The op.Save and Load methods exist to support the need for
transformation, clip, pointer area state to behave as stacks. For
example, layout needs to apply an offset to its children but not
subsequent operations.
Before this change, op.Save and Load were used to save and restore the
state:
ops := new(op.Ops)
// Save state.
state := op.Save(ops)
// Apply offset.
op.Offset(...).Add(ops)
// Draw with offset applied.
draw(ops)
// Restore state.
state.Load()
A drawback with the op.Save mechanism is that there is no direct
connection between the state change and the saving and loading of state.
This causes confusion as to when a Save/Load is needed and who is
responsible for performing them, which leads to subtle bugs and over-use
of Save/Loads.
This change gets rid of the general state stack and replaces it with
per-state stacks. There is now a stack for transformation, clip, pointer
areas, and they can only be restored by the code pushing state to them.
The example above now becomes:
ops := new(op.Ops)
// Push offset to the transformation stack.
stack := op.Offset(...).Push(ops)
// Draw with offset applied.
draw(ops)
// Restore state.
stack.Pop()
For convenience, transformation also be Add'ed if the stack operation is
not required.
Simple state such as the current material no longer has a way to be
restored; it is assumed the client of a PaintOp adds their desired
material operation before it.
API change: replace op.Save/Load with explicit Push/Pop scopes for
op.TransformOps, pointer.AreaOps, clip.Ops.
To ease porting, this change retains a version of op.Save/Load that
saves and restores the transformation and clip stacks. It also retains
an Add method for clip.Op.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
key.InputOp and pointer.InputOp handlers are reset on first registration
through a key.FocusEvent{false} or pointer.Cancel, respectively.
However, the mere act of registering a handle shouldn't result in a
redraw. This is particularly true for misconfigured handlers where a new
tag is supplied every frame, resulting in continously redrawing.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
The target of FocusOp is too subtle; be explicit instead and remove
any doubt.
Multiple SoftKeyboardOp in a single frame is rare, but if they do occur,
they should behave as if they were from separate frames: the last one
applies.
As a side-effect the key event router can be much simplified.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
The semantics were relaxed in a previous commit; this change renames
to operations accordingly.
API change. Use gofmt to adjust your code accordingly:
gofmt -r 'op.Push(a).Pop() -> op.Save(a).Load()'
gofmt -r 'op.Push(a) -> op.Save(a)'
gofmt -r 'v.Pop() -> v.Load()'
gofmt -r 'op.StackOp -> op.StateOp'
Signed-off-by: Elias Naur <mail@eliasnaur.com>
The existing implementation cannot remove the focus of some widget,
doesn't have an option to focus without display the on-screen keyboard
and it automatically focuses the first InputOp, aggressively.
That change aims to make possible: remove focus from any widget. Add
focus without displaying the on-screen-keyboard/soft keyboard. Don't
automatically focus any widget. Don't recover focus when the widget is
visible again.
Fixes gio#180.
Signed-off-by: Inkeliz <inkeliz@inkeliz.com>
Elias Naur