caca_get_dither_contrast(3) - Linux man page
Name
libcaca bitmap dithering -
Functions
- __extern caca_dither_t * caca_create_dither (int, int, int, int, uint32_t, uint32_t, uint32_t, uint32_t)
- Create an internal dither object.
- __extern int caca_set_dither_palette (caca_dither_t *, uint32_t r[], uint32_t g[], uint32_t b[], uint32_t a[])
- Set the palette of an 8bpp dither object.
- __extern int caca_set_dither_brightness (caca_dither_t *, float)
- Set the brightness of a dither object.
- __extern float caca_get_dither_brightness (caca_dither_t const *)
- Get the brightness of a dither object.
- __extern int caca_set_dither_gamma (caca_dither_t *, float)
- Set the gamma of a dither object.
- __extern float caca_get_dither_gamma (caca_dither_t const *)
- Get the gamma of a dither object.
- __extern int caca_set_dither_contrast (caca_dither_t *, float)
- Set the contrast of a dither object.
- __extern float caca_get_dither_contrast (caca_dither_t const *)
- Get the contrast of a dither object.
- __extern int caca_set_dither_antialias (caca_dither_t *, char const *)
- Set dither antialiasing.
- __extern char const *const * caca_get_dither_antialias_list (caca_dither_t const *)
- Get available antialiasing methods.
- __extern char const * caca_get_dither_antialias (caca_dither_t const *)
- Get current antialiasing method.
- __extern int caca_set_dither_color (caca_dither_t *, char const *)
- Choose colours used for dithering.
- __extern char const *const * caca_get_dither_color_list (caca_dither_t const *)
- Get available colour modes.
- __extern char const * caca_get_dither_color (caca_dither_t const *)
- Get current colour mode.
- __extern int caca_set_dither_charset (caca_dither_t *, char const *)
- Choose characters used for dithering.
- __extern char const *const * caca_get_dither_charset_list (caca_dither_t const *)
- Get available dither character sets.
- __extern char const * caca_get_dither_charset (caca_dither_t const *)
- Get current character set.
- __extern int caca_set_dither_algorithm (caca_dither_t *, char const *)
- Set dithering algorithm.
- __extern char const *const * caca_get_dither_algorithm_list (caca_dither_t const *)
- Get dithering algorithms.
- __extern char const * caca_get_dither_algorithm (caca_dither_t const *)
- Get current dithering algorithm.
- __extern int caca_dither_bitmap (caca_canvas_t *, int, int, int, int, caca_dither_t const *, void const *)
- Dither a bitmap on the canvas.
- __extern int caca_free_dither (caca_dither_t *)
- Free the memory associated with a dither.
Detailed Description
These functions provide high level routines for dither allocation and rendering.
Function Documentation
__extern caca_dither_t* caca_create_dither (int bpp, int w, int h, int pitch, uint32_t rmask, uint32_t gmask, uint32_t bmask, uint32_t amask)
- Create a dither structure from its coordinates (depth, width, height and pitch) and pixel mask values. If the depth is 8 bits per pixel, the mask values are
ignored and the colour palette should be set using the caca_set_dither_palette() function. For depths greater than 8 bits per pixel, a zero alpha mask
causes the alpha values to be ignored.
If an error occurs, NULL is returned and errno is set accordingly:
- • EINVAL Requested width, height, pitch or bits per pixel value was invalid.
• ENOMEM Not enough memory to allocate dither structure.
- Parameters:
- • EINVAL Requested width, height, pitch or bits per pixel value was invalid.
- bpp Bitmap depth in bits per pixel.
w Bitmap width in pixels.
h Bitmap height in pixels.
pitch Bitmap pitch in bytes.
rmask Bitmask for red values.
gmask Bitmask for green values.
bmask Bitmask for blue values.
amask Bitmask for alpha values. - Returns:
- Dither object upon success, NULL if an error occurred.
__extern int caca_set_dither_palette (caca_dither_t * d, uint32_t red[], uint32_t green[], uint32_t blue[], uint32_t alpha[])
- Set the palette of an 8 bits per pixel bitmap. Values should be between 0 and 4095 (0xfff).
If an error occurs, -1 is returned and errno is set accordingly:
- • EINVAL Dither bits per pixel value is not 8, or one of the pixel values was outside the range 0 - 4095.
- Parameters:
- • EINVAL Dither bits per pixel value is not 8, or one of the pixel values was outside the range 0 - 4095.
