// [DEAR IMGUI]

// This is a slightly modified version of stb_textedit.h 1.14.

// Those changes would need to be pushed into nothings/stb:

// - Fix in stb_textedit_discard_redo (see https://github.com/nothings/stb/issues/321)

// - Fix in stb_textedit_find_charpos to handle last line (see https://github.com/ocornut/imgui/issues/6000 + #6783)

// - Added name to struct or it may be forward declared in our code.

// - Added UTF-8 support (see https://github.com/nothings/stb/issues/188 + https://github.com/ocornut/imgui/pull/7925)

// Grep for [DEAR IMGUI] to find the changes.

// - Also renamed macros used or defined outside of IMSTB_TEXTEDIT_IMPLEMENTATION block from STB_TEXTEDIT_* to IMSTB_TEXTEDIT_*

// stb_textedit.h - v1.14  - public domain - Sean Barrett

// Development of this library was sponsored by RAD Game Tools

//

// This C header file implements the guts of a multi-line text-editing

// widget; you implement display, word-wrapping, and low-level string

// insertion/deletion, and stb_textedit will map user inputs into

// insertions & deletions, plus updates to the cursor position,

// selection state, and undo state.

//

// It is intended for use in games and other systems that need to build

// their own custom widgets and which do not have heavy text-editing

// requirements (this library is not recommended for use for editing large

// texts, as its performance does not scale and it has limited undo).

//

// Non-trivial behaviors are modelled after Windows text controls.

//

//

// LICENSE

//

// See end of file for license information.

//

//

// DEPENDENCIES

//

// Uses the C runtime function 'memmove', which you can override

// by defining IMSTB_TEXTEDIT_memmove before the implementation.

// Uses no other functions. Performs no runtime allocations.

//

//

// VERSION HISTORY

//

//   1.14 (2021-07-11) page up/down, various fixes

//   1.13 (2019-02-07) fix bug in undo size management

//   1.12 (2018-01-29) user can change STB_TEXTEDIT_KEYTYPE, fix redo to avoid crash

//   1.11 (2017-03-03) fix HOME on last line, dragging off single-line textfield

//   1.10 (2016-10-25) suppress warnings about casting away const with -Wcast-qual

//   1.9  (2016-08-27) customizable move-by-word

//   1.8  (2016-04-02) better keyboard handling when mouse button is down

//   1.7  (2015-09-13) change y range handling in case baseline is non-0

//   1.6  (2015-04-15) allow STB_TEXTEDIT_memmove

//   1.5  (2014-09-10) add support for secondary keys for OS X

//   1.4  (2014-08-17) fix signed/unsigned warnings

//   1.3  (2014-06-19) fix mouse clicking to round to nearest char boundary

//   1.2  (2014-05-27) fix some RAD types that had crept into the new code

//   1.1  (2013-12-15) move-by-word (requires STB_TEXTEDIT_IS_SPACE )

//   1.0  (2012-07-26) improve documentation, initial public release

//   0.3  (2012-02-24) bugfixes, single-line mode; insert mode

//   0.2  (2011-11-28) fixes to undo/redo

//   0.1  (2010-07-08) initial version

//

// ADDITIONAL CONTRIBUTORS

//

//   Ulf Winklemann: move-by-word in 1.1

//   Fabian Giesen: secondary key inputs in 1.5

//   Martins Mozeiko: STB_TEXTEDIT_memmove in 1.6

//   Louis Schnellbach: page up/down in 1.14

//

//   Bugfixes:

//      Scott Graham

//      Daniel Keller

//      Omar Cornut

//      Dan Thompson

//

// USAGE

//

// This file behaves differently depending on what symbols you define

// before including it.

//

//

// Header-file mode:

//

//   If you do not define STB_TEXTEDIT_IMPLEMENTATION before including this,

//   it will operate in "header file" mode. In this mode, it declares a

//   single public symbol, STB_TexteditState, which encapsulates the current

//   state of a text widget (except for the string, which you will store

//   separately).

//

//   To compile in this mode, you must define STB_TEXTEDIT_CHARTYPE to a

//   primitive type that defines a single character (e.g. char, wchar_t, etc).

