Destroy the dummy XImage we create even on success.
http://bugzilla.openedhand.com/show_bug.cgi?id=1918
Based on a patch by: Carlos Martín Nieto <carlos@cmartin.tk>
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
PropertyInfo should store a copy of the JsonNodes it references, so
that property_info_free() can safely dispose them, and we can reference
values across different UI definition data.
The implicit timeline parsing code is not copying the JsonNode; this
leads to a double free in some cases, which is masked by the GSlice
allocator and produces a heap corruption later on.
Allow the user of the ClutterMedia interface to specify an external (as
in not multiplexed with the audio/video streams) location of a subtitle
stream.
Both the ::insert-text and ::delete-text are "action" signals, that is
signals that are safe to (and should) be emitted using g_signal_emit()
directly.
A timeline advancement might cause another timeline to be
destroyed, which will likely lead to a segmentation fault.
Before advancing the timelines we should take a reference
on them - just like we do for the stages before doing
event processing. This will prevent dispose() from running
until the end of the advancement.
http://bugzilla.openedhand.com/show_bug.cgi?id=1854
Apparently, calling g_set_prgname() multiple times is not allowed
anymore, and hence clutter_init_* calls should not do that. Though this
is really GLib's fault - and a massive nuisance for us - we should
prolly comply to avoid the test suite dying on us.
* animate-layout-manager:
layout-manager: Document the animation support
layout-manager: Rewind the timeline in begin_animation()
box-layout: Remove the allocations hash table
docs: Clean up the README file
layout: Let begin_animation() return the Alpha
box-layout: Add knobs for controlling animations
box-layout: Animate layout properties
layout: Add animation support to LayoutManager
Add ActorBox animation methods
Add a section inside the LayoutManager class API reference documenting,
with examples, how to implement animation support inside a layout
manager sub-class.
If the default implementation begin_animation() is called twice then we
should rewind the timeline, as well as updating its duration and the
easing mode of the alpha.
The BoxLayout uses a HashTable to map the latest stable allocation of
each child, in order to use that as the initial value during an
animation; this in spite of already having a perfectly valid per-child
storage as part of the layout manager: ClutterBoxChild.
The last stable allocation should be stored inside the ClutterBoxChild
instead of having it in the private data for ClutterBoxLayout. The
access remains O(1), since there is a 1:1 mapping between child and
BoxChild instances, but we save a little bit of memory and we avoid
keeping aroud allocations for old children.
* stage-use-alpha:
tests: Use accessor methods for :use-alpha
stage: Add accessors for :use-alpha
tests: Allow setting the stage opacity in test-paint-wrapper
stage: Premultiply the stage color
stage: Composite the opacity with the alpha channel
glx: Always request an ARGB visual
stage: Add :use-alpha property
materials: Get the right blend function for alpha
ClutterActor checks, when destroying and reparenting, if the parent
actor implements the Container interface, and automatically calls the
remove() method to perform a clean removal.
Actors implementing Container, though, might have internal children;
that is, children that are not added through the Container API. It is
already possible to iterate through them using the Container API to
avoid breaking invariants - but calling clutter_actor_destroy() on
these children (even from the Container implementation, and thus outside
of Clutter's control) will either lead to leaks or to segmentation
faults.
Clutter needs a way to distinguish a clutter_actor_set_parent() done on
an internal child from one done on a "public" child; for this reason, a
push/pop pair of functions should be available to Actor implementations
to mark the section where they wish to add internal children:
➔ clutter_actor_push_internal ();
...
clutter_actor_set_parent (child1, parent);
clutter_actor_set_parent (child2, parent);
...
➔ clutter_actor_pop_internal ();
The set_parent() call will automatically set the newly added
INTERNAL_CHILD private flag on each child, and both
clutter_actor_destroy() and clutter_actor_unparent() will check for the
flag before deciding whether to call the Container's remove method.
When beginning a new animation for a LayoutManager, the implementation
should return the ClutterAlpha used. This allows controlling the
timeline and/or modifying the animation parameters on the fly.
