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Implement generic object subclass creation in a more... generic... way

Browse source 
That actually works for subclasses of subclasses too without too much
boilerplate, and also keeps the GObject boilerplate in a single file
instead of having it for every single subclass.
This commit is contained in:
Sebastian Dröge 2017-09-22 00:23:40 +03:00
parent 8d253fd46a
commit cda23d5c41
5 changed files with 381 additions and 242 deletions
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89
gst-plugin/src/base_src.rs Normal file
View file

@ -0,0 +1,89 @@
// Copyright (C) 2017 Sebastian Dröge <sebastian@centricular.com>
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use std::ptr;
use std::mem;
use mopa;
use glib_ffi;
use gobject_ffi;
use gst_ffi;
use gst_base_ffi;
use glib;
use glib::translate::*;
use gst;
use gst::prelude::*;
use gst_base;
use gst_base::prelude::*;
use object::*;
use element::*;
pub trait BaseSrcImpl: mopa::Any + ElementImpl + Send + Sync + 'static {}
mopafy!(BaseSrcImpl);
pub unsafe trait BaseSrc: IsA<gst_base::BaseSrc> {}
pub unsafe trait BaseSrcClass<T: ObjectType>
where
T::RsType: IsA<gst_base::BaseSrc>,
T::ImplType: BaseSrcImpl,
{
}
glib_wrapper! {
pub struct RsBaseSrc(Object<InstanceStruct<RsBaseSrc>>): [gst_base::BaseSrc => gst_base_ffi::GstBaseSrc,
gst::Element => gst_ffi::GstElement,
gst::Object => gst_ffi::GstObject];
match fn {
get_type => || get_type::<RsBaseSrc>(),
}
}
unsafe impl<T: IsA<gst_base::BaseSrc>> BaseSrc for T {}
pub type RsBaseSrcClass = ClassStruct<RsBaseSrc>;
// FIXME: Boilerplate
unsafe impl BaseSrcClass<RsBaseSrc> for gst_base_ffi::GstBaseSrcClass {}
unsafe impl BaseSrcClass<RsBaseSrc> for RsBaseSrcClass {}
unsafe impl ElementClass<RsBaseSrc> for gst_base_ffi::GstBaseSrcClass {}
unsafe impl ElementClass<RsBaseSrc> for RsBaseSrcClass {}
// FIXME: Boilerplate
impl BaseSrcImpl for Box<BaseSrcImpl> {}
// FIXME: Boilerplate
impl ElementImpl for Box<BaseSrcImpl> {
fn change_state(
&self,
element: &gst::Element,
transition: gst::StateChange,
) -> gst::StateChangeReturn {
let imp: &BaseSrcImpl = self.as_ref();
imp.change_state(element, transition)
}
}
impl ObjectType for RsBaseSrc {
const NAME: &'static str = "RsBaseSrc";
type GlibType = gst_base_ffi::GstBaseSrc;
type GlibClassType = gst_base_ffi::GstBaseSrcClass;
type RsType = RsBaseSrc;
type ImplType = Box<BaseSrcImpl>;
fn glib_type() -> glib::Type {
unsafe { from_glib(gst_base_ffi::gst_base_src_get_type()) }
}
fn class_init(klass: &mut Self::GlibClassType) {
ElementClass::override_vfuncs(klass);
}
}