//

//   To save space or increase undo-ability, you can optionally define the

//   following things that are used by the undo system:

//

//      STB_TEXTEDIT_POSITIONTYPE         small int type encoding a valid cursor position

//      STB_TEXTEDIT_UNDOSTATECOUNT       the number of undo states to allow

//      STB_TEXTEDIT_UNDOCHARCOUNT        the number of characters to store in the undo buffer

//

//   If you don't define these, they are set to permissive types and

//   moderate sizes. The undo system does no memory allocations, so

//   it grows STB_TexteditState by the worst-case storage which is (in bytes):

//

//        [4 + 3 * sizeof(STB_TEXTEDIT_POSITIONTYPE)] * STB_TEXTEDIT_UNDOSTATECOUNT

//      +          sizeof(STB_TEXTEDIT_CHARTYPE)      * STB_TEXTEDIT_UNDOCHARCOUNT

//

//

// Implementation mode:

//

//   If you define STB_TEXTEDIT_IMPLEMENTATION before including this, it

//   will compile the implementation of the text edit widget, depending

//   on a large number of symbols which must be defined before the include.

//

//   The implementation is defined only as static functions. You will then

//   need to provide your own APIs in the same file which will access the

//   static functions.

//

//   The basic concept is that you provide a "string" object which

//   behaves like an array of characters. stb_textedit uses indices to

//   refer to positions in the string, implicitly representing positions

//   in the displayed textedit. This is true for both plain text and

//   rich text; even with rich text stb_truetype interacts with your

//   code as if there was an array of all the displayed characters.

//

// Symbols that must be the same in header-file and implementation mode:

//

//     STB_TEXTEDIT_CHARTYPE             the character type

//     STB_TEXTEDIT_POSITIONTYPE         small type that is a valid cursor position

//     STB_TEXTEDIT_UNDOSTATECOUNT       the number of undo states to allow

//     STB_TEXTEDIT_UNDOCHARCOUNT        the number of characters to store in the undo buffer

//

// Symbols you must define for implementation mode:

//

//    STB_TEXTEDIT_STRING               the type of object representing a string being edited,

//                                      typically this is a wrapper object with other data you need

//

//    STB_TEXTEDIT_STRINGLEN(obj)       the length of the string (ideally O(1))

//    STB_TEXTEDIT_LAYOUTROW(&r,obj,n)  returns the results of laying out a line of characters

//                                        starting from character #n (see discussion below)

//    STB_TEXTEDIT_GETWIDTH(obj,n,i)    returns the pixel delta from the xpos of the i'th character

//                                        to the xpos of the i+1'th char for a line of characters

//                                        starting at character #n (i.e. accounts for kerning

//                                        with previous char)

//    STB_TEXTEDIT_KEYTOTEXT(k)         maps a keyboard input to an insertable character

//                                        (return type is int, -1 means not valid to insert)

//    STB_TEXTEDIT_GETCHAR(obj,i)       returns the i'th character of obj, 0-based

//    STB_TEXTEDIT_NEWLINE              the character returned by _GETCHAR() we recognize

//                                        as manually wordwrapping for end-of-line positioning

//

//    STB_TEXTEDIT_DELETECHARS(obj,i,n)      delete n characters starting at i

//    STB_TEXTEDIT_INSERTCHARS(obj,i,c*,n)   insert n characters at i (pointed to by STB_TEXTEDIT_CHARTYPE*)

//

//    STB_TEXTEDIT_K_SHIFT       a power of two that is or'd in to a keyboard input to represent the shift key

//

//    STB_TEXTEDIT_K_LEFT        keyboard input to move cursor left

//    STB_TEXTEDIT_K_RIGHT       keyboard input to move cursor right

//    STB_TEXTEDIT_K_UP          keyboard input to move cursor up

//    STB_TEXTEDIT_K_DOWN        keyboard input to move cursor down

//    STB_TEXTEDIT_K_PGUP        keyboard input to move cursor up a page

//    STB_TEXTEDIT_K_PGDOWN      keyboard input to move cursor down a page

//    STB_TEXTEDIT_K_LINESTART   keyboard input to move cursor to start of line  // e.g. HOME