ClutterLayoutManager does not have any state associated with it, and
defers all the state to its sub-classes.
The BoxLayout is thus in charge of controlling:
• whether or not animations should be used
• the duration of the animation
• the easing mode of the animation
By adding three new properties:
• ClutterBoxLayout:use-animations
• ClutterBoxLayout:easing-duration
• ClutterBoxLayout:easing-mode
And their relative accessors pairs we can make BoxLayout decide whether
or not, and with which parameters, call the begin_animation() method of
ClutterLayoutManager.
The test-box-layout has been modified to reflect this new functionality,
by checking the key-press event for the 'a' key symbol to toggle the use
of animations.
Use the newly added animation support inside LayoutManager to animate
between state changes of the BoxLayout properties.
The implementation is based on equivalent code from Mx, written by:
Thomas Wood <thomas.wood@intel.com>
In order to animate a fluid layout we cannot use the common animation
code paths as they will override the size request and allocation paths
that are handled by the layout manager itself.
One way to introduce animations in the allocation sequence is to use a
Timeline and an Alpha to compute a progress value and then use that
value to interpolate an ActorBox between the initial and final states of
the animation - with the initial state being the last allocation of the
child prior to the animation start, and the final state the allocation
of the child at the end; for every frame of the Timeline we then queue a
relayout on the layout manager's container, which will result in an
animation.
ClutterLayoutManager is the most likely place to add a generic API for
beginning and ending an animation, as well as the place to provide a
default code path to create the ancillary Timeline and Alpha instances
needed to drive the animation.
A LayoutManager sub-class will need to:
• call clutter_layout_manager_begin_animation() whenever it should
animate between two states, for instance: whenever a layout property
changes value;
• eventually override begin_animation() and end_animation() in case
further state needs to be set up, and then chain up to the default
implementation provided by LayoutManager;
• if a completely different implementation is required, the layout
manager sub-class should override begin_animation(), end_animation()
and get_animation_progress().
Inside the allocate() implementation the sub-class should also
interpolate between the last known allocation of a child and the newly
computed allocation.
ClutterActorBox should have an interpolate() method that allows to
compute the intermediate values between two states, given a progress
value, e.g.:
clutter_actor_box_interpolate (start, end, alpha, &result);
Another utility method, useful for layout managers, is a modifier
that clamps the members of the actor box to the nearest integer
value.
When getting signals from higher level toolkits, occasionally
one wants access to the underlying event; say for a Button
widget's "clicked" signal, to get the keyboard state.
Rather than having all of the highlevel widgets emit
ClutterEvent just for the more unusual use cases,
add a global function to access the event state.
http://bugzilla.openedhand.com/show_bug.cgi?id=1888
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
Old-style X11 terminals require that even modern X11 send KeyPress
and KeyRelease pairs when auto-repeating. For this reason modern(-ish)
API like XKB has a way to detect auto-repeat and do a single KeyRelease
at the end of a KeyPress sequence.
The newly added check emulates XKB's detectable auto-repeat by peeking
the next event after a KeyRelease and checking if it's a KeyPress for
the same key and timestamp - and then ignoring the KeyRelease if it
matches.
If a Stage has been set to use a foreign Window then Clutter should not
be managing it; calling XWithdrawWindow and XMapWindow should be
reserved to the windows we manage ourselves.
Some actor implementation might avoid imposing any layout on their
children. The Actor base class usually assumes some sort of layout
management is in place, so it will queue relayouts when, for instance,
an actor is shown or is hidden. If the parent of the actor does not
impose any layout, though, showing or hiding one of its children will
not affect the layout of the others.
An example of this kind of container is ClutterGroup.
By adding a new Actor flag, CLUTTER_ACTOR_NO_LAYOUT, and by making
the Group actor set it on itself, the Actor base class can now decide
whether or not to queue a relayout. The flag is not meant to be used
by application code, and should only be set when implementing a new
container.
http://bugzilla.openedhand.com/show_bug.cgi?id=1838
clutter_actor_get_preferred_width/height currently caches only one size
requests, for a given height / width.
