Add a TRIVIAL layer-mode flag, and corresponding
gimp_layer_mode_is_trivial() function, which indicates if the blend
function of a given layer mode is trivial, i.e., either never
modifies the source pixels (for non-subtractive modes), or always
clears the destination pixels (for subtractive modes).
(cherry picked from commit 8adec5fb3a)
... which determines if a layer mode's blend function only affects
the alpha, maintaining the backdrop's color. This is currently
true only for ERASE, SPLIT, and ANTI_ERASE modes.
Commit 3635cf04ab moved the special
handling of bottom-layer compositing to GimpOperationLayerMode.
This required giving the op more control over the process()
function of its subclasses. As a temporary workaround, the commit
bypassed the subclasses entirely, using "gimp:layer-mode" for all
modes. This is the reckoning :)
Add a process() virtual function to GimpOperationLayerMode, which
its subclasses should override instead of
GeglOperationPointComposer3's process() functions. Reinstate the
subclasses (by returning the correct op in
gimp_layer_mode_get_oepration()), and have them override this
function.
Improve the way gimp_operation_layer_mode_process() dispatches to
the actual process function, to slightly lower its overhead and
fix some thread-safety issues.
Remove the "function" field of the layer-mode info array, and have
gimp_layer_mode_get_function() return the
GimpOperationLayerMode::process() function of the corresponding
op's class (caching the result, to keep it cheap.) This reduces
redundancy, allows us to make the ops' process() functions private,
and simplifies SSE dispatching (only used by NORMAL mode,
currently.)
Move the blend and composite functions of the non-specialized
layer modes to gimpoperationlayermode-{blend,composite}.[hc],
respectively, to improve code organization.
Move the SSE2 composite functions to a separate file, so that they
can be built as part of libapplayermodes_sse2, allowing
libapplayermodes to be built without SSE2 compiler flags. This
allows building GIMP with SSE acceleration enabled, while running
the resulting binary on a target with no SSE accelration.
Add a "blend_function" field to the layer-mode info array, and use
it to specify the blend function for the non-specialized modes.
This replaces the separate switch() statement that we used
previously.
Remove the "affected_region" field of the layer-mode info array.
We don't need it anymore, since we can go back to using
GimpOperationLayerMode's virtual get_affected_region() function.
Last but not least, a bunch of code cleanups and consistency
adjustments.
GimpFilter's is_last_node field only reflects the item's position
within the parent stack. When a layer is contained in a pass-
through group, it can be the last layer of the group, while not
being the last layer in the graph as a whole (paticularly, if
there are visible layers below the group). In fact, when we have
nested pass-through groups, whether or not a layer is the last
node depends on which group we're considering as the root (since
we exclude the backdrop from the group's projection, resulting in
different graphs for different groups).
Instead of rolling our own graph traversal, just move the relevant
logic to GimpOperationLayerMode, and let GEGL do the work for us.
At processing time, we can tell if we're the last node by checking
if we have any input.
For this to work, GimpOperationLayerMode's process() function needs
to have control over what's going on. Replace the derived op
classes, which override process(), with a call to the layer mode's
function (as per gimp_layer_mode_get_function()) in
GimpOperationLayerMode's process() function. (Well, actually, this
commit keeps the ops around, and just hacks around them in
gimp_layer_mode_get_operation(), because laziness :P)
Keep using the layer's is_last_node property to do the invalidation.
Takes a layer mode and a composite mode, and returns the region
included in the composition.
Use this function in GimpOperationLayerMode, instead of testing
for specific composite modes directly. Will also be used by
the next commit.
Indentation cleanup in gimp_layer_modes.h
Most modes only modify the *color* of overlapping dest/src regions,
however, erase and color-erase may also reduce their *alpha*, i.e.,
eliminate some of the overlapping content. Flag these modes with
the new SUBTRACTIVE flag, as they require more general compositing
code. The next commit adds the said code.
which returns an array of modes in the order they would appear in a
GimpLayerModeContext's UI (like tool options or the layers dialog),
without the separators.
Use it in context-commands.c and layers-commands.c instead of static
(and outdated) arrays for the actions that cycle through modes.
Instead, add a gimp_layer_mode_get_format() function, which takes
the layer mode, composite space, and blend space, and returns the
I/O format.
Currently, we always use the composite space format as the I/O
format. This simplifies gimp_composite_blend(), and gives us
composite-space support for the "special" layer mode ops for free.
A bitmask, specifying in which contexts a layer mode is applicable.
Can be a combination of:
- LAYER: usable as a layer mode for actual layers.
- GROUP: usable as a layer mode for layer groups. Currently, all
modes that specify LAYER also specify GROUP, and vice versa,
but the planned pass-through mode will be GROUP only.
- PAINT: can be used as a paint mode.
- FADE: can be used for fading.
Add a 'context' field to _GimpLayerModeInfo, and provide context
masks to all the modes.
Use the context mask for validation when setting a layer's mode.
The next commit will use the mask when populating the layer mode
menus.
Add a "paint_composite_mode" field to GimpLayerModeInfo and set the
mode of the eraser to SRC_ATOP. Defaulting to SRC_OVER for all
painting didn't quite do it for all modes.
set all legacy modes to completely immutable and the LAB modes'
blend mode to immutable. Change GimpLayer setters and the UI
accordingly. Remove the LAB color spaces from the GUI, they can
only be used with the LAB blend modes anyway and not changed.
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().
