ui_scrollregion.h

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/* (c) Magnus Auvinen. See licence.txt in the root of the distribution for more information. */
/* If you are missing that file, acquire a complete release at teeworlds.com.                */
#ifndef GAME_CLIENT_UI_SCROLLREGION_H
#define GAME_CLIENT_UI_SCROLLREGION_H
 
#include "ui.h"
 
struct CScrollRegionParams
{
    float m_ScrollbarThickness;
    float m_ScrollbarMargin;
    bool m_ScrollbarNoOuterMargin;
    float m_SliderMinSize;
    float m_ScrollUnit;
    ColorRGBA m_ClipBgColor;
    ColorRGBA m_ScrollbarBgColor;
    ColorRGBA m_RailBgColor;
    ColorRGBA m_SliderColor;
    ColorRGBA m_SliderColorHover;
    ColorRGBA m_SliderColorGrabbed;
    bool m_ForceShowScrollbar;
    bool m_ScrollHorizontal;
 
    CScrollRegionParams()
    {
        m_ScrollbarThickness = 20.0f;
        m_ScrollbarMargin = 5.0f;
        m_ScrollbarNoOuterMargin = false;
        m_SliderMinSize = 25.0f;
        m_ScrollUnit = 10.0f;
        m_ClipBgColor = ColorRGBA(0.0f, 0.0f, 0.0f, 0.0f);
        m_ScrollbarBgColor = ColorRGBA(0.0f, 0.0f, 0.0f, 0.0f);
        m_RailBgColor = ColorRGBA(1.0f, 1.0f, 1.0f, 0.25f);
        m_SliderColor = ColorRGBA(0.8f, 0.8f, 0.8f, 1.0f);
        m_SliderColorHover = ColorRGBA(1.0f, 1.0f, 1.0f, 1.0f);
        m_SliderColorGrabbed = ColorRGBA(0.9f, 0.9f, 0.9f, 1.0f);
        m_ForceShowScrollbar = false;
        m_ScrollHorizontal = false;
    }
 
    ColorRGBA SliderColor(bool Active, bool Hovered) const
    {
        if(Active)
            return m_SliderColorGrabbed;
        else if(Hovered)
            return m_SliderColorHover;
        return m_SliderColor;
    }
};
 
/*
Usage example:
 
    // -- Layout --
    CUIRect View = ...; // parent UI rect initialized elsewhere
    CUIRect Content; // rect for scrollable content
    View.HSplitTop(500.0f, &Content, &View); // split maximum size of scrollable content
 
    // -- Initialization --
    static CScrollRegion s_ScrollRegion;
    s_ScrollRegion.Begin(&Content);
    // Content rect is now offset by the scroll offset
 
    // -- [Optional] Initialization with parameters --
    static CScrollRegion s_ScrollRegion;
    CScrollRegionParams ScrollParams;
    ScrollParams.m_ScrollUnit = 3 * LineHeight;
    s_ScrollRegion.Begin(&Content, &ScrollParams);
    // Content rect is now offset by the scroll offset
 
    // -- "Register" your content rects --
    CUIRect Rect;
    Content.HSplitTop(SomeValue, &Rect, &Content);
    s_ScrollRegion.AddRect(Rect);
 
    // -- [Optional] Knowing if a rect is clipped --
    s_ScrollRegion.RectClipped(Rect);
 
    // -- [Optional] Scroll to the last added rect --
    s_ScrollRegion.AddRect(Rect);
    s_ScrollRegion.ScrollHere(Option);
 
    // -- [Convenience] Add rect and check for visibility at the same time --
    if(s_ScrollRegion.AddRect(Rect))
    {
        // The rect is visible (not clipped)
    }
 
    // -- [Convenience] Add rect and scroll to it if it's selected --
    if(s_ScrollRegion.AddRect(Rect, ScrollToSelection && IsSelected))
    {
        // The rect is visible (not clipped)
    }
 
    // -- End --
    s_ScrollRegion.End();
*/
 
// Instances of CScrollRegion must be static, as member addresses are used as UI item IDs
class CScrollRegion : private CUIElementBase
{
public:
    enum EScrollRelative
    {
        SCROLLRELATIVE_UP = -1,
        SCROLLRELATIVE_NONE = 0,
        SCROLLRELATIVE_DOWN = 1,
    };
 
private:
    float m_ScrollPos;
    float m_ContentSize;
    float m_RequestScrollPos; // [0, ContentSize]
    EScrollRelative m_ScrollDirection;
    float m_ScrollSpeedMultiplier;
 
    float m_AnimTimeMax;
    float m_AnimTime;
    float m_AnimInitScrollPos;
    float m_AnimTargetScrollPos;
 
    CUIRect m_ContentAreaRect;
    CUIRect m_RailRect;
    CUIRect m_LastAddedRect; // saved for ScrollHere()
    float m_SliderGrabPos; // where did user grab the slider
    float m_ContentScrollOffset;
    CScrollRegionParams m_Params;
 
public:
    enum EScrollOption
    {
        SCROLLHERE_KEEP_IN_VIEW = 0,
        SCROLLHERE_TOP,
        SCROLLHERE_BOTTOM,
    };
 
    CScrollRegion();
    void Reset();
 
    void Begin(CUIRect *pClipRect, const CScrollRegionParams *pParams = nullptr);
    void End();
    bool AddRect(const CUIRect &Rect, bool ShouldScrollHere = false); // returns true if the added rect is visible (not clipped)
    void ScrollHere(EScrollOption Option = SCROLLHERE_KEEP_IN_VIEW);
    void ScrollRelative(EScrollRelative Direction, float SpeedMultiplier = 1.0f);
    void ScrollRelativeDirect(vec2 ScrollAmount);
    void DoEdgeScrolling();
    bool RectClipped(const CUIRect &Rect) const;
    bool ContentOverflows() const;
    bool ScrollbarShown() const;
    bool Animating() const;
    bool Active() const;
 
private:
    float ContentAreaPos() const;
    float ContentAreaSize() const;
    float MaxScroll() const;
    CUIRect SplitContentArea();
    void DrawBackground(const CUIRect &ScrollbarBg);
    void DoScrollInput();
    void UpdateHotScrollRegion();
    void AdvanceAnimation();
    void DoSlider();
};
 
#endif