caca_create_canvas (3)

NAME

libcaca - libcaca basic functions

Functions

__extern caca_canvas_t * caca_create_canvas (int, int)
Initialise a libcaca canvas.
__extern int caca_manage_canvas (caca_canvas_t *, int(*)(void *), void *)
Manage a canvas.
__extern int caca_unmanage_canvas (caca_canvas_t *, int(*)(void *), void *)
unmanage a canvas.
__extern int caca_set_canvas_size (caca_canvas_t *, int, int)
Resize a canvas.
__extern int caca_get_canvas_width (caca_canvas_t const *)
Get the canvas width.
__extern int caca_get_canvas_height (caca_canvas_t const *)
Get the canvas height.
__extern uint32_t const * caca_get_canvas_chars (caca_canvas_t const *)
Get the canvas character array.
__extern uint32_t const * caca_get_canvas_attrs (caca_canvas_t const *)
Get the canvas attribute array.
__extern int caca_free_canvas (caca_canvas_t *)
Free a libcaca canvas.
__extern int caca_rand (int, int)

__extern char const * caca_get_version (void)
Return the libcaca version.

Detailed Description

These functions provide the basic libcaca routines for library initialisation, system information retrieval and configuration.

Function Documentation

__extern caca_canvas_t* caca_create_canvas (int width, int height)

Initialise internal libcaca structures and the backend that will be used for subsequent graphical operations. It must be the first libcaca function to be called in a function. caca_free_canvas() should be called at the end of the program to free all allocated resources.

Both the cursor and the canvas' handle are initialised at the top-left corner.

If an error occurs, NULL is returned and errno is set accordingly:

*

EINVAL Specified width or height is invalid.

*

ENOMEM Not enough memory for the requested canvas size.

Parameters:

width The desired canvas width
height The desired canvas height

Returns:

A libcaca canvas handle upon success, NULL if an error occurred.

References CACA_DEFAULT, caca_set_color_ansi(), and CACA_TRANSPARENT.

Referenced by caca_conio_movetext(), caca_create_display_with_driver(), caca_export_area_to_memory(), caca_import_area_from_file(), caca_import_area_from_memory(), and caca_set_canvas_boundaries().

__extern int caca_manage_canvas (caca_canvas_t * cv, int(*)(void *) callback, void * p)

Lock a canvas to prevent it from being resized. If non-NULL, the callback function pointer will be called upon each caca_set_canvas_size call and if the returned value is zero, the canvas resize request will be denied.

This function is only useful for display drivers such as the libcaca library.

If an error occurs, -1 is returned and errno is set accordingly:

*

EBUSY The canvas is already being managed.

Parameters:

cv A libcaca canvas.
callback An optional callback function pointer.
p The argument to be passed to callback.

Returns:

0 in case of success, -1 if an error occurred.

Referenced by caca_create_display_with_driver().

__extern int caca_unmanage_canvas (caca_canvas_t * cv, int(*)(void *) callback, void * p)

unlock a canvas previously locked by caca_manage_canvas(). for safety reasons, the callback and callback data arguments must be the same as for the caca_manage_canvas() call.

this function is only useful for display drivers such as the libcaca library.

if an error occurs, -1 is returned and errno is set accordingly:

*

einval the canvas is not managed, or the callback arguments do not match.

Parameters:

cv a libcaca canvas.
callback the callback argument previously passed to caca_manage_canvas().
p the p argument previously passed to caca_manage_canvas().

Returns:

0 in case of success, -1 if an error occurred.

Referenced by caca_create_display_with_driver(), and caca_free_display().

__extern int caca_set_canvas_size (caca_canvas_t * cv, int width, int height)

Set the canvas' width and height, in character cells.

The contents of the canvas are preserved to the extent of the new canvas size. Newly allocated character cells at the right and/or at the bottom of the canvas are filled with spaces.

If as a result of the resize the cursor coordinates fall outside the new canvas boundaries, they are readjusted. For instance, if the current X cursor coordinate is 11 and the requested width is 10, the new X cursor coordinate will be 10.

It is an error to try to resize the canvas if an output driver has been attached to the canvas using caca_create_display(). You need to remove the output driver using caca_free_display() before you can change the canvas size again. However, the caca output driver can cause a canvas resize through user interaction. See the caca_event() documentation for more about this.

If an error occurs, -1 is returned and errno is set accordingly:

*

EINVAL Specified width or height is invalid.

*

EBUSY The canvas is in use by a display driver and cannot be resized.

*

ENOMEM Not enough memory for the requested canvas size. If this happens, the canvas handle becomes invalid and should not be used.

Parameters:

cv A libcaca canvas.
width The desired canvas width.
height The desired canvas height.

Returns:

0 in case of success, -1 if an error occurred.

Referenced by caca_canvas_set_figfont(), caca_flush_figlet(), and caca_put_figchar().

__extern int caca_get_canvas_width (caca_canvas_t const * cv)

Return the current canvas' width, in character cells.

This function never fails.

Parameters:

cv A libcaca canvas.

Returns:

The canvas width.

Referenced by caca_conio_clreol(), caca_conio_movetext(), and caca_get_mouse_x().

__extern int caca_get_canvas_height (caca_canvas_t const * cv)

Returns the current canvas' height, in character cells.

This function never fails.

Parameters:

cv A libcaca canvas.

Returns:

The canvas height.

Referenced by caca_flush_figlet(), and caca_get_mouse_y().

__extern uint32_t const* caca_get_canvas_chars (caca_canvas_t const * cv)

Return the current canvas' internal character array. The array elements consist in native endian 32-bit Unicode values as returned by caca_get_char().

This function is probably only useful for libcaca 's internal display drivers.

This function never fails.

Parameters:

cv A libcaca canvas.

Returns:

The canvas character array.

__extern uint32_t const* caca_get_canvas_attrs (caca_canvas_t const * cv)

Returns the current canvas' internal attribute array. The array elements consist in native endian 32-bit attribute values as returned by caca_get_attr().

This function is probably only useful for libcaca 's internal display drivers.

This function never fails.

Parameters:

cv A libcaca canvas.

Returns:

The canvas attribute array.

__extern int caca_free_canvas (caca_canvas_t * cv)

Free all resources allocated by caca_create_canvas(). The canvas pointer becomes invalid and must no longer be used unless a new call to caca_create_canvas() is made.

If an error occurs, -1 is returned and errno is set accordingly:

*

EBUSY The canvas is in use by a display driver and cannot be freed.

Parameters:

cv A libcaca canvas.

Returns:

0 in case of success, -1 if an error occurred.

References caca_canvas_set_figfont().

Referenced by caca_canvas_set_figfont(), caca_create_display_with_driver(), caca_export_area_to_memory(), caca_free_display(), caca_import_area_from_file(), and caca_import_area_from_memory().

__extern char const* caca_get_version (void)

Return a read-only string with the libcaca version information.

This function never fails.

Returns:

The libcaca version information.

Author

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