问题
I wanted to find the element within a main window handle that allows scrolling. So instead of finding scrollbars and then the owner of the scrollbars I wanted to just return the items that allow scrolling via a ScrollPattern so I setup the condition on that but nothing is found. if I search for scrollbar owner window then get the ScrollPattern it works. Why can't I just find the elements that have a scroll pattern available?
Here's the common code:
BOOL CUIAutomateScroller::FindWindow(HWND hwnd, IUIAutomationElement **windowelement)
{
BOOL result=FALSE;
// make sure init completed
if (m_pClientUIA) {
// get window element
HRESULT hr=m_pClientUIA->ElementFromHandle(hwnd, windowelement);
// check result
result=SUCCEEDED(hr);
// output debug info
if (FAILED(hr)) {
CDebugPrint::DebugPrint(_T("ElementFromHandle error: %d\n"), hr);
}
else {
_ASSERT(*windowelement!=NULL);
}
}
return result;
}
BOOL CUIAutomateScroller::FindContainerWindowElement(const long controltype, IUIAutomationElement **pelement)
{
// Create search condition
VARIANT varprop;
varprop.vt=VT_I4;
varprop.uintVal=controltype;
CComPtr<IUIAutomationCondition> pcondition;
HRESULT hr=m_pClientUIA->CreatePropertyCondition(UIA_ControlTypePropertyId, varprop, &pcondition);
if (FAILED(hr)) {
CDebugPrint::DebugPrint(_T("CreatePropertyCondition error: %d\n"), hr);
return NULL;
}
// find the control based on condition
CComPtr<IUIAutomationElementArray> pcontrolelementarr;
hr=m_pWindowElement->FindAll(TreeScope_Subtree, pcondition, &pcontrolelementarr);
if (FAILED(hr)) {
CDebugPrint::DebugPrint(_T("CreatePropertyCondition error: %d\n"), hr);
return NULL;
}
// get number of controls found
int numfound;
pcontrolelementarr->get_Length(&numfound);
CDebugPrint::DebugPrint(_T("Controls Found: %d\n"), numfound);
// process controls found, but really we exit earily if container window found
for (int i=0; i < numfound; i++) {
// get individual control element
CComPtr<IUIAutomationElement> pcontrolelement;
hr=pcontrolelementarr->GetElement(i, &pcontrolelement);
if (FAILED(hr)) {
// skip element unable to be retreived
CDebugPrint::DebugPrint(_T("GetElement error: %d\n"), hr);
continue;
}
// output debug information
CComBSTR name;
hr=pcontrolelement->get_CurrentName(&name);
if (FAILED(hr)) {
CDebugPrint::DebugPrint(_T("GetCurrentName error: %d\n"), hr);
}
CDebugPrint::DebugPrint(_T("Control Name: %s\n"), name);
name.Empty();
hr=pcontrolelement->get_CurrentClassName(&name);
if (FAILED(hr)) {
CDebugPrint::DebugPrint(_T("GetCurrentClass error: %d\n"), hr);
}
CDebugPrint::DebugPrint(_T("Class Name: %s\n"), name);
name.Empty();
CComPtr<IUIAutomationTreeWalker> pcontentwalker=NULL;
hr=m_pClientUIA->get_ContentViewWalker(&pcontentwalker);
if (pcontentwalker == NULL) {
return NULL;
}
// Get ancestor element nearest to the scrollbar UI Automation element in the tree view
hr=pcontentwalker->NormalizeElement(pcontrolelement, pelement);
if (FAILED(hr)) {
CDebugPrint::DebugPrint(_T("NormalizeElement error: %d\n"), hr);
return NULL;
}
// output debug information
hr=(*pelement)->get_CurrentName(&name);
if (FAILED(hr)) {
CDebugPrint::DebugPrint(_T("get_CurrentName error: %d\n"), hr);
}
CDebugPrint::DebugPrint(_T("Ancestor Name: %s\n"), name);
name.Empty();
return TRUE;
}
return FALSE;
