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_ScrollbarWidth;
    float m_ScrollbarMargin;
    bool m_ScrollbarNoMarginRight;
    float m_SliderMinHeight;
    float m_ScrollUnit;
    ColorRGBA m_ClipBgColor;
    ColorRGBA m_ScrollbarBgColor;
    ColorRGBA m_RailBgColor;
    ColorRGBA m_SliderColor;
    ColorRGBA m_SliderColorHover;
    ColorRGBA m_SliderColorGrabbed;
    unsigned m_Flags;
 
    enum
    {
        FLAG_CONTENT_STATIC_WIDTH = 1 << 0,
    };
 
    CScrollRegionParams()
    {
        m_ScrollbarWidth = 20.0f;
        m_ScrollbarMargin = 5.0f;
        m_ScrollbarNoMarginRight = false;
        m_SliderMinHeight = 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_Flags = 0;
    }
 
    ColorRGBA SliderColor(bool Active, bool Hovered) const
    {
        if(Active)
            return m_SliderColorGrabbed;
        else if(Hovered)
            return m_SliderColorHover;
        return m_SliderColor;
    }
};
 
/*
Usage:
    -- Initialization --
    static CScrollRegion s_ScrollRegion;
    vec2 ScrollOffset(0, 0);
    s_ScrollRegion.Begin(&ScrollRegionRect, &ScrollOffset);
    Content = ScrollRegionRect;
    Content.y += ScrollOffset.y;
 
    -- "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 a rect (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:
    // TODO: Properly fix whatever is causing the 1-pixel discrepancy in scrolling rect height and remove this magic value.
    // Currently this must be added when calculating the required height of a UI rect for a scroll region to get a perfect fit.
    static constexpr float HEIGHT_MAGIC_FIX = 1.0f;
 
    enum EScrollRelative
    {
        SCROLLRELATIVE_UP = -1,
        SCROLLRELATIVE_NONE = 0,
        SCROLLRELATIVE_DOWN = 1,
    };
 
private:
    float m_ScrollY;
    float m_ContentH;
    float m_RequestScrollY; // [0, ContentHeight]
    EScrollRelative m_ScrollDirection;
    float m_ScrollSpeedMultiplier;
 
    float m_AnimTimeMax;
    float m_AnimTime;
    float m_AnimInitScrollY;
    float m_AnimTargetScrollY;
 
    CUIRect m_ClipRect;
    CUIRect m_RailRect;
    CUIRect m_LastAddedRect; // saved for ScrollHere()
    float m_SliderGrabPos; // where did user grab the slider
    vec2 m_ContentScrollOff;
    CScrollRegionParams m_Params;
 
public:
    enum EScrollOption
    {
        SCROLLHERE_KEEP_IN_VIEW = 0,
        SCROLLHERE_TOP,
        SCROLLHERE_BOTTOM,
    };
 
    CScrollRegion();
    void Begin(CUIRect *pClipRect, vec2 *pOutOffset, 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(float ScrollAmount);
    const CUIRect *ClipRect() const { return &m_ClipRect; }
    void DoEdgeScrolling();
    bool RectClipped(const CUIRect &Rect) const;
    bool ScrollbarShown() const;
    bool Animating() const;
    bool Active() const;
    const CScrollRegionParams &Params() const { return m_Params; }
};
 
#endif