TODO

// Tasks

// Context creation and access

// Each context create its own ImFontAtlas by default. You may
// instance one yourself and pass it to CreateContext() to share a
// font atlas between imgui contexts.  All those functions are not
// reliant on the current context.
IMGUI_API ImGuiContext* CreateContext(ImFontAtlas* shared_font_atlas = NULL);
IMGUI_API void          DestroyContext(ImGuiContext* ctx = NULL);   // NULL = destroy current context
IMGUI_API ImGuiContext* GetCurrentContext();
IMGUI_API void          SetCurrentContext(ImGuiContext* ctx);
IMGUI_API bool          DebugCheckVersionAndDataLayout(const char* version_str, size_t sz_io, size_t sz_style, size_t sz_vec2, size_t sz_vec4, size_t sz_drawvert);

// Main

// access the IO structure (mouse/keyboard/gamepad inputs, time,
// various configuration options/flags)
IMGUI_API ImGuiIO&      GetIO();
// access the Style structure (colors, sizes). Always use
// PushStyleCol(), PushStyleVar() to modify style mid-frame.
IMGUI_API ImGuiStyle&   GetStyle();
// start a new Dear ImGui frame, you can submit any command from this
// point until Render()/EndFrame().
IMGUI_API void          NewFrame();
// ends the Dear ImGui frame. automatically called by Render(), you
// likely don't need to call that yourself directly. If you don't need
// to render data (skipping rendering) you may call EndFrame() but
// you'll have wasted CPU already! If you don't need to render, better
// to not create any imgui windows and not call NewFrame() at all!
IMGUI_API void          EndFrame();
// ends the Dear ImGui frame, finalize the draw data. You can get call
// GetDrawData() to obtain it and run your rendering
// function. (Obsolete: this used to call
// io.RenderDrawListsFn(). Nowadays, we allow and prefer calling your
// render function yourself.)
IMGUI_API void          Render();
// valid after Render() and until the next call to NewFrame(). this is
// what you have to render.
IMGUI_API ImDrawData*   GetDrawData();

// Windows Utilities

// "current window" = the window we are appending into while inside a
// Begin()/End() block. "next window" = next window we will Begin()
// into.
// get draw list associated to the current window, to append your own
// drawing primitives
IMGUI_API ImDrawList*   GetWindowDrawList();

// Prefer using SetNextXXX functions (before Begin) rather that SetXXX
// functions (after Begin).
//
// set next window size limits. use -1,-1 on either X/Y axis to
// preserve the current size. Use callback to apply non-trivial
// programmatic constraints.
IMGUI_API void          SetNextWindowSizeConstraints(const ImVec2& size_min, const ImVec2& size_max, ImGuiSizeCallback custom_callback = NULL, void* custom_callback_data = NULL);

// Parameters stacks (shared)

// use NULL as a shortcut to push default font
IMGUI_API void          PushFont(ImFont* font);
IMGUI_API void          PopFont();
// retrieve style color as stored in ImGuiStyle structure. use to feed
// back into PushStyleColor(), otherwise use GetColorU32() to get
// style color with style alpha baked in.
IMGUI_API const ImVec4& GetStyleColorVec4(ImGuiCol idx);
// get current font
IMGUI_API ImFont*       GetFont();
// get current font size (= height in pixels) of current font with
// current scale applied
IMGUI_API float         GetFontSize();
// get UV coordinate for a while pixel, useful to draw custom shapes
// via the ImDrawList API
IMGUI_API ImVec2        GetFontTexUvWhitePixel();
// retrieve given style color with style alpha applied and optional
// extra alpha multiplier
IMGUI_API ImU32         GetColorU32(ImGuiCol idx, float alpha_mul = 1.0f);
// retrieve given color with style alpha applied
IMGUI_API ImU32         GetColorU32(const ImVec4& col);
// retrieve given color with style alpha applied
IMGUI_API ImU32         GetColorU32(ImU32 col);

