src/nvim/grid_defs.h


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#ifndef NVIM_GRID_DEFS_H
#define NVIM_GRID_DEFS_H

#include <stdint.h>

#include "nvim/types.h"

#define MAX_MCO  6  // maximum value for 'maxcombine'

// The characters and attributes drawn on grids.
typedef char_u schar_T[(MAX_MCO+1) * 4 + 1];
typedef int16_t sattr_T;

/// ScreenGrid represents a resizable rectuangular grid displayed by UI clients.
///
/// ScreenLines contains the UTF-8 text that is currently displayed on the grid.
/// It is stored as a single block of cells. When redrawing a part of the grid,
/// the new state can be compared with the existing state of the grid. This way
/// we can avoid sending bigger updates than neccessary to the Ul layer.
///
/// Screen cells are stored as NUL-terminated UTF-8 strings, and a cell can
/// contain up to MAX_MCO composing characters after the base character.
/// The composing characters are to be drawn on top of the original character.
/// The content after the NUL is not defined (so comparison must be done a
/// single cell at a time). Double-width characters are stored in the left cell,
/// and the right cell should only contain the empty string. When a part of the
/// screen is cleared, the cells should be filled with a single whitespace char.
///
/// ScreenAttrs[] contains the highlighting attribute for each cell.
/// LineOffset[n] is the offset from ScreenLines[] and ScreenAttrs[] for the
/// start of line 'n'. These offsets are in general not linear, as full screen
/// scrolling is implemented by rotating the offsets in the LineOffset array.
/// LineWraps[] is an array of boolean flags indicating if the screen line wraps
/// to the next line. It can only be true if a window occupies the entire screen
/// width.
typedef struct {
  handle_T handle;

  schar_T  *ScreenLines;
  sattr_T  *ScreenAttrs;
  unsigned *LineOffset;
  char_u   *LineWraps;

  // the size of the allocated grid
  int Rows;
  int Columns;

  // offsets for the grid relative to the global screen
  int OffsetRow;
  int OffsetColumn;

  // the size expected to be allocated to the internal grid
  int internal_rows;
  int internal_columns;

  int was_resized;
} ScreenGrid;

#endif  // NVIM_GRID_DEFS_H