73
gst-plugin/src/demuxer.rs
View file

@ -13,6 +13,7 @@ use std::u64;
use std::collections::BTreeMap;
use error::*;
use object::{register_type, ImplTypeStatic};
use element::*;
use glib;
@ -92,6 +93,7 @@ impl Stream {
}
}
// TODO: Get rid of this wrapper
pub struct DemuxerWrapper {
cat: gst::DebugCategory,
demuxer: Mutex<Box<DemuxerImpl>>,
@ -384,22 +386,19 @@ impl Demuxer {
}
}
fn class_init(
klass: &mut RsElementClass,
long_name: &str,
classification: &str,
description: &str,
author: &str,
input_caps: &gst::Caps,
output_caps: &gst::Caps,
) {
klass.set_metadata(long_name, classification, description, author);
fn class_init(klass: &mut RsElementClass, demuxer_info: &DemuxerInfo) {
klass.set_metadata(
&demuxer_info.long_name,
&demuxer_info.classification,
&demuxer_info.description,
&demuxer_info.author,
);
let pad_template = gst::PadTemplate::new(
"sink",
gst::PadDirection::Sink,
gst::PadPresence::Always,
input_caps,
&demuxer_info.input_caps,
);
klass.add_pad_template(pad_template);
@ -407,7 +406,7 @@ impl Demuxer {
"src_%u",
gst::PadDirection::Src,
gst::PadPresence::Sometimes,
output_caps,
&demuxer_info.output_caps,
);
klass.add_pad_template(pad_template);
}
@ -688,7 +687,7 @@ impl Demuxer {
impl ElementImpl for Demuxer {
fn change_state(
&self,
element: &RsElement,
element: &gst::Element,
transition: gst::StateChange,
) -> gst::StateChangeReturn {
let mut ret = gst::StateChangeReturn::Success;
@ -725,32 +724,34 @@ impl ElementImpl for Demuxer {
}
}
struct DemuxerStatic {
name: String,
demuxer_info: DemuxerInfo,
}
impl ImplTypeStatic<RsElement> for DemuxerStatic {
fn get_name(&self) -> &str {
self.name.as_str()
}
fn new(&self, element: &RsElement) -> Box<ElementImpl> {
Demuxer::init(element, &self.demuxer_info)
}
fn class_init(&self, klass: &mut RsElementClass) {
Demuxer::class_init(klass, &self.demuxer_info);
}
}
pub fn demuxer_register(plugin: &gst::Plugin, demuxer_info: DemuxerInfo) {
let name = demuxer_info.name.clone();
let rank = demuxer_info.rank;
let long_name = demuxer_info.long_name.clone();
let classification = demuxer_info.classification.clone();
let description = demuxer_info.description.clone();
let author = demuxer_info.author.clone();
let input_caps = demuxer_info.input_caps.clone();
let output_caps = demuxer_info.output_caps.clone();
let demuxer_static = DemuxerStatic {
name: format!("Demuxer-{}", name),
demuxer_info: demuxer_info,
};
element_register(
plugin,
&name,
rank,
move |klass| {
Demuxer::class_init(
klass,
&long_name,
&classification,
&description,
&author,
&input_caps,
&output_caps,
)
},
move |element| Demuxer::init(element, &demuxer_info),
);
let type_ = register_type(demuxer_static);
gst::Element::register(plugin, &name, rank, type_);
}

