nick black



notcurses_plane - operations on ncplanes


#include <notcurses/notcurses.h>


typedef struct ncplane_options {
  int y;            // vertical placement relative to parent plane
  int x;            // horizontal placement relative to parent plane
  int rows;         // number of rows, must be positive
  int cols;         // number of columns, must be positive
  void* userptr;    // user curry, may be NULL
  const char* name; // name (used only for debugging), may be NULL
  int (*resizecb)(struct ncplane*); // called on parent resize
  uint64_t flags;   // closure over NCPLANE_OPTION_*
  int margin_b, margin_r; // bottom and right margins
} ncplane_options;

struct ncplane* ncplane_create(struct ncplane* n, const ncplane_options* nopts);

struct ncplane* ncpile_create(struct notcurses* n, const ncplane_options* nopts);

struct ncplane* notcurses_top(struct notcurses* n);

struct ncplane* notcurses_bottom(struct notcurses* n);

struct ncplane* ncpile_top(struct ncplane* n);

struct ncplane* ncpile_bottom(struct ncplane* n);

struct ncplane* ncplane_reparent(struct ncplane* n, struct ncplane* newparent);

struct ncplane* ncplane_reparent_family(struct ncplane* n, struct ncplane* newparent);

int ncplane_descendant_p(const struct ncplane* n, const struct ncplane* ancestor);

int ncplane_resize_realign(struct ncplane* n);

int ncplane_resize_maximize(struct ncplane* n);

int ncplane_resize_marginalized(struct ncplane* n);

void ncplane_set_resizecb(struct ncplane* n, int(resizecb)(struct ncplane));

int (ncplane_resizecb(const struct ncplane n**))(struct ncplane*);**

struct ncplane* ncplane_dup(struct ncplane* n, void* opaque);

int ncplane_resize(struct ncplane* n, int keepy, int keepx, int keepleny, int keeplenx, int yoff, int xoff, int ylen, int xlen);

int ncplane_move_yx(struct ncplane* n, int y, int x);

void ncplane_yx(const struct ncplane* n, int* restrict y, int* restrict x);

int ncplane_y(const struct ncplane* n);

int ncplane_x(const struct ncplane* n);

void ncplane_abs_yx(const struct ncplane* n, int* y, int* x);

int ncplane_abs_y(const struct ncplane* n);

int ncplane_abs_x(const struct ncplane* n);

struct ncplane* ncplane_parent(struct ncplane* n);

const struct ncplane* ncplane_parent_const(const struct ncplane* n);

int ncplane_set_base_cell(struct ncplane* ncp, const nccell* c);

int ncplane_set_base(struct ncplane* ncp, const char* egc, uint32_t stylemask, uint64_t channels);

int ncplane_base(struct ncplane* ncp, nccell* c);

int ncplane_move_top(struct ncplane* n);

int ncplane_move_bottom(struct ncplane* n);

int ncplane_move_above(struct ncplane* restrict n, struct ncplane* restrict above);

int ncplane_move_below(struct ncplane* restrict n, struct ncplane* restrict below);

struct ncplane* ncplane_below(struct ncplane* n);

struct ncplane* ncplane_above(struct ncplane* n);

char* ncplane_at_cursor(struct ncplane* n, uint16_t* stylemask, uint64_t* channels);

int ncplane_at_cursor_cell(struct ncplane* n, nccell* c);

char* ncplane_at_yx(const struct ncplane* n, int y, int x, uint16_t* stylemask, uint64_t* channels);

int ncplane_at_yx_cell(struct ncplane* n, int y, int x, nccell* c);

uint32_t* ncplane_as_rgba(const struct ncplane* nc, int begy, int begx, int leny, int lenx, int* pxdimy, int* pxdimx);

char* ncplane_contents(const struct ncplane* nc, int begy, int begx, int leny, int lenx);

void* ncplane_set_userptr(struct ncplane* n, void* opaque);

void* ncplane_userptr(struct ncplane* n);

void ncplane_dim_yx(const struct ncplane* n, int* restrict rows, int* restrict cols);

static inline int ncplane_dim_y(const struct ncplane* n);

static inline int ncplane_dim_x(const struct ncplane* n);

void ncplane_cursor_yx(const struct ncplane* n, int* restrict y, int* restrict x);

void ncplane_translate(const struct ncplane* src, const struct ncplane* dst, int* restrict y, int* restrict x);

