow(int hwnd, int dwId, ref Guid riid);

[DllImport("oleacc.dll")]
public static extern int AccessibleObjectFromWindow(IntPtr hwnd, uint id, ref Guid iid, [In, Out, MarshalAs(UnmanagedType.IUnknown)] ref object ppvObject);

[DllImport("oleacc.dll")]
public static extern int AccessibleChildren(IAccessible paccContainer, int iChildStart, int cChildren, [Out()] [MarshalAs(UnmanagedType.LPArray, SizeParamIndex = 4)] object[] rgvarChildren, ref int pcObtained);

抽出的一些常量 (很多都位于 WinUser.h)：

public enum ObjectIdentifiers : uint
{
    OBJID_WINDOW            = 0x00000000,
    OBJID_SYSMENU           = 0xFFFFFFFF,
    OBJID_TITLEBAR          = 0xFFFFFFFE,
    OBJID_MENU              = 0xFFFFFFFD,
    OBJID_CLIENT            = 0xFFFFFFFC,
    OBJID_VSCROLL           = 0xFFFFFFFB,
    OBJID_HSCROLL           = 0xFFFFFFFA,
    OBJID_SIZEGRIP          = 0xFFFFFFF9,
    OBJID_CARET             = 0xFFFFFFF8,
    OBJID_CURSOR            = 0xFFFFFFF7,
    OBJID_ALERT             = 0xFFFFFFF6,
    OBJID_SOUND             = 0xFFFFFFF5,
    OBJID_QUERYCLASSNAMEIDX = 0xFFFFFFF4,
    OBJID_NATIVEOM          = 0xFFFFFFF0,
    CHILDID_SELF            = 0
}

public static class ReferenceIdentifiers
{
    public static Guid IID_IUnknown = new Guid(0x00000000, 0x0000, 0x0000, 0xc0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x46);
    public static Guid IID_IDispatch = new Guid(0x00020400, 0x0000, 0x0000, 0xC0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x46);
    public static Guid IID_IAccessible = new Guid(0x618736e0, 0x3c3d, 0x11cf, 0x81, 0x0c, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71);
}

实现：

public static class GMSAAManager
{

    public static String GetElementName(IAccessible element)
    {
        try
        {
            return element.get_accName((int)ObjectIdentifiers.CHILDID_SELF);
        }
        catch (Exception)
        {
            return "";
        }
    }


    public static Rect GetElementBounds(IAccessible element)
    {
        try
        {
            element.accLocation(out int pxLeft, out int pyTop, out int pcxWidth, out int pcyHeight, (int)ObjectIdentifiers.CHILDID_SELF);
            return new Rect(pxLeft, pyTop, pcxWidth, pcyHeight);
        }
        catch (Exception)
        {
            return new Rect(0, 0, 0, 0);
        }
    }


    public static IAccessible[] GetChildren(IAccessible element)
    {
        try
        {
            IAccessible[] children = new IAccessible[element.accChildCount];
            int obtained = 0;
            Win32API.AccessibleChildren(element, 0, element.accChildCount, children, ref obtained);
            if (obtained == 0) return null;
            return children;
        }
        catch (Exception)
        {
            return null;
        }
    }


    public static GUIElement GetElement(IAccessible element)
    {
        return new GUIElement(GetElementBounds(element), GetElementName(element));
    }


    public static GUIElement GetElement(IAccessible element, Rect bounds)
    {
        return new GUIElement(bounds, GetElementName(element));
    }

    public static List<GUIElement> GetLeafElements(IAccessible element)
    {
        List<GUIElement> res = new List<GUIElement>();
        try
        {
            Rect bounds = GetElementBounds(element);
            if (!JudgeBounding(bounds)) return res;
            GetLeafElementsDFS(element, res, bounds);
        }
        catch (Exception)
        {
            return res;
        }
        return res;
    }


    public static IAccessible GetWindow(IntPtr hWnd)
    {
        object obj = null;
        Win32API.AccessibleObjectFromWindow(hWnd, (uint)ObjectIdentifiers.OBJID_WINDOW, ref ReferenceIdentifiers.IID_IAccessible, ref obj);
        return (IAccessible)obj;
    }


    private static bool JudgeBounding(Rect bounds)
    {
        try
        {
            if (bounds.Width == 0 || bounds.Height == 0)
                return false;
            return !bounds.IsEmpty;
        }
        catch (Exception)
        {
            return false;
        }
    }


    private static void GetLeafElementsDFS(IAccessible element, List<GUIElement> res, Rect bounds)
    {
        var children = GetChildren(element);
        if (children == null)
        {
            res.Add(GetElement(element, bounds));
            return;
        }
        if (children.Length == 0)
        {
            res.Add(GetElement(element, bounds));
            return;
        }
        foreach (var child in children)
        {
            if (child == null) continue;
            if (!child.GetType().IsCOMObject) continue;
            Rect rect = GetElementBounds(child);
            if (!JudgeBounding(rect)) continue;
            if (rect.Bottom <= bounds.Top || rect.Right <= bounds.Left) continue;
            if (rect.Top >= bounds.Bottom || rect.Left >= bounds.Right) continue;
            GetLeafElementsDFS(child, res, rect);
        }
    }

}

注意: 在这个过程中一定要注意类型问题。特别是C++的类型和C#之间对应的问题。我在这里就不列了，记得文档里用到什么就去查类型，有的时候该强制转换就强制转换。还有，C#的Enum后面就算跟了类型也没用，也要强制转换。总而言之，类型问题基本上贡献了这块90%的Bug（大概），所以一定要谨慎。

结论：比UIAutomation还要慢，基本上可以实锤是FFI (跨语言调用) 的锅了，过两天拿C++试试看。

最后修改：2021 年 08 月 03 日 11 : 46 PM
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