JUCE/modules/juce_gui_basics/native/accessibility/juce_win32_UIAValueProvider.h

/*
  ==============================================================================

   This file is part of the JUCE library.
   Copyright (c) 2020 - Raw Material Software Limited

   JUCE is an open source library subject to commercial or open-source
   licensing.

   By using JUCE, you agree to the terms of both the JUCE 6 End-User License
   Agreement and JUCE Privacy Policy (both effective as of the 16th June 2020).

   End User License Agreement: www.juce.com/juce-6-licence
   Privacy Policy: www.juce.com/juce-privacy-policy

   Or: You may also use this code under the terms of the GPL v3 (see
   www.gnu.org/licenses).

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

//==============================================================================
class UIAValueProvider  : public UIAProviderBase,
                          public ComBaseClassHelper<IValueProvider>
{
public:
    UIAValueProvider (AccessibilityNativeHandle* nativeHandle)
        : UIAProviderBase (nativeHandle)
    {
    }

    //==============================================================================
    JUCE_COMRESULT SetValue (LPCWSTR val) override
    {
        if (! isElementValid())
            return UIA_E_ELEMENTNOTAVAILABLE;

        const auto& handler = getHandler();

        const auto sendValuePropertyChangeMessage = [&]()
        {
            VARIANT newValue;
            VariantHelpers::setString (getCurrentValueString(), &newValue);

            sendAccessibilityPropertyChangedEvent (handler, UIA_ValueValuePropertyId, newValue);
        };

        if (isEditableText (handler))
        {
            handler.getTextInterface()->setText (String (val));
            sendValuePropertyChangeMessage();

            return S_OK;
        }

        if (auto* valueInterface = handler.getValueInterface())
        {
            if (! valueInterface->isReadOnly())
            {
                valueInterface->setValueAsString (String (val));
                sendValuePropertyChangeMessage();

                return S_OK;
            }
        }

        return UIA_E_NOTSUPPORTED;
    }

    JUCE_COMRESULT get_Value (BSTR* pRetVal) override
    {
        return withCheckedComArgs (pRetVal, *this, [&]
        {
            auto currentValue = getCurrentValueString();

            *pRetVal = SysAllocString ((const OLECHAR*) currentValue.toWideCharPointer());
            return S_OK;
        });
    }

    JUCE_COMRESULT get_IsReadOnly (BOOL* pRetVal) override
    {
        return withCheckedComArgs (pRetVal, *this, [&]
        {
            *pRetVal = true;

            const auto& handler = getHandler();

            if (isEditableText (handler)
                || (handler.getValueInterface() != nullptr
                    && ! handler.getValueInterface()->isReadOnly()))
            {
                *pRetVal = false;
            }

            return S_OK;
        });
    }

private:
    String getCurrentValueString() const
    {
        const auto& handler = getHandler();

        if (isEditableText (handler))
            if (auto* textInterface = getHandler().getTextInterface())
                return textInterface->getText ({ 0, textInterface->getTotalNumCharacters() });

        if (auto* valueInterface = getHandler().getValueInterface())
            return valueInterface->getCurrentValueAsString();

        jassertfalse;
        return {};
    }

    //==============================================================================
    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (UIAValueProvider)
};

} // namespace juce