bool ncplane_translate_abs(const struct ncplane* n, int* restrict y, int* restrict x);

uint64_t ncplane_channels(const struct ncplane* n);

void ncplane_set_channels(struct ncplane* nc, uint64_t channels);

static inline unsigned ncplane_bchannel(struct ncplane* nc);

static inline unsigned ncplane_fchannel(struct ncplane* nc);

static inline unsigned ncplane_fg_rgb8(struct ncplane* nc);

static inline unsigned ncplane_bg_rgb8(struct ncplane* nc);

static inline unsigned ncplane_fg_alpha(struct ncplane* nc);

static inline unsigned ncplane_bg_alpha(struct ncplane* nc);

static inline unsigned ncplane_fg_rgb8(struct ncplane* n, unsigned* r, unsigned* g, unsigned* b);

static inline unsigned ncplane_bg_rgb8(struct ncplane* n, unsigned* r, unsigned* g, unsigned* b);

int ncplane_set_fg_rgb8(struct ncplane* n, int r, int g, int b);

int ncplane_set_bg_rgb8(struct ncplane* n, int r, int g, int b);

void ncplane_set_fg_rgb8_clipped(struct ncplane* n, int r, int g, int b);

void ncplane_set_bg_rgb8_clipped(struct ncplane* n, int r, int g, int b);

int ncplane_set_fg_rgb8(struct ncplane* n, uint32_t channel);

int ncplane_set_bg_rgb8(struct ncplane* n, uint32_t channel);

void ncplane_set_fg_default(struct ncplane* n);

void ncplane_set_bg_default(struct ncplane* n);

int ncplane_set_fg_alpha(struct ncplane* n, unsigned alpha);

int ncplane_set_bg_alpha(struct ncplane* n, unsigned alpha);

int ncplane_set_fg_palindex(struct ncplane* n, int idx);

int ncplane_set_bg_palindex(struct ncplane* n, int idx);

uint16_t ncplane_styles(const struct ncplane* n);

void ncplane_set_styles(struct ncplane* n, unsigned stylebits);

void ncplane_on_styles(struct ncplane* n, unsigned stylebits);

void ncplane_off_styles(struct ncplane* n, unsigned stylebits);

void ncplane_greyscale(struct ncplane* n);

int ncplane_blit_bgrx(struct ncplane* nc, int placey, int placex, int linesize, ncblitter_e blitter, const unsigned char* data, int begy, int begx, int leny, int lenx);

int ncplane_blit_rgba(struct ncplane* nc, int placey, int placex, int linesize, ncblitter_e blitter, const unsigned char* data, int begy, int begx, int leny, int lenx);

int ncplane_destroy(struct ncplane* ncp);

void notcurses_drop_planes(struct notcurses* nc);

int ncplane_mergedown(struct ncplane* src, struct ncplane* dst, int begsrcy, int begsrcx, int leny, int lenx, int dsty, int dstx);

int ncplane_mergedown_simple(struct ncplane* restrict src, struct ncplane* restrict dst);

void ncplane_erase(struct ncplane* n);

int ncplane_erase_region(struct ncplane* n, int ystart, int xstart, int ylen, int xlen);

bool ncplane_set_scrolling(struct ncplane* n, bool scrollp);

int ncplane_rotate_cw(struct ncplane* n);

int ncplane_rotate_ccw(struct ncplane* n);

void ncplane_pixelgeom(struct notcurses* n, int* restrict pxy, int* restrict pxx, int* restrict celldimy, int* restrict celldimx, int* restrict maxbmapy, int* restrict maxbmapx);


Ncplanes are the fundamental drawing object of notcurses. All output functions take a struct ncplane as an argument. They can be any size, and placed anywhere. In addition to its framebuffer--a rectilinear matrix of nccells (see notcurses_cell(3))--an ncplane is defined by:

New planes can be created with ncplane_create. If a plane is bound to another, x and y coordinates are relative to the plane to which it is bound, and if this latter plane moves, all its bound planes move along with it. When a plane is destroyed, all planes bound to it (directly or transitively) are destroyed.

If the NCPLANE_OPTION_HORALIGNED flag is provided, x is interpreted as an ncalign_e rather than an absolute position. If the NCPLANE_OPTION_VERALIGNED flag is provided, y is interpreted as an ncalign_e rather than an absolute postiion. Either way, all positions are relative to the parent plane. ncplane_resize_realign should usually be used together with these flags, so that the plane is automatically realigned upon a resize of its parent.

