Function InputViewportDragContinue

src/openrct2-ui/input/MouseInput.cpp:555–626

    }

    static void InputViewportDragContinue()
    {
        WindowBase* w;
        Viewport* viewport;

        auto newDragCoords = ContextGetCursorPosition();

        auto differentialCoords = newDragCoords - gInputDragLast;
        if (differentialCoords.x == 0 && differentialCoords.y == 0)
            return;

        auto* windowMgr = GetWindowManager();
        w = windowMgr->FindByNumber(_dragWidget.windowClassification, _dragWidget.windowNumber);

        // #3294: Window can be closed during a drag session, so just finish
        //        the session if the window no longer exists
        if (w == nullptr)
        {
            InputViewportDragEnd();
            return;
        }

        viewport = w->viewport;
        if (viewport == nullptr)
        {
            ContextShowCursor();
            _inputState = InputState::reset;
        }
        else if (differentialCoords.x != 0 || differentialCoords.y != 0)
        {
            if (!w->flags.has(WindowFlag::noScrolling))
            {
                // User dragged a scrollable viewport

                // If the drag time is less than 500 the "drag" is usually interpreted as a right click.
                // As the user moved the mouse, don't interpret it as right click in any case.
                _ticksSinceDragStart = std::nullopt;

                // applying the zoom only with negative values avoids a "deadzone" effect where small positive value round to
                // zero.
                const bool posX = differentialCoords.x > 0;
                const bool posY = differentialCoords.y > 0;
                differentialCoords.x = (viewport->zoom + 1).ApplyTo(-std::abs(differentialCoords.x));
                differentialCoords.y = (viewport->zoom + 1).ApplyTo(-std::abs(differentialCoords.y));
                differentialCoords.x = posX ? -differentialCoords.x : differentialCoords.x;
                differentialCoords.y = posY ? -differentialCoords.y : differentialCoords.y;

                if (Config::Get().general.invertViewportDrag)
                {
                    w->savedViewPos -= differentialCoords;
                }
                else
                {
                    w->savedViewPos += differentialCoords;
                }
            }
        }