Re: Custom widgets in ATK
This was very helpful, thank you for pointing me in the right direction.
Eric
On 08/22/2017 04:25 AM, Alejandro Piñeiro wrote:
On 14/08/17 23:11, Eric Williams wrote:
Hello,
Hi,
a quick answer for your email below. Sorry for not answering before, I
have just came back from holidays.
I am an Eclipse SWT developer, working to improve accessibility
support for SWT on Linux.
Some background: SWT is a cross-platform Java UI toolkit which runs
using GTK on Linux. Most SWT widgets match up to GTK widgets -- these
are accessible by default via GTK. However we implement a custom GTK
container, called SwtFixed, for custom widgets. These custom widgets
do not map up to native GTK widgets and are drawn manually. The role
of these widgets vary: from text editing to custom combos, etc. The
main text editor in Eclipse is a custom widget, which means that
accessibility for these widgets is important.
The issue: at present time, Orca is unable to read these custom
widgets. It works on GTK2 semi-reliably, but GTK3 is unusable. Orca
either hangs, crashes, or fails to read events/information from the
custom widgets.
We currently have an accessibility implementation in SWT that was
created long before GTK3 was around. From what I gather, it has not
been regularly maintained since ~2012. The existing implementation
uses ATK to enable accessibility in areas that GTK cannot (i.e., for
custom widgets). I am virtually certain that the problem lies in the
accessibility implementation, as the custom container implementation
is accessible by default through GTK. I have confirmed this via testing.
Here is some of the code to register a custom widget with ATK:
(I've removed some of the Java typing to make it easier to read)
widgetType = G_OBJECT_TYPE (widget);
registry = atk_get_default_registry ();
factory = atk_registry_get_factory (registry, widgetType);
if (ATK_IS_NO_OP_OBJECT_FACTORY(factory)) return;
factoryName = FACTORY_TYPENAME + getTypeName(widgetType);
if (g_type_from_name (factoryName) == 0) {
/* register the factory */
GTypeInfo typeInfo = new GTypeInfo ();
typeInfo.base_init = GTypeInfo_base_init_factory.getAddress ();
typeInfo.class_size = (short)AtkObjectFactoryClass_sizeof ();
typeInfo.instance_size = (short)AtkObjectFactory_sizeof ();
info = g_malloc (GTypeInfo.sizeof);
memmove (info, typeInfo, GTypeInfo.sizeof);
swtFactoryType = g_type_register_static
(ATK_TYPE_OBJECT_FACTORY(), factoryName, info, 0);
parentType = atk_object_factory_get_accessible_type(factory);
atk_registry_set_factory_type (registry, widgetType,
swtFactoryType);
}
ATK Factories are not the way to go anymore to extend already existing
accessible objects/containers, now that most moder ATK implementations
are not modules anymore. In fact, now I then I'm tempted to mark them as
deprecated on ATK itself. The only reason I didn't do that is that there
are still plenty of implementations using them, without no plans to port
that code (AFAIK).
Another thing: I tried investigating with Accerciser, but it hangs and
gives me the following error message:
WARNING **: AT-SPI: Error in GetItems, sender=(null), error=Did not
receive a reply. Possible causes include: the remote application did
not send a reply, the message bus security policy blocked the reply,
the reply timeout expired, or the network connection was broken.
I would appreciate it if someone could point me in the right
direction. Is the code provided correct? Is there something additional
we need to be doing to register with ATK?
On GTK3, the accessible implementation is public. We needed to ask that
when they stopped to use factories, so apps/toolkits providing custom
widgets could extend them. The poster boy at that moment was Evince. You
mention that you have a custom container, so I hope that you are just
extending GtkContainer. If that is the case this code could be used as
an example:
https://git.gnome.org/browse/evince/tree/libview/ev-view-accessible.c#n71
I hope this helps.
BR
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Re: Custom widgets in ATK
On 14/08/17 23:11, Eric Williams wrote:
> Hello,
Hi,
a quick answer for your email below. Sorry for not answering before, I
have just came back from holidays.
>
> I am an Eclipse SWT developer, working to improve accessibility
> support for SWT on Linux.
>
> Some background: SWT is a cross-platform Java UI toolkit which runs
> using GTK on Linux. Most SWT widgets match up to GTK widgets -- these
> are accessible by default via GTK. However we implement a custom GTK
> container, called SwtFixed, for custom widgets. These custom widgets
> do not map up to native GTK widgets and are drawn manually. The role
> of these widgets vary: from text editing to custom combos, etc. The
> main text editor in Eclipse is a custom widget, which means that
> accessibility for these widgets is important.
>
> The issue: at present time, Orca is unable to read these custom
> widgets. It works on GTK2 semi-reliably, but GTK3 is unusable. Orca
> either hangs, crashes, or fails to read events/information from the
> custom widgets.
>
> We currently have an accessibility implementation in SWT that was
> created long before GTK3 was around. From what I gather, it has not
> been regularly maintained since ~2012. The existing implementation
> uses ATK to enable accessibility in areas that GTK cannot (i.e., for
> custom widgets). I am virtually certain that the problem lies in the
> accessibility implementation, as the custom container implementation
> is accessible by default through GTK. I have confirmed this via testing.
