The "Clutter Cookbook" is a document designed to contain solutions
to common problems applications developers might encounter when using
Clutter. It is meant as a companion to the API reference but it
requires knowledge of the Clutter API and framework.
The ClutterLayoutMeta instances should be created on demand, whenever
the layout manager needs them - if the layout manager supports layout
properties.
This removes the requirement to call add_child_meta() and
remove_child_meta() on add and remove respectively; it also simplifies
the implementation of LayoutManager sub-classes since we can add
fallback code in the base abstract class.
Eventually, this will also lead to an easier to implement ClutterScript
parser for layout properties.
With the new scheme, the ClutterLayoutMeta instance is created whenever
the layout manager tries to access it; if there isn't an instance
already attached to the container's child, one is created -- assuming
that the LayoutManager sub-class has overridden the
get_child_meta_type() virtual function and it's returning a valid GType.
We can also provide a default implementation for create_child_meta(),
by getting the GType and instantiating a ClutterLayoutMeta with all the
fields already set. If the layout manager requires more work then it can
obviously override the default implementation (and even chain up to it).
The ClutterBox actor has been updated, as well as the ClutterBoxLayout
layout manager, to take advantage of the changes of LayoutManager.
cogl_push_draw_buffer, cogl_set_draw_buffer and cogl_pop_draw_buffer are now
deprecated and new code should use the new cogl_framebuffer_* API instead.
Code that previously did:
cogl_push_draw_buffer ();
cogl_set_draw_buffer (COGL_OFFSCREEN_BUFFER, buffer);
/* draw */
cogl_pop_draw_buffer ();
should now be re-written as:
cogl_push_framebuffer (buffer);
/* draw */
cogl_pop_framebuffer ();
As can be seen from the example above the rename has been used as an
opportunity to remove the redundant target argument from
cogl_set_draw_buffer; it now only takes one call to redirect to an offscreen
buffer, and finally the term framebuffer may be a bit more familiar to
anyone coming from an OpenGL background.
This function was #if 0'd before we released Clutter 1.0 so there's no
implementation of it. At some point we thought it might assist with
developers breaking out into raw OpenGL. Breaking out to raw GL is a
difficult problem though so we decided instead we will wait for a specific
use case to arrise before trying to support it.
The Clutter API reference has an index of the symbols for each minor
version, and a list of deprecated symbols. The Cogl API reference
should have the same layout.
The order in which the MacPorts are installed is important otherwise we open
the user up to a world of pain.
This patch also tweaks the OS X docs to follow the formatting of the rest of
the docs and to discuss the option of GtkDoc.
http://bugzilla.openedhand.com/show_bug.cgi?id=1865
cogl_clip_push() which accepts a rectangle in model space shouldn't have
been defined to take x,y,width,height arguments because this isn't consistant
with other Cogl API dealing with model space rectangles. If you are using a
coordinate system with the origin at the center and the y+ extending up,
then x,y,width,height isn't as natural as (x0,y0)(x1,y1). This API has
now been replace with cogl_clip_push_rectangle()
(As a general note: the Cogl API should only use the x,y,width,height style
when the appropriate coordinate space is defined by Cogl to have a top left
origin. E.g. window coordinates, or potentially texture coordinates)
cogl_clip_push_window_rect() shouldn't have been defined to take float
arguments since we only clip with integral pixel precision. We also
shouldn't have abbreviated "rectangle". This API has been replaced with
cogl_clip_push_window_rectangle()
cogl_clip_ensure() wasn't documented at all in Clutter 1.0 and probably
no one even knew it existed. This API isn't useful, and so it's now
deprecated. If no one complains we may remove the API altogether for
Clutter 1.2.
cogl_clip_stack_save() and cogl_clip_stack_restore() were originally added
to allow us to save/restore the clip when switching to/from offscreen
rendering. Now that offscreen draw buffers are defined to own their clip
state and the state will be automatically saved and restored this API is now
redundant and so deprecated.
Just like CLUTTER_CHECK_VERSION does version checking at compile
time, we need a way to verify the version of the library that we
are linking against. This is mostly needed for language bindings
and for run-time loadable modules -- when we'll get those.
The indirection through this API isn't necessary since we no longer
arbitrate between the OpenGL matrix API and Cogl's client side API. Also it
doesn't help to maintain an OpenGL style matrix mode API for internal use
since it's awkward to keep restoring the MODELVIEW mode and easy enough to
directly work with the matrix stacks of interest.
This replaces use of the _cogl_current_matrix API with direct use of the
_cogl_matrix_stack API. All the unused cogl_current_matrix API is removed
and the matrix utility code left in cogl-current-matrix.c was moved to
cogl.c.
• Fix list_stages() and peek_stages() documentation
• Fix clutter_text_set_preedit_string() arguments in the header
to match source and documentation
• Add clutter_units_cm() to the private section for Units
• Rename the LayoutManager section
• Add FlowLayout:homogeneous accessors
* layout-manager: (50 commits)
docs: Reword a link
layout, docs: Add more documentation to LayoutManager
layout, docs: Fix description of Bin properties
layout, bin: Use ceilf() instead of casting to int
layout, docs: Add long description for FlowLayout
layout, box: Clean up
layout, box: Write long description for Box
layout, docs: Remove unused functions
layout: Document BoxLayout
layout: Add BoxLayout, a single line layout manager
layout: Report the correct size of FlowLayout
layout: Resizing the stage resizes the FlowLayout box
layout: Use the get_request_mode() getter in BinLayout
layout: Change the request-mode along with the orientation
actor: Add set_request_mode() method
[layout] Remove FlowLayout:wrap
[layout] Rename BinLayout and FlowLayout interactive tests
[layout] Skip invisible children in FlowLayout
[layout] Clean up and document FlowLayout
[layout] Snap children of FlowLayout to column/row
...
