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
  19 /* this is handy wrapper around JSAPI to make it more pleasant to use.
  20  * We collect the JSAPI errors and so that callers don't need to */
  21 class MOZ_STACK_CLASS InfoObject
  22 {
  23   friend class GfxInfoBase;
  24
  25   public:
  26   void DefineProperty(const char *name, int value);
  27   void DefineProperty(const char *name, nsAString &value);
  28   void DefineProperty(const char *name, const char *value);
  29
  30   private:
  31   // We need to ensure that this object lives on the stack so that GC sees it properly
  32   explicit InfoObject(JSContext *aCx);
  33   InfoObject(InfoObject&);
  34
  35   JSContext *mCx;
  36   JS::Rooted<JSObject*> mObj;
  37   bool mOk;
  38 };
  39
  40 /*
  41
  42    Here's an example usage:
  43
  44    class Foo {
  45    Foo::Foo() : mInfoCollector(this, &Foo::GetAweseomeness) {}
  46
  47    void GetAwesomeness(InfoObject &obj) {
  48      obj.DefineProperty("awesome", mAwesome);
  49    }
  50
  51    int mAwesome;
  52
  53    GfxInfoCollector<Foo> mInfoCollector;
  54    }
  55
  56    This will define a property on the object
  57    returned from calling getInfo() on a
  58    GfxInfo object. e.g.
  59
  60        gfxInfo = Cc["@mozilla.org/gfx/info;1"].getService(Ci.nsIGfxInfo);
  61        info = gfxInfo.getInfo();
  62        if (info.awesome)
  63           alert(info.awesome);
  64
  65 */
  66
  67 class GfxInfoCollectorBase
  68 {
  69   public:
  70   GfxInfoCollectorBase();
  71   virtual void GetInfo(InfoObject &obj) = 0;
  72   virtual ~GfxInfoCollectorBase();
  73 };
  74
  75 template<class T>
  76 class GfxInfoCollector : public GfxInfoCollectorBase
  77 {
  78   public:
  79   GfxInfoCollector(T* aPointer, void (T::*aFunc)(InfoObject &obj)) : mPointer(aPointer), mFunc(aFunc) {
  80   }
  81   virtual void GetInfo(InfoObject &obj) override {
  82     (mPointer->*mFunc)(obj);
  83   }
  84
  85   protected:
  86   T* mPointer;
  87   void (T::*mFunc)(InfoObject &obj);
  88
  89 };
  90
  91 }
  92 }
  93
  94 #endif