Add support for sending VSYNC events to the framework

use gui/DisplayEvent to receive the events. Events are
dispatched through a unix pipe, so the API is compatible
with utils/Looper. see gui/DisplayEvent.h for more info.

Bug: 1475048
Change-Id: Ia720f64d1b950328b47b22c6a86042e481d35f09

1 files changed, 105 insertions, 0 deletions

diff --git a/include/gui/DisplayEventReceiver.h b/include/gui/DisplayEventReceiver.h
new file mode 100644
index 0000000..8d07c0e
--- /dev/null
+++ b/include/gui/DisplayEventReceiver.h
@@ -0,0 +1,105 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_GUI_DISPLAY_EVENT_H
+#define ANDROID_GUI_DISPLAY_EVENT_H
+
+#include <stdint.h>
+#include <sys/types.h>
+
+#include <utils/Errors.h>
+#include <utils/RefBase.h>
+#include <utils/Timers.h>
+
+#include <binder/IInterface.h>
+
+// ----------------------------------------------------------------------------
+
+namespace android {
+
+// ----------------------------------------------------------------------------
+
+class BitTube;
+class IDisplayEventConnection;
+
+// ----------------------------------------------------------------------------
+
+class DisplayEventReceiver {
+public:
+    enum {
+        DISPLAY_EVENT_VSYNC = 'vsyn'
+    };
+
+    struct Event {
+
+        struct Header {
+            uint32_t type;
+            nsecs_t timestamp;
+        };
+
+        struct VSync {
+            uint32_t count;
+        };
+
+        Header header;
+        union {
+            VSync vsync;
+        };
+    };
+
+public:
+    /*
+     * DisplayEventReceiver creates and registers an event connection with
+     * SurfaceFlinger. Events start being delivered immediately.
+     */
+    DisplayEventReceiver();
+
+    /*
+     * ~DisplayEventReceiver severs the connection with SurfaceFlinger, new events
+     * stop being delivered immediately. Note that the queue could have
+     * some events pending. These will be delivered.
+     */
+    ~DisplayEventReceiver();
+
+    /*
+     * initCheck returns the state of DisplayEventReceiver after construction.
+     */
+    status_t initCheck() const;
+
+    /*
+     * getFd returns the file descriptor to use to receive events.
+     * OWNERSHIP IS RETAINED by DisplayEventReceiver. DO NOT CLOSE this
+     * file-descriptor.
+     */
+    int getFd() const;
+
+    /*
+     * getEvents reads event from the queue and returns how many events were
+     * read. Returns 0 if there are no more events or a negative error code.
+     * If NOT_ENOUGH_DATA is returned, the object has become invalid forever, it
+     * should be destroyed and getEvents() shouldn't be called again.
+     */
+    ssize_t getEvents(Event* events, size_t count);
+
+private:
+    sp<IDisplayEventConnection> mEventConnection;
+    sp<BitTube> mDataChannel;
+};
+
+// ----------------------------------------------------------------------------
+}; // namespace android
+
+#endif // ANDROID_GUI_DISPLAY_EVENT_H