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/* vim: se cin sw=2 ts=2 et : */
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at */
#ifndef __mozilla_widget_GfxInfoCollector_h__
#define __mozilla_widget_GfxInfoCollector_h__
#include "mozilla/Attributes.h"
#include "nsStringFwd.h"
#include "js/RootingAPI.h"
namespace mozilla {
namespace widget {
/* this is handy wrapper around JSAPI to make it more pleasant to use.
* We collect the JSAPI errors and so that callers don't need to */
class MOZ_STACK_CLASS InfoObject {
friend class GfxInfoBase;
void DefineProperty(const char* name, int value);
void DefineProperty(const char* name, const nsAString& value);
void DefineProperty(const char* name, const char* value);
// We need to ensure that this object lives on the stack so that GC sees it
// properly
explicit InfoObject(JSContext* aCx);
JSContext* mCx;
JS::Rooted<JSObject*> mObj;
bool mOk;
Here's an example usage:
class Foo {
Foo::Foo() : mInfoCollector(this, &Foo::GetAweseomeness) {}
void GetAwesomeness(InfoObject &obj) {
obj.DefineProperty("awesome", mAwesome);
int mAwesome;
GfxInfoCollector<Foo> mInfoCollector;
This will define a property on the object
returned from calling getInfo() on a
GfxInfo object. e.g.
gfxInfo = Cc[";1"].getService(Ci.nsIGfxInfo);
info = gfxInfo.getInfo();
if (info.awesome)
class GfxInfoCollectorBase {
virtual void GetInfo(InfoObject& obj) = 0;
virtual ~GfxInfoCollectorBase();
template <class T>
class GfxInfoCollector : public GfxInfoCollectorBase {
GfxInfoCollector(T* aPointer, void (T::*aFunc)(InfoObject& obj))
: mPointer(aPointer), mFunc(aFunc) {}
virtual void GetInfo(InfoObject& obj) override { (mPointer->*mFunc)(obj); }
T* mPointer;
void (T::*mFunc)(InfoObject& obj);
} // namespace widget
} // namespace mozilla