guiScrollBar.h

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/*
Copyright (C) 2002-2013 Nikolaus Gebhardt
This file is part of the "Irrlicht Engine".
For conditions of distribution and use, see copyright notice in irrlicht.h
 
Modified 2019.05.01 by stujones11, Stuart Jones <stujones111@gmail.com>
 
This is a heavily modified copy of the Irrlicht CGUIScrollBar class
which includes automatic scaling of the thumb slider and hiding of
the arrow buttons where there is insufficient space.
*/
 
#pragma once
 
#include "irrlichttypes_extrabloated.h"
#include <optional>
 
class ISimpleTextureSource;
 
using namespace irr;
using namespace gui;
 
class GUIScrollBar : public IGUIElement
{
public:
    GUIScrollBar(IGUIEnvironment *environment, IGUIElement *parent, s32 id,
            core::rect<s32> rectangle, bool horizontal, bool auto_scale,
            ISimpleTextureSource *tsrc);
 
    enum ArrowVisibility
    {
        HIDE,
        SHOW,
        DEFAULT
    };
 
    virtual void draw() override;
    virtual void updateAbsolutePosition() override;
    virtual bool OnEvent(const SEvent &event) override;
    virtual void OnPostRender(u32 time_ms) override;
 
    s32 getMax() const { return max_pos; }
    s32 getMin() const { return min_pos; }
    s32 getLargeStep() const { return large_step; }
    s32 getSmallStep() const { return small_step; }
    s32 getPos() const;
    s32 getTargetPos() const;
 
    void setMax(const s32 &max);
    void setMin(const s32 &min);
    void setSmallStep(const s32 &step);
    void setLargeStep(const s32 &step);
    // setPos does not send EGET_SCROLL_BAR_CHANGED events for you.
    void setPos(const s32 &pos);
    // If you want to do an interpolated addition, use
    // setPosInterpolated(getTargetPos() + x).
    // setPosInterpolated takes care of sending EGET_SCROLL_BAR_CHANGED events.
    void setPosInterpolated(const s32 &pos);
    void setPageSize(const s32 &size);
    void setArrowsVisible(ArrowVisibility visible);
 
private:
    void refreshControls();
    s32 getPosFromMousePos(const core::position2di &p) const;
    f32 range() const { return f32(max_pos - min_pos); }
 
    IGUIButton *up_button;
    IGUIButton *down_button;
    ArrowVisibility arrow_visibility = DEFAULT;
    bool is_dragging;
    bool is_horizontal;
    bool is_auto_scaling;
    bool dragged_by_slider;
    bool tray_clicked;
    s32 scroll_pos;
    s32 draw_center;
    s32 thumb_size;
    s32 min_pos;
    s32 max_pos;
    s32 small_step;
    s32 large_step;
    s32 drag_offset;
    s32 page_size;
    s32 border_size;
 
    core::rect<s32> slider_rect;
    video::SColor current_icon_color;
 
    ISimpleTextureSource *m_tsrc;
 
    void setPosRaw(const s32 &pos);
    void updatePos();
    std::optional<s32> target_pos;
    u32 last_time_ms = 0;
    u32 last_delta_ms = 17; // assume 60 FPS
    void interpolatePos();
};