If the NCPLANE_OPTION_MARGINALIZED flag is provided, neither NCPLANE_OPTION_HORALIGNED nor NCPLANE_OPTION_VERALIGNED may be provided, and rows and cols must both be 0. y and x will be interpreted as top and left margins. margin_b and margin_r will be interpreted as bottom and right margins. The plane will take the maximum space possible subject to its parent planes and these margins. The plane cannot become smaller than 1x1 (the margins are best-effort). ncplane_resize_marginalized should usually be used together with this flag, so that the plane is automatically resized.

ncplane_reparent detaches the plane n from any plane to which it is bound, and binds it to newparent. Its children are reparented to its previous parent. The standard plane cannot be reparented. If newparent is NULL, the plane becomes the root plane of a new, unrendered stack. When ncplane_reparent_family is used, all planes bound to n move along with it during a reparenting operation. See Piles below.

ncplane_destroy destroys a particular ncplane, after which it must not be used again. notcurses_drop_planes destroys all ncplanes other than the stdplane. Any references to such planes are, of course, invalidated. It is undefined to destroy a plane concurrently with any other operation involving that plane, or any operation involving the z-axis.

It is an error for two threads to concurrently mutate a single ncplane. So long as rendering is not taking place, however, multiple threads may safely output to multiple ncplanes. So long as all threads are readers, multiple threads may work with a single ncplane. A reading function is any which accepts a const struct ncplane.

ncplane_yx returns the coordinates of the specified plane's origin, relative to the plane to which it is bound. Either or both of y and x may be NULL. ncplane_y and ncplane_x allow a single component of this location to be retrieved. ncplane_abs_yx returns the coordinates of the specified plane's origin relative to its pile.

ncplane_translate translates coordinates expressed relative to the plane src, and writes the coordinates of that cell relative to dst. The cell need not intersect with dst, though this will yield coordinates which are invalid for writing or reading on dst. If dst is NULL, it is taken to refer to the standard plane. ncplane_translate_abs takes coordinates expressed relative to the standard plane, and returns coordinates relative to dst, returning false if the coordinates are invalid for dst.

ncplane_mergedown writes to dst the frame that would be rendered if only src and dst existed on the z-axis, ad dst represented the entirety of the rendering region. Only those cells where src intersects with dst might see changes. It is an error to merge a plane onto itself.

ncplane_erase zeroes out every cell of the plane, dumps the egcpool, and homes the cursor. The base cell is preserved, as are the active attributes. ncplane_erase_region does the same for a subregion of the plane. For the latter, supply 0 for ylen and/or xlen to erase through that dimension, starting at the specified point.

When a plane is resized (whether by ncplane_resize, SIGWINCH, or any other mechanism), a depth-first recursion is performed on its children. Each child plane having a non-NULL resizecb will see that callback invoked following resizing of its parent's plane. If it returns non-zero, the resizing cascade terminates, returning non-zero. Otherwise, resizing proceeds recursively.

Base cells

Each plane has a base cell, initialized to all zeroes. When rendering, the cells of the plane are examined in turn. Each cell has three independent rendering elements--its EGC, its foreground channel, and its background channel. Any default channel is replaced with the corresponding channel from that plane's base cell. ncplane_erase has no effect on the base cell. Calling ncplane_erase on a plane whose base cell is a purple 'A' results (for rendering purposes) in a plane made up entirely of purple 'A's.

ncplane_set_base_cell uses the nccell c (which must be bound to the ncplane ncp, and must be the first nccell of a multicolumn sequence) to set the base cell. ncplane_set_base does the same with egc, stylemask, and channels.


A single notcurses context is made up of one or more piles. A pile is a set of one or more ncplanes, including the partial orderings made up of their binding and z-axis pointers. A pile has a top and bottom ncplane (this might be a single plane), and one or more root planes (planes which are bound to themselves). Multiple threads can concurrently operate on distinct piles, even changing one while rendering another.

Each plane is part of one and only one pile. By default, a plane is part of the same pile containing that plane to which it is bound. If ncpile_create is used in the place of ncplane_create, the returned plane becomes the root plane, top, and bottom of a new pile. As a root plane, it is bound to itself. A new pile can also be created by reparenting a plane to itself, though if the plane is already a root plane, this is a no-op.

