Add an n_components parameter to gimp_histogram_clear_values(),
which allows to set the new component count when clearing the
histogram. This is useful to seed the histogram with the correct
number of channels, for display purposes, before starting an async
histogram calculation. We use this in GimpHistogramEditor, to
avoid resetting the view's channel back to "Value" each time the
active drawable changes.
(cherry picked from commit eb6f544c18)
In GimpHistogram, get rid of the "n-channels" property and
corresponding gimp_histogram_n_channels() function. The former
returned the actual number of channels, but this wasn't too useful,
as channel values may not be sequential; the latter returned the
number of components. Instead, add an "n-components" property and
a corresponding gimp_histogram_n_components() function, both of
which return the number of components. Furthermore, add a
gimp_histogram_has_channel() function, which determines if the
histogram has a given channel; this allows for simple testing for
channel availability, which was done wrong in various places.
Adjust the GimpHistogram code for the changes, and clean it up,
fixing a few bugs.
Adjust users of GimpHisotgram for the changes. In particular,
in GimpHisotgramView, fix the channel-availability test when
setting the view's histogram (which happens whenever the active
drawable's preview is frozen), to avoid erroneously swithcing the
view's channel back to "Value" when a non-RGB channel is selected.
(cherry picked from commit fc17f0ed0c)
Change GimpHistogram to take a "gboolean linear" parameter and always
honor that parameter, so both kinds of histograms can now be created
for all drawables.
Add a horrible "Linear" toggle to the histogram dockable which always
defaults to the active layer's actual pixel format, but can be
switched at any time. This UI is ugly and needs to change.
On the PDB, default to gamma-corrected if the plug-in is unaware of
higher precision, and to the drawable's native pixel format otherwise.
Other places using histograms (e.g. levels, curves) are unchanged.
so we can make histograms of the gamma-corrected image data. Pass
TRUE all over the place so the histogram works perceptually. This
needs more thinking...
