win_surface_lifecycle.hpp

Go to the documentation of this file.

#pragma once
 
// win_surface_lifecycle.hpp — the Windows editor host's "create after reparent,
// destroy on detach" GPU-surface contract.
//
// Split out of win_pointer_input.hpp (WAH-9), which had accumulated three
// unrelated things: the pointer session, the Win32 message/key-code mappings,
// and this. A reader looking for how surfaces are created had no reason to open
// a header called "pointer input", and a reader changing pointer dispatch had
// no reason to expect surface lifetime to live under their hands.
//
// Kept HWND-free for the same reason the pointer decisions are: Pulp's required
// CI gate is macOS, so anything behind `_WIN32` is never executed by a gate.
// The state machine here is the part with a real invariant, so it is the part
// that most needs to be testable off Windows.
 
namespace pulp::view::win_input {

class SurfaceLifecycle {
public:
    constexpr bool surfaces_created() const noexcept { return created_; }

    constexpr bool note_attached() noexcept {
        if (created_) return false;
        created_ = true;
        return true;
    }

    constexpr bool note_detached() noexcept {
        if (!created_) return false;
        created_ = false;
        return true;
    }

    constexpr void note_creation_failed() noexcept { created_ = false; }
 
private:
    bool created_ = false;
};
 
}  // namespace pulp::view::win_input