It's common for a layout manager to call get_preferred_width with 2
different heights during the same allocation cycle. Typically once in
the size request, once in the allocation. If
clutter_actor_get_preferred_width is called
alternatively with 2 different for_height, the cache is totally
inefficient, and we end up always querying the actor size even
when the actor does not need a re-allocation.
http://bugzilla.openedhand.com/show_bug.cgi?id=1876
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
Fix a copy-and-paste thinko where the cell size was computed using the
minimum size instead of the natural size. For actors with a minimum size
of zero, like Textures, this implied always a zero allocation.
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
Commit 558b17ee1e added support for rectangle textures to the
framebuffer code. Under GLES there is no GL_TEXTURE_RECTANGLE_ARB
definition so this was breaking the build. The rest of Cogl uses
ifdef's around that constant so we should do the same here.
• The debug flags are pre-processor ones, so they should be listed
inside AM_CPPFLAGS.
• Clutter's publicly exported symbols match the following regular
expression:
^(clutter|cogl|json)_*
The old one also listed "pango" as a possible prefix, but the
Pango API is now under the Cogl namespace.
We need to add the row-spacing value when calculating the y position for lines
of actors in horizontal flowing layouts.
Similarly we need to add the col-spacing value when calculating the x posution
for actors in vertical flowing layouts.
When requesting the GLXFBConfig for creating the GLX context, we should
always request one that links to an ARGB visual instead of a plain RGB
one.
By using an ARGB visual we allow the ClutterStage:use-alpha property to
work as intended when running Clutter under a compositing manager.
The default behaviour of requesting an ARGB visual can be disabled by
using the:
CLUTTER_DISABLE_ARGB_VISUAL
Environment variable.
The ClutterStage:use-alpha property is used to let a stage know that it
should honour the alpha component of the ClutterStage:color property.
If :use-alpha is set to FALSE the stage always uses the full opacity
when clearing itself before a paint(); otherwise, the alpha value is
used.
The correct blend function for the alpha channel is:
GL_ONE, GL_ONE_MINUS_SRC_ALPHA
As per bug 1406. This fix was dropped when the switch to premultiplied
alpha was merged.
* text-direction:
docs: Add text-direction accessors
Set the default language on the Pango context
actor: Set text direction on parenting
tests: Display the index inside text-box-layout
box-layout: Honour :text-direction
text: Dirty layout cache on text direction changes
actor: Add :text-direction property
Use the newly added ClutterTextDirection enumeration
Add ClutterTextDirection enumeration
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.
The colour test for the stage in _clutter_do_pick checks for white to
determine whether the stage was picked but since 47db7af4d we were
setting the colur to black. This usually worked because the id of the
default stage ends up being 0 which equates to black. However if a
second stage is created then it will always end up picking the first
stage.
We currently enable blending if the material colour has
transparency. This patch makes it also enable blending if any of the
lighting colours have transparency. Arguably this isn't neccessary
because we don't expose any API to enable lighting so there is no
bug. However it is currently possible to enable lighting with a direct
call to glEnable and this otherwise works so it is a shame not to have
it.
http://bugzilla.openedhand.com/show_bug.cgi?id=1907
The stage's pick id can be written to the framebuffer when we call
cogl_clear so there's no need for the stage to also chain up in it's pick
function resulting in clutter-actor.c also emitting a rectangle for the
stage.
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.
Instead of storing an enum with the backend type for each texture and
then using a switch statement to decide which function to call, we
should store pointers to all of the functions in a struct and have
each texture point to that struct. This is potentially slightly faster
when there are more backends and it makes implementing new backends
easier because it's more obvious which functions have to be
implemented.
cogl_offscreen_new_to_texture previously bailed out if the given texture's
GL target was anything but GL_TEXTURE_2D, but it now also allows
foreign GL_TEXTURE_RECTANGLE_ARB textures.
Thanks to Owen for reporting this issue, ref:
https://bugzilla.gnome.org/show_bug.cgi?id=601032
cogl_material_copy can be used to create a new CoglHandle referencing a copy
of some given material.
