imgui/imgui_internal.h

// ImGui library v1.44 WIP
// Internals
// You may use this file to debug, understand or extend ImGui features but we don't provide any guarantee of forward compatibility!

// Implement maths operators for ImVec2 (disabled by default to not collide with using IM_VEC2_CLASS_EXTRA along with your own math types+operators)
//   #define IMGUI_DEFINE_MATH_OPERATORS

#pragma once

#include <stdio.h>      // FILE*
#include <math.h>       // sqrtf()

//-----------------------------------------------------------------------------
// Forward Declarations
//-----------------------------------------------------------------------------

struct ImRect;
struct ImGuiColMod;
struct ImGuiStyleMod;
struct ImGuiGroupData;
struct ImGuiSimpleColumns;
struct ImGuiDrawContext;
struct ImGuiTextEditState;
struct ImGuiIniData;
struct ImGuiMouseCursorData;
struct ImGuiPopupRef;
struct ImGuiState;
struct ImGuiWindow;

typedef int ImGuiLayoutType;      // enum ImGuiLayoutType_
typedef int ImGuiButtonFlags;     // enum ImGuiButtonFlags_

//-------------------------------------------------------------------------
// STB libraries
//-------------------------------------------------------------------------

namespace ImGuiStb
{

#ifdef __clang__
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wunused-function"
#pragma clang diagnostic ignored "-Wmissing-prototypes"
#endif

#undef STB_TEXTEDIT_STRING
#undef STB_TEXTEDIT_CHARTYPE
#define STB_TEXTEDIT_STRING             ImGuiTextEditState
#define STB_TEXTEDIT_CHARTYPE           ImWchar
#define STB_TEXTEDIT_GETWIDTH_NEWLINE   -1.0f
#include "stb_textedit.h"

#ifdef __clang__
#pragma clang diagnostic pop
#endif

} // namespace ImGuiStb

//-----------------------------------------------------------------------------
// Context
//-----------------------------------------------------------------------------

extern ImGuiState*  GImGui;

//-----------------------------------------------------------------------------
// Helpers
//-----------------------------------------------------------------------------

#define IM_ARRAYSIZE(_ARR)      ((int)(sizeof(_ARR)/sizeof(*_ARR)))
#define IM_PI                   3.14159265358979323846f

// Helpers: UTF-8 <> wchar
int                 ImTextStrToUtf8(char* buf, int buf_size, const ImWchar* in_text, const ImWchar* in_text_end);      // return output UTF-8 bytes count
int                 ImTextCharFromUtf8(unsigned int* out_char, const char* in_text, const char* in_text_end);          // return input UTF-8 bytes count
int                 ImTextStrFromUtf8(ImWchar* buf, int buf_size, const char* in_text, const char* in_text_end, const char** in_remaining = NULL);   // return input UTF-8 bytes count
int                 ImTextCountCharsFromUtf8(const char* in_text, const char* in_text_end);                            // return number of UTF-8 code-points (NOT bytes count)
int                 ImTextCountUtf8BytesFromStr(const ImWchar* in_text, const ImWchar* in_text_end);                   // return number of bytes to express string as UTF-8 code-points

// Helpers: Misc
ImU32               ImHash(const void* data, int data_size, ImU32 seed);
bool                ImLoadFileToMemory(const char* filename, const char* file_open_mode, void** out_file_data, int* out_file_size = NULL, int padding_bytes = 0);
bool                ImIsPointInTriangle(const ImVec2& p, const ImVec2& a, const ImVec2& b, const ImVec2& c);
static inline bool  ImCharIsSpace(int c)            { return c == ' ' || c == '\t' || c == 0x3000; }
static inline int   ImUpperPowerOfTwo(int v)        { v--; v |= v >> 1; v |= v >> 2; v |= v >> 4; v |= v >> 8; v |= v >> 16; v++; return v; }

// Helpers: String
int                 ImStricmp(const char* str1, const char* str2);
int                 ImStrnicmp(const char* str1, const char* str2, int count);
char*               ImStrdup(const char* str);
int                 ImStrlenW(const ImWchar* str);
const ImWchar*      ImStrbolW(const ImWchar* buf_mid_line, const ImWchar* buf_begin); // Find beginning-of-line
const char*         ImStristr(const char* haystack, const char* needle, const char* needle_end);
int                 ImFormatString(char* buf, int buf_size, const char* fmt, ...);
int                 ImFormatStringV(char* buf, int buf_size, const char* fmt, va_list args);

