Implement asynchronous interface/plumbing for GetDefaultPrintSettings.

ppapi/cpp/dev/printing_dev.cc

Index: ppapi/cpp/dev/printing_dev.cc
diff --git a/ppapi/cpp/dev/printing_dev.cc b/ppapi/cpp/dev/printing_dev.cc
index 8c307251fbac70261bd2fa8089976449852f8966..05477e83fa85490ee24c9df1108235dc69fa0059 100644
--- a/ppapi/cpp/dev/printing_dev.cc
+++ b/ppapi/cpp/dev/printing_dev.cc
@@ -5,6 +5,7 @@
 #include "ppapi/cpp/dev/printing_dev.h"
 
 #include "ppapi/c/dev/ppb_printing_dev.h"
+#include "ppapi/cpp/completion_callback.h"
 #include "ppapi/cpp/instance.h"
 #include "ppapi/cpp/instance_handle.h"
 #include "ppapi/cpp/module.h"
@@ -16,6 +17,10 @@ namespace {
 
 static const char kPPPPrintingInterface[] = PPP_PRINTING_DEV_INTERFACE;
 
+template <> const char* interface_name<PPB_Printing_Dev_0_7>() {
+  return PPB_PRINTING_DEV_INTERFACE_0_7;
+}
+
 template <> const char* interface_name<PPB_Printing_Dev_0_6>() {
   return PPB_PRINTING_DEV_INTERFACE_0_6;
 }
@@ -88,7 +93,8 @@ Printing_Dev::~Printing_Dev() {
 
 // static
 bool Printing_Dev::IsAvailable() {
-  return has_interface<PPB_Printing_Dev_0_6>();
+  return has_interface<PPB_Printing_Dev_0_7>() ||
+      has_interface<PPB_Printing_Dev_0_6>();
 }
 
 bool Printing_Dev::GetDefaultPrintSettings(
@@ -100,4 +106,23 @@ bool Printing_Dev::GetDefaultPrintSettings(
           associated_instance_.pp_instance(), print_settings));
 }
 
+int32_t Printing_Dev::GetDefaultPrintSettings(

[viettrungluu, 2012/07/24 00:44:35]

This isn't a very good design, since Printing_Dev isn't a resource, and thus
there's no way to cancel the callback (and how exactly would one manage the
lifetime of |print_settings|?).

Moreover, C++ wrappers should use the callback-with-output stuff.

[viettrungluu, 2012/07/24 01:08:37]

(Probably using the callback-with-output solves the problem enough for our
purposes, since the caller can use a completion callback factory.)

But you should make this respect the flags in |callback| -- i.e., only return
something other than |PP_OK_COMPLETIONPENDING| when
|PP_COMPLETIONCALLBACK_FLAG_OPTIONAL| is set. Actually, it'd probably be easier
to make this return void and post the callback if necessary.

+    PP_PrintSettings_Dev* print_settings,
+    const CompletionCallback& callback) const {
+  if (has_interface<PPB_Printing_Dev_0_6>()) {

[viettrungluu, 2012/07/24 00:44:35]

These interface checks are in the wrong order.

+    bool success =
+        get_interface<PPB_Printing_Dev_0_6>()->GetDefaultPrintSettings(

[viettrungluu, 2012/07/24 00:44:35]

You should convert from a PP_Bool to a bool properly.

+            associated_instance_.pp_instance(), print_settings);
+    Module::Get()->core()->CallOnMainThread(0, callback,
+                                            success ? PP_OK : PP_ERROR);

[viettrungluu, 2012/07/24 00:44:35]

PP_ERROR_FAILED

+    return PP_OK_COMPLETIONPENDING;
+  }
+  if (has_interface<PPB_Printing_Dev_0_7>()) {
+    return get_interface<PPB_Printing_Dev_0_7>()->GetDefaultPrintSettings(
+        associated_instance_.pp_instance(), print_settings,
+        callback.pp_completion_callback());
+  }
+  return PP_ERROR_FAILED;
+}
+
 }  // namespace pp