//    STB_TEXTEDIT_K_LINEEND     keyboard input to move cursor to end of line    // e.g. END

//    STB_TEXTEDIT_K_TEXTSTART   keyboard input to move cursor to start of text  // e.g. ctrl-HOME

//    STB_TEXTEDIT_K_TEXTEND     keyboard input to move cursor to end of text    // e.g. ctrl-END

//    STB_TEXTEDIT_K_DELETE      keyboard input to delete selection or character under cursor

//    STB_TEXTEDIT_K_BACKSPACE   keyboard input to delete selection or character left of cursor

//    STB_TEXTEDIT_K_UNDO        keyboard input to perform undo

//    STB_TEXTEDIT_K_REDO        keyboard input to perform redo

//

// Optional:

//    STB_TEXTEDIT_K_INSERT              keyboard input to toggle insert mode

//    STB_TEXTEDIT_IS_SPACE(ch)          true if character is whitespace (e.g. 'isspace'),

//                                          required for default WORDLEFT/WORDRIGHT handlers

//    STB_TEXTEDIT_MOVEWORDLEFT(obj,i)   custom handler for WORDLEFT, returns index to move cursor to

//    STB_TEXTEDIT_MOVEWORDRIGHT(obj,i)  custom handler for WORDRIGHT, returns index to move cursor to

//    STB_TEXTEDIT_K_WORDLEFT            keyboard input to move cursor left one word // e.g. ctrl-LEFT

//    STB_TEXTEDIT_K_WORDRIGHT           keyboard input to move cursor right one word // e.g. ctrl-RIGHT

//    STB_TEXTEDIT_K_LINESTART2          secondary keyboard input to move cursor to start of line

//    STB_TEXTEDIT_K_LINEEND2            secondary keyboard input to move cursor to end of line

//    STB_TEXTEDIT_K_TEXTSTART2          secondary keyboard input to move cursor to start of text

//    STB_TEXTEDIT_K_TEXTEND2            secondary keyboard input to move cursor to end of text

//

// Keyboard input must be encoded as a single integer value; e.g. a character code

// and some bitflags that represent shift states. to simplify the interface, SHIFT must

// be a bitflag, so we can test the shifted state of cursor movements to allow selection,

// i.e. (STB_TEXTEDIT_K_RIGHT|STB_TEXTEDIT_K_SHIFT) should be shifted right-arrow.

//

// You can encode other things, such as CONTROL or ALT, in additional bits, and

// then test for their presence in e.g. STB_TEXTEDIT_K_WORDLEFT. For example,

// my Windows implementations add an additional CONTROL bit, and an additional KEYDOWN

// bit. Then all of the STB_TEXTEDIT_K_ values bitwise-or in the KEYDOWN bit,

// and I pass both WM_KEYDOWN and WM_CHAR events to the "key" function in the

// API below. The control keys will only match WM_KEYDOWN events because of the

// keydown bit I add, and STB_TEXTEDIT_KEYTOTEXT only tests for the KEYDOWN

// bit so it only decodes WM_CHAR events.

//

// STB_TEXTEDIT_LAYOUTROW returns information about the shape of one displayed

// row of characters assuming they start on the i'th character--the width and

// the height and the number of characters consumed. This allows this library

// to traverse the entire layout incrementally. You need to compute word-wrapping

// here.

//

// Each textfield keeps its own insert mode state, which is not how normal

// applications work. To keep an app-wide insert mode, update/copy the

// "insert_mode" field of STB_TexteditState before/after calling API functions.

//

// API

//

//    void stb_textedit_initialize_state(STB_TexteditState *state, int is_single_line)

//

//    void stb_textedit_click(STB_TEXTEDIT_STRING *str, STB_TexteditState *state, float x, float y)

//    void stb_textedit_drag(STB_TEXTEDIT_STRING *str, STB_TexteditState *state, float x, float y)

//    int  stb_textedit_cut(STB_TEXTEDIT_STRING *str, STB_TexteditState *state)

//    int  stb_textedit_paste(STB_TEXTEDIT_STRING *str, STB_TexteditState *state, STB_TEXTEDIT_CHARTYPE *text, int len)

//    void stb_textedit_key(STB_TEXTEDIT_STRING *str, STB_TexteditState *state, STB_TEXEDIT_KEYTYPE key)

//    void stb_textedit_text(STB_TEXTEDIT_STRING *str, STB_TexteditState *state, STB_TEXTEDIT_CHARTYPE *text, int text_len)

//

//    Each of these functions potentially updates the string and updates the

//    state.

