caca_attributes(3) 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(), caca_dither_bitmap(), caca_flush_figlet(), and caca_put_figchar().

__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(), and caca_put_figchar().

__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.

Referenced by caca_flush_figlet(), and caca_put_figchar().

__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, -1 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().

Author

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