JUCE/modules/juce_audio_processors/utilities/juce_NativeScaleFactorNotifier.h

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

   This file is part of the JUCE library.
   Copyright (c) 2022 - 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 7 End-User License
   Agreement and JUCE Privacy Policy.

   End User License Agreement: www.juce.com/juce-7-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
{

/**
    Calls a function every time the native scale factor of a component's peer changes.

    This is used in the VST and VST3 wrappers to ensure that the editor's scale is kept in sync with
    the scale of its containing component.

    @tags{GUI}
*/
class NativeScaleFactorNotifier : private ComponentMovementWatcher,
                                  private ComponentPeer::ScaleFactorListener
{
public:
    /** Constructs an instance.

        While the instance is alive, it will listen for changes to the scale factor of the
        comp's peer, and will call onScaleChanged whenever this scale factor changes.

        @param comp             The component to observe
        @param onScaleChanged   A function that will be called when the backing scale factor changes
    */
    NativeScaleFactorNotifier (Component* comp, std::function<void (float)> onScaleChanged);
    ~NativeScaleFactorNotifier() override;

private:
    void nativeScaleFactorChanged (double newScaleFactor) override;
    void componentPeerChanged() override;

    using ComponentMovementWatcher::componentVisibilityChanged;
    void componentVisibilityChanged() override {}

    using ComponentMovementWatcher::componentMovedOrResized;
    void componentMovedOrResized (bool, bool) override {}

    ComponentPeer* peer = nullptr;
    std::function<void (float)> scaleChanged;

    JUCE_DECLARE_NON_COPYABLE (NativeScaleFactorNotifier)
    JUCE_DECLARE_NON_MOVEABLE (NativeScaleFactorNotifier)
};

} // namespace juce