// Helpers: Math
// We are keeping those not leaking to the user by default, in the case the user has implicit cast operators between ImVec2 and its own types (when IM_VEC2_CLASS_EXTRA is defined)
#ifdef IMGUI_DEFINE_MATH_OPERATORS
static inline ImVec2 operator*(const ImVec2& lhs, const float rhs)              { return ImVec2(lhs.x*rhs, lhs.y*rhs); }
static inline ImVec2 operator/(const ImVec2& lhs, const float rhs)              { return ImVec2(lhs.x/rhs, lhs.y/rhs); }
static inline ImVec2 operator+(const ImVec2& lhs, const ImVec2& rhs)            { return ImVec2(lhs.x+rhs.x, lhs.y+rhs.y); }
static inline ImVec2 operator-(const ImVec2& lhs, const ImVec2& rhs)            { return ImVec2(lhs.x-rhs.x, lhs.y-rhs.y); }
static inline ImVec2 operator*(const ImVec2& lhs, const ImVec2& rhs)            { return ImVec2(lhs.x*rhs.x, lhs.y*rhs.y); }
static inline ImVec2 operator/(const ImVec2& lhs, const ImVec2& rhs)            { return ImVec2(lhs.x/rhs.x, lhs.y/rhs.y); }
static inline ImVec2& operator+=(ImVec2& lhs, const ImVec2& rhs)                { lhs.x += rhs.x; lhs.y += rhs.y; return lhs; }
static inline ImVec2& operator-=(ImVec2& lhs, const ImVec2& rhs)                { lhs.x -= rhs.x; lhs.y -= rhs.y; return lhs; }
static inline ImVec2& operator*=(ImVec2& lhs, const float rhs)                  { lhs.x *= rhs; lhs.y *= rhs; return lhs; }
static inline ImVec2& operator/=(ImVec2& lhs, const float rhs)                  { lhs.x /= rhs; lhs.y /= rhs; return lhs; }
static inline ImVec4 operator-(const ImVec4& lhs, const ImVec4& rhs)            { return ImVec4(lhs.x-rhs.x, lhs.y-rhs.y, lhs.z-rhs.z, lhs.w-lhs.w); }
#endif

static inline int    ImMin(int lhs, int rhs)                                    { return lhs < rhs ? lhs : rhs; }
static inline int    ImMax(int lhs, int rhs)                                    { return lhs >= rhs ? lhs : rhs; }
static inline float  ImMin(float lhs, float rhs)                                { return lhs < rhs ? lhs : rhs; }
static inline float  ImMax(float lhs, float rhs)                                { return lhs >= rhs ? lhs : rhs; }
static inline ImVec2 ImMin(const ImVec2& lhs, const ImVec2& rhs)                { return ImVec2(ImMin(lhs.x,rhs.x), ImMin(lhs.y,rhs.y)); }
static inline ImVec2 ImMax(const ImVec2& lhs, const ImVec2& rhs)                { return ImVec2(ImMax(lhs.x,rhs.x), ImMax(lhs.y,rhs.y)); }
static inline int    ImClamp(int v, int mn, int mx)                             { return (v < mn) ? mn : (v > mx) ? mx : v; }
static inline float  ImClamp(float v, float mn, float mx)                       { return (v < mn) ? mn : (v > mx) ? mx : v; }
static inline ImVec2 ImClamp(const ImVec2& f, const ImVec2& mn, ImVec2 mx)      { return ImVec2(ImClamp(f.x,mn.x,mx.x), ImClamp(f.y,mn.y,mx.y)); }
static inline float  ImSaturate(float f)                                        { return (f < 0.0f) ? 0.0f : (f > 1.0f) ? 1.0f : f; }
static inline float  ImLerp(float a, float b, float t)                          { return a + (b - a) * t; }
static inline ImVec2 ImLerp(const ImVec2& a, const ImVec2& b, const ImVec2& t)  { return ImVec2(a.x + (b.x - a.x) * t.x, a.y + (b.y - a.y) * t.y); }
static inline float  ImLengthSqr(const ImVec2& lhs)                             { return lhs.x*lhs.x + lhs.y*lhs.y; }
static inline float  ImLengthSqr(const ImVec4& lhs)                             { return lhs.x*lhs.x + lhs.y*lhs.y + lhs.z*lhs.z + lhs.w*lhs.w; }
static inline float  ImInvLength(const ImVec2& lhs, float fail_value)           { float d = lhs.x*lhs.x + lhs.y*lhs.y; if (d > 0.0f) return 1.0f / sqrtf(d); return fail_value; }

//-----------------------------------------------------------------------------
// Types
//-----------------------------------------------------------------------------

enum ImGuiButtonFlags_
{
    ImGuiButtonFlags_Repeat             = 1 << 0,
    ImGuiButtonFlags_PressedOnClick     = 1 << 1,   // return pressed on click only (default requires click+release)
    ImGuiButtonFlags_PressedOnRelease   = 1 << 2,   // return pressed on release only (default requires click+release)
    ImGuiButtonFlags_FlattenChilds      = 1 << 3,
    ImGuiButtonFlags_DontClosePopups    = 1 << 4,
    ImGuiButtonFlags_Disabled           = 1 << 5,
    ImGuiButtonFlags_AlignTextBaseLine  = 1 << 6
};

enum ImGuiSelectableFlagsPrivate_
{
    // NB: need to be in sync with last value of ImGuiSelectableFlags_
    ImGuiSelectableFlags_Menu               = 1 << 2,
    ImGuiSelectableFlags_MenuItem           = 1 << 3,
    ImGuiSelectableFlags_Disabled           = 1 << 4,
    ImGuiSelectableFlags_DrawFillAvailWidth = 1 << 5
};