- d Dither object.
red Array of 256 red values.
green Array of 256 green values.
blue Array of 256 blue values.
alpha Array of 256 alpha values. - Returns:
- 0 in case of success, -1 if an error occurred.
__extern int caca_set_dither_brightness (caca_dither_t * d, float brightness)
- Set the brightness of dither.
If an error occurs, -1 is returned and errno is set accordingly:
- • EINVAL Brightness value was out of range.
- Parameters:
- • EINVAL Brightness value was out of range.
- d Dither object.
brightness brightness value. - Returns:
- 0 in case of success, -1 if an error occurred.
__extern float caca_get_dither_brightness (caca_dither_t const * d)
- Get the brightness of the given dither object.
This function never fails.
Parameters:
- d Dither object.
- Returns:
- Brightness value.
__extern int caca_set_dither_gamma (caca_dither_t * d, float gamma)
- Set the gamma of the given dither object. A negative value causes colour inversion.
If an error occurs, -1 is returned and errno is set accordingly:
- • EINVAL Gamma value was out of range.
- Parameters:
- • EINVAL Gamma value was out of range.
- d Dither object.
gamma Gamma value. - Returns:
- 0 in case of success, -1 if an error occurred.
__extern float caca_get_dither_gamma (caca_dither_t const * d)
- Get the gamma of the given dither object.
This function never fails.
Parameters:
- d Dither object.
- Returns:
- Gamma value.
__extern int caca_set_dither_contrast (caca_dither_t * d, float contrast)
- Set the contrast of dither.
If an error occurs, -1 is returned and errno is set accordingly:
- • EINVAL Contrast value was out of range.
- Parameters:
- • EINVAL Contrast value was out of range.
- d Dither object.
contrast contrast value. - Returns:
- 0 in case of success, -1 if an error occurred.
__extern float caca_get_dither_contrast (caca_dither_t const * d)
- Get the contrast of the given dither object.
This function never fails.
Parameters:
- d Dither object.
- Returns:
- Contrast value.
__extern int caca_set_dither_antialias (caca_dither_t * d, char const * str)
- Tell the renderer whether to antialias the dither. Antialiasing smoothens the rendered image and avoids the commonly seen staircase effect.
- • "none": no antialiasing.
• "prefilter" or "default": simple prefilter antialiasing. This is the default value.
- If an error occurs, -1 is returned and errno is set accordingly:
- • EINVAL Invalid antialiasing mode.
- Parameters:
- • "none": no antialiasing.
- d Dither object.
str A string describing the antialiasing method that will be used for the dithering. - Returns:
- 0 in case of success, -1 if an error occurred.
__extern char const* const* caca_get_dither_antialias_list (caca_dither_t const * d)
- Return a list of available antialiasing methods for a given dither. The list is a NULL-terminated array of strings, interleaving a string containing the
internal value for the antialiasing method to be used with caca_set_dither_antialias(), and a string containing the natural language description for
that antialiasing method.
This function never fails.
Parameters:
- d Dither object.
- Returns:
- An array of strings.
__extern char const* caca_get_dither_antialias (caca_dither_t const * d)
- Return the given dither's current antialiasing method.
This function never fails.
Parameters:
- d Dither object.
- Returns:
- A static string.
__extern int caca_set_dither_color (caca_dither_t * d, char const * str)
- Tell the renderer which colours should be used to render the bitmap. Valid values for str are:
- • "mono": use light gray on a black background.
• "gray": use white and two shades of gray on a black background.
• "8": use the 8 ANSI colours on a black background.
• "16": use the 16 ANSI colours on a black background.
• "fullgray": use black, white and two shades of gray for both the characters and the background.
• "full8": use the 8 ANSI colours for both the characters and the background.
• "full16" or "default": use the 16 ANSI colours for both the characters and the background. This is the default value.
- If an error occurs, -1 is returned and errno is set accordingly:
- • EINVAL Invalid colour set.
- Parameters:
- • "mono": use light gray on a black background.
- d Dither object.
str A string describing the colour set that will be used for the dithering. - Returns:
- 0 in case of success, -1 if an error occurred.
__extern char const* const* caca_get_dither_color_list (caca_dither_t const * d)
- Return a list of available colour modes for a given dither. The list is a NULL-terminated array of strings, interleaving a string containing the internal value for the colour mode, to be used with