As part of an incremental process to have Cogl be a standalone project we
want to re-consider how we organise the Cogl source code.
Currently this is the structure I'm aiming for:
cogl/
cogl/
<put common source here>
winsys/
cogl-glx.c
cogl-wgl.c
driver/
gl/
gles/
os/ ?
utils/
cogl-fixed
cogl-matrix-stack?
cogl-journal?
cogl-primitives?
pango/
The new winsys component is a starting point for migrating window system
code (i.e. x11,glx,wgl,osx,egl etc) from Clutter to Cogl.
The utils/ and pango/ directories aren't added by this commit, but they are
noted because I plan to add them soon.
Overview of the planned structure:
* The winsys/ API is the API that binds OpenGL to a specific window system,
be that X11 or win32 etc. Example are glx, wgl and egl. Much of the logic
under clutter/{glx,osx,win32 etc} should migrate here.
* Note there is also the idea of a winsys-base that may represent a window
system for which there are multiple winsys APIs. An example of this is
x11, since glx and egl may both be used with x11. (currently only Clutter
has the idea of a winsys-base)
* The driver/ represents a specific varient of OpenGL. Currently we have "gl"
representing OpenGL 1.4-2.1 (mostly fixed function) and "gles" representing
GLES 1.1 (fixed funciton) and 2.0 (fully shader based)
* Everything under cogl/ should fundamentally be supporting access to the
GPU. Essentially Cogl's most basic requirement is to provide a nice GPU
Graphics API and drawing a line between this and the utility functionality
we add to support Clutter should help keep this lean and maintainable.
* Code under utils/ as suggested builds on cogl/ adding more convenient
APIs or mechanism to optimize special cases. Broadly speaking you can
compare cogl/ to OpenGL and utils/ to GLU.
* clutter/pango will be moved to clutter/cogl/pango
How some of the internal configure.ac/pkg-config terminology has changed:
backendextra -> CLUTTER_WINSYS_BASE # e.g. "x11"
backendextralib -> CLUTTER_WINSYS_BASE_LIB # e.g. "x11/libclutter-x11.la"
clutterbackend -> {CLUTTER,COGL}_WINSYS # e.g. "glx"
CLUTTER_FLAVOUR -> {CLUTTER,COGL}_WINSYS
clutterbackendlib -> CLUTTER_WINSYS_LIB
CLUTTER_COGL -> COGL_DRIVER # e.g. "gl"
Note: The CLUTTER_FLAVOUR and CLUTTER_COGL defines are kept for apps
As the first thing to take advantage of the new winsys component in Cogl;
cogl_get_proc_address() has been moved from cogl/{gl,gles}/cogl.c into
cogl/common/cogl.c and this common implementation first trys
_cogl_winsys_get_proc_address() but if that fails then it falls back to
gmodule.
Input Methods require to be able to set a "pre-edit string", that is
a string that it's just displayed into the Text actor without being
committed to the actor's buffer. The string might require custom Pango
attributes, and an update of the cursor position.
FlowLayout is a layout manager that arranges its children in a
reflowing line; the orientation controls the major axis for the
layout: horizontal, for reflow on the Y axis, and vertical, for
reflow on the X axis.
The BinLayout should store a pointer to the Container that it is
using it as the layout manager.
This allows us to fix the API and drop the additional Container
arguments from set_alignment() and get_alignment().
This also allows us to add a ClutterBinLayout::add() method which
adds an actor and sets the alignment policies without dealing with
variadic arguments functions and GValue (de)marshalling.
Use the LayoutManager API to set a back pointer to the Box actor
inside the LayoutManager used by the box.
This also allows us to replace the LayoutManager on a Box, since
the LayoutManager will be able to replace all the metadata if
needed.
The LayoutManager implementation might opt to take a back pointer
to the Container that is using the layout instance; this allows
direct access to the container itself from within the implementation.
The ClutterBox::add method is a simple wrapper around the Container
add_actor() method and the LayoutManager layout properties API. It
allows adding an actor to a Box and setting the layout properties in
one call.
If the LayoutManager used by the Box does not support layout properties
then the add() method short-circuits out.
Along with the varargs version of the method there's also a vector-based
variant, for language bindings to use.
Instead of overloading ClutterChildMeta with both container and layout
metadata and delegate to every LayoutManager implementation to keep a
backpointer to the layout manager instance, we can simply subclass
ChildMeta into LayoutMeta and presto! everything works out pretty well
for everyone.
The chapter on how to subclass ClutterActor inside the API reference for
Clutter is still using ClutterUnit and referencing to concepts that have
been changed since the document was written.
ClutterBehaviourPath has been changed and ClutterBehaviourBspline has
been removed; now we use ClutterPath everywhere we need to describe a
path. This warrants a chapter in the migration guide.
The get_type() function for ClutterInterval is missing from the
known GObject types, so gtk-doc doesn't know that it has to
introspect it for hierarchy, properties and signals.
Currently, to update a property inside an animation you have to
get the interval for that property and then call the set_final_value()
method.
We can provide a simpler, bind()-like method for the convenience of
the developers that just validates everything and then calls the
Interval.set_final_value().
The version number in the title made sense when we were breaking
API with every minor release. Now that we're API stable we can
drop that and make the output in Devhelp and on the website slightly
more good looking.
We should follow the convention for boxed types initializers of:
<type_name>_from_<another_type> (boxed, value)
For ClutterUnits as well; so:
clutter_units_pixels -> clutter_units_from_pixels
clutter_units_em -> clutter_units_from_em
...
We should still keep the short-hand version as a macro, though.
