Improve the VSYNC api a bit.

- add the ability to set the vsync delivery rate, when the rate is
set to N>1 (ie: receive every N vsync), SF process' is woken up for
all of vsync, but clients only see the every N events.

- add the concept of one-shot vsync events, with a call-back
to request the next one. currently the call-back is a binder IPC.

Change-Id: I09f71df0b0ba0d88ed997645e2e2497d553c9a1b

2 files changed, 45 insertions, 0 deletions

diff --git a/libs/gui/DisplayEventReceiver.cpp b/libs/gui/DisplayEventReceiver.cpp
index 3b29a113e4..fee1febb9b 100644
--- a/libs/gui/DisplayEventReceiver.cpp
+++ b/libs/gui/DisplayEventReceiver.cpp
@@ -58,6 +58,26 @@ int DisplayEventReceiver::getFd() const {
     return mDataChannel->getFd();
 }
 
+status_t DisplayEventReceiver::setVsyncRate(uint32_t count) {
+    if (int32_t(count) < 0)
+        return BAD_VALUE;
+
+    if (mEventConnection != NULL) {
+        mEventConnection->setVsyncRate(count);
+        return NO_ERROR;
+    }
+    return NO_INIT;
+}
+
+status_t DisplayEventReceiver::requestNextVsync() {
+    if (mEventConnection != NULL) {
+        mEventConnection->requestNextVsync();
+        return NO_ERROR;
+    }
+    return NO_INIT;
+}
+
+
 ssize_t DisplayEventReceiver::getEvents(DisplayEventReceiver::Event* events,
         size_t count) {
     ssize_t size = mDataChannel->read(events, sizeof(events[0])*count);
diff --git a/libs/gui/IDisplayEventConnection.cpp b/libs/gui/IDisplayEventConnection.cpp
index 44127fb4ac..887d176b44 100644
--- a/libs/gui/IDisplayEventConnection.cpp
+++ b/libs/gui/IDisplayEventConnection.cpp
@@ -32,6 +32,8 @@ namespace android {
 
 enum {
     GET_DATA_CHANNEL = IBinder::FIRST_CALL_TRANSACTION,
+    SET_VSYNC_RATE,
+    REQUEST_NEXT_VSYNC
 };
 
 class BpDisplayEventConnection : public BpInterface<IDisplayEventConnection>
@@ -49,6 +51,19 @@ public:
         remote()->transact(GET_DATA_CHANNEL, data, &reply);
         return new BitTube(reply);
     }
+
+    virtual void setVsyncRate(uint32_t count) {
+        Parcel data, reply;
+        data.writeInterfaceToken(IDisplayEventConnection::getInterfaceDescriptor());
+        data.writeInt32(count);
+        remote()->transact(SET_VSYNC_RATE, data, &reply);
+    }
+
+    virtual void requestNextVsync() {
+        Parcel data, reply;
+        data.writeInterfaceToken(IDisplayEventConnection::getInterfaceDescriptor());
+        remote()->transact(REQUEST_NEXT_VSYNC, data, &reply, IBinder::FLAG_ONEWAY);
+    }
 };
 
 IMPLEMENT_META_INTERFACE(DisplayEventConnection, "android.gui.DisplayEventConnection");
@@ -65,6 +80,16 @@ status_t BnDisplayEventConnection::onTransact(
             channel->writeToParcel(reply);
             return NO_ERROR;
         } break;
+        case SET_VSYNC_RATE: {
+            CHECK_INTERFACE(IDisplayEventConnection, data, reply);
+            setVsyncRate(data.readInt32());
+            return NO_ERROR;
+        } break;
+        case REQUEST_NEXT_VSYNC: {
+            CHECK_INTERFACE(IDisplayEventConnection, data, reply);
+            requestNextVsync();
+            return NO_ERROR;
+        } break;
     }
     return BBinder::onTransact(code, data, reply, flags);
 }