// FIXME: this is in development, not exposed/functional as a generic feature yet.
enum ImGuiLayoutType_
{
    ImGuiLayoutType_Vertical,
    ImGuiLayoutType_Horizontal
};

enum ImGuiPlotType
{
    ImGuiPlotType_Lines,
    ImGuiPlotType_Histogram
};

// 2D axis aligned bounding-box
// NB: we can't rely on ImVec2 math operators being available here
struct ImRect
{
    ImVec2          Min;    // Upper-left
    ImVec2          Max;    // Lower-right

    ImRect()                                        : Min(FLT_MAX,FLT_MAX), Max(-FLT_MAX,-FLT_MAX)  {}
    ImRect(const ImVec2& min, const ImVec2& max)    : Min(min), Max(max)                            {}
    ImRect(const ImVec4& v)                         : Min(v.x, v.y), Max(v.z, v.w)                  {}
    ImRect(float x1, float y1, float x2, float y2)  : Min(x1, y1), Max(x2, y2)                      {}

    ImVec2          GetCenter() const               { return ImVec2((Min.x+Max.x)*0.5f, (Min.y+Max.y)*0.5f); }
    ImVec2          GetSize() const                 { return ImVec2(Max.x-Min.x, Max.y-Min.y); }
    float           GetWidth() const                { return Max.x-Min.x; }
    float           GetHeight() const               { return Max.y-Min.y; }
    ImVec2          GetTL() const                   { return Min; }
    ImVec2          GetTR() const                   { return ImVec2(Max.x, Min.y); }
    ImVec2          GetBL() const                   { return ImVec2(Min.x, Max.y); }
    ImVec2          GetBR() const                   { return Max; }
    bool            Contains(const ImVec2& p) const { return p.x >= Min.x     && p.y >= Min.y     && p.x < Max.x     && p.y < Max.y; }
    bool            Contains(const ImRect& r) const { return r.Min.x >= Min.x && r.Min.y >= Min.y && r.Max.x < Max.x && r.Max.y < Max.y; }
    bool            Overlaps(const ImRect& r) const { return r.Min.y < Max.y  && r.Max.y > Min.y  && r.Min.x < Max.x && r.Max.x > Min.x; }
    void            Add(const ImVec2& rhs)          { if (Min.x > rhs.x)     Min.x = rhs.x;     if (Min.y > rhs.y) Min.y = rhs.y;         if (Max.x < rhs.x) Max.x = rhs.x;         if (Max.y < rhs.y) Max.y = rhs.y; }
    void            Add(const ImRect& rhs)          { if (Min.x > rhs.Min.x) Min.x = rhs.Min.x; if (Min.y > rhs.Min.y) Min.y = rhs.Min.y; if (Max.x < rhs.Max.x) Max.x = rhs.Max.x; if (Max.y < rhs.Max.y) Max.y = rhs.Max.y; }
    void            Expand(const float amount)      { Min.x -= amount;   Min.y -= amount;   Max.x += amount;   Max.y += amount; }
    void            Expand(const ImVec2& amount)    { Min.x -= amount.x; Min.y -= amount.y; Max.x += amount.x; Max.y += amount.y; }
    void            Reduce(const ImVec2& amount)    { Min.x += amount.x; Min.y += amount.y; Max.x -= amount.x; Max.y -= amount.y; }
    void            Clip(const ImRect& clip)        { if (Min.x < clip.Min.x) Min.x = clip.Min.x; if (Min.y < clip.Min.y) Min.y = clip.Min.y; if (Max.x > clip.Max.x) Max.x = clip.Max.x; if (Max.y > clip.Max.y) Max.y = clip.Max.y; }
    void            Round()                         { Min.x = (float)(int)Min.x; Min.y = (float)(int)Min.y; Max.x = (float)(int)Max.x; Max.y = (float)(int)Max.y; } 
    ImVec2          GetClosestPoint(ImVec2 p, bool on_edge) const
    {
        if (!on_edge && Contains(p))
            return p;
        if (p.x > Max.x) p.x = Max.x;
        else if (p.x < Min.x) p.x = Min.x;
        if (p.y > Max.y) p.y = Max.y;
        else if (p.y < Min.y) p.y = Min.y;
        return p;
    }
};

// Stacked color modifier, backup of modified data so we can restore it
struct ImGuiColMod
{
    ImGuiCol        Col;
    ImVec4          PreviousValue;
};

// Stacked style modifier, backup of modified data so we can restore it
struct ImGuiStyleMod
{
    ImGuiStyleVar   Var;
    ImVec2          PreviousValue;
};

// Stacked data for BeginGroup()/EndGroup()
struct ImGuiGroupData
{
    ImVec2          BackupCursorPos;
    ImVec2          BackupCursorMaxPos;
    float           BackupColumnsStartX;
    float           BackupCurrentLineHeight;
    float           BackupCurrentLineTextBaseOffset;
    float           BackupLogLinePosY;
    bool            AdvanceCursor;
};

// Simple column measurement currently used for MenuItem() only. This is very short-sighted for now and not a generic helper.
struct ImGuiSimpleColumns
{
    int             Count;
    float           Spacing;
    float           Width, NextWidth;
    float           Pos[8], NextWidths[8];

