commit 60aee1c46b52852e140f05748f69e38f4e3de36e
author Alec Mouri <alecmouri@google.com> Mon Oct 28 16:18:59 2019 -0700
committer Alec Mouri <alecmouri@google.com> Thu Dec 26 10:28:47 2019 -0800
tree 7a29657039f1f8911fdef5689aa39e7fd4f3f6bd
parent 516de508aa52a0907a496890dc191501481bca7b

[AChoreographer] Add refresh rate callback.

This will augment the NDK to respond to display events where the display
refresh rate changes. Consumers of this api will include:
* HWUI, for implementing a policy for determining whether to use
render-ahead,
* Swappy, to potentially replace jumping into Java from native code to
respond to display evnets there.
* Any other native app that would rely on the up-to-date display refresh
rate.

Currently however this is not yet exposed to NDK as CTS is not yet
written. Once CTS is written then this will be formally exposed to NDK.
For now we'll leave these as APEX apis to represent incremental
progress.

Bug: 136262896
Test: builds
Change-Id: I66d393f93eb5d681547411e330ef1b8950a35c5d

libs/gui/DisplayEventDispatcher.cpp

diff --git a/libs/gui/DisplayEventDispatcher.cpp b/libs/gui/DisplayEventDispatcher.cpp
index 54f383e..208d729 100644
--- a/libs/gui/DisplayEventDispatcher.cpp
+++ b/libs/gui/DisplayEventDispatcher.cpp
@@ -36,7 +36,10 @@
 DisplayEventDispatcher::DisplayEventDispatcher(const sp<Looper>& looper,
                                                ISurfaceComposer::VsyncSource vsyncSource,
                                                ISurfaceComposer::ConfigChanged configChanged)
-      : mLooper(looper), mReceiver(vsyncSource, configChanged), mWaitingForVsync(false) {
+      : mLooper(looper),
+        mReceiver(vsyncSource, configChanged),
+        mWaitingForVsync(false),
+        mConfigChangeFlag(configChanged) {
     ALOGV("dispatcher %p ~ Initializing display event dispatcher.", this);
 }
 
@@ -86,6 +89,18 @@
     return OK;
 }
 
+void DisplayEventDispatcher::toggleConfigEvents(ISurfaceComposer::ConfigChanged configChangeFlag) {
+    if (mConfigChangeFlag == configChangeFlag) {
+        return;
+    }
+    status_t status = mReceiver.toggleConfigEvents(configChangeFlag);
+    if (status) {
+        ALOGW("Failed enable config events, status=%d", status);
+        return;
+    }
+    mConfigChangeFlag = configChangeFlag;
+}
+
 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.  "
@@ -140,7 +155,7 @@
                     break;
                 case DisplayEventReceiver::DISPLAY_EVENT_CONFIG_CHANGED:
                     dispatchConfigChanged(ev.header.timestamp, ev.header.displayId,
-                                          ev.config.configId);
+                                          ev.config.configId, ev.config.vsyncPeriod);
                     break;
                 default:
                     ALOGW("dispatcher %p ~ ignoring unknown event type %#x", this, ev.header.type);