When a plane is moved to a different pile (whether new or preexisting), any planes which were bound to it are rebound to its previous parent. If the plane was a root plane of some pile, any bound planes become root planes. The new plane is placed immediately atop its new parent on its new pile's z-axis. When ncplane_reparent_family() is used, all planes bound to the reparented plane are moved along with it. Their relative z-order is maintained.


All planes, including the standard plane, are created with scrolling disabled. Control scrolling on a per-plane basis with ncplane_set_scrolling. Attempting to print past the end of a line will stop at the plane boundary, and indicate an error. On a plane 10 columns wide and two rows high, printing "0123456789" at the origin should succeed, but printing "01234567890" will by default fail at the eleventh character. In either case, the cursor will be left at location 0x10; it must be moved before further printing can take place. If scrolling is enabled, the first row will be filled with 01234546789, the second row will have 0 written to its first column, and the cursor will end up at 1x1. Note that it is still an error to manually attempt to move the cursor off-plane, or to specify off-plane output. Boxes do not scroll; attempting to draw a 2x11 box on our 2x10 plane will result in an error and no output. When scrolling is enabled, and output takes place while the cursor is past the end of the last row, the first row is discarded, all other rows are moved up, the last row is cleared, and output begins at the beginning of the last row. This does not take place until output is generated (i.e. it is possible to fill a plane when scrolling is enabled).


ncplane_pixelgeom retrieves pixel geometry details. pxy and pxx return the size of the plane in pixels. celldimy and celldimx return the size of a cell in pixels (these ought be the same across planes). maxbmapy and maxbmapx describe the largest bitmap which can be displayed in the plane. This function transitively calls notcurses_check_pixel_support, possibly leading to terminal interrogation (see notcurses_capabilities(3) for why this may be undesirable). Any parameter (save n) may be NULL.

When a plane is blitted to using ncvisual_render and NCBLIT_PIXEL (see notcurses_visual(3)), it ceases to accept cell-based output. The sprixel will remain associated until a new sprixel is blitted to the plane, the plane is resized, the plane is erased, or the plane is destroyed. The base cell of a sprixelated plane has no effect; if the sprixel is not even multiples of the cell geometry, the "excess plane" is ignored during rendering.

ncplane_at_yx and ncplane_at_yx_cell retrieve the contents of the plane at the specified coordinate. The content is returned as it will be used during rendering, and thus integrates any base cell as appropriate. If called on the secondary columns of a wide glyph, ncplane_at_yx returns the EGC, and thus cannot be used to distinguish between primary and secondary columns. ncplane_at_yx_cell, however, preserves this information: retrieving a secondary column of a wide glyph with ncplane_at_yx_cell will fill in the nccell argument such that nccell_extended_gcluster(3) returns an empty string, and nccell_wide_right_p(3) returns true.


ncplane_create and ncplane_dup return a new struct ncplane on success, or NULL on failure.

ncplane_userptr returns the configured user pointer for the ncplane, and cannot fail.

ncplane_below returns the plane below the specified ncplane. If the provided plane is the bottommost plane, NULL is returned. It cannot fail.

ncplane_set_scrolling returns true if scrolling was previously enabled, and false otherwise.

ncpile_top and ncpile_bottom return the topmost and bottommost planes, respectively, of the pile containing their argument. notcurses_top and notcurses_bottom do the same for the standard pile.

ncplane_at_yx and ncplane_at_cursor return a heap-allocated copy of the EGC at the relevant cell, or NULL if the cell is invalid. The caller should free this result. ncplane_at_yx_cell and ncplane_at_cursor_cell instead load these values into an nccell, which is invalidated if the associated plane is destroyed. The caller should release this nccell with nccell_release.

ncplane_as_rgba returns a heap-allocated array of uint32_t values, each representing a single RGBA pixel, or NULL on failure.

ncplane_erase_region returns -1 if any of its parameters are negative, or if they specify any area beyond the plane.

Functions returning int return 0 on success, and non-zero on error.

All other functions cannot fail (and return void).


ncplane_new is defined as a deprecated wrapper around ncplane_create. It should not be used in new code.


ncplane_at_yx doesn't yet account for bitmap-based graphics (see notcurses_visual). Whatever glyph-based contents existed on the plane when the bitmap was blitted will continue to be returned.


notcurses(3), notcurses_capabilities(3), notcurses_cell(3), notcurses_output(3), notcurses_stdplane(3), notcurses_visual(3)