From now on we will advise that developers always aim to use this function
instead of cogl_material_new() when creating a material that is in any way
derived from another.
By using cogl_material_copy, Cogl can maintain an ancestry for each material
and keep track of "similar" materials. The plan is that Cogl will use this
information to minimize the cost of GPU state transitions.
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.
Actors, unlike objects, can effectively go away whilst being
animated - usually because of an explicit destoy().
The Animation created by clutter_actor_animate() and friends
should keep a weak reference on the actor and eventually
get rid of the animation itself in case the actor goes away
whilst being animated.
_cogl_material_get_layer expects a CoglMaterial* pointer but it was
being called with a CoglHandle. This doesn't matter because the
CoglHandle is actually just the CoglMaterial* pointer anyway but it
breaks the ability to change the _cogl_material_pointer_from_handle
macro.
• Use the same style for the Cogl API reference as the one used for
the Clutter API reference.
• Fix the introspection annotations for cogl_bitmap_get_size_from_file()
The imported Mesa matrix code has some documentation annotations
that make gtk-doc very angry. Since it's all private anyway we
can safely make gtk-doc ignore the offending stuff.
$(COGL_DRIVER)/cogl-defines.h is generated in the configure script so
it ends up in the build directory. Therefore the build rule for
cogl/cogl-defines.h should depend on the file in $(builddir) not
$(srcdir).
The deprecation notices in gtk-doc should also refer to the
release that added the deprecation, and if the deprecated
symbol has been replaced by something else then the new symbol
should be correctly referenced.
The main COGL header cogl.h is currently created at configure time
because it conditionally includes the driver-dependent defines. This
sometimes leads to a stale cogl.h with old definitions which can
break the build until you clean out the whole tree and start from
scratch.
We can generate a stable cogl-defines.h at build time from the
equivalent driver-dependent header and let cogl.h include that
file instead.
_cogl_feature_check expects the array of function names to be
terminated with a NULL pointer but I forgot to add this. This was
causing crashes depending on what happened to be in memory after the
array.
For VBOs, we don't need to check for the extension if the GL version
is greater than 1.5. Non-power-of-two textures are given in 2.0.
We could also assume shader support in GL 2.0 except that the function
names are different from those in the extension so it wouldn't work
well with the current mechanism.
Previously if you need to depend on a new GL feature you had to:
- Add typedefs for all of the functions in cogl-defines.h.in
- Add function pointers for each of the functions in
cogl-context-driver.h
- Add an initializer for the function pointers in
cogl-context-driver.c
- Add a check for the extension and all of the functions in
cogl_features_init. If the extension is available under multiple
names then you have to duplicate the checks.
This is quite tedious and error prone. This patch moves all of the
features and their functions into a list of macro invocations in
cogl-feature-functions.h. The macros can be redefined to implement all
of the above tasks from the same header.
The features are described in a struct with a pointer to a table of
functions. A new function takes the feature description from this
struct and checks for its availability. The feature can take a list of
extension names with a list of alternate namespaces (such as "EXT" or
"ARB"). It can also detect the feature from a particular version of
GL.
The typedefs are now gone and instead the function pointer in the Cogl
context just directly contains the type.
Some of the functions in the context were previously declared with the
'ARB' extension. This has been removed so that now all the functions
have no suffix. This makes more sense when the extension could
potentially be merged into GL core as well.
There is a new internal Cogl function called _cogl_check_driver_valid
which looks at the value of the GL_VERSION string to determine whether
the driver is supported. Clutter now calls this after the stage is
realized. If it fails then the stage is marked as unrealized and a
warning is shown.
_cogl_features_init now also checks the version number before getting
the function pointers for glBlendFuncSeparate and
glBlendEquationSeparate. It is not safe to just check for the presence
of the functions because some drivers may define the function without
fully implementing the spec.
The GLES version of _cogl_check_driver_valid just always returns TRUE
because there are no version requirements yet.
