Win 7中的C++ UIA TextPattern不在RichEdit控件上，但C# UIA确实找到了它。

Question

在Win 7 SP1和方便更新(最新发布的Win 7)上，我的C++代码使用WindowsAutomation3.0的CUIAutomation无法从内置WordPad应用程序中的RichEdit控件获取TextPattern。但是，使用UIAutomationClient和UIAutomationTypes的等效的UIAutomationTypes代码可以。

Win 10更好的成功: C++代码和C#代码都成功地获得了TextPattern。

我的主要项目与另一个C# UIA应用程序有兼容性问题，当我在Win 10上使用C++代码时，这个应用程序就消失了。所以我真的很想在Win 7上使用C++代码。有人知道为什么C++代码失败以及如何修复吗？我很惊讶从内置的TextPattern控件中获取一个简单的RichEdit不能可靠地工作！

下面是C#代码(更容易阅读！)，后面是C++代码：

using System;
using System.Threading;
using System.Windows.Automation;

namespace UIAutomationNET
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Getting element at cursor in 3 seconds...");
            Thread.Sleep(3000);

            var element = AutomationElement.FocusedElement;

            if (element != null)
            {
                var textPatternElement = element.FindFirst(
                    TreeScope.Subtree,
                    new PropertyCondition(AutomationElement.IsTextPatternAvailableProperty, true));

                if (textPatternElement == null)
                    Console.WriteLine("No element supporting TextPattern found.");
                else
                    Console.WriteLine("TextPattern is supported!  :-)");
            }
        }
    }
}

以下C++代码基于此MSDN代码库示例

#include <windows.h>
#include <ole2.h>
#include <uiautomation.h>
#include <strsafe.h>

IUIAutomation *_automation;


int _cdecl wmain(_In_ int argc, _In_reads_(argc) WCHAR* argv[])
{
    UNREFERENCED_PARAMETER(argc);
    UNREFERENCED_PARAMETER(argv);

    // Initialize COM before using UI Automation
    HRESULT hr = CoInitialize(NULL);
    if (FAILED(hr))
    {
        wprintf(L"CoInitialize failed, HR:0x%08x\n", hr);
    }
    else
    {
        // Use CUIAutomation instead of CUIAutomation8 on Win 7
        hr = CoCreateInstance(__uuidof(CUIAutomation), NULL,
            CLSCTX_INPROC_SERVER, IID_PPV_ARGS(&_automation));
        if (FAILED(hr))
        {
            wprintf(L"Failed to create a CUIAutomation, HR: 0x%08x\n", hr);
        }
        else
        {
            IUIAutomationElement *element = NULL;
            wprintf( L"Getting element at cursor in 3 seconds...\n" );
            Sleep(3000);

            POINT pt;
            GetCursorPos(&pt);
            hr = _automation->ElementFromPoint(pt, &element);
            if (FAILED(hr))
            {
                wprintf( L"Failed to ElementFromPoint, HR: 0x%08x\n\n", hr );
            }

            if (SUCCEEDED(hr) && element != NULL)
            {
                IUIAutomationElement *textElement = NULL;

                // Create a condition that will be true for anything that supports Text Pattern
                // Use UIA_IsTextPatternAvailablePropertyId instead of UIA_IsTextPattern2AvailablePropertyId on Win 7
                IUIAutomationCondition* textPatternCondition;
                VARIANT trueVar;
                trueVar.vt = VT_BOOL;
                trueVar.boolVal = VARIANT_TRUE;
                hr = _automation->CreatePropertyCondition(UIA_IsTextPatternAvailablePropertyId, trueVar, &textPatternCondition);

                if (FAILED(hr))
                {
                    wprintf(L"Failed to CreatePropertyCondition, HR: 0x%08x\n", hr);
                }
                else
                {
                    // Actually do the search
                    hr = element->FindFirst(TreeScope_Subtree, textPatternCondition, &textElement);
                    if (FAILED(hr))
                    {
                        wprintf(L"FindFirst failed, HR: 0x%08x\n", hr);
                    }
                    else if (textElement == NULL)
                    {
                        wprintf(L"No element supporting TextPattern found.\n");
                        hr = E_FAIL;
                    }
                    else
                    {
                        wprintf(L"TextPattern is supported!  :-)\n");
                    }
                    textPatternCondition->Release();
                }
            }
            _automation->Release();
        }
        CoUninitialize();
    }

    return 0;
}

Answer 1

如果我没记错的话，Win7本机UI自动化提供程序不支持TextPattern，而托管UI自动化提供程序支持。

本机UI自动化提供程序直到Windows8才添加TextPattern支持。