// Miscellaneous Utilities

// this draw list will be the first rendering one. Useful to quickly draw shapes/text behind dear imgui contents.
IMGUI_API ImDrawList*   GetBackgroundDrawList();
// this draw list will be the last rendered one. Useful to quickly draw shapes/text over dear imgui contents.
IMGUI_API ImDrawList*   GetForegroundDrawList();
// you may use this when creating your own ImDrawList instances.
IMGUI_API ImDrawListSharedData* GetDrawListSharedData();
// get a string corresponding to the enum value (for display, saving, etc.).
IMGUI_API const char*   GetStyleColorName(ImGuiCol idx);
// replace current window storage with our own (if you want to manipulate it yourself, typically clear subsection of it)
IMGUI_API void          SetStateStorage(ImGuiStorage* storage);
IMGUI_API ImGuiStorage* GetStateStorage();

//-----------------------------------------------------------------------------
// ImGuiIO
// Communicate most settings and inputs/outputs to Dear ImGui using this structure.
// Access via ImGui::GetIO(). Read 'Programmer guide' section in .cpp file for general usage.
//-----------------------------------------------------------------------------

struct ImGuiIO
{
    //------------------------------------------------------------------
    // Configuration (fill once)                // Default value
    //------------------------------------------------------------------

    ImGuiConfigFlags   ConfigFlags;             // = 0              // See ImGuiConfigFlags_ enum. Set by user/application. Gamepad/keyboard navigation options, etc.
    ImGuiBackendFlags  BackendFlags;            // = 0              // See ImGuiBackendFlags_ enum. Set by back-end (imgui_impl_xxx files or custom back-end) to communicate features supported by the back-end.
    ImVec2      DisplaySize;                    // <unset>          // Main display size, in pixels.
    float       DeltaTime;                      // = 1.0f/60.0f     // Time elapsed since last frame, in seconds.
    float       IniSavingRate;                  // = 5.0f           // Minimum time between saving positions/sizes to .ini file, in seconds.
    const char* IniFilename;                    // = "imgui.ini"    // Path to .ini file. Set NULL to disable automatic .ini loading/saving, if e.g. you want to manually load/save from memory.
    const char* LogFilename;                    // = "imgui_log.txt"// Path to .log file (default parameter to ImGui::LogToFile when no file is specified).
    float       MouseDoubleClickTime;           // = 0.30f          // Time for a double-click, in seconds.
    float       MouseDoubleClickMaxDist;        // = 6.0f           // Distance threshold to stay in to validate a double-click, in pixels.
    float       MouseDragThreshold;             // = 6.0f           // Distance threshold before considering we are dragging.
    int         KeyMap[ImGuiKey_COUNT];         // <unset>          // Map of indices into the KeysDown[512] entries array which represent your "native" keyboard state.
    float       KeyRepeatDelay;                 // = 0.250f         // When holding a key/button, time before it starts repeating, in seconds (for buttons in Repeat mode, etc.).
    float       KeyRepeatRate;                  // = 0.050f         // When holding a key/button, rate at which it repeats, in seconds.
    void*       UserData;                       // = NULL           // Store your own data for retrieval by callbacks.

    ImFontAtlas*Fonts;                          // <auto>           // Load, rasterize and pack one or more fonts into a single texture.
    float       FontGlobalScale;                // = 1.0f           // Global scale all fonts
    bool        FontAllowUserScaling;           // = false          // Allow user scaling text of individual window with CTRL+Wheel.
    ImFont*     FontDefault;                    // = NULL           // Font to use on NewFrame(). Use NULL to uses Fonts->Fonts[0].
    ImVec2      DisplayFramebufferScale;        // = (1, 1)         // For retina display or other situations where window coordinates are different from framebuffer coordinates. This generally ends up in ImDrawData::FramebufferScale.