//

//      initialize_state:

//          set the textedit state to a known good default state when initially

//          constructing the textedit.

//

//      click:

//          call this with the mouse x,y on a mouse down; it will update the cursor

//          and reset the selection start/end to the cursor point. the x,y must

//          be relative to the text widget, with (0,0) being the top left.

//

//      drag:

//          call this with the mouse x,y on a mouse drag/up; it will update the

//          cursor and the selection end point

//

//      cut:

//          call this to delete the current selection; returns true if there was

//          one. you should FIRST copy the current selection to the system paste buffer.

//          (To copy, just copy the current selection out of the string yourself.)

//

//      paste:

//          call this to paste text at the current cursor point or over the current

//          selection if there is one.

//

//      key:

//          call this for keyboard inputs sent to the textfield. you can use it

//          for "key down" events or for "translated" key events. if you need to

//          do both (as in Win32), or distinguish Unicode characters from control

//          inputs, set a high bit to distinguish the two; then you can define the

//          various definitions like STB_TEXTEDIT_K_LEFT have the is-key-event bit

//          set, and make STB_TEXTEDIT_KEYTOCHAR check that the is-key-event bit is

//          clear. STB_TEXTEDIT_KEYTYPE defaults to int, but you can #define it to

//          anything other type you want before including.

//          if the STB_TEXTEDIT_KEYTOTEXT function is defined, selected keys are

//          transformed into text and stb_textedit_text() is automatically called.

//

//      text: [DEAR IMGUI] added 2024-09

//          call this to text inputs sent to the textfield.

//

//

//   When rendering, you can read the cursor position and selection state from

//   the STB_TexteditState.

//

//

// Notes:

//

// This is designed to be usable in IMGUI, so it allows for the possibility of

// running in an IMGUI that has NOT cached the multi-line layout. For this

// reason, it provides an interface that is compatible with computing the

// layout incrementally--we try to make sure we make as few passes through

// as possible. (For example, to locate the mouse pointer in the text, we

// could define functions that return the X and Y positions of characters

// and binary search Y and then X, but if we're doing dynamic layout this

// will run the layout algorithm many times, so instead we manually search

// forward in one pass. Similar logic applies to e.g. up-arrow and

// down-arrow movement.)

//

// If it's run in a widget that *has* cached the layout, then this is less

// efficient, but it's not horrible on modern computers. But you wouldn't

// want to edit million-line files with it.

////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////

////

////   Header-file mode

////

////

#ifndef INCLUDE_IMSTB_TEXTEDIT_H

#define INCLUDE_IMSTB_TEXTEDIT_H

////////////////////////////////////////////////////////////////////////

//

//     STB_TexteditState

//

// Definition of STB_TexteditState which you should store

// per-textfield; it includes cursor position, selection state,

// and undo state.

//

#ifndef IMSTB_TEXTEDIT_UNDOSTATECOUNT

#define IMSTB_TEXTEDIT_UNDOSTATECOUNT   99

#endif

#ifndef IMSTB_TEXTEDIT_UNDOCHARCOUNT

#define IMSTB_TEXTEDIT_UNDOCHARCOUNT   999

#endif

#ifndef IMSTB_TEXTEDIT_CHARTYPE

#define IMSTB_TEXTEDIT_CHARTYPE        int

#endif

#ifndef IMSTB_TEXTEDIT_POSITIONTYPE

#define IMSTB_TEXTEDIT_POSITIONTYPE    int

#endif

typedef struct

{

   // private data

   IMSTB_TEXTEDIT_POSITIONTYPE  where;

   IMSTB_TEXTEDIT_POSITIONTYPE  insert_length;

   IMSTB_TEXTEDIT_POSITIONTYPE  delete_length;

   int                        char_storage;

} StbUndoRecord;

typedef struct

{

   // private data

   StbUndoRecord          undo_rec [IMSTB_TEXTEDIT_UNDOSTATECOUNT];

   IMSTB_TEXTEDIT_CHARTYPE  undo_char[IMSTB_TEXTEDIT_UNDOCHARCOUNT];

   short undo_point, redo_point;

   int undo_char_point, redo_char_point;

} StbUndoState;

typedef struct STB_TexteditState

{

   /////////////////////

   //

   // public data

   //

   int cursor;

   // position of the text cursor within the string

   int select_start;          // selection start point

   int select_end;

   // selection start and end point in characters; if equal, no selection.