271
gst-plugin/src/element.rs
View file

@ -6,10 +6,8 @@
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use std::ffi::CString;
use std::ptr;
use std::mem;
use std::sync::atomic::AtomicBool;
use mopa;
use glib_ffi;
@ -21,10 +19,12 @@ use glib::translate::*;
use gst;
use gst::prelude::*;
use object::*;
pub trait ElementImpl: mopa::Any + Send + Sync + 'static {
fn change_state(
&self,
element: &RsElement,
element: &gst::Element,
transition: gst::StateChange,
) -> gst::StateChangeReturn {
element.parent_change_state(transition)
@ -53,7 +53,11 @@ pub unsafe trait Element: IsA<gst::Element> {
}
}
pub unsafe trait ElementClass {
pub unsafe trait ElementClass<T: ObjectType>
where
T::RsType: IsA<gst::Element>,
T::ImplType: ElementImpl,
{
fn add_pad_template(&mut self, pad_template: gst::PadTemplate) {
unsafe {
gst_ffi::gst_element_class_add_pad_template(
@ -80,14 +84,21 @@ pub unsafe trait ElementClass {
);
}
}
fn override_vfuncs(&mut self) {
unsafe {
let klass = &mut *(self as *const Self as *mut gst_ffi::GstElementClass);
klass.change_state = Some(element_change_state::<T>);
}
}
}
glib_wrapper! {
pub struct RsElement(Object<ffi::RsElement>): [gst::Element => gst_ffi::GstElement,
gst::Object => gst_ffi::GstObject];
pub struct RsElement(Object<InstanceStruct<RsElement>>): [gst::Element => gst_ffi::GstElement,
gst::Object => gst_ffi::GstObject];
match fn {
get_type => || ffi::rs_element_get_type(),
get_type => || get_type::<RsElement>(),
}
}
@ -95,211 +106,59 @@ impl RsElement {
pub fn get_impl(&self) -> &ElementImpl {
unsafe {
let stash = self.to_glib_none();
let ptr: *const ffi::RsElement = stash.0;
(*ptr).get_impl()
let ptr: *mut InstanceStruct<RsElement> = stash.0;
(*ptr).get_impl().as_ref()
}
}
}
unsafe impl<T: IsA<gst::Element>> Element for T {}
unsafe impl ElementClass for RsElementClass {}
pub type RsElementClass = ClassStruct<RsElement>;
unsafe impl ElementClass<RsElement> for RsElementClass {}
unsafe impl ElementClass<RsElement> for gst_ffi::GstElementClass {}
struct ElementData {
class_init: Box<Fn(&mut RsElementClass) + Send + 'static>,
init: Box<Fn(&RsElement) -> Box<ElementImpl> + Send + Sync + 'static>,
}
pub mod ffi {
use super::*;
use super::RsElement as RsElementWrapper;
#[repr(C)]
pub struct RsElement {
parent: gst_ffi::GstElement,
imp: *const Box<ElementImpl>,
panicked: AtomicBool,
}
impl RsElement {
pub fn get_impl(&self) -> &ElementImpl {
unsafe {
assert!(!self.imp.is_null());
&*(*self.imp)
}
}
}
#[repr(C)]
pub struct RsElementClass {
parent_class: gst_ffi::GstElementClass,
element_data: *const ElementData,
}
pub unsafe fn rs_element_get_type() -> glib_ffi::GType {
use std::sync::{Once, ONCE_INIT};
static mut TYPE: glib_ffi::GType = gobject_ffi::G_TYPE_INVALID;
static ONCE: Once = ONCE_INIT;
ONCE.call_once(|| {
let type_info = gobject_ffi::GTypeInfo {
class_size: mem::size_of::<RsElementClass>() as u16,
base_init: None,
base_finalize: None,
class_init: Some(element_class_init),
class_finalize: None,
class_data: ptr::null_mut(),
instance_size: mem::size_of::<RsElement>() as u16,
n_preallocs: 0,
instance_init: None,
value_table: ptr::null(),
};
let type_name = {
let mut idx = 0;
loop {
let type_name = CString::new(format!("RsElement-{}", idx)).unwrap();
if gobject_ffi::g_type_from_name(type_name.as_ptr()) ==
gobject_ffi::G_TYPE_INVALID
{
break type_name;
}
idx += 1;
}
};
TYPE = gobject_ffi::g_type_register_static(
gst_ffi::gst_element_get_type(),
type_name.as_ptr(),
&type_info,
gobject_ffi::GTypeFlags::empty(),
);
});
TYPE
}
unsafe extern "C" fn element_finalize(obj: *mut gobject_ffi::GObject) {
callback_guard!();
let element = &mut *(obj as *mut RsElement);
drop(Box::from_raw(element.imp as *mut Box<ElementImpl>));
element.imp = ptr::null_mut();
let klass = *(obj as *const glib_ffi::gpointer);
let parent_klass = gobject_ffi::g_type_class_peek_parent(klass);
let parent_klass = &*(gobject_ffi::g_type_class_peek_parent(parent_klass) as