    // Miscellaneous options
    bool        MouseDrawCursor;                // = false          // Request ImGui to draw a mouse cursor for you (if you are on a platform without a mouse cursor). Cannot be easily renamed to 'io.ConfigXXX' because this is frequently used by back-end implementations.
    bool        ConfigMacOSXBehaviors;          // = defined(__APPLE__) // OS X style: Text editing cursor movement using Alt instead of Ctrl, Shortcuts using Cmd/Super instead of Ctrl, Line/Text Start and End using Cmd+Arrows instead of Home/End, Double click selects by word instead of selecting whole text, Multi-selection in lists uses Cmd/Super instead of Ctrl (was called io.OptMacOSXBehaviors prior to 1.63)
    bool        ConfigInputTextCursorBlink;     // = true           // Set to false to disable blinking cursor, for users who consider it distracting. (was called: io.OptCursorBlink prior to 1.63)
    bool        ConfigWindowsResizeFromEdges;   // = true           // Enable resizing of windows from their edges and from the lower-left corner. This requires (io.BackendFlags & ImGuiBackendFlags_HasMouseCursors) because it needs mouse cursor feedback. (This used to be a per-window ImGuiWindowFlags_ResizeFromAnySide flag)
    bool        ConfigWindowsMoveFromTitleBarOnly; // = false       // [BETA] Set to true to only allow moving windows when clicked+dragged from the title bar. Windows without a title bar are not affected.

    //------------------------------------------------------------------
    // Platform Functions
    // (the imgui_impl_xxxx back-end files are setting those up for you)
    //------------------------------------------------------------------

    // Optional: Platform/Renderer back-end name (informational only! will be displayed in About Window) + User data for back-end/wrappers to store their own stuff.
    const char* BackendPlatformName;            // = NULL
    const char* BackendRendererName;            // = NULL
    void*       BackendPlatformUserData;        // = NULL
    void*       BackendRendererUserData;        // = NULL
    void*       BackendLanguageUserData;        // = NULL

    // Optional: Access OS clipboard
    // (default to use native Win32 clipboard on Windows, otherwise uses a private clipboard. Override to access OS clipboard on other architectures)
    const char* (*GetClipboardTextFn)(void* user_data);
    void        (*SetClipboardTextFn)(void* user_data, const char* text);
    void*       ClipboardUserData;

    // Optional: Notify OS Input Method Editor of the screen position of your cursor for text input position (e.g. when using Japanese/Chinese IME on Windows)
    // (default to use native imm32 api on Windows)
    void        (*ImeSetInputScreenPosFn)(int x, int y);
    void*       ImeWindowHandle;                // = NULL           // (Windows) Set this to your HWND to get automatic IME cursor positioning.

#ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
    // [OBSOLETE since 1.60+] Rendering function, will be automatically called in Render(). Please call your rendering function yourself now!
    // You can obtain the ImDrawData* by calling ImGui::GetDrawData() after Render(). See example applications if you are unsure of how to implement this.
    void        (*RenderDrawListsFn)(ImDrawData* data);
#else
    // This is only here to keep ImGuiIO the same size/layout, so that IMGUI_DISABLE_OBSOLETE_FUNCTIONS can exceptionally be used outside of imconfig.h.
    void*       RenderDrawListsFnUnused;
#endif

    //------------------------------------------------------------------
    // Input - Fill before calling NewFrame()
    //------------------------------------------------------------------

    ImVec2      MousePos;                       // Mouse position, in pixels. Set to ImVec2(-FLT_MAX,-FLT_MAX) if mouse is unavailable (on another screen, etc.)
    bool        MouseDown[5];                   // Mouse buttons: 0=left, 1=right, 2=middle + extras. ImGui itself mostly only uses left button (BeginPopupContext** are using right button). Others buttons allows us to track if the mouse is being used by your application + available to user as a convenience via IsMouse** API.
    float       MouseWheel;                     // Mouse wheel Vertical: 1 unit scrolls about 5 lines text.
    float       MouseWheelH;                    // Mouse wheel Horizontal. Most users don't have a mouse with an horizontal wheel, may not be filled by all back-ends.
    bool        KeyCtrl;                        // Keyboard modifier pressed: Control
    bool        KeyShift;                       // Keyboard modifier pressed: Shift
    bool        KeyAlt;                         // Keyboard modifier pressed: Alt
    bool        KeySuper;                       // Keyboard modifier pressed: Cmd/Super/Windows
    bool        KeysDown[512];                  // Keyboard keys that are pressed (ideally left in the "native" order your engine has access to keyboard keys, so you can use your own defines/enums for keys).
    float       NavInputs[ImGuiNavInput_COUNT]; // Gamepad inputs. Cleared back to zero by EndFrame(). Keyboard keys will be auto-mapped and be written here by NewFrame().

