使用 UI 自动化通过 C++ 获取 URL 信息 (Firefox) 会导致使用 Firefox 的人延迟

如何解决使用 UI 自动化通过 C++ 获取 URL 信息 (Firefox) 会导致使用 Firefox 的人延迟

我们创建了一个程序来监控 Firefox 浏览器的域/url 信息，所以每隔几秒 该程序将使用 UI Automation 抓取浏览器地址栏信息（类似于这里 Get active Tab URL in FireFox with C++）。当这 发生，当该人尝试与 Firefox，例如在控制字段中输入字符、在选项卡之间切换（如果多个选项卡 open) 等。使用任务管理器资源监视器，我可以看到 CPU 使用率的持续“高原峰值” 当 UI 自动化“触发”（尝试获取 URL 信息）时。所以我的问题是：这会变慢吗 性能可能只是由 UI 自动化通过浏览器迭代引起的 页面，或者与网页交互（由用户）和 UI 自动化是否存在某种冲突 （在监视器程序中运行）？

Example UI Auto code:
    QString firefoxqstr = "Search with Google or enter address";

if(title.contains("mozilla firefox",Qt::CaseInsensitive))
    {
        addressBarIdentifier = (wchar_t*)firefoxqstr.utf16();
        //addressBarIdentifier = (LPWSTR)(L"Search with Google or enter address");
        getBrowserDomain(3,topWindow,addressBarIdentifier,title,domain,errqstr);
}



void getBrowserDomain(int xtrytype,HWND topWindow,LPWSTR addressBarIdentifier,QString title,QString& domain,QString& errqstr)
{
        errqstr = "blank";    
        // It's a Non IE browser.  Get the URL using addressBarIdentifier
    // main UIAutomation interface
    IUIAutomation *uiauto;

    // initial value assigned to UIAutomation
    uiauto = NULL;
    // Initialing COM functionality
    // My approach uses UI Automation
    CoInitialize(NULL);
    HRESULT hr =
            CoCreateInstance(__uuidof(CUIAutomation),NULL,CLSCTX_INPROC_SERVER,__uuidof(IUIAutomation),(void**)&uiauto);

    // Normally,this shouldn't happen but just in case
    if(FAILED(hr))
    {
        errqstr = "ERROR UIAutomation init failed";
        qWarning() << "Get Window Domain:  Cannot initialize UIAutomation.";
        if (uiauto != NULL) uiauto->Release();

        CoUninitialize();
        return;
}

// Convert handle to UIAutomation Element to access address bar.
IUIAutomationElement *windElem;
hr = uiauto->ElementFromHandle(topWindow,&windElem);

if(FAILED(hr))
{
    errqstr = "ERROR Cannot access Window in focus";
    qWarning() << "Get Window Domain:  Cannot access Window in focus.";

    if (windElem != NULL) windElem->Release();
    uiauto->Release();
    CoUninitialize();
    return;
}

VARIANT idVar;
IUIAutomationCondition *cond;
IUIAutomationCondition *cond1;
IUIAutomationCondition *cond2;

// First we store identifier in a VARIANT
// This is required for finding the Address Bar Component
// Create condition to access Address Bar

if (xtrytype == 3) //SearchFireFoxCase
{
    idVar.vt = VT_I4;
    idVar.lVal = UIA_EditControlTypeId;
    // Create condition to make sure it's an edit box we're talking about (specially with firefox)
    hr = uiauto->CreatePropertyCondition(UIA_ControlTypePropertyId,idVar,&cond);
    //find the top editboxes
    CComPtr<IUIAutomationElementArray> editboxes;
    //if(FAILED(windElem->FindAll(TreeScope_Children,cond,&editboxes)) || !editboxes)
    if(FAILED(windElem->FindAll(TreeScope_Descendants,&editboxes)) || !editboxes) //use Descendants instead of Children
        return;
    int editboxes_count = 0;
    editboxes->get_Length(&editboxes_count);
    domain = QString::number(editboxes_count);
    for(int icnt = 0; icnt < editboxes_count; icnt++)
    {
        //domain = domain + "icnt:" + QString::number(icnt);
        CComPtr<IUIAutomationElement> editbox;
        if(FAILED(editboxes->GetElement(icnt,&editbox)) || !editbox)
            continue;
        VARIANT urlVar;
        if(FAILED(editbox->GetCurrentPropertyValue(UIA_ValueValuePropertyId,&urlVar)))
        {
            continue;
        }
        else
        {
            // convert URL from BSTR to QString
            domain = QString::fromStdWString(std::wstring(
                            urlVar.bstrVal,SysStringLen(urlVar.bstrVal)));
                           icnt = editboxes_count;  //terminate for loop
        }
    }
    // Cleanup
    cond->Release();
    windElem->Release();
    uiauto->Release(); // Cleanup code for UIAutomation
    CoUninitialize(); // Uninitialize COM
    return;
}

}

解决方法

似乎如果地址栏字符串的匹配（即“用 Google 搜索或输入地址”）失败，那么在 HTML 中继续搜索控件可能会很长（取决于网页）。所以解决方案是在多次迭代后放弃 UI 自动化搜索，因为地址栏编辑框应该在搜索的早期。在这种情况下，Firefox 使用 Bing 搜索引擎而不是 Google，因此要匹配的正确地址栏字符串应该是“使用 Bing 搜索或输入地址”