   // note that start may be less than or greater than end (e.g. when

   // dragging the mouse, start is where the initial click was, and you

   // can drag in either direction)

   unsigned char insert_mode;

   // each textfield keeps its own insert mode state. to keep an app-wide

   // insert mode, copy this value in/out of the app state

   int row_count_per_page;

   // page size in number of row.

   // this value MUST be set to >0 for pageup or pagedown in multilines documents.

   /////////////////////

   //

   // private data

   //

   unsigned char cursor_at_end_of_line; // not implemented yet

   unsigned char initialized;

   unsigned char has_preferred_x;

   unsigned char single_line;

   unsigned char padding1, padding2, padding3;

   float preferred_x; // this determines where the cursor up/down tries to seek to along x

   StbUndoState undostate;

} STB_TexteditState;

////////////////////////////////////////////////////////////////////////

//

//     StbTexteditRow

//

// Result of layout query, used by stb_textedit to determine where

// the text in each row is.

// result of layout query

typedef struct

{

   float x0,x1;             // starting x location, end x location (allows for align=right, etc)

   float baseline_y_delta;  // position of baseline relative to previous row's baseline

   float ymin,ymax;         // height of row above and below baseline

   int num_chars;

} StbTexteditRow;

#endif //INCLUDE_IMSTB_TEXTEDIT_H

////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////

////

////   Implementation mode

////

////

// implementation isn't include-guarded, since it might have indirectly

// included just the "header" portion

#ifdef IMSTB_TEXTEDIT_IMPLEMENTATION

#ifndef IMSTB_TEXTEDIT_memmove

#include <string.h>

#define IMSTB_TEXTEDIT_memmove memmove

#endif

/////////////////////////////////////////////////////////////////////////////

//

//      Mouse input handling

//

// traverse the layout to locate the nearest character to a display position

static int stb_text_locate_coord(IMSTB_TEXTEDIT_STRING *str, float x, float y)

{

   StbTexteditRow r;

   int n = STB_TEXTEDIT_STRINGLEN(str);

   float base_y = 0, prev_x;

   int i=0, k;

   r.x0 = r.x1 = 0;

   r.ymin = r.ymax = 0;

   r.num_chars = 0;

   // search rows to find one that straddles 'y'

   while (i < n) {

      STB_TEXTEDIT_LAYOUTROW(&r, str, i);

      if (r.num_chars <= 0)

         return n;

      if (i==0 && y < base_y + r.ymin)

         return 0;

      if (y < base_y + r.ymax)

         break;

      i += r.num_chars;

      base_y += r.baseline_y_delta;

   }

   // below all text, return 'after' last character

   if (i >= n)

      return n;

   // check if it's before the beginning of the line

   if (x < r.x0)

      return i;

   // check if it's before the end of the line

   if (x < r.x1) {

      // search characters in row for one that straddles 'x'

      prev_x = r.x0;

      for (k=0; k < r.num_chars; k = IMSTB_TEXTEDIT_GETNEXTCHARINDEX(str, i + k) - i) {

         float w = STB_TEXTEDIT_GETWIDTH(str, i, k);

         if (x < prev_x+w) {

            if (x < prev_x+w/2)

               return k+i;

            else

               return IMSTB_TEXTEDIT_GETNEXTCHARINDEX(str, i + k);

         }

         prev_x += w;

      }

      // shouldn't happen, but if it does, fall through to end-of-line case

   }

   // if the last character is a newline, return that. otherwise return 'after' the last character

   if (STB_TEXTEDIT_GETCHAR(str, i+r.num_chars-1) == STB_TEXTEDIT_NEWLINE)

      return i+r.num_chars-1;

   else

      return i+r.num_chars;

