... raises a CRITICAL
gimp_item_{start,end}_move() currently serves two different
purposes: It is used by GimpLayer to suspend/resume mask resizing
of the layer's ancestors; this is necessary whenever an operation
on a layer might affect the size of its ancestors. It is also used
by GimpGroupLayer to suspend/resume its own mask resizing; this, on
the other hand, is only necessary before applying one of the
transformation functions to the group, so that mask modification is
handled by GimpLayer. In other words, the effects of
gimp_item_{start,end}_move() on group layers are only necessary in
a subset of the cases in which these functions are used.
While in itself this isn't a problem, it does cause issues when
removing a group layer: gimp_image_remove_layer() calls
gimp_item_start_move() before removing the layer, and
gimp_item_end_move() afterwards. While the former function is
called while the layer is still attached to the image, the latter
function is called after the layer is no longer attached. Since
GimpGroupLayer pushes an undo step in response to these calls, only
the call to start_move() results in an undo step, while the call to
end_move() doesn't, resulting in an unbalanced
GIMP_UNDO_GROUP_LAYER_START_MOVE undo step on the stack. This
causes problems when undoing the operation.
Add gimp_item_{start,end}_transform() functions, and corresponding
GimpItem::{start,end}_transform() virtual functions, which are more
specialized versions of gimp_item_{start,end}_move(), which should
be used instead of the former before/after transforming an item; in
other cases, such as when removing ot reordering an item,
gimp_item_{start,end}_move() should still be used. The default
implementation of GimpItem::{start,end}_transform() calls
gimp_item_{start,end}_move(), respectively, so subclasses that
override these functions don't have to do that themselves.
In GimpGroupLayer, override GimpItem::{start,end}_transform(),
instead of GimpItem::{start,end}_move(), for the same purpose of
suspending mask resize. This avoids these functions from being
called when removing a layer group, fixing the bug.
In gimp_group_layer_{start,end}_move(), push corresponding undo
steps, which perform the opposite operation during undo, and make
sure that mask-cropping is frozen during group-layer move
operations.
This fixed erroneous group-layer mask cropping when undoing/redoing
a group-layer move operation multiple times.
Add layer-mask support for group layers. Group-layer masks work
similarly to ordinary-layer masks, with the following
considerations:
The group's mask size is the same as group's size (i.e., the
bounding box of its children) at all times. When the group's size
changes, the mask is cropped to the new size -- areas of the mask
that fall outside of the new bounds are discarded and their data is
lost (sans undo), and newly added areas are filled with black (and
hence are transparent by default).
The new gimp_group_layer_{suspend,resume}_mask() functions can be
used to modify this behavior. Between the outermost pair of
suspend/resume calls, the old mask data is remembered, and is used
to fill the newly added areas while cropping the mask when the
group is resized. We override GimpItem::{start,end}_move() for
GimpLayer, to call these functions (suspend() in start_move(), and
resume() in end_move()) for each of the layer's ancestors.
As a result, while moving a layer, or a set of layers, atomically,
such as while dragging with the move tool, or moving linked layers,
the ancestors' mask data is not lost, and is only discarded at the
end of the operation.
This commit also takes care of properly handling undo for group-
layer mask crops, properly invalidating the image when the group
layer's mask is shown, and enabling the mask actions for group
layers (obviously :).
* app/core/gimpgrouplayer.[ch]: add gimp_group_layer_suspend_resize()
and gimp_group_layer_resume_resize() and call them around functions
where all a group's children are transformed (translated, resized
etc). This way we go from the worst case of reallocating the
group's projection tiles once for each child down to exactly one
reallocation.
* app/core/Makefile.am
* app/core/core-enums.[ch]
* app/core/core-types.h
* app/core/gimpimage-undo-push.[ch]
* app/core/gimpgrouplayerundo.[ch]: add new undo class
GimpGroupLayerUndo which implements undos for suspend/resume of
group layers and calls them in reverse order when undoing.
Insert a gegl:translate node into the group layer's projection
graph. Produces identical results as the legacy projection now, but is
not yet switched on by checking View->Use Gegl.
Implement the GimpProjectable interface and keep a GimpProjection
around that projects the GimpDrawableStack of our children. Propagate
the childrens' "update" signals to our own "update" signal so our
parent projection picks up all changes.
Michael Natterer