libcaca documentation

libcaca attribute conversions

Functions

__extern uint32_t caca_get_attr (caca_canvas_t const *, int, int)
 Get the text attribute at the given coordinates.
__extern int caca_set_attr (caca_canvas_t *, uint32_t)
 Set the default character attribute.
__extern int caca_unset_attr (caca_canvas_t *, uint32_t)
 Unset flags in the default character attribute.
__extern int caca_toggle_attr (caca_canvas_t *, uint32_t)
 Toggle flags in the default character attribute.
__extern int caca_put_attr (caca_canvas_t *, int, int, uint32_t)
 Set the character attribute at the given coordinates.
__extern int caca_set_color_ansi (caca_canvas_t *, uint8_t, uint8_t)
 Set the default colour pair for text (ANSI version).
__extern int caca_set_color_argb (caca_canvas_t *, uint16_t, uint16_t)
 Set the default colour pair for text (truecolor version).
__extern uint8_t caca_attr_to_ansi (uint32_t)
 Get DOS ANSI information from attribute.
__extern uint8_t caca_attr_to_ansi_fg (uint32_t)
 Get ANSI foreground information from attribute.
__extern uint8_t caca_attr_to_ansi_bg (uint32_t)
 Get ANSI background information from attribute.
__extern uint16_t caca_attr_to_rgb12_fg (uint32_t)
 Get 12-bit RGB foreground information from attribute.
__extern uint16_t caca_attr_to_rgb12_bg (uint32_t)
 Get 12-bit RGB background information from attribute.
__extern void caca_attr_to_argb64 (uint32_t, uint8_t[8])
 Get 64-bit ARGB information from attribute.

Detailed Description

These functions perform conversions between attribute values.

Function Documentation

__extern uint32_t caca_get_attr ( caca_canvas_t const *  cv,
int  x,
int  y 
)

Get the internal libcaca attribute value of the character at the given coordinates. The attribute value has 32 significant bits, organised as follows from MSB to LSB:

  • 3 bits for the background alpha
  • 4 bits for the background red component
  • 4 bits for the background green component
  • 3 bits for the background blue component
  • 3 bits for the foreground alpha
  • 4 bits for the foreground red component
  • 4 bits for the foreground green component
  • 3 bits for the foreground blue component
  • 4 bits for the bold, italics, underline and blink flags

If the coordinates are outside the canvas boundaries, the current attribute is returned.

This function never fails.

Parameters:
cv A handle to the libcaca canvas.
x X coordinate.
y Y coordinate.
Returns:
The requested attribute.

Referenced by caca_conio_textbackground(), caca_conio_textcolor(), and caca_dither_bitmap().

__extern int caca_set_attr ( caca_canvas_t *  cv,
uint32_t  attr 
)

Set the default character attribute for drawing. Attributes define foreground and background colour, transparency, bold, italics and underline styles, as well as blink. String functions such as caca_printf() and graphical primitive functions such as caca_draw_line() will use this attribute.

The value of attr is either:

  • a 32-bit integer as returned by caca_get_attr(), in which case it also contains colour information,
  • a combination (bitwise OR) of style values (CACA_UNDERLINE, CACA_BLINK, CACA_BOLD and CACA_ITALICS), in which case setting the attribute does not modify the current colour information.

To retrieve the current attribute value, use caca_get_attr(-1,-1).

This function never fails.

Parameters:
cv A handle to the libcaca canvas.
attr The requested attribute value.
Returns:
This function always returns 0.

Referenced by caca_dither_bitmap().

__extern int caca_unset_attr ( caca_canvas_t *  cv,
uint32_t  attr 
)

Unset flags in the default character attribute for drawing. Attributes define foreground and background colour, transparency, bold, italics and underline styles, as well as blink. String functions such as caca_printf() and graphical primitive functions such as caca_draw_line() will use this attribute.

The value of attr is a combination (bitwise OR) of style values (CACA_UNDERLINE, CACA_BLINK, CACA_BOLD and CACA_ITALICS). Unsetting these attributes does not modify the current colour information.

To retrieve the current attribute value, use caca_get_attr(-1,-1).

This function never fails.

Parameters:
cv A handle to the libcaca canvas.
attr The requested attribute values to unset.
Returns:
This function always returns 0.
__extern int caca_toggle_attr ( caca_canvas_t *  cv,
uint32_t  attr 
)

Toggle flags in the default character attribute for drawing. Attributes define foreground and background colour, transparency, bold, italics and underline styles, as well as blink. String functions such as caca_printf() and graphical primitive functions such as caca_draw_line() will use this attribute.

The value of attr is a combination (bitwise OR) of style values (CACA_UNDERLINE, CACA_BLINK, CACA_BOLD and CACA_ITALICS). Toggling these attributes does not modify the current colour information.

To retrieve the current attribute value, use caca_get_attr(-1,-1).

This function never fails.

Parameters:
cv A handle to the libcaca canvas.
attr The requested attribute values to toggle.
Returns:
This function always returns 0.
__extern int caca_put_attr ( caca_canvas_t *  cv,
int  x,
int  y,
uint32_t  attr 
)

Set the character attribute, without changing the character's value. If the character at the given coordinates is a fullwidth character, both cells' attributes are replaced.

The value of attr is either:

  • a 32-bit integer as returned by caca_get_attr(), in which case it also contains colour information,
  • a combination (bitwise OR) of style values (CACA_UNDERLINE, CACA_BLINK, CACA_BOLD and CACA_ITALICS), in which case setting the attribute does not modify the current colour information.

This function never fails.

Parameters:
cv A handle to the libcaca canvas.
x X coordinate.
y Y coordinate.
attr The requested attribute value.
Returns:
This function always returns 0.