    // Functions
    IMGUI_API void  AddInputCharacter(ImWchar c);               // Queue new character input
    IMGUI_API void  AddInputCharactersUTF8(const char* str);    // Queue new characters input from an UTF-8 string
    IMGUI_API void  ClearInputCharacters();                     // Clear the text input buffer manually

    //------------------------------------------------------------------
    // Output - Retrieve after calling NewFrame()
    //------------------------------------------------------------------

    bool        WantCaptureMouse;               // When io.WantCaptureMouse is true, imgui will use the mouse inputs, do not dispatch them to your main game/application (in both cases, always pass on mouse inputs to imgui). (e.g. unclicked mouse is hovering over an imgui window, widget is active, mouse was clicked over an imgui window, etc.).
    bool        WantCaptureKeyboard;            // When io.WantCaptureKeyboard is true, imgui will use the keyboard inputs, do not dispatch them to your main game/application (in both cases, always pass keyboard inputs to imgui). (e.g. InputText active, or an imgui window is focused and navigation is enabled, etc.).
    bool        WantTextInput;                  // Mobile/console: when io.WantTextInput is true, you may display an on-screen keyboard. This is set by ImGui when it wants textual keyboard input to happen (e.g. when a InputText widget is active).
    bool        WantSetMousePos;                // MousePos has been altered, back-end should reposition mouse on next frame. Set only when ImGuiConfigFlags_NavEnableSetMousePos flag is enabled.
    bool        WantSaveIniSettings;            // When manual .ini load/save is active (io.IniFilename == NULL), this will be set to notify your application that you can call SaveIniSettingsToMemory() and save yourself. IMPORTANT: You need to clear io.WantSaveIniSettings yourself.
    bool        NavActive;                      // Directional navigation is currently allowed (will handle ImGuiKey_NavXXX events) = a window is focused and it doesn't use the ImGuiWindowFlags_NoNavInputs flag.
    bool        NavVisible;                     // Directional navigation is visible and allowed (will handle ImGuiKey_NavXXX events).
    float       Framerate;                      // Application framerate estimation, in frame per second. Solely for convenience. Rolling average estimation based on IO.DeltaTime over 120 frames
    int         MetricsRenderVertices;          // Vertices output during last call to Render()
    int         MetricsRenderIndices;           // Indices output during last call to Render() = number of triangles * 3
    int         MetricsRenderWindows;           // Number of visible windows
    int         MetricsActiveWindows;           // Number of active windows
    int         MetricsActiveAllocations;       // Number of active allocations, updated by MemAlloc/MemFree based on current context. May be off if you have multiple imgui contexts.
    ImVec2      MouseDelta;                     // Mouse delta. Note that this is zero if either current or previous position are invalid (-FLT_MAX,-FLT_MAX), so a disappearing/reappearing mouse won't have a huge delta.

    //------------------------------------------------------------------
    // [Internal] ImGui will maintain those fields. Forward compatibility not guaranteed!
    //------------------------------------------------------------------

    ImVec2      MousePosPrev;                   // Previous mouse position (note that MouseDelta is not necessary == MousePos-MousePosPrev, in case either position is invalid)
    ImVec2      MouseClickedPos[5];             // Position at time of clicking
    double      MouseClickedTime[5];            // Time of last click (used to figure out double-click)
    bool        MouseClicked[5];                // Mouse button went from !Down to Down
    bool        MouseDoubleClicked[5];          // Has mouse button been double-clicked?
    bool        MouseReleased[5];               // Mouse button went from Down to !Down
    bool        MouseDownOwned[5];              // Track if button was clicked inside a window. We don't request mouse capture from the application if click started outside ImGui bounds.
    float       MouseDownDuration[5];           // Duration the mouse button has been down (0.0f == just clicked)
    float       MouseDownDurationPrev[5];       // Previous time the mouse button has been down
    ImVec2      MouseDragMaxDistanceAbs[5];     // Maximum distance, absolute, on each axis, of how much mouse has traveled from the clicking point
    float       MouseDragMaxDistanceSqr[5];     // Squared maximum distance of how much mouse has traveled from the clicking point
    float       KeysDownDuration[512];          // Duration the keyboard key has been down (0.0f == just pressed)
    float       KeysDownDurationPrev[512];      // Previous duration the key has been down
    float       NavInputsDownDuration[ImGuiNavInput_COUNT];
    float       NavInputsDownDurationPrev[ImGuiNavInput_COUNT];
    ImVector<ImWchar> InputQueueCharacters;     // Queue of _characters_ input (obtained by platform back-end). Fill using AddInputCharacter() helper.