}

// API click: on mouse down, move the cursor to the clicked location, and reset the selection

static void stb_textedit_click(IMSTB_TEXTEDIT_STRING *str, STB_TexteditState *state, float x, float y)

{

   // In single-line mode, just always make y = 0. This lets the drag keep working if the mouse

   // goes off the top or bottom of the text

   if( state->single_line )

   {

      StbTexteditRow r;

      STB_TEXTEDIT_LAYOUTROW(&r, str, 0);

      y = r.ymin;

   }

   state->cursor = stb_text_locate_coord(str, x, y);

   state->select_start = state->cursor;

   state->select_end = state->cursor;

   state->has_preferred_x = 0;

}

// API drag: on mouse drag, move the cursor and selection endpoint to the clicked location

static void stb_textedit_drag(IMSTB_TEXTEDIT_STRING *str, STB_TexteditState *state, float x, float y)

{

   int p = 0;

   // In single-line mode, just always make y = 0. This lets the drag keep working if the mouse

   // goes off the top or bottom of the text

   if( state->single_line )

   {

      StbTexteditRow r;

      STB_TEXTEDIT_LAYOUTROW(&r, str, 0);

      y = r.ymin;

   }

   if (state->select_start == state->select_end)

      state->select_start = state->cursor;

   p = stb_text_locate_coord(str, x, y);

   state->cursor = state->select_end = p;

}

/////////////////////////////////////////////////////////////////////////////

//

//      Keyboard input handling

//

// forward declarations

static void stb_text_undo(IMSTB_TEXTEDIT_STRING *str, STB_TexteditState *state);

static void stb_text_redo(IMSTB_TEXTEDIT_STRING *str, STB_TexteditState *state);

static void stb_text_makeundo_delete(IMSTB_TEXTEDIT_STRING *str, STB_TexteditState *state, int where, int length);

static void stb_text_makeundo_insert(STB_TexteditState *state, int where, int length);

static void stb_text_makeundo_replace(IMSTB_TEXTEDIT_STRING *str, STB_TexteditState *state, int where, int old_length, int new_length);

typedef struct

{

   float x,y;    // position of n'th character

   float height; // height of line

   int first_char, length; // first char of row, and length

   int prev_first;  // first char of previous row

} StbFindState;

// find the x/y location of a character, and remember info about the previous row in

// case we get a move-up event (for page up, we'll have to rescan)

static void stb_textedit_find_charpos(StbFindState *find, IMSTB_TEXTEDIT_STRING *str, int n, int single_line)

{

   StbTexteditRow r;

   int prev_start = 0;

   int z = STB_TEXTEDIT_STRINGLEN(str);

   int i=0, first;

   if (n == z && single_line) {

      // special case if it's at the end (may not be needed?)

      STB_TEXTEDIT_LAYOUTROW(&r, str, 0);

      find->y = 0;

      find->first_char = 0;

      find->length = z;

      find->height = r.ymax - r.ymin;

      find->x = r.x1;

      return;

   }

   // search rows to find the one that straddles character n

   find->y = 0;

   for(;;) {

      STB_TEXTEDIT_LAYOUTROW(&r, str, i);

      if (n < i + r.num_chars)

         break;

      if (i + r.num_chars == z && z > 0 && STB_TEXTEDIT_GETCHAR(str, z - 1) != STB_TEXTEDIT_NEWLINE)  // [DEAR IMGUI] special handling for last line

         break;   // [DEAR IMGUI]

      prev_start = i;

      i += r.num_chars;

      find->y += r.baseline_y_delta;

      if (i == z) // [DEAR IMGUI]

      {

         r.num_chars = 0; // [DEAR IMGUI]

         break;   // [DEAR IMGUI]

      }

   }

   find->first_char = first = i;

   find->length = r.num_chars;

   find->height = r.ymax - r.ymin;

   find->prev_first = prev_start;

   // now scan to find xpos

   find->x = r.x0;

   for (i=0; first+i < n; i = IMSTB_TEXTEDIT_GETNEXTCHARINDEX(str, first + i) - first)

      find->x += STB_TEXTEDIT_GETWIDTH(str, first, i);

