Your GetSelection() implementation is expected to return a SAFEARRAY of IRawElementProviderSimple interface pointers. However, you are creating a SAFEARRAY of VARIANT elements instead, but then populating the elements with TAutomationStringGridItem object pointers. SafeArrayPutElement() requires you to pass it a value that matches the type of the array (which in your code would be a pointer to a VARIANT whose value will then be copied). So it makes sense that UIAutomation would not be able to use your malformed array when initializing the IUIAutomationElementArray for the client app.
Try something more like this instead:
type
TAutomationStringGridItem = class(TInterfacedObject, IRawElementProviderSimple, IValueProvider, ...)
...
public
constructor Create(AGrid: TAutomationStringGrid; ARow, ACol: Integer; const AValue: string);
...
end;
constructor TAutomationStringGridItem.Create(AGrid: TAutomationStringGrid; ARow, ACol: Integer; const AValue: string);
begin
...
Self.Row := ARow;
Self.Column := ACol;
Self.Value := AValue;
...
end;
function TAutomationStringGrid.get_CanSelectMultiple(out pRetVal: BOOL): HResult;
begin
pRetVal := False;
Result := S_OK;
end;
function TAutomationStringGrid.get_IsSelectionRequired(out pRetVal: BOOL): HResult;
begin
pRetVal := False;
Result := S_OK;
end;
function TAutomationStringGrid.GetSelection(out pRetVal: PSafeArray): HResult;
var
intf: IRawElementProviderSimple;
unk: IUnknown;
outBuffer : PSafeArray;
offset, iRow, iCol : integer;
begin
// get the current selected cell, if any...
iRow := Self.Row;
iCol := Self.Col;
// is a cell selected?
if (iRow > -1) and (iCol > -1) then
begin
// yes...
intf := TAutomationStringGridItem.Create(Self, iRow, iCol, Self.Cells[iCol, iRow]);
outBuffer := SafeArrayCreateVector(VT_UNKNOWN, 0, 1);
end else
begin
// no ...
// you would have to check if UIA allows you to return a nil
// array, possibly with S_FALSE instead of S_OK, so as to
// avoid having to allocate memory for an empty array...
{
// pRetVal is already nil because of 'out'...
Result := S_FALSE; // or S_OK if S_FALSE is not allowed...
Exit;
}
outBuffer := SafeArrayCreateVector(VT_UNKNOWN, 0, 0);
end;
if outBuffer = nil then
begin
Result := E_OUTOFMEMORY;
Exit;
end;
if intf <> nil then
begin
offset := 0;
unk := intf as IUnknown;
Result := SafeArrayPutElement(outBuffer, offset, unk);
if Result <> S_OK then
begin
SafeArrayDestroy(outBuffer);
Exit;
end;
end;
pRetVal := outBuffer;
end;
With that said, TStringGrid supports multi-selection, and the output of GetSelection() is expected to return an array of all selected items. So a more accurate implementation would look more like this instead:
function TAutomationStringGrid.get_CanSelectMultiple(out pRetVal: BOOL): HResult;
begin
pRetVal := goRangeSelect in Self.Options;
Result := S_OK;
end;
function TAutomationStringGrid.get_IsSelectionRequired(out pRetVal: BOOL): HResult;
begin
pRetVal := False;
Result := S_OK;
end;
function TAutomationStringGrid.GetSelection(out pRetVal: PSafeArray): HResult;
var
intfs: array of IRawElementProviderSimple;
unk: IUnknown;
outBuffer : PSafeArray;
offset, iRow, iCol: Integer;
R: TGridRect;
begin
// get the current range of selected cells, if any...
R := Self.Selection;
// are any cells selected?
if (R.Left > -1) and (R.Right > -1) and (R.Top > -1) and (R.Bottom > -1) then
begin
// yes...
SetLength(intfs, ((R.Right-R.Left)+1)*((R.Bottom-R.Top)+1));
offset := Low(intfs);
for iRow := R.Top to R.Bottom do
begin
for iCol := R.Left to R.Right do
begin
intfs[offset] := TAutomationStringGridItem.Create(Self, iRow, iCol, Self.Cells[iCol, iRow]);
Inc(offset);
end;
end;
end;
// you would have to check if UIA allows you to return a nil
// array, possibly with S_FALSE instead of S_OK, so as to
// avoid having to allocate memory for an empty array...
{
if Length(intfs) = 0 then
begin
// pRetVal is already nil because of 'out'...
Result := S_FALSE; // or S_OK if S_FALSE is not allowed...
Exit;
end;
}
outBuffer := SafeArrayCreateVector(VT_UNKNOWN, Low(intfs), Length(intfs));
if outBuffer = nil then
begin
Result := E_OUTOFMEMORY;
Exit;
end;
for offset := Low(intfs) to High(intfs) do
begin
unk := intfs[offset] as IUnknown;
Result := SafeArrayPutElement(outBuffer, offset, unk);
if Result <> S_OK then
begin
SafeArrayDestroy(outBuffer);
Exit;
end;
end;
pRetVal := outBuffer;
Result := S_OK;
end;