    ImGuiSimpleColumns();
    void            Update(int count, float spacing, bool clear);
    float           DeclColumns(float w0, float w1, float w2);
    float           CalcExtraSpace(float avail_w);
};

// Internal state of the currently focused/edited text input box
struct ImGuiTextEditState
{
    ImGuiID             Id;                             // widget id owning the text state
    ImVector<ImWchar>   Text;                           // edit buffer, we need to persist but can't guarantee the persistence of the user-provided buffer. so we copy into own buffer.
    ImVector<char>      InitialText;                    // backup of end-user buffer at the time of focus (in UTF-8, unaltered)
    ImVector<char>      TempTextBuffer;
    int                 CurLenA, CurLenW;               // we need to maintain our buffer length in both UTF-8 and wchar format.
    int                 BufSizeA;                       // end-user buffer size
    float               ScrollX;
    ImGuiStb::STB_TexteditState   StbState;
    float               CursorAnim;
    bool                CursorFollow;
    ImVec2              InputCursorScreenPos;           // Cursor position in screen space to be used by IME callback.
    bool                SelectedAllMouseLock;

    ImGuiTextEditState()                                { memset(this, 0, sizeof(*this)); }
    void                CursorAnimReset()               { CursorAnim = -0.30f; }                                   // After a user-input the cursor stays on for a while without blinking
    bool                HasSelection() const            { return StbState.select_start != StbState.select_end; }
    void                ClearSelection()                { StbState.select_start = StbState.select_end = StbState.cursor; }
    void                SelectAll()                     { StbState.select_start = 0; StbState.select_end = CurLenW; StbState.cursor = StbState.select_end; StbState.has_preferred_x = false; }
    void                OnKeyPressed(int key);
};

// Data saved in imgui.ini file
struct ImGuiIniData
{
    char*               Name;
    ImGuiID             ID;
    ImVec2              Pos;
    ImVec2              Size;
    bool                Collapsed;
};

// Mouse cursor data (used when io.MouseDrawCursor is set)
struct ImGuiMouseCursorData
{
    ImGuiMouseCursor    Type;
    ImVec2              HotOffset;
    ImVec2              Size;
    ImVec2              TexUvMin[2];
    ImVec2              TexUvMax[2];
};

// Storage for current popup stack
struct ImGuiPopupRef
{
    ImGuiID             PopupID;        // Set on OpenPopup()
    ImGuiWindow*        Window;         // Resolved on BeginPopup() - may stay unresolved if user never calls OpenPopup()
    ImGuiWindow*        ParentWindow;   // Set on OpenPopup()
    ImGuiID             ParentMenuSet;  // Set on OpenPopup()

    ImGuiPopupRef(ImGuiID id, ImGuiWindow* parent_window, ImGuiID parent_menu_set) { PopupID = id; Window = NULL; ParentWindow = parent_window; ParentMenuSet = parent_menu_set; }
};

// Main state for ImGui
struct ImGuiState
{
    bool                    Initialized;
    ImGuiIO                 IO;
    ImGuiStyle              Style;
    ImFont*                 Font;                               // (Shortcut) == FontStack.empty() ? IO.Font : FontStack.back()
    float                   FontSize;                           // (Shortcut) == FontBaseSize * g.CurrentWindow->FontWindowScale == window->FontSize()
    float                   FontBaseSize;                       // (Shortcut) == IO.FontGlobalScale * Font->Scale * Font->FontSize. Size of characters.
    ImVec2                  FontTexUvWhitePixel;                // (Shortcut) == Font->TexUvForWhite

    float                   Time;
    int                     FrameCount;
    int                     FrameCountRendered;
    ImVector<ImGuiWindow*>  Windows;
    ImVector<ImGuiWindow*>  WindowsSortBuffer;
    ImGuiWindow*            CurrentWindow;                      // Being drawn into
    ImVector<ImGuiWindow*>  CurrentWindowStack;
    ImGuiWindow*            FocusedWindow;                      // Will catch keyboard inputs
    ImGuiWindow*            HoveredWindow;                      // Will catch mouse inputs
    ImGuiWindow*            HoveredRootWindow;                  // Will catch mouse inputs (for focus/move only)
    ImGuiID                 HoveredId;                          // Hovered widget
    ImGuiID                 HoveredIdPreviousFrame;
    ImGuiID                 ActiveId;                           // Active widget
    ImGuiID                 ActiveIdPreviousFrame;
    bool                    ActiveIdIsAlive;
    bool                    ActiveIdIsJustActivated;            // Set at the time of activation for one frame
    bool                    ActiveIdIsFocusedOnly;              // Set only by active widget. Denote focus but no active interaction
    ImGuiWindow*            ActiveIdWindow;
    ImGuiWindow*            MovedWindow;                        // Track the child window we clicked on to move a window. Pointer is only valid if ActiveID is the "#MOVE" identifier of a window.
    ImVector<ImGuiIniData>  Settings;                           // .ini Settings
    float                   SettingsDirtyTimer;                 // Save .ini settinngs on disk when time reaches zero
    int                     DisableHideTextAfterDoubleHash;
    ImVector<ImGuiColMod>   ColorModifiers;                     // Stack for PushStyleColor()/PopStyleColor()
    ImVector<ImGuiStyleMod> StyleModifiers;                     // Stack for PushStyleVar()/PopStyleVar()
    ImVector<ImFont*>       FontStack;                          // Stack for PushFont()/PopFont()
    ImVector<ImGuiPopupRef> OpenedPopupStack;                   // Which popups are open (persistent)
    ImVector<ImGuiPopupRef> CurrentPopupStack;                  // Which level of BeginPopup() we are in (reset every frame)