References caca_add_dirty_rect(), and CACA_MAGIC_FULLWIDTH.

__extern int caca_set_color_ansi ( caca_canvas_t *  cv,
uint8_t  fg,
uint8_t  bg 
)

Set the default ANSI colour pair for text drawing. String functions such as caca_printf() and graphical primitive functions such as caca_draw_line() will use these attributes.

Color values are those defined in caca.h, such as CACA_RED or CACA_TRANSPARENT.

If an error occurs, 0 is returned and errno is set accordingly:

  • EINVAL At least one of the colour values is invalid.
Parameters:
cv A handle to the libcaca canvas.
fg The requested ANSI foreground colour.
bg The requested ANSI background colour.
Returns:
0 in case of success, -1 if an error occurred.

Referenced by caca_conio_textbackground(), caca_conio_textcolor(), caca_create_canvas(), and caca_dither_bitmap().

__extern int caca_set_color_argb ( caca_canvas_t *  cv,
uint16_t  fg,
uint16_t  bg 
)

Set the default ARGB colour pair for text drawing. String functions such as caca_printf() and graphical primitive functions such as caca_draw_line() will use these attributes.

Colors are 16-bit ARGB values, each component being coded on 4 bits. For instance, 0xf088 is solid dark cyan (A=15 R=0 G=8 B=8), and 0x8fff is white with 50% alpha (A=8 R=15 G=15 B=15).

This function never fails.

Parameters:
cv A handle to the libcaca canvas.
fg The requested ARGB foreground colour.
bg The requested ARGB background colour.
Returns:
This function always returns 0.
__extern uint8_t caca_attr_to_ansi ( uint32_t  attr  ) 

Get the ANSI colour pair for a given attribute. The returned value is an 8-bit value whose higher 4 bits are the background colour and lower 4 bits are the foreground colour.

If the attribute has ARGB colours, the nearest colour is used. Special attributes such as CACA_DEFAULT and CACA_TRANSPARENT are not handled and are both replaced with CACA_LIGHTGRAY for the foreground colour and CACA_BLACK for the background colour.

This function never fails. If the attribute value is outside the expected 32-bit range, higher order bits are simply ignored.

Parameters:
attr The requested attribute value.
Returns:
The corresponding DOS ANSI value.

References CACA_BLACK, and CACA_LIGHTGRAY.

__extern uint8_t caca_attr_to_ansi_fg ( uint32_t  attr  ) 

Get the ANSI foreground colour value for a given attribute. The returned value is either one of the CACA_RED, CACA_BLACK etc. predefined colours, or the special value CACA_DEFAULT meaning the media's default foreground value, or the special value CACA_TRANSPARENT.

If the attribute has ARGB colours, the nearest colour is returned.

This function never fails. If the attribute value is outside the expected 32-bit range, higher order bits are simply ignored.

Parameters:
attr The requested attribute value.
Returns:
The corresponding ANSI foreground value.

Referenced by caca_conio_textbackground().

__extern uint8_t caca_attr_to_ansi_bg ( uint32_t  attr  ) 

Get the ANSI background colour value for a given attribute. The returned value is either one of the CACA_RED, CACA_BLACK etc. predefined colours, or the special value CACA_DEFAULT meaning the media's default background value, or the special value CACA_TRANSPARENT.

If the attribute has ARGB colours, the nearest colour is returned.

This function never fails. If the attribute value is outside the expected 32-bit range, higher order bits are simply ignored.

Parameters:
attr The requested attribute value.
Returns:
The corresponding ANSI background value.

Referenced by caca_conio_textcolor().

__extern uint16_t caca_attr_to_rgb12_fg ( uint32_t  attr  ) 

Get the 12-bit foreground colour value for a given attribute. The returned value is a native-endian encoded integer with each red, green and blue values encoded on 8 bits in the following order:

  • 8-11 most significant bits: red
  • 4-7 most significant bits: green
  • least significant bits: blue

This function never fails. If the attribute value is outside the expected 32-bit range, higher order bits are simply ignored.

Parameters:
attr The requested attribute value.
Returns:
The corresponding 12-bit RGB foreground value.

References CACA_DEFAULT, CACA_LIGHTGRAY, and CACA_TRANSPARENT.

__extern uint16_t caca_attr_to_rgb12_bg ( uint32_t  attr  ) 

Get the 12-bit background colour value for a given attribute. The returned value is a native-endian encoded integer with each red, green and blue values encoded on 8 bits in the following order:

  • 8-11 most significant bits: red
  • 4-7 most significant bits: green
  • least significant bits: blue

This function never fails. If the attribute value is outside the expected 32-bit range, higher order bits are simply ignored.

Parameters:
attr The requested attribute value.
Returns:
The corresponding 12-bit RGB background value.

References CACA_BLACK, CACA_DEFAULT, and CACA_TRANSPARENT.

__extern void caca_attr_to_argb64 ( uint32_t  attr,
uint8_t  argb[8] 
)

Get the 64-bit colour and alpha values for a given attribute. The values are written as 8-bit integers in the argb array in the following order:

  • argb[0]: background alpha value
  • argb[1]: background red value
  • argb[2]: background green value
  • argb[3]: background blue value
  • argb[4]: foreground alpha value
  • argb[5]: foreground red value
  • argb[6]: foreground green value
  • argb[7]: foreground blue value

This function never fails. If the attribute value is outside the expected 32-bit range, higher order bits are simply ignored.

Parameters:
attr The requested attribute value.
argb An array of 8-bit integers.

References CACA_BLACK, CACA_DEFAULT, CACA_LIGHTGRAY, and CACA_TRANSPARENT.

Referenced by caca_render_canvas().