}
This does NOT work (It doesn't find anything):
// get main window
if (FindWindow(hwnd, &m_pWindowElement)) {
HRESULT hr;
VARIANT varprop;
// create condition for elements that have UIA_IsScrollPatternAvailablePropertyId available
CComPtr<IUIAutomationCondition> pscrollpatterncondition;
varprop.vt=VT_BOOL;
varprop.boolVal=TRUE;
hr=m_pClientUIA->CreatePropertyCondition(UIA_IsScrollPatternAvailablePropertyId, varprop, &pscrollpatterncondition);
// check result
if (FAILED(hr)) {
CDebugPrint::DebugPrint(_T("CreatePropertyCondition for ScrollPattern Error: %d\n"), hr);
}
else {
// find the matching element
CComPtr<IUIAutomationElementArray> pscrollpatternarr;
hr=m_pWindowElement->FindAll(TreeScope_Subtree, pscrollpatterncondition, &pscrollpatternarr);
// check result (normal is success with empty array if not found)
if (FAILED(hr)) {
CDebugPrint::DebugPrint(_T("FindAll Error: %d\n"), hr);
}
else {
// get number of elements in array
int numfound=0;
pscrollpatternarr->get_Length(&numfound);
// make sure we only get one scrollable area - in the future we could figure out the rect
// **numfound is 0**
This DOES work:
// get main window
if (FindWindow(hwnd, &m_pWindowElement)) {
// get scrollable window element based on scrollbar
if (FindContainerWindowElement(UIA_ScrollBarControlTypeId, &m_pScrollableElement)) {
HRESULT hr;
// get the scroll pattern
hr=m_pScrollableElement->GetCurrentPattern(UIA_ScrollPatternId, (IUnknown**) &m_pScrollPattern);
if (FAILED(hr)) {
CDebugPrint::DebugPrint(_T("GetCurrentPattern for Scroll Pattern Error %d:\n"), hr);
}
else if (m_pScrollPattern!=NULL) {
// **we're good!!**
回答1:
Why can't I just find the elements that have a scroll pattern available?
As @HansPassant pointed out, use VARIANT_TRUE
(-1
) instead of TRUE
(1
).
After correct above error the following code work for me for finding the elements that have a scroll pattern (IUIAutomationScrollPattern
) available and scrolling (vertical scrollbar).
VARIANT varprop;
// create condition for elements that have UIA_IsScrollPatternAvailablePropertyId available
CComPtr<IUIAutomationCondition> pscrollpatterncondition;
varprop.vt = VT_BOOL;
varprop.boolVal = VARIANT_TRUE;
hr = m_pClientUIA->CreatePropertyCondition(UIA_IsScrollPatternAvailablePropertyId, varprop, &pscrollpatterncondition);
// check result
if (FAILED(hr)) {
}
else {
// find the matching element
CComPtr<IUIAutomationElementArray> pscrollpatternarr;
hr = m_pWindowElement->FindAll(TreeScope_Subtree, pscrollpatterncondition, &pscrollpatternarr);
// check result (normal is success with empty array if not found)
if (FAILED(hr)) {
}
else {
// get number of elements in array
numfound = 0;
pscrollpatternarr->get_Length(&numfound);
for (int i = 0; i < numfound; i++)
{
IUIAutomationElement *element = NULL;
pscrollpatternarr->GetElement(i, &element);
IUIAutomationScrollPattern *m_pScrollPattern = NULL;
hr = element->GetCurrentPattern(UIA_ScrollPatternId, (IUnknown**)&m_pScrollPattern);
if (FAILED(hr)) {
}
else if (m_pScrollPattern != NULL) {
// Scroll vertical scrollbar
m_pScrollPattern->Scroll(ScrollAmount_NoAmount, ScrollAmount_LargeIncrement);
}
}
}
}
来源:https://stackoverflow.com/questions/63063225/why-doesnt-ui-automation-condition-find-element-by-uia-isscrollpatternavailable