When changing the layer-mode group in a GimpLayerModeComboBox, check
the new mode against the combo's context, and fall back to normal if
it's not applicable. This is necessary for the color-erase mode,
which has both a legacy and non-legacy variants. The former is
applicable for painting contexts, so we want to map the non-legacy
mode to it when changing groups, however, it's not applicable for
layer contexts, so, in this case, we want to map the non-legacy mode
to normal.
this commit changes just those which make no difference to
functionality: property and object member defaults that get overridden
anyway, return values of g_return_val_if_fail(), some other stuff.
Replace the 'with-behind' and 'with-replace' properties with a
single 'context' property, and use it to select the included
layer modes, according to their context mask.
Add a dummy GIMP_LAYER_MODE_SEPARATOR value to the GimpLayerMode
enum, and use it to explicitly mark the menu separators in the
layer-mode group arrays; add separators to the layer-mode menu
accordingly.
Update the rest of the code to use 'context' instead of 'with-behind'
and 'with-replace'. In particular, in the layers and layer options
dialogs, select the right context based on whether or not the
selected layer is a group.
and to operations/layer-modes/, respectively.
Add gimp_layer_modes_init() which asserts on the correct order of the
GimpLayerModeInfo array, and switch to accessing the array directly in
gimp_layer_mode_info().
Similar to the Photoshop mode of the same name. Assigns
either 0 or 1 to each of the channels, depending on whether the
sum of source and destination channel values is less than, or
greater than (or equals to), one, respectively.
This is equivalent to inverting the source, and using it to perform
per-pixel, per-channel threshold against the destination, which is
useful for various effects.