*const gobject_ffi::GObjectClass);
parent_klass.finalize.map(|f| f(obj));
}
unsafe extern "C" fn element_sub_class_init(
klass: glib_ffi::gpointer,
klass_data: glib_ffi::gpointer,
) {
callback_guard!();
let element_data = &*(klass_data as *const ElementData);
{
let klass = &mut *(klass as *mut RsElementClass);
klass.element_data = element_data;
(element_data.class_init)(klass);
}
}
unsafe extern "C" fn element_class_init(
klass: glib_ffi::gpointer,
_klass_data: glib_ffi::gpointer,
) {
callback_guard!();
{
let gobject_klass = &mut *(klass as *mut gobject_ffi::GObjectClass);
gobject_klass.finalize = Some(element_finalize);
}
{
let element_klass = &mut *(klass as *mut gst_ffi::GstElementClass);
element_klass.change_state = Some(element_change_state);
}
}
unsafe extern "C" fn element_change_state(
ptr: *mut gst_ffi::GstElement,
transition: gst_ffi::GstStateChange,
) -> gst_ffi::GstStateChangeReturn {
callback_guard!();
let element = &*(ptr as *mut RsElement);
let wrap: RsElementWrapper = from_glib_borrow(ptr as *mut RsElement);
let imp = &*element.imp;
panic_to_error2!(&wrap, &element.panicked, gst::StateChangeReturn::Failure, {
imp.change_state(&wrap, from_glib(transition))
}).to_glib()
}
unsafe extern "C" fn element_sub_init(
instance: *mut gobject_ffi::GTypeInstance,
klass: glib_ffi::gpointer,
) {
callback_guard!();
let element = &mut *(instance as *mut RsElement);
let wrap: RsElementWrapper = from_glib_borrow(instance as *mut RsElement);
let klass = &*(klass as *const RsElementClass);
let element_data = &*klass.element_data;
let imp = (element_data.init)(&wrap);
element.imp = Box::into_raw(Box::new(imp));
}
pub fn element_register<F, G>(
plugin: &gst::Plugin,
name: &str,
rank: u32,
class_init: F,
init: G,
) where
F: Fn(&mut RsElementClass) + Send + 'static,
G: Fn(&RsElementWrapper) -> Box<ElementImpl> + Send + Sync + 'static,
{
unsafe {
let parent_type = rs_element_get_type();
let type_name = format!("RsElement-{}", name);
let element_data = ElementData {
class_init: Box::new(class_init),
init: Box::new(init),
};
let element_data = Box::into_raw(Box::new(element_data)) as glib_ffi::gpointer;
let type_info = gobject_ffi::GTypeInfo {
class_size: mem::size_of::<RsElementClass>() as u16,
base_init: None,
base_finalize: None,
class_init: Some(element_sub_class_init),
class_finalize: None,
class_data: element_data,
instance_size: mem::size_of::<RsElement>() as u16,
n_preallocs: 0,
instance_init: Some(element_sub_init),
value_table: ptr::null(),
};
let type_ = gobject_ffi::g_type_register_static(
parent_type,
type_name.to_glib_none().0,
&type_info,
gobject_ffi::GTypeFlags::empty(),
);
gst::Element::register(plugin, &name, rank, from_glib(type_));
}
// FIXME: Boilerplate
impl ElementImpl for Box<ElementImpl> {
fn change_state(
&self,
element: &gst::Element,
transition: gst::StateChange,
) -> gst::StateChangeReturn {
let imp: &ElementImpl = self.as_ref();
imp.change_state(element, transition)
}
}
pub use self::ffi::RsElementClass;
pub use self::ffi::element_register;
impl ObjectType for RsElement {
const NAME: &'static str = "RsElement";
type GlibType = gst_ffi::GstElement;
type GlibClassType = gst_ffi::GstElementClass;
type RsType = RsElement;
type ImplType = Box<ElementImpl>;
fn glib_type() -> glib::Type {
unsafe { from_glib(gst_ffi::gst_element_get_type()) }
}
fn class_init(klass: &mut Self::GlibClassType) {
klass.override_vfuncs();
}
}
unsafe extern "C" fn element_change_state<T: ObjectType>(
ptr: *mut gst_ffi::GstElement,
transition: gst_ffi::GstStateChange,
) -> gst_ffi::GstStateChangeReturn
where
T::RsType: IsA<gst::Element>,
T::ImplType: ElementImpl,
{
callback_guard!();
let element = &*(ptr as *mut InstanceStruct<T>);
let wrap: gst::Element = from_glib_borrow(ptr as *mut gst_ffi::GstElement);
let imp = &*element.imp;
panic_to_error2!(&wrap, &element.panicked, gst::StateChangeReturn::Failure, {
imp.change_state(&wrap, from_glib(transition))
}).to_glib()
}

