widget/GfxInfoCollector.h

   1 /* vim: se cin sw=2 ts=2 et : */
   2 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   3  *
   4  * This Source Code Form is subject to the terms of the Mozilla Public
   5  * License, v. 2.0. If a copy of the MPL was not distributed with this
   6  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   7
   8 #ifndef __mozilla_widget_GfxInfoCollector_h__
   9 #define __mozilla_widget_GfxInfoCollector_h__
  10
  11 #include "mozilla/Attributes.h"
  12 #include "nsStringFwd.h"
  13 #include "js/RootingAPI.h"
  14
  15 namespace mozilla {
  16 namespace widget {
  17
  18 /* this is handy wrapper around JSAPI to make it more pleasant to use.
  19  * We collect the JSAPI errors and so that callers don't need to */
  20 class MOZ_STACK_CLASS InfoObject {
  21   friend class GfxInfoBase;
  22
  23  public:
  24   void DefineProperty(const char* name, int value);
  25   void DefineProperty(const char* name, const nsAString& value);
  26   void DefineProperty(const char* name, const char* value);
  27
  28  private:
  29   // We need to ensure that this object lives on the stack so that GC sees it
  30   // properly
  31   explicit InfoObject(JSContext* aCx);
  32   InfoObject(InfoObject&);
  33
  34   JSContext* mCx;
  35   JS::Rooted<JSObject*> mObj;
  36   bool mOk;
  37 };
  38
  39 /*
  40
  41    Here's an example usage:
  42
  43    class Foo {
  44    Foo::Foo() : mInfoCollector(this, &Foo::GetAweseomeness) {}
  45
  46    void GetAwesomeness(InfoObject &obj) {
  47      obj.DefineProperty("awesome", mAwesome);
  48    }
  49
  50    int mAwesome;
  51
  52    GfxInfoCollector<Foo> mInfoCollector;
  53    }
  54
  55    This will define a property on the object
  56    returned from calling getInfo() on a
  57    GfxInfo object. e.g.
  58
  59        gfxInfo = Cc["@mozilla.org/gfx/info;1"].getService(Ci.nsIGfxInfo);
  60        info = gfxInfo.getInfo();
  61        if (info.awesome)
  62           alert(info.awesome);
  63
  64 */
  65
  66 class GfxInfoCollectorBase {
  67  public:
  68   GfxInfoCollectorBase();
  69   virtual void GetInfo(InfoObject& obj) = 0;
  70   virtual ~GfxInfoCollectorBase();
  71 };
  72
  73 template <class T>
  74 class GfxInfoCollector : public GfxInfoCollectorBase {
  75  public:
  76   GfxInfoCollector(T* aPointer, void (T::*aFunc)(InfoObject& obj))
  77       : mPointer(aPointer), mFunc(aFunc) {}
  78   virtual void GetInfo(InfoObject& obj) override { (mPointer->*mFunc)(obj); }
  79
  80  protected:
  81   T* mPointer;
  82   void (T::*mFunc)(InfoObject& obj);
  83 };
  84
  85 }  // namespace widget
  86 }  // namespace mozilla
  87
  88 #endif