    IMGUI_API   ImGuiIO();
};

// Draw command list
// This is the low-level list of polygons that ImGui functions are filling. At the end of the frame, all command lists are passed to your ImGuiIO::RenderDrawListFn function for rendering.
// Each ImGui window contains its own ImDrawList. You can use ImGui::GetWindowDrawList() to access the current window draw list and draw custom primitives.
// You can interleave normal ImGui:: calls and adding primitives to the current draw list.
// All positions are generally in pixel coordinates (top-left at (0,0), bottom-right at io.DisplaySize), but you are totally free to apply whatever transformation matrix to want to the data (if you apply such transformation you'll want to apply it to ClipRect as well)
// Important: Primitives are always added to the list and not culled (culling is done at higher-level by ImGui:: functions), if you use this API a lot consider coarse culling your drawn objects.
struct ImDrawList
{
    // This is what you have to render
    ImVector<ImDrawCmd>     CmdBuffer;          // Draw commands. Typically 1 command = 1 GPU draw call, unless the command is a callback.
    ImVector<ImDrawIdx>     IdxBuffer;          // Index buffer. Each command consume ImDrawCmd::ElemCount of those
    ImVector<ImDrawVert>    VtxBuffer;          // Vertex buffer.
    ImDrawListFlags         Flags;              // Flags, you may poke into these to adjust anti-aliasing settings per-primitive.

    // [Internal, used while building lists]
    const ImDrawListSharedData* _Data;          // Pointer to shared draw data (you can use ImGui::GetDrawListSharedData() to get the one from current ImGui context)
    const char*             _OwnerName;         // Pointer to owner window's name for debugging
    unsigned int            _VtxCurrentIdx;     // [Internal] == VtxBuffer.Size
    ImDrawVert*             _VtxWritePtr;       // [Internal] point within VtxBuffer.Data after each add command (to avoid using the ImVector<> operators too much)
    ImDrawIdx*              _IdxWritePtr;       // [Internal] point within IdxBuffer.Data after each add command (to avoid using the ImVector<> operators too much)
    ImVector<ImVec4>        _ClipRectStack;     // [Internal]
    ImVector<ImTextureID>   _TextureIdStack;    // [Internal]
    ImVector<ImVec2>        _Path;              // [Internal] current path building
    int                     _ChannelsCurrent;   // [Internal] current channel number (0)
    int                     _ChannelsCount;     // [Internal] number of active channels (1+)
    ImVector<ImDrawChannel> _Channels;          // [Internal] draw channels for columns API (not resized down so _ChannelsCount may be smaller than _Channels.Size)

    // If you want to create ImDrawList instances, pass them ImGui::GetDrawListSharedData() or create and use your own ImDrawListSharedData (so you can use ImDrawList without ImGui)
    ImDrawList(const ImDrawListSharedData* shared_data) { _Data = shared_data; _OwnerName = NULL; Clear(); }
    ~ImDrawList() { ClearFreeMemory(); }
    IMGUI_API void  PushClipRect(ImVec2 clip_rect_min, ImVec2 clip_rect_max, bool intersect_with_current_clip_rect = false);  // Render-level scissoring. This is passed down to your render function but not used for CPU-side coarse clipping. Prefer using higher-level ImGui::PushClipRect() to affect logic (hit-testing and widget culling)
    IMGUI_API void  PushClipRectFullScreen();
    IMGUI_API void  PopClipRect();
    IMGUI_API void  PushTextureID(ImTextureID texture_id);
    IMGUI_API void  PopTextureID();
    inline ImVec2   GetClipRectMin() const { const ImVec4& cr = _ClipRectStack.back(); return ImVec2(cr.x, cr.y); }
    inline ImVec2   GetClipRectMax() const { const ImVec4& cr = _ClipRectStack.back(); return ImVec2(cr.z, cr.w); }

