From 3d3fe5026a6a3e951ef56ad16a100b8d5ae84574 Mon Sep 17 00:00:00 2001
From: Michael Wright <michaelwr@google.com>
Date: Fri, 4 Dec 2015 17:59:42 +0000
Subject: Add choreographer API to the NDK.

Change-Id: Icb8cffd3cd3bd06814466be72db3e26f6a62cbc6
---
 libs/androidfw/DisplayEventDispatcher.cpp | 147 ++++++++++++++++++++++++++++++
 1 file changed, 147 insertions(+)
 create mode 100644 libs/androidfw/DisplayEventDispatcher.cpp

(limited to 'libs/androidfw/DisplayEventDispatcher.cpp')

diff --git a/libs/androidfw/DisplayEventDispatcher.cpp b/libs/androidfw/DisplayEventDispatcher.cpp
new file mode 100644
index 000000000000..99cd1732031c
--- /dev/null
+++ b/libs/androidfw/DisplayEventDispatcher.cpp
@@ -0,0 +1,147 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+#define LOG_TAG "DisplayEventDispatcher"
+
+#include <cinttypes>
+#include <cstdint>
+
+#include <androidfw/DisplayEventDispatcher.h>
+#include <gui/DisplayEventReceiver.h>
+#include <utils/Log.h>
+#include <utils/Looper.h>
+
+#include <utils/Timers.h>
+
+namespace android {
+
+// Number of events to read at a time from the DisplayEventDispatcher pipe.
+// The value should be large enough that we can quickly drain the pipe
+// using just a few large reads.
+static const size_t EVENT_BUFFER_SIZE = 100;
+
+DisplayEventDispatcher::DisplayEventDispatcher(const sp<Looper>& looper) :
+        mLooper(looper), mWaitingForVsync(false) {
+    ALOGV("dispatcher %p ~ Initializing display event dispatcher.", this);
+}
+
+status_t DisplayEventDispatcher::initialize() {
+    status_t result = mReceiver.initCheck();
+    if (result) {
+        ALOGW("Failed to initialize display event receiver, status=%d", result);
+        return result;
+    }
+
+    int rc = mLooper->addFd(mReceiver.getFd(), 0, Looper::EVENT_INPUT,
+            this, NULL);
+    if (rc < 0) {
+        return UNKNOWN_ERROR;
+    }
+    return OK;
+}
+
+void DisplayEventDispatcher::dispose() {
+    ALOGV("dispatcher %p ~ Disposing display event dispatcher.", this);
+
+    if (!mReceiver.initCheck()) {
+        mLooper->removeFd(mReceiver.getFd());
+    }
+}
+
+status_t DisplayEventDispatcher::scheduleVsync() {
+    if (!mWaitingForVsync) {
+        ALOGV("dispatcher %p ~ Scheduling vsync.", this);
+
+        // Drain all pending events.
+        nsecs_t vsyncTimestamp;
+        int32_t vsyncDisplayId;
+        uint32_t vsyncCount;
+        if (processPendingEvents(&vsyncTimestamp, &vsyncDisplayId, &vsyncCount)) {
+            ALOGE("dispatcher %p ~ last event processed while scheduling was for %" PRId64 "",
+                    this, ns2ms(static_cast<nsecs_t>(vsyncTimestamp)));
+        }
+
+        status_t status = mReceiver.requestNextVsync();
+        if (status) {
+            ALOGW("Failed to request next vsync, status=%d", status);
+            return status;
+        }
+
+        mWaitingForVsync = true;
+    }
+    return OK;
+}
+
+int DisplayEventDispatcher::handleEvent(int, int events, void*) {
+    if (events & (Looper::EVENT_ERROR | Looper::EVENT_HANGUP)) {
+        ALOGE("Display event receiver pipe was closed or an error occurred.  "
+                "events=0x%x", events);
+        return 0; // remove the callback
+    }
+
+    if (!(events & Looper::EVENT_INPUT)) {
+        ALOGW("Received spurious callback for unhandled poll event.  "
+                "events=0x%x", events);
+        return 1; // keep the callback
+    }
+
+    // Drain all pending events, keep the last vsync.
+    nsecs_t vsyncTimestamp;
+    int32_t vsyncDisplayId;
+    uint32_t vsyncCount;
+    if (processPendingEvents(&vsyncTimestamp, &vsyncDisplayId, &vsyncCount)) {
+        ALOGE("dispatcher %p ~ Vsync pulse: timestamp=%" PRId64 ", id=%d, count=%d",
+                this, ns2ms(vsyncTimestamp), vsyncDisplayId, vsyncCount);
+        mWaitingForVsync = false;
+        dispatchVsync(vsyncTimestamp, vsyncDisplayId, vsyncCount);
+    }
+
+    return 1; // keep the callback
+}
+
+bool DisplayEventDispatcher::processPendingEvents(
+        nsecs_t* outTimestamp, int32_t* outId, uint32_t* outCount) {
+    bool gotVsync = false;
+    DisplayEventReceiver::Event buf[EVENT_BUFFER_SIZE];
+    ssize_t n;
+    while ((n = mReceiver.getEvents(buf, EVENT_BUFFER_SIZE)) > 0) {
+        ALOGV("dispatcher %p ~ Read %d events.", this, int(n));
+        for (ssize_t i = 0; i < n; i++) {
+            const DisplayEventReceiver::Event& ev = buf[i];
+            switch (ev.header.type) {
+            case DisplayEventReceiver::DISPLAY_EVENT_VSYNC:
+                // Later vsync events will just overwrite the info from earlier
+                // ones. That's fine, we only care about the most recent.
+                gotVsync = true;
+                *outTimestamp = ev.header.timestamp;
+                *outId = ev.header.id;
+                *outCount = ev.vsync.count;
+                break;
+            case DisplayEventReceiver::DISPLAY_EVENT_HOTPLUG:
+                dispatchHotplug(ev.header.timestamp, ev.header.id, ev.hotplug.connected);
+                break;
+            default:
+                ALOGW("dispatcher %p ~ ignoring unknown event type %#x", this, ev.header.type);
+                break;
+            }
+        }
+    }
+    if (n < 0) {
+        ALOGW("Failed to get events from display event dispatcher, status=%d", status_t(n));
+    }
+    return gotVsync;
+}
+}
-- 
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