}

#define STB_TEXT_HAS_SELECTION(s)   ((s)->select_start != (s)->select_end)

// make the selection/cursor state valid if client altered the string

static void stb_textedit_clamp(IMSTB_TEXTEDIT_STRING *str, STB_TexteditState *state)

{

   int n = STB_TEXTEDIT_STRINGLEN(str);

   if (STB_TEXT_HAS_SELECTION(state)) {

      if (state->select_start > n) state->select_start = n;

      if (state->select_end   > n) state->select_end = n;

      // if clamping forced them to be equal, move the cursor to match

      if (state->select_start == state->select_end)

         state->cursor = state->select_start;

   }

   if (state->cursor > n) state->cursor = n;

}

// delete characters while updating undo

static void stb_textedit_delete(IMSTB_TEXTEDIT_STRING *str, STB_TexteditState *state, int where, int len)

{

   stb_text_makeundo_delete(str, state, where, len);

   STB_TEXTEDIT_DELETECHARS(str, where, len);

   state->has_preferred_x = 0;

}

// delete the section

static void stb_textedit_delete_selection(IMSTB_TEXTEDIT_STRING *str, STB_TexteditState *state)

{

   stb_textedit_clamp(str, state);

   if (STB_TEXT_HAS_SELECTION(state)) {

      if (state->select_start < state->select_end) {

         stb_textedit_delete(str, state, state->select_start, state->select_end - state->select_start);

         state->select_end = state->cursor = state->select_start;

      } else {

         stb_textedit_delete(str, state, state->select_end, state->select_start - state->select_end);

         state->select_start = state->cursor = state->select_end;

      }

      state->has_preferred_x = 0;

   }

}

// canoncialize the selection so start <= end

static void stb_textedit_sortselection(STB_TexteditState *state)

{

   if (state->select_end < state->select_start) {

      int temp = state->select_end;

      state->select_end = state->select_start;

      state->select_start = temp;

   }

}

// move cursor to first character of selection

static void stb_textedit_move_to_first(STB_TexteditState *state)

{

   if (STB_TEXT_HAS_SELECTION(state)) {

      stb_textedit_sortselection(state);

      state->cursor = state->select_start;

      state->select_end = state->select_start;

      state->has_preferred_x = 0;

   }

}

// move cursor to last character of selection

static void stb_textedit_move_to_last(IMSTB_TEXTEDIT_STRING *str, STB_TexteditState *state)

{

   if (STB_TEXT_HAS_SELECTION(state)) {

      stb_textedit_sortselection(state);

      stb_textedit_clamp(str, state);

      state->cursor = state->select_end;

      state->select_start = state->select_end;

      state->has_preferred_x = 0;

   }

}

// [DEAR IMGUI]

// Functions must be implemented for UTF8 support

// Code in this file that uses those functions is modified for [DEAR IMGUI] and deviates from the original stb_textedit.

// There is not necessarily a '[DEAR IMGUI]' at the usage sites.

#ifndef IMSTB_TEXTEDIT_GETPREVCHARINDEX

#define IMSTB_TEXTEDIT_GETPREVCHARINDEX(obj, idx) (idx - 1)

#endif

#ifndef IMSTB_TEXTEDIT_GETNEXTCHARINDEX

#define IMSTB_TEXTEDIT_GETNEXTCHARINDEX(obj, idx) (idx + 1)

#endif

#ifdef STB_TEXTEDIT_IS_SPACE

static int is_word_boundary( IMSTB_TEXTEDIT_STRING *str, int idx )

{

   return idx > 0 ? (STB_TEXTEDIT_IS_SPACE( STB_TEXTEDIT_GETCHAR(str,idx-1) ) && !STB_TEXTEDIT_IS_SPACE( STB_TEXTEDIT_GETCHAR(str, idx) ) ) : 1;

}

#ifndef STB_TEXTEDIT_MOVEWORDLEFT

static int stb_textedit_move_to_word_previous( IMSTB_TEXTEDIT_STRING *str, int c )

{

   --c; // always move at least one character

   while( c >= 0 && !is_word_boundary( str, c ) )