2
gst-plugin/src/lib.rs
View file

@ -43,4 +43,6 @@ pub mod sink;
pub mod demuxer;
pub mod bytes;
pub mod object;
pub mod element;
pub mod base_src;

188
gst-plugin/src/object.rs Normal file
View file

@ -0,0 +1,188 @@
// Copyright (C) 2017 Sebastian Dröge <sebastian@centricular.com>
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use std::ffi::CString;
use std::ptr;
use std::mem;
use std::sync::atomic::AtomicBool;
use glib_ffi;
use gobject_ffi;
use glib;
use glib::translate::*;
pub trait ImplTypeStatic<T: ObjectType>: Send + Sync + 'static {
fn get_name(&self) -> &str;
fn new(&self, &T::RsType) -> T::ImplType;
fn class_init(&self, &mut ClassStruct<T>);
}
pub trait ObjectType: 'static
where
Self: Sized,
{
const NAME: &'static str;
type GlibType;
type GlibClassType;
type RsType: FromGlibPtrBorrow<*mut InstanceStruct<Self>>;
type ImplType: 'static;
fn glib_type() -> glib::Type;
fn class_init(klass: &mut Self::GlibClassType);
}
#[repr(C)]
pub struct InstanceStruct<T: ObjectType> {
pub parent: T::GlibType,
pub imp: *const T::ImplType,
pub panicked: AtomicBool,
}
impl<T: ObjectType> InstanceStruct<T> {
pub fn get_impl(&self) -> &T::ImplType {
unsafe { &*self.imp }
}
}
#[repr(C)]
pub struct ClassStruct<T: ObjectType> {
pub parent: T::GlibClassType,
pub imp_static: *const Box<ImplTypeStatic<T>>,
}
unsafe extern "C" fn class_init<T: ObjectType>(
klass: glib_ffi::gpointer,
_klass_data: glib_ffi::gpointer,
) {
callback_guard!();
{
let gobject_klass = &mut *(klass as *mut gobject_ffi::GObjectClass);
gobject_klass.finalize = Some(finalize::<T>);
}
T::class_init(&mut *(klass as *mut T::GlibClassType));
}
unsafe extern "C" fn finalize<T: ObjectType>(obj: *mut gobject_ffi::GObject) {
callback_guard!();
let instance = &mut *(obj as *mut InstanceStruct<T>);
drop(Box::from_raw(instance.imp as *mut T::ImplType));
instance.imp = ptr::null_mut();
let klass = *(obj as *const glib_ffi::gpointer);
let parent_klass = gobject_ffi::g_type_class_peek_parent(klass);
let parent_klass =
&*(gobject_ffi::g_type_class_peek_parent(parent_klass) as *const gobject_ffi::GObjectClass);
parent_klass.finalize.map(|f| f(obj));
}
pub unsafe fn get_type<T: ObjectType>() -> glib_ffi::GType {
use std::sync::{Once, ONCE_INIT};
static mut TYPE: glib_ffi::GType = gobject_ffi::G_TYPE_INVALID;
static ONCE: Once = ONCE_INIT;
ONCE.call_once(|| {
let type_info = gobject_ffi::GTypeInfo {
class_size: mem::size_of::<ClassStruct<T>>() as u16,
base_init: None,
base_finalize: None,
class_init: Some(class_init::<T>),
class_finalize: None,
class_data: ptr::null_mut(),
instance_size: mem::size_of::<InstanceStruct<T>>() as u16,
n_preallocs: 0,
instance_init: None,
value_table: ptr::null(),
};
let type_name = {
let mut idx = 0;
loop {
let type_name = CString::new(format!("{}-{}", T::NAME, idx)).unwrap();
if gobject_ffi::g_type_from_name(type_name.as_ptr()) == gobject_ffi::G_TYPE_INVALID
{
break type_name;
}
idx += 1;
}
};
TYPE = gobject_ffi::g_type_register_static(
T::glib_type().to_glib(),
type_name.as_ptr(),
&type_info,
gobject_ffi::GTypeFlags::empty(),
);
});
TYPE
}
unsafe extern "C" fn sub_class_init<T: ObjectType>(
klass: glib_ffi::gpointer,
klass_data: glib_ffi::gpointer,
) {
callback_guard!();
{
let klass = &mut *(klass as *mut ClassStruct<T>);
let imp_static = klass_data as *const Box<ImplTypeStatic<T>>;
klass.imp_static = imp_static;
(*imp_static).class_init(klass);
}
}
unsafe extern "C" fn sub_init<T: ObjectType>(
obj: *mut gobject_ffi::GTypeInstance,
_klass: glib_ffi::gpointer,
) {
callback_guard!();
let instance = &mut *(obj as *mut InstanceStruct<T>);
let klass = &**(obj as *const *const ClassStruct<T>);
let rs_instance: T::RsType = from_glib_borrow(obj as *mut InstanceStruct<T>);
let imp = (*klass.imp_static).new(&rs_instance);
instance.imp = Box::into_raw(Box::new(imp));
}
pub fn register_type<T: ObjectType, I: ImplTypeStatic<T>>(imp: I) -> glib::Type {
unsafe {
let parent_type = get_type::<T>();
let type_name = format!("{}-{}", T::NAME, imp.get_name());
let imp: Box<ImplTypeStatic<T>> = Box::new(imp);
let type_info = gobject_ffi::GTypeInfo {
class_size: mem::size_of::<ClassStruct<T>>() as u16,
base_init: None,
base_finalize: None,
class_init: Some(sub_class_init::<T>),
class_finalize: None,
class_data: Box::into_raw(Box::new(imp)) as glib_ffi::gpointer,
instance_size: mem::size_of::<InstanceStruct<T>>() as u16,
n_preallocs: 0,
instance_init: Some(sub_init::<T>),
value_table: ptr::null(),
};
let type_ = gobject_ffi::g_type_register_static(
parent_type,
type_name.to_glib_none().0,
&type_info,
gobject_ffi::GTypeFlags::empty(),
);
from_glib(type_)
}
}