wxWidgets/tests/waitfor.h

///////////////////////////////////////////////////////////////////////////////
// Name:        tests/waitfor.h
// Purpose:     Helper WaitForPaint class
// Author:      Vadim Zeitlin
// Created:     2019-10-17 (extracted from tests/window/setsize.cpp)
// Copyright:   (c) 2019 Vadim Zeitlin <vadim@wxwidgets.org>
///////////////////////////////////////////////////////////////////////////////

#ifndef _WX_TESTS_WAITFOR_H_
#define _WX_TESTS_WAITFOR_H_

#include "wx/stopwatch.h"
#include "wx/window.h"

#include <functional>

// Function used to wait until the given predicate becomes true or timeout
// expires.
inline bool
WaitFor(const char* what, const std::function<bool ()>& pred, int timeout = 500)
{
    wxStopWatch sw;
    for ( ;; )
    {
        wxYield();

        if ( pred() )
            break;

        if ( sw.Time() > timeout )
        {
            WARN("Timed out waiting for " << what);
            return false;
        }
    }

    return true;
}

// An even simpler version which doesn't wait for anything but just calls
// wxYield() until the given timeout expires.
inline void
YieldForAWhile(int timeout = 50)
{
    wxStopWatch sw;
    for ( ;; )
    {
        wxYield();

        if ( sw.Time() > timeout )
            break;
    }
}

// Class used to check if we received the (first) paint event: this is
// currently used under GTK only, as MSW doesn't seem to need to wait for the
// things to work, while under Mac nothing works anyhow.
#ifdef __WXGTK__

class WaitForPaint
{
public:
    explicit WaitForPaint(wxWindow* win)
        : m_win(*win),
          m_painted(false),
          m_handler(&m_painted)
    {
        m_win.Bind(wxEVT_PAINT, m_handler);
    }

    // This function waits up to the given number of milliseconds for the paint
    // event to come and logs a warning if we didn't get it.
    void YieldUntilPainted(int timeoutInMS = 250)
    {
        if ( WaitFor("repaint", [this]() { return m_painted; }, timeoutInMS) )
        {
            // Reset it in case YieldUntilPainted() is called again.
            m_painted = false;
        }
    }

    ~WaitForPaint()
    {
        m_win.Unbind(wxEVT_PAINT, m_handler);
    }

private:
    wxWindow& m_win;
    bool m_painted;

    class PaintHandler
    {
    public:
        // Note that we have to use a pointer here, i.e. we can't just store
        // the flag inside the class itself because it's going to be cloned
        // inside wx and querying the flag of the original copy wouldtn' work.
        explicit PaintHandler(bool* painted)
            : m_painted(*painted)
        {
        }

        void operator()(wxPaintEvent& event)
        {
            event.Skip();
            m_painted = true;
        }

    private:
        bool& m_painted;
    } m_handler;
};

#else // !__WXGTK__

class WaitForPaint
{
public:
    explicit WaitForPaint(wxWindow* WXUNUSED(win))
    {
    }

    void YieldUntilPainted(int WXUNUSED(timeoutInMS) = 250)
    {
    }
};

#endif // __WXGTK__/!__WXGTK__

#endif // _WX_TESTS_WAITFOR_H_