webkit/glue/cpp_binding_example.h

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 /*
   6   CppBindingExample class:
   7   This provides an example of how to use the CppBoundClass to create methods
   8   and properties that can be exposed to JavaScript by an appropriately built
   9   embedding client. It is also used by the CppBoundClass unit test.
  10
  11   Typically, a class intended to be bound to JavaScript will define a
  12   constructor, any methods and properties to be exposed, and optionally a
  13   destructor.  An embedding client can then bind the class to a JavaScript
  14   object in a frame's window using the CppBoundClass::BindToJavascript() method,
  15   generally called from the WebFrameClient's DidClearWindowObject().
  16
  17   Once this class has been bound, say to the name "example", it might be called
  18   from JavaScript in the following way:
  19
  20   <script>
  21     if (window.example) {
  22       document.writeln(example.echoValue(false));
  23       document.writeln(example.echoType("Hello world!"));
  24       document.writeln(example.plus(2, 3.1));
  25
  26       example.my_value = 15;
  27       example.my_other_value = 2.1;
  28       document.writeln(example.plus(example.my_value, example.my_other_value));
  29     }
  30   </script>
  31 */
  32
  33 #ifndef CPP_BINDING_EXAMPLE_H__
  34 #define CPP_BINDING_EXAMPLE_H__
  35
  36 #include "webkit/glue/cpp_bound_class.h"
  37
  38 class CppBindingExample : public CppBoundClass {
  39  public:
  40   // The default constructor initializes the property and method lists needed
  41   // to bind this class to a JS object.
  42   CppBindingExample();
  43
  44   //
  45   // These public member variables and methods implement the methods and
  46   // properties that will be exposed to JavaScript. If needed, the class could
  47   // also contain other methods or variables, which will be hidden from JS
  48   // as long as they're not mapped in the property and method lists created in
  49   // the constructor.
  50   //
  51   // The signatures of any methods to be bound must match
  52   // CppBoundClass::Callback.
  53   //
  54
  55   // Returns the value that was passed in as its first (only) argument.
  56   void echoValue(const CppArgumentList& args, CppVariant* result);
  57
  58   // Returns a hard-coded value of the same type (bool, number (double),
  59   // string, or null) that was passed in as an argument.
  60   void echoType(const CppArgumentList& args, CppVariant* result);
  61
  62   // Returns the sum of the (first) two arguments as a double, if they are both
  63   // numbers (integers or doubles).  Otherwise returns null.
  64   void plus(const CppArgumentList& args, CppVariant* result);
  65
  66   // Always returns the same value -- an example of a read-only property.
  67   void same(CppVariant* result);
  68
  69   // Invoked when a nonexistent method is called on this example object, this
  70   // prints an error message.
  71   void fallbackMethod(const CppArgumentList& args, CppVariant* result);
  72
  73   // These properties will also be exposed to JavaScript.
  74   CppVariant my_value;
  75   CppVariant my_other_value;
  76 };
  77
  78 #endif  // CPP_BINDING_EXAMPLE_H__