>
> Here is some of the code to register a custom widget with ATK:
>
> (I've removed some of the Java typing to make it easier to read)
>
> widgetType = G_OBJECT_TYPE (widget);
> registry = atk_get_default_registry ();
> factory = atk_registry_get_factory (registry, widgetType);
> if (ATK_IS_NO_OP_OBJECT_FACTORY(factory)) return;
>
> factoryName = FACTORY_TYPENAME + getTypeName(widgetType);
>
> if (g_type_from_name (factoryName) == 0) {
> /* register the factory */
> GTypeInfo typeInfo = new GTypeInfo ();
> typeInfo.base_init = GTypeInfo_base_init_factory.getAddress ();
> typeInfo.class_size = (short)AtkObjectFactoryClass_sizeof ();
> typeInfo.instance_size = (short)AtkObjectFactory_sizeof ();
>
> info = g_malloc (GTypeInfo.sizeof);
> memmove (info, typeInfo, GTypeInfo.sizeof);
> swtFactoryType = g_type_register_static
> (ATK_TYPE_OBJECT_FACTORY(), factoryName, info, 0);
> parentType = atk_object_factory_get_accessible_type(factory);
> atk_registry_set_factory_type (registry, widgetType,
> swtFactoryType);
> }
ATK Factories are not the way to go anymore to extend already existing
accessible objects/containers, now that most moder ATK implementations
are not modules anymore. In fact, now I then I'm tempted to mark them as
deprecated on ATK itself. The only reason I didn't do that is that there
are still plenty of implementations using them, without no plans to port
that code (AFAIK).
>
>
> Another thing: I tried investigating with Accerciser, but it hangs and
> gives me the following error message:
>
> WARNING **: AT-SPI: Error in GetItems, sender=(null), error=Did not
> receive a reply. Possible causes include: the remote application did
> not send a reply, the message bus security policy blocked the reply,
> the reply timeout expired, or the network connection was broken.
>
> I would appreciate it if someone could point me in the right
> direction. Is the code provided correct? Is there something additional
> we need to be doing to register with ATK?
On GTK3, the accessible implementation is public. We needed to ask that
when they stopped to use factories, so apps/toolkits providing custom
widgets could extend them. The poster boy at that moment was Evince. You
mention that you have a custom container, so I hope that you are just
extending GtkContainer. If that is the case this code could be used as
an example:
https://git.gnome.org/browse/evince/tree/libview/ev-view-accessible.c#n71
I hope this helps.
BR
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Custom widgets in ATK
Hello,
I am an Eclipse SWT developer, working to improve accessibility support
for SWT on Linux.
Some background: SWT is a cross-platform Java UI toolkit which runs
using GTK on Linux. Most SWT widgets match up to GTK widgets -- these
are accessible by default via GTK. However we implement a custom GTK
container, called SwtFixed, for custom widgets. These custom widgets do
not map up to native GTK widgets and are drawn manually. The role of
these widgets vary: from text editing to custom combos, etc. The main
text editor in Eclipse is a custom widget, which means that
accessibility for these widgets is important.
The issue: at present time, Orca is unable to read these custom widgets.
It works on GTK2 semi-reliably, but GTK3 is unusable. Orca either hangs,
crashes, or fails to read events/information from the custom widgets.
We currently have an accessibility implementation in SWT that was
created long before GTK3 was around. From what I gather, it has not been
regularly maintained since ~2012. The existing implementation uses ATK
to enable accessibility in areas that GTK cannot (i.e., for custom
widgets). I am virtually certain that the problem lies in the
accessibility implementation, as the custom container implementation is
accessible by default through GTK. I have confirmed this via testing.
Here is some of the code to register a custom widget with ATK:
(I've removed some of the Java typing to make it easier to read)
widgetType = G_OBJECT_TYPE (widget);
registry = atk_get_default_registry ();
factory = atk_registry_get_factory (registry, widgetType);
if (ATK_IS_NO_OP_OBJECT_FACTORY(factory)) return;
factoryName = FACTORY_TYPENAME + getTypeName(widgetType);
if (g_type_from_name (factoryName) == 0) {
/* register the factory */
GTypeInfo typeInfo = new GTypeInfo ();
typeInfo.base_init = GTypeInfo_base_init_factory.getAddress ();
typeInfo.class_size = (short)AtkObjectFactoryClass_sizeof ();
typeInfo.instance_size = (short)AtkObjectFactory_sizeof ();
info = g_malloc (GTypeInfo.sizeof);
memmove (info, typeInfo, GTypeInfo.sizeof);
swtFactoryType = g_type_register_static
(ATK_TYPE_OBJECT_FACTORY(), factoryName, info, 0);
parentType = atk_object_factory_get_accessible_type(factory);
atk_registry_set_factory_type (registry, widgetType,
swtFactoryType);
}
Another thing: I tried investigating with Accerciser, but it hangs and
gives me the following error message:
WARNING **: AT-SPI: Error in GetItems, sender=(null), error=Did not
receive a reply. Possible causes include: the remote application did not
send a reply, the message bus security policy blocked the reply, the
reply timeout expired, or the network connection was broken.
I would appreciate it if someone could point me in the right direction.
Is the code provided correct? Is there something additional we need to
be doing to register with ATK?
Thanks,
--
Eric Williams
Associate Software Engineer - Eclipse Team
Red Hat
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