    // Storage for SetNexWindow** and SetNextTreeNode*** functions
    ImVec2                  SetNextWindowPosVal;
    ImVec2                  SetNextWindowSizeVal;
    bool                    SetNextWindowCollapsedVal;
    ImGuiSetCond            SetNextWindowPosCond;
    ImGuiSetCond            SetNextWindowSizeCond;
    ImGuiSetCond            SetNextWindowCollapsedCond;
    bool                    SetNextWindowFocus;
    bool                    SetNextTreeNodeOpenedVal;
    ImGuiSetCond            SetNextTreeNodeOpenedCond;

    // Render
    ImVector<ImDrawList*>   RenderDrawLists[3];
    float                   ModalWindowDarkeningRatio;
    ImDrawList              OverlayDrawList;                    // Optional software render of mouse cursors, if io.MouseDrawCursor is set + a few debug overlays
    ImGuiMouseCursor        MouseCursor;
    ImGuiMouseCursorData    MouseCursorData[ImGuiMouseCursor_Count_];

    // Widget state
    ImGuiTextEditState      InputTextState;
    ImGuiID                 ScalarAsInputTextId;                // Temporary text input when CTRL+clicking on a slider, etc.
    ImGuiStorage            ColorEditModeStorage;               // Store user selection of color edit mode
    ImVec2                  ActiveClickDeltaToCenter;
    float                   DragCurrentValue;                   // Currently dragged value, always float, not rounded by end-user precision settings
    ImVec2                  DragLastMouseDelta;
    float                   DragSpeedDefaultRatio;              // If speed == 0.0f, uses (max-min) * DragSpeedDefaultRatio
    float                   DragSpeedScaleSlow;
    float                   DragSpeedScaleFast;
    float                   ScrollbarClickDeltaToGrabCenter;    // Distance between mouse and center of grab box, normalized in parent space
    char                    Tooltip[1024];
    char*                   PrivateClipboard;                   // If no custom clipboard handler is defined

    // Logging
    bool                    LogEnabled;
    FILE*                   LogFile;                            // If != NULL log to stdout/ file 
    ImGuiTextBuffer*        LogClipboard;                       // Else log to clipboard. This is pointer so our GImGui static constructor doesn't call heap allocators.
    int                     LogStartDepth;
    int                     LogAutoExpandMaxDepth;

    // Misc
    float                   FramerateSecPerFrame[120];          // calculate estimate of framerate for user
    int                     FramerateSecPerFrameIdx;
    float                   FramerateSecPerFrameAccum;
    bool                    CaptureMouseNextFrame;              // explicit capture via CaptureInputs() sets those flags
    bool                    CaptureKeyboardNextFrame;
    char                    TempBuffer[1024*3+1];               // temporary text buffer

    ImGuiState()
    {
        Initialized = false;
        Font = NULL;
        FontSize = FontBaseSize = 0.0f;
        FontTexUvWhitePixel = ImVec2(0.0f, 0.0f);

        Time = 0.0f;
        FrameCount = 0;
        FrameCountRendered = -1;
        CurrentWindow = NULL;
        FocusedWindow = NULL;
        HoveredWindow = NULL;
        HoveredRootWindow = NULL;
        HoveredId = 0;
        HoveredIdPreviousFrame = 0;
        ActiveId = 0;
        ActiveIdPreviousFrame = 0;
        ActiveIdIsAlive = false;
        ActiveIdIsJustActivated = false;
        ActiveIdIsFocusedOnly = false;
        ActiveIdWindow = NULL;
        MovedWindow = NULL;
        SettingsDirtyTimer = 0.0f;
        DisableHideTextAfterDoubleHash = 0;

        SetNextWindowPosVal = ImVec2(0.0f, 0.0f);
        SetNextWindowSizeVal = ImVec2(0.0f, 0.0f);
        SetNextWindowCollapsedVal = false;
        SetNextWindowPosCond = 0;
        SetNextWindowSizeCond = 0;
        SetNextWindowCollapsedCond = 0;
        SetNextWindowFocus = false;
        SetNextTreeNodeOpenedVal = false;
        SetNextTreeNodeOpenedCond = 0;

        ScalarAsInputTextId = 0;
        ActiveClickDeltaToCenter = ImVec2(0.0f, 0.0f);
        DragCurrentValue = 0.0f;
        DragLastMouseDelta = ImVec2(0.0f, 0.0f);
        DragSpeedDefaultRatio = 0.01f;
        DragSpeedScaleSlow = 0.01f;
        DragSpeedScaleFast = 10.0f;
        ScrollbarClickDeltaToGrabCenter = 0.0f;
        memset(Tooltip, 0, sizeof(Tooltip));
        PrivateClipboard = NULL;

