rgb_color: Add new APIs: Contrast(), IsLight(), IsDark()

- Remove perceptual_brightness
- Change implementation of rgb_color::Brightness() to the previous BPrivate::perceptual_brightness()
- Introduce convenience methods Contrast(rgb_color), IsLight() and IsDark()

Change-Id: Id677d4a32ce43d73bffecf9baf8cffaafb01a16d
Reviewed-on: https://review.haiku-os.org/c/haiku/+/7399
Reviewed-by: waddlesplash <waddlesplash@gmail.com>

Tracker: improve algorithm to decide desktop text color

Fixes #16673

* Introduced PaletteConverter::IndexForRGBA32() which checks if the alpha
component of a 32 bit color is below 128 and returns the special CMAP8 index
for indicating transparency.
* Changed the WriteCMAP() color conversion function to expext a 32bit RGBA
value and use IndexForRGBA32().
* Adapted B_CMAP8 target color space case of ConvertBits() to the new
semantics.

This allows transparency in bitmaps when converting B_RGBA32 bitmaps to
B_CMAP8, tested only for this case and working as expected.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@36549 a95241bf-73f2-0310-859d-f6bbb57e9c96

Use pthread_once() to guard the initialization of sPaletteConverter. This
changes the semantics slightly: Previously after a failed initialization
another invocation of InitializeDefault() could theoretically initialize the
converter. Since the only error conditions are out of memory and broken app
server connection, this shouldn't really matter, though.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@34383 a95241bf-73f2-0310-859d-f6bbb57e9c96

* Rewrote BeBuild.h which had "a few" consequences (got rid of all those class
definitions).
* Minor cleanup here and there.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@22577 a95241bf-73f2-0310-859d-f6bbb57e9c96

PaletteConverter now exports a static InitializeDefault() method, which
can be used (and is, by _init_interface_kit()) to initialize the ...
er... default instance of
PaletteConverter using the system color map, thus avoid building the
list of colors, which takes some time. Fixes bug #505.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@22508 a95241bf-73f2-0310-859d-f6bbb57e9c96

* Fixed a swapping bug for 16 bit colorspaces
* Added some comments
* Added some checking to avoid noop shifts
* Added buffer length checks
* Implemented (as Stephan suggested) a version of ConvertBits() that takes offsets.
This new version allows to move a region of the source into a region (possibly not at the same point) on the dest while converting colorspaces on the fly.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@16592 a95241bf-73f2-0310-859d-f6bbb57e9c96

Wrote a new color conversion engine. It's 2-5 times faster than the old one (depending on colorspaces) and about half in size.
I've put it into ColorConversion.cpp and moved PaletteConverter there too, cleaning up Bitmap.cpp.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@16580 a95241bf-73f2-0310-859d-f6bbb57e9c96

* Introduced PaletteConverter::IndexForRGBA32() which checks if the alpha
component of a 32 bit color is below 128 and returns the special CMAP8 index
for indicating transparency.
* Changed the WriteCMAP() color conversion function to expext a 32bit RGBA
value and use IndexForRGBA32().
* Adapted B_CMAP8 target color space case of ConvertBits() to the new
semantics.

This allows transparency in bitmaps when converting B_RGBA32 bitmaps to
B_CMAP8, tested only for this case and working as expected.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@36549 a95241bf-73f2-0310-859d-f6bbb57e9c96

Use pthread_once() to guard the initialization of sPaletteConverter. This
changes the semantics slightly: Previously after a failed initialization
another invocation of InitializeDefault() could theoretically initialize the
converter. Since the only error conditions are out of memory and broken app
server connection, this shouldn't really matter, though.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@34383 a95241bf-73f2-0310-859d-f6bbb57e9c96

* Rewrote BeBuild.h which had "a few" consequences (got rid of all those class
definitions).
* Minor cleanup here and there.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@22577 a95241bf-73f2-0310-859d-f6bbb57e9c96

PaletteConverter now exports a static InitializeDefault() method, which
can be used (and is, by _init_interface_kit()) to initialize the ...
er... default instance of
PaletteConverter using the system color map, thus avoid building the
list of colors, which takes some time. Fixes bug #505.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@22508 a95241bf-73f2-0310-859d-f6bbb57e9c96

* Fixed a swapping bug for 16 bit colorspaces
* Added some comments
* Added some checking to avoid noop shifts
* Added buffer length checks
* Implemented (as Stephan suggested) a version of ConvertBits() that takes offsets.
This new version allows to move a region of the source into a region (possibly not at the same point) on the dest while converting colorspaces on the fly.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@16592 a95241bf-73f2-0310-859d-f6bbb57e9c96

Wrote a new color conversion engine. It's 2-5 times faster than the old one (depending on colorspaces) and about half in size.
I've put it into ColorConversion.cpp and moved PaletteConverter there too, cleaning up Bitmap.cpp.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@16580 a95241bf-73f2-0310-859d-f6bbb57e9c96