      --c;

   if( c < 0 )

      c = 0;

   return c;

}

#define STB_TEXTEDIT_MOVEWORDLEFT stb_textedit_move_to_word_previous

#endif

#ifndef STB_TEXTEDIT_MOVEWORDRIGHT

static int stb_textedit_move_to_word_next( IMSTB_TEXTEDIT_STRING *str, int c )

{

   const int len = STB_TEXTEDIT_STRINGLEN(str);

   ++c; // always move at least one character

   while( c < len && !is_word_boundary( str, c ) )

      ++c;

   if( c > len )

      c = len;

   return c;

}

#define STB_TEXTEDIT_MOVEWORDRIGHT stb_textedit_move_to_word_next

#endif

#endif

// update selection and cursor to match each other

static void stb_textedit_prep_selection_at_cursor(STB_TexteditState *state)

{

   if (!STB_TEXT_HAS_SELECTION(state))

      state->select_start = state->select_end = state->cursor;

   else

      state->cursor = state->select_end;

}

// API cut: delete selection

static int stb_textedit_cut(IMSTB_TEXTEDIT_STRING *str, STB_TexteditState *state)

{

   if (STB_TEXT_HAS_SELECTION(state)) {

      stb_textedit_delete_selection(str,state); // implicitly clamps

      state->has_preferred_x = 0;

      return 1;

   }

   return 0;

}

// API paste: replace existing selection with passed-in text

static int stb_textedit_paste_internal(IMSTB_TEXTEDIT_STRING *str, STB_TexteditState *state, IMSTB_TEXTEDIT_CHARTYPE *text, int len)

{

   // if there's a selection, the paste should delete it

   stb_textedit_clamp(str, state);

   stb_textedit_delete_selection(str,state);

   // try to insert the characters

   if (STB_TEXTEDIT_INSERTCHARS(str, state->cursor, text, len)) {

      stb_text_makeundo_insert(state, state->cursor, len);

      state->cursor += len;

      state->has_preferred_x = 0;

      return 1;

   }

   // note: paste failure will leave deleted selection, may be restored with an undo (see https://github.com/nothings/stb/issues/734 for details)

   return 0;

}

#ifndef STB_TEXTEDIT_KEYTYPE

#define STB_TEXTEDIT_KEYTYPE int

#endif

// [DEAR IMGUI] Added stb_textedit_text(), extracted out and called by stb_textedit_key() for backward compatibility.

static void stb_textedit_text(IMSTB_TEXTEDIT_STRING* str, STB_TexteditState* state, const IMSTB_TEXTEDIT_CHARTYPE* text, int text_len)

{

   // can't add newline in single-line mode

   if (text[0] == '\n' && state->single_line)

      return;

   if (state->insert_mode && !STB_TEXT_HAS_SELECTION(state) && state->cursor < STB_TEXTEDIT_STRINGLEN(str)) {

      stb_text_makeundo_replace(str, state, state->cursor, 1, 1);

      STB_TEXTEDIT_DELETECHARS(str, state->cursor, 1);

      if (STB_TEXTEDIT_INSERTCHARS(str, state->cursor, text, text_len)) {

         state->cursor += text_len;

         state->has_preferred_x = 0;

      }

   }

   else {

      stb_textedit_delete_selection(str, state); // implicitly clamps

      if (STB_TEXTEDIT_INSERTCHARS(str, state->cursor, text, text_len)) {

         stb_text_makeundo_insert(state, state->cursor, text_len);

         state->cursor += text_len;

         state->has_preferred_x = 0;

      }

   }

}

// API key: process a keyboard input

static void stb_textedit_key(IMSTB_TEXTEDIT_STRING *str, STB_TexteditState *state, STB_TEXTEDIT_KEYTYPE key)

{

retry:

   switch (key) {

      default: {

#ifdef STB_TEXTEDIT_KEYTOTEXT

         int c = STB_TEXTEDIT_KEYTOTEXT(key);

         if (c > 0) {

            IMSTB_TEXTEDIT_CHARTYPE ch = (IMSTB_TEXTEDIT_CHARTYPE)c;

            stb_textedit_text(str, state, &ch, 1);