    // Primitives
    IMGUI_API void  AddLine(const ImVec2& a, const ImVec2& b, ImU32 col, float thickness = 1.0f);
    IMGUI_API void  AddRect(const ImVec2& a, const ImVec2& b, ImU32 col, float rounding = 0.0f, int rounding_corners_flags = ImDrawCornerFlags_All, float thickness = 1.0f);   // a: upper-left, b: lower-right (== upper-left + size), rounding_corners_flags: 4-bits corresponding to which corner to round
    IMGUI_API void  AddRectFilled(const ImVec2& a, const ImVec2& b, ImU32 col, float rounding = 0.0f, int rounding_corners_flags = ImDrawCornerFlags_All);                     // a: upper-left, b: lower-right (== upper-left + size)
    IMGUI_API void  AddRectFilledMultiColor(const ImVec2& a, const ImVec2& b, ImU32 col_upr_left, ImU32 col_upr_right, ImU32 col_bot_right, ImU32 col_bot_left);
    IMGUI_API void  AddQuad(const ImVec2& a, const ImVec2& b, const ImVec2& c, const ImVec2& d, ImU32 col, float thickness = 1.0f);
    IMGUI_API void  AddQuadFilled(const ImVec2& a, const ImVec2& b, const ImVec2& c, const ImVec2& d, ImU32 col);
    IMGUI_API void  AddTriangle(const ImVec2& a, const ImVec2& b, const ImVec2& c, ImU32 col, float thickness = 1.0f);
    IMGUI_API void  AddTriangleFilled(const ImVec2& a, const ImVec2& b, const ImVec2& c, ImU32 col);
    IMGUI_API void  AddCircle(const ImVec2& centre, float radius, ImU32 col, int num_segments = 12, float thickness = 1.0f);
    IMGUI_API void  AddCircleFilled(const ImVec2& centre, float radius, ImU32 col, int num_segments = 12);
    IMGUI_API void  AddText(const ImVec2& pos, ImU32 col, const char* text_begin, const char* text_end = NULL);
    IMGUI_API void  AddText(const ImFont* font, float font_size, const ImVec2& pos, ImU32 col, const char* text_begin, const char* text_end = NULL, float wrap_width = 0.0f, const ImVec4* cpu_fine_clip_rect = NULL);
    IMGUI_API void  AddImage(ImTextureID user_texture_id, const ImVec2& a, const ImVec2& b, const ImVec2& uv_a = ImVec2(0,0), const ImVec2& uv_b = ImVec2(1,1), ImU32 col = IM_COL32_WHITE);
    IMGUI_API void  AddImageQuad(ImTextureID user_texture_id, const ImVec2& a, const ImVec2& b, const ImVec2& c, const ImVec2& d, const ImVec2& uv_a = ImVec2(0,0), const ImVec2& uv_b = ImVec2(1,0), const ImVec2& uv_c = ImVec2(1,1), const ImVec2& uv_d = ImVec2(0,1), ImU32 col = IM_COL32_WHITE);
    IMGUI_API void  AddImageRounded(ImTextureID user_texture_id, const ImVec2& a, const ImVec2& b, const ImVec2& uv_a, const ImVec2& uv_b, ImU32 col, float rounding, int rounding_corners = ImDrawCornerFlags_All);
    IMGUI_API void  AddPolyline(const ImVec2* points, int num_points, ImU32 col, bool closed, float thickness);
    IMGUI_API void  AddConvexPolyFilled(const ImVec2* points, int num_points, ImU32 col); // Note: Anti-aliased filling requires points to be in clockwise order.
    IMGUI_API void  AddBezierCurve(const ImVec2& pos0, const ImVec2& cp0, const ImVec2& cp1, const ImVec2& pos1, ImU32 col, float thickness, int num_segments = 0);