        ModalWindowDarkeningRatio = 0.0f;
        OverlayDrawList._OwnerName = "##Overlay"; // Give it a name for debugging
        MouseCursor = ImGuiMouseCursor_Arrow;

        LogEnabled = false;
        LogFile = NULL;
        LogClipboard = NULL;
        LogStartDepth = 0;
        LogAutoExpandMaxDepth = 2;

        memset(FramerateSecPerFrame, 0, sizeof(FramerateSecPerFrame));
        FramerateSecPerFrameIdx = 0;
        FramerateSecPerFrameAccum = 0.0f;
        CaptureMouseNextFrame = CaptureKeyboardNextFrame = false;
    }
};

// Transient per-window data, reset at the beginning of the frame
// FIXME: That's theory, in practice the delimitation between ImGuiWindow and ImGuiDrawContext is quite tenuous and could be reconsidered.
struct ImGuiDrawContext
{
    ImVec2                  CursorPos;
    ImVec2                  CursorPosPrevLine;
    ImVec2                  CursorStartPos;
    ImVec2                  CursorMaxPos;           // Implicitly calculate the size of our contents, always extending. Saved into window->SizeContents at the end of the frame
    float                   CurrentLineHeight;
    float                   CurrentLineTextBaseOffset;
    float                   PrevLineHeight;
    float                   PrevLineTextBaseOffset;
    float                   LogLinePosY;
    int                     TreeDepth;
    ImGuiID                 LastItemID;
    ImRect                  LastItemRect;
    bool                    LastItemHoveredAndUsable;
    bool                    LastItemHoveredRect;
    bool                    MenuBarAppending;
    float                   MenuBarOffsetX;
    ImVector<ImGuiWindow*>  ChildWindows;
    ImGuiStorage*           StateStorage;
    ImGuiLayoutType         LayoutType;

    // We store the current settings outside of the vectors to increase memory locality (reduce cache misses). The vectors are rarely modified. Also it allows us to not heap allocate for short-lived windows which are not using those settings.
    bool                    ButtonRepeat;           // == ButtonRepeatStack.back() [empty == false]
    bool                    AllowKeyboardFocus;     // == AllowKeyboardFocusStack.back() [empty == true]
    float                   ItemWidth;              // == ItemWidthStack.back(). 0.0: default, >0.0: width in pixels, <0.0: align xx pixels to the right of window
    float                   TextWrapPos;            // == TextWrapPosStack.back() [empty == -1.0f]
    ImVector<bool>          ButtonRepeatStack;
    ImVector<bool>          AllowKeyboardFocusStack;
    ImVector<float>         ItemWidthStack;
    ImVector<float>         TextWrapPosStack;
    ImVector<ImGuiGroupData>GroupStack;
    ImGuiColorEditMode      ColorEditMode;
    int                     StackSizesBackup[6];    // Store size of various stacks for asserting

    float                   ColumnsStartX;          // Indentation / start position from left of window (increased by TreePush/TreePop, etc.)
    float                   ColumnsOffsetX;         // Offset to the current column (if ColumnsCurrent > 0). FIXME: This and the above should be a stack to allow use cases like Tree->Column->Tree. Need revamp columns API.
    int                     ColumnsCurrent;
    int                     ColumnsCount;
    ImVec2                  ColumnsStartPos;
    float                   ColumnsCellMinY;
    float                   ColumnsCellMaxY;
    bool                    ColumnsShowBorders;
    ImGuiID                 ColumnsSetID;
    ImVector<float>         ColumnsOffsetsT;        // Columns offset normalized 0.0 (far left) -> 1.0 (far right)

    ImGuiDrawContext()
    {
        CursorPos = CursorPosPrevLine = CursorStartPos = CursorMaxPos = ImVec2(0.0f, 0.0f);
        CurrentLineHeight = PrevLineHeight = 0.0f;
        CurrentLineTextBaseOffset = PrevLineTextBaseOffset = 0.0f;
        LogLinePosY = -1.0f;
        TreeDepth = 0;
        LastItemID = 0;
        LastItemRect = ImRect(0.0f,0.0f,0.0f,0.0f);
        LastItemHoveredAndUsable = LastItemHoveredRect = false;
        MenuBarAppending = false;
        MenuBarOffsetX = 0.0f;
        StateStorage = NULL;
        LayoutType = ImGuiLayoutType_Vertical;
        ItemWidth = 0.0f;
        ButtonRepeat = false;
        AllowKeyboardFocus = true;
        TextWrapPos = -1.0f;
        ColorEditMode = ImGuiColorEditMode_RGB;
        memset(StackSizesBackup, 0, sizeof(StackSizesBackup));

        ColumnsStartX = 0.0f;
        ColumnsOffsetX = 0.0f;
        ColumnsCurrent = 0;
        ColumnsCount = 1;
        ColumnsStartPos = ImVec2(0.0f, 0.0f);
        ColumnsCellMinY = ColumnsCellMaxY = 0.0f;
        ColumnsShowBorders = true;
        ColumnsSetID = 0;
    }
};