Eventually the function could also check for mandatory extensions if
there were any.
http://bugzilla.openedhand.com/show_bug.cgi?id=1875
We can not process events for a stage that has been destroyed so we
should make sure that the events for the stage are removed from the
global event queue during dispose.
http://bugzilla.openedhand.com/show_bug.cgi?id=1882
Both ClutterAlpha:mode and ClutterAnimation:mode can be defined using:
• an integer id
• the "nick" field of the AnimationMode GEnumValue
• a custom, tweener-like string
All these methods should be documented.
Like in ClutterAlpha, ClutterAnimation:mode must be overridden when
parsing a Script definition, as we accept both a numeric id and the
string id for easing modes.
When _cogl_add_path_to_stencil_buffer is used to draw a path we don't
need to clear the entire stencil buffer. Instead it can clear just the
bounding box of the path. This adds an extra parameter called
'need_clear' which is only set if the stencil buffer is being used for
clipping.
http://bugzilla.openedhand.com/show_bug.cgi?id=1829
When the text direction changes we should evict the cached layouts
to avoid stale entries in case the direction change produces a layout
with the same size.
Every actor should have a property for retrieving (and setting) the
text direction.
The text direction is used to provide a consisten behaviour in both
left-to-right and right-to-left languages. For instance, ClutterText
should perform key navigation following text direction. Layout
managers should also take into account text direction to derive the
right packing order for their children.
Instead of using PangoDirection directly we should use the
ClutterTextDirection enumeration.
We also need a pair of accessor functions for setting and
getting the default text direction.
This fixes a warning about an uninitialised value. It could also
potentially fix some crashes for example if the enable_flags value
happened to include a bit for enabling a vertex array if no vertex
buffer pointer was set.
While loading a JPEG from disk (with clutter_texture_new_from_file),
I got the following:
<Error>: CGBitmapContextCreate: unsupported parameter combination: 8
integer bits/component; 24 bits/pixel; 3-component colorspace;
kCGImageAlphaNone; 3072 bytes/row.
<Error>: CGContextDrawImage: invalid context
Looking around, I found that CGBitmapContextCreate can't make 24bpp
offscreen pixmaps without an alpha channel...
This fixes the bug, and seems to not break other things...
http://bugzilla.openedhand.com/show_bug.cgi?id=1159
Signed-off-by: Emmanuele Bassi <ebassi@linux.intel.com>
Apple where nice and changed API between releases. This patch checks the
version of the compilation environment and tries to use the right parameter
type.
http://bugzilla.openedhand.com/show_bug.cgi?id=1866
In the new Clutter world backend stage implementations should be lightweight
objects implementing the ClutterStageWindow interface and not ClutterActor
subclasses.
This patch performs various cut-n-pastes to acheive that for the OSX backend
http://bugzilla.openedhand.com/show_bug.cgi?id=1864
ClutterBehaviour should implement the Scriptable interface
and parse ClutterAlpha when implicitly defined, instead of
having this ad hoc code inside ClutterScriptParser itself.
After all, only ClutterBehaviour supports Alpha defined
implicitly.
The ClutterScriptParser should do most of the heavy-lifting for
parsing a JSON object member defining another JSON object into
a GObject property defined using a GParamSpecObject.
cogl_clip_push, and cogl_clip_push_window_rect which are now deprecated were
used in various places internally so this just switches to using the
replacement functions.
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.
For a long time now the GLES driver for Cogl has supported a fallback
scanline rasterizer for filling paths when no stencil buffer is available,
but now that we build the same cogl-primitives code for GL and GLES I
thought it may sometimes be useful for debugging to force Cogl to use the
scanline rasterizer instead of the current stencil buffer approach.
In order to know if a layout property exists and retrieve its
description in form of a GParamSpec, we need a wrapper API inside
ClutterLayoutManager. This allows introspecting a LayoutManager
sub-class and eventually serialize and deserialize it.