    // Stateful path API, add points then finish with PathFillConvex() or PathStroke()
    inline    void  PathClear()                                                 { _Path.Size = 0; }
    inline    void  PathLineTo(const ImVec2& pos)                               { _Path.push_back(pos); }
    inline    void  PathLineToMergeDuplicate(const ImVec2& pos)                 { if (_Path.Size == 0 || memcmp(&_Path.Data[_Path.Size-1], &pos, 8) != 0) _Path.push_back(pos); }
    inline    void  PathFillConvex(ImU32 col)                                   { AddConvexPolyFilled(_Path.Data, _Path.Size, col); _Path.Size = 0; }  // Note: Anti-aliased filling requires points to be in clockwise order.
    inline    void  PathStroke(ImU32 col, bool closed, float thickness = 1.0f)  { AddPolyline(_Path.Data, _Path.Size, col, closed, thickness); _Path.Size = 0; }
    IMGUI_API void  PathArcTo(const ImVec2& centre, float radius, float a_min, float a_max, int num_segments = 10);
    IMGUI_API void  PathArcToFast(const ImVec2& centre, float radius, int a_min_of_12, int a_max_of_12);                                            // Use precomputed angles for a 12 steps circle
    IMGUI_API void  PathBezierCurveTo(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, int num_segments = 0);
    IMGUI_API void  PathRect(const ImVec2& rect_min, const ImVec2& rect_max, float rounding = 0.0f, int rounding_corners_flags = ImDrawCornerFlags_All);

    // Channels
    // - Use to simulate layers. By switching channels to can render out-of-order (e.g. submit foreground primitives before background primitives)
    // - Use to minimize draw calls (e.g. if going back-and-forth between multiple non-overlapping clipping rectangles, prefer to append into separate channels then merge at the end)
    IMGUI_API void  ChannelsSplit(int channels_count);
    IMGUI_API void  ChannelsMerge();
    IMGUI_API void  ChannelsSetCurrent(int channel_index);

    // Advanced
    IMGUI_API void  AddCallback(ImDrawCallback callback, void* callback_data);  // Your rendering function must check for 'UserCallback' in ImDrawCmd and call the function instead of rendering triangles.
    IMGUI_API void  AddDrawCmd();                                               // This is useful if you need to forcefully create a new draw call (to allow for dependent rendering / blending). Otherwise primitives are merged into the same draw-call as much as possible
    IMGUI_API ImDrawList* CloneOutput() const;                                  // Create a clone of the CmdBuffer/IdxBuffer/VtxBuffer.

    // Internal helpers
    // NB: all primitives needs to be reserved via PrimReserve() beforehand!
    IMGUI_API void  Clear();
    IMGUI_API void  ClearFreeMemory();
    IMGUI_API void  PrimReserve(int idx_count, int vtx_count);
    IMGUI_API void  PrimRect(const ImVec2& a, const ImVec2& b, ImU32 col);      // Axis aligned rectangle (composed of two triangles)
    IMGUI_API void  PrimRectUV(const ImVec2& a, const ImVec2& b, const ImVec2& uv_a, const ImVec2& uv_b, ImU32 col);
    IMGUI_API void  PrimQuadUV(const ImVec2& a, const ImVec2& b, const ImVec2& c, const ImVec2& d, const ImVec2& uv_a, const ImVec2& uv_b, const ImVec2& uv_c, const ImVec2& uv_d, ImU32 col);
    inline    void  PrimWriteVtx(const ImVec2& pos, const ImVec2& uv, ImU32 col){ _VtxWritePtr->pos = pos; _VtxWritePtr->uv = uv; _VtxWritePtr->col = col; _VtxWritePtr++; _VtxCurrentIdx++; }
    inline    void  PrimWriteIdx(ImDrawIdx idx)                                 { *_IdxWritePtr = idx; _IdxWritePtr++; }
    inline    void  PrimVtx(const ImVec2& pos, const ImVec2& uv, ImU32 col)     { PrimWriteIdx((ImDrawIdx)_VtxCurrentIdx); PrimWriteVtx(pos, uv, col); }
    IMGUI_API void  UpdateClipRect();
    IMGUI_API void  UpdateTextureID();
};