// Windows data
struct ImGuiWindow
{
    char*                   Name;
    ImGuiID                 ID;
    ImGuiWindowFlags        Flags;
    ImVec2                  PosFloat;
    ImVec2                  Pos;                                // Position rounded-up to nearest pixel
    ImVec2                  Size;                               // Current size (==SizeFull or collapsed title bar size)
    ImVec2                  SizeFull;                           // Size when non collapsed
    ImVec2                  SizeContents;                       // Size of contents (== extents reach of the drawing cursor) from previous frame
    ImVec2                  WindowPadding;                      // Window padding at the time of begin. We need to lock it, in particular manipulation of the ShowBorder would have an effect
    ImGuiID                 MoveID;                             // == window->GetID("#MOVE")
    float                   ScrollY;
    float                   ScrollTargetRelY;                   // target scroll position. stored as cursor position with scrolling canceled out, so the highest point is always 0.0f. (FLT_MAX for no change)
    float                   ScrollTargetCenterRatioY;           // 0.0f = scroll so that target position is at top, 0.5f = scroll so that target position is centered
    bool                    ScrollbarY;
    bool                    Active;                             // Set to true on Begin()
    bool                    WasActive;
    bool                    Accessed;                           // Set to true when any widget access the current window
    bool                    Collapsed;                          // Set when collapsing window to become only title-bar
    bool                    SkipItems;                          // == Visible && !Collapsed
    int                     BeginCount;                         // Number of Begin() during the current frame (generally 0 or 1, 1+ if appending via multiple Begin/End pairs)
    ImGuiID                 PopupID;                            // ID in the popup stack when this window is used as a popup/menu (because we use generic Name/ID for recycling) 
    int                     AutoFitFramesX, AutoFitFramesY;
    bool                    AutoFitOnlyGrows;
    int                     AutoPosLastDirection;
    int                     HiddenFrames;
    int                     SetWindowPosAllowFlags;             // bit ImGuiSetCond_*** specify if SetWindowPos() call will succeed with this particular flag. 
    int                     SetWindowSizeAllowFlags;            // bit ImGuiSetCond_*** specify if SetWindowSize() call will succeed with this particular flag. 
    int                     SetWindowCollapsedAllowFlags;       // bit ImGuiSetCond_*** specify if SetWindowCollapsed() call will succeed with this particular flag. 
    bool                    SetWindowPosCenterWanted;

    ImGuiDrawContext        DC;                                 // Temporary per-window data, reset at the beginning of the frame
    ImVector<ImGuiID>       IDStack;                            // ID stack. ID are hashes seeded with the value at the top of the stack
    ImVec4                  ClipRect;                           // = DrawList->clip_rect_stack.back(). Scissoring / clipping rectangle. x1, y1, x2, y2.
    ImRect                  ClippedWindowRect;                  // = ClipRect just after setup in Begin()
    int                     LastFrameDrawn;
    float                   ItemWidthDefault;
    ImGuiSimpleColumns      MenuColumns;                        // Simplified columns storage for menu items
    ImGuiStorage            StateStorage;
    float                   FontWindowScale;                    // Scale multiplier per-window
    ImDrawList*             DrawList;
    ImGuiWindow*            RootWindow;
    ImGuiWindow*            RootNonPopupWindow;

    // Focus
    int                     FocusIdxAllCounter;                 // Start at -1 and increase as assigned via FocusItemRegister()
    int                     FocusIdxTabCounter;                 // (same, but only count widgets which you can Tab through)
    int                     FocusIdxAllRequestCurrent;          // Item being requested for focus
    int                     FocusIdxTabRequestCurrent;          // Tab-able item being requested for focus
    int                     FocusIdxAllRequestNext;             // Item being requested for focus, for next update (relies on layout to be stable between the frame pressing TAB and the next frame)
    int                     FocusIdxTabRequestNext;             // "

public:
    ImGuiWindow(const char* name);
    ~ImGuiWindow();

    ImGuiID     GetID(const char* str, const char* str_end = NULL);
    ImGuiID     GetID(const void* ptr);

    ImRect      Rect() const                            { return ImRect(Pos.x, Pos.y, Pos.x+Size.x, Pos.y+Size.y); }
    float       CalcFontSize() const                    { return GImGui->FontBaseSize * FontWindowScale; }
    float       TitleBarHeight() const                  { return (Flags & ImGuiWindowFlags_NoTitleBar) ? 0.0f : CalcFontSize() + GImGui->Style.FramePadding.y * 2.0f; }
    ImRect      TitleBarRect() const                    { return ImRect(Pos, ImVec2(Pos.x + SizeFull.x, Pos.y + TitleBarHeight())); }
    float       MenuBarHeight() const                   { return (Flags & ImGuiWindowFlags_MenuBar) ? CalcFontSize() + GImGui->Style.FramePadding.y * 2.0f : 0.0f; }
    ImRect      MenuBarRect() const                     { float y1 = Pos.y + TitleBarHeight(); return ImRect(Pos.x, y1, Pos.x + SizeFull.x, y1 + MenuBarHeight()); }
    float       ScrollbarWidth() const                  { return ScrollbarY ? GImGui->Style.ScrollbarWidth : 0.0f; }
    ImU32       Color(ImGuiCol idx, float a=1.f) const  { ImVec4 c = GImGui->Style.Colors[idx]; c.w *= GImGui->Style.Alpha * a; return ImGui::ColorConvertFloat4ToU32(c); }
    ImU32       Color(const ImVec4& col) const          { ImVec4 c = col; c.w *= GImGui->Style.Alpha; return ImGui::ColorConvertFloat4ToU32(c); }
};