The ClutterScript parser needs to be extended to parse child properties
and apply them after an actor has been added to a container. In order to
distinguish child properties from regular GObject properties we can use
the "child::" prefix, e.g.:
{
"type" : "ClutterRectangle",
"id" : "child-01",
"child::has-focus" : true,
...
}
Parsing child properties can be deferred to the ClutterScriptable
interface, just like regular properties.
These files were practically identical, except the gles code had additional
support for filling paths without a stencil buffer. All the driver code has
now been moved into cogl/cogl-primitives.c
All the ClutterColor parsing rules should be coalesced inside
clutter_script_parse_color(): object, array and string notations
are the canonical ways of defining a ClutterColor inside a
ClutterScript definition. Having a single function in charge of
the parsing cleans up the code.
Currently, ClutterScriptParser will construct the object (using the
construct-only and construct parameters), apply the properties from
the ClutterScript definition, and eventuall will add children and
behaviours.
The construction phase should be more compartimentalized: the objects
should be constructed first and eventual children and behaviours
added. Then, once an object is requested or when the parsing process
has terminated, all the properties should be applied.
This change allows us to set up the actors before setting their
non-construct properties.
ClutterScript is currently a mix of parser-related code and
the ClutterScript object. All the parser-related code should
be moved inside a private class, ClutterScriptParser, inheriting
from JsonParser.
Instead of counting on a JsonNode pointer to survive we should take
a copy. This allows keeping unresolved properties across different
ClutterScript passes.
It's useful when initialzing offscreen draw buffers to be able to ask
Cogl to create a texture of a given size and with the default internal
pixel format.
When rendering to an fbo for supporting clutter_texture_new_from_actor we
render to an fbo with the same size as the source actor, but with a viewport
the same size as the stage. We offset the viewport so when we render the
source actor in its normal transformed stage position it lands on the fbo.
Previously we were rounding the transformed position given as a float by
truncating the fraction (just using a C cast) but that resulted in an
incorrect pixel offset when rendering offscreen depending on the source
position.
We now simply + 0.5 before casting (or -0.5 for negative numbers)
For supporting clutter_texture_new_from_actor(): when updating a
ClutterTexture's fbo we previously set up an offset frustum in the
perspective matrix before rendering source actors to an offscreen draw
buffer so as to give a perspective as if it were being drawn at its
original stage location.
Now that Cogl supports offset viewports there is a simpler way...
When we come to render the source actor to our offscreen draw buffer we
now copy the projection matrix from the stage; we create a viewport
that's also the same size as the stage (though larger than the offscreen
draw buffer) and as before we apply the modelview transformations of
the source actors ancestry before painting it.
The only trick we need now is to offset the viewport according to the
transformed (to screen space) allocation of the source actor (something we
required previously too). We negatively offset the stage sized viewport
such that the smaller offscreen draw buffer is positioned to sit underneath
the source actor in stage coordinates.
To help keep clutter_texture_paint maintainable this splits out a big
chunk of standalone code that's responsible for updating the fbo when
clutter_texture_new_from_actor has been used.
When updating the FBO for a source actor (to support
clutter_texture_new_from_actor()) we used to simply set an offscreen draw
buffer to be current, paint the source actor and then explicitly set the
window to be current again. This precluded chaining texture_new_from_actor
though because updating another FBO associated with a source actor would end
up restoring the window as the current buffer instead of the previous
offscreen buffer. Now that we use Cogl's draw buffer stack; chaining
clutter_texture_new_from_actor() should be possible.
Before we call glViewport we need to convert Cogl viewport coordinates
(where the origin is defined to be top left) to OpenGL coordinates
(where the origin is defined to be bottom left)
We weren't considering that offscreen rendering is always upside down
and in this case Cogl coordinates == OpenGL coordinates.
Firstly this now uses the draw buffer height not the viewport height
when we need to perform a y = height - y conversion, since (as the
name suggests) we are dealing with window coordinates not viewport
coordinates.
Secondly this skips any conversion when the current draw buffer is an
offscreen draw buffer since offscreen rendering is always forced to be
upside down and in this case Cogl window coordinates == GL window
coordinates.
