#ifndef IMGUI_ADJUST_HH

#define IMGUI_ADJUST_HH

#include "ImGuiPartInterface.hh"

#include "gl_vec.hh"

namespace openmsx {

// Keep the imgui window in the 'same' position in the main view port (= the

// main openMSX window) when that view port changes size. This happens when

// changing scale_factor, but also when switching to/from fullscreen.

//

// Without this adjustment, after the resize, the window can e.g. move from the

// border to somewhere in the middle of the view port, or even outside the view

// port. This is not desired for stuff like the OSD icons or the reverse-bar.

//

// The heuristic for keeping the window in the 'same' position is:

// * Only make adjustment when the window is shown fully inside the main view port.

// * Separately for the horizontal and vertical direction:

// * Check if the window is closer to the left or the right (or top or bottom)

//   border of the viewport.

// * Keep this closet distance the same after rescaling. In other words, if the

//   window was e.g. close to the bottom, it will remain near the bottom.

// * And some stuff for boundary conditions, see comments in the code for details.

class AdjustWindowInMainViewPort

{

public:

	// should be called right before the call to im::Window()

	void pre();

	// should be called right after the call to im::Window()

	bool post();

	void save(ImGuiTextBuffer& buf);

	bool loadLine(std::string_view name, zstring_view value);

private:

	gl::vec2 oldViewPortSize;

	gl::vec2 oldRelWindowPos;

	bool oldIsOnMainViewPort = false;

	bool setMainViewPort = false;

	static constexpr auto persistentElements = std::tuple{

		PersistentElement{"viewPortSize",   &AdjustWindowInMainViewPort::oldViewPortSize},

		PersistentElement{"windowPos",      &AdjustWindowInMainViewPort::oldRelWindowPos},

		PersistentElement{"onMainViewPort", &AdjustWindowInMainViewPort::oldIsOnMainViewPort}

	};

};

} // namespace openmsx

#endif