//-----------------------------------------------------------------------------
// Internal API
// No guarantee of forward compatibility here.
//-----------------------------------------------------------------------------

namespace ImGui
{
    IMGUI_API bool          ItemAdd(const ImRect& bb, const ImGuiID* id);
    IMGUI_API void          ItemSize(const ImVec2& size, float text_offset_y = 0.0f);
    IMGUI_API void          ItemSize(const ImRect& bb, float text_offset_y = 0.0f);
    IMGUI_API bool          IsClippedEx(const ImRect& bb, const ImGuiID* id, bool clip_even_when_logged);
    IMGUI_API bool          IsHovered(const ImRect& bb, ImGuiID id, bool flatten_childs = false);
    IMGUI_API bool          FocusableItemRegister(ImGuiWindow* window, bool is_active, bool tab_stop = true);      // Return true if focus is requested
    IMGUI_API void          FocusableItemUnregister(ImGuiWindow* window);
    IMGUI_API ImVec2        CalcItemSize(ImVec2 size, float default_x, float default_y);
    IMGUI_API float         CalcWrapWidthForPos(const ImVec2& pos, float wrap_pos_x);

    IMGUI_API void          SetActiveID(ImGuiID id, ImGuiWindow* window);
    IMGUI_API void          KeepAliveID(ImGuiID id);

    IMGUI_API ImGuiWindow*  GetCurrentWindow();
    IMGUI_API ImGuiWindow*  GetParentWindow();
    IMGUI_API void          FocusWindow(ImGuiWindow* window);

    IMGUI_API void          RenderText(ImVec2 pos, const char* text, const char* text_end = NULL, bool hide_text_after_hash = true);
    IMGUI_API void          RenderTextWrapped(ImVec2 pos, const char* text, const char* text_end, float wrap_width);
    IMGUI_API void          RenderTextClipped(const ImVec2& pos_min, const ImVec2& pos_max, const char* text, const char* text_end, const ImVec2* text_size_if_known, ImGuiAlign align = ImGuiAlign_Default, const ImVec2* clip_min = NULL, const ImVec2* clip_max = NULL);
    IMGUI_API void          RenderFrame(ImVec2 p_min, ImVec2 p_max, ImU32 fill_col, bool border = true, float rounding = 0.0f);
    IMGUI_API void          RenderCollapseTriangle(ImVec2 p_min, bool opened, float scale = 1.0f, bool shadow = false);
    IMGUI_API void          RenderCheckMark(ImVec2 pos, ImU32 col);

    IMGUI_API bool          ButtonBehavior(const ImRect& bb, ImGuiID id, bool* out_hovered, bool* out_held, bool allow_key_modifiers, ImGuiButtonFlags flags = 0);
    IMGUI_API bool          ButtonEx(const char* label, const ImVec2& size_arg = ImVec2(0,0), ImGuiButtonFlags flags = 0);

    IMGUI_API bool          SliderBehavior(const ImRect& frame_bb, ImGuiID id, float* v, float v_min, float v_max, float power, int decimal_precision, bool horizontal);
    IMGUI_API bool          SliderFloatN(const char* label, float* v, int components, float v_min, float v_max, const char* display_format, float power);
    IMGUI_API bool          SliderIntN(const char* label, int* v, int components, int v_min, int v_max, const char* display_format);

    IMGUI_API bool          DragBehavior(const ImRect& frame_bb, ImGuiID id, float* v, float v_speed, float v_min, float v_max, int decimal_precision, float power);
    IMGUI_API bool          DragFloatN(const char* label, float* v, int components, float v_speed, float v_min, float v_max, const char* display_format, float power);
    IMGUI_API bool          DragIntN(const char* label, int* v, int components, float v_speed, int v_min, int v_max, const char* display_format);

    IMGUI_API bool          InputTextEx(const char* label, char* buf, int buf_size, const ImVec2& size_arg, ImGuiInputTextFlags flags, ImGuiTextEditCallback callback = NULL, void* user_data = NULL);
    IMGUI_API bool          InputFloatN(const char* label, float* v, int components, int decimal_precision, ImGuiInputTextFlags extra_flags);
    IMGUI_API bool          InputIntN(const char* label, int* v, int components, ImGuiInputTextFlags extra_flags);
    IMGUI_API bool          InputFloatReplaceWidget(const ImRect& aabb, const char* label, float* v, ImGuiID id, int decimal_precision);

    IMGUI_API void          PlotEx(ImGuiPlotType plot_type, const char* label, float (*values_getter)(void* data, int idx), void* data, int values_count, int values_offset, const char* overlay_text, float scale_min, float scale_max, ImVec2 graph_size);

    IMGUI_API int           ParseFormatPrecision(const char* fmt, int default_value);
    IMGUI_API float         RoundScalar(float value, int decimal_precision);

} // namespace ImGuiP