From 076acace33a13f588d3e7450872e738bc1fa3f06 Mon Sep 17 00:00:00 2001
From: Chavi Weingarten <chaviw@google.com>
Date: Thu, 19 Jan 2023 17:20:43 +0000
Subject: SurfaceFlinger: Add TrustedPresentationListener API

TrustedPresentationListener is intended to allow the producer
of a buffer layer to gain a trusted signal on whether and to
what extent a layer is presented. A strawman design would be to
provide the producer details on it's presentation (alpha,
position, scale, final crop, covered region, etc). In the strawman
design the client end would then decide itself whether each of these
parameters were in an acceptable range.

However providing the client feedback on it's per frame position would have
a negative system health impact. Furthermore in some of the target use cases
we can't even be sure the layer of interest is actively producing buffers
and so there may be no existing callback to piggy-back on.

Because of this we use a server side thresholding approach, where the client
expresses some visibility threshold and a time stability constraint. See
SurfaceComposerClient.h comment for details on these thresholds and their
computation.

Bug: 256993331
Test: LayerTrustedPresentationListener_test.cpp
Change-Id: If4bef60dc6b22ce4959c353fa2a19b0994a00f5c
---
 libs/gui/LayerState.cpp | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

(limited to 'libs/gui/LayerState.cpp')

diff --git a/libs/gui/LayerState.cpp b/libs/gui/LayerState.cpp
index 59b62fe58c..43acb16299 100644
--- a/libs/gui/LayerState.cpp
+++ b/libs/gui/LayerState.cpp
@@ -185,6 +185,8 @@ status_t layer_state_t::write(Parcel& output) const
     if (hasBufferData) {
         SAFE_PARCEL(output.writeParcelable, *bufferData);
     }
+    SAFE_PARCEL(output.writeParcelable, trustedPresentationThresholds);
+    SAFE_PARCEL(output.writeParcelable, trustedPresentationListener);
     return NO_ERROR;
 }
 
@@ -315,6 +317,10 @@ status_t layer_state_t::read(const Parcel& input)
     } else {
         bufferData = nullptr;
     }
+
+    SAFE_PARCEL(input.readParcelable, &trustedPresentationThresholds);
+    SAFE_PARCEL(input.readParcelable, &trustedPresentationListener);
+
     return NO_ERROR;
 }
 
@@ -553,6 +559,11 @@ void layer_state_t::merge(const layer_state_t& other) {
         what |= eBufferChanged;
         bufferData = other.bufferData;
     }
+    if (other.what & eTrustedPresentationInfoChanged) {
+        what |= eTrustedPresentationInfoChanged;
+        trustedPresentationListener = other.trustedPresentationListener;
+        trustedPresentationThresholds = other.trustedPresentationThresholds;
+    }
     if (other.what & eDataspaceChanged) {
         what |= eDataspaceChanged;
         dataspace = other.dataspace;
@@ -998,4 +1009,20 @@ status_t BufferData::readFromParcel(const Parcel* input) {
     return NO_ERROR;
 }
 
+status_t TrustedPresentationListener::writeToParcel(Parcel* parcel) const {
+    SAFE_PARCEL(parcel->writeStrongBinder, callbackInterface);
+    SAFE_PARCEL(parcel->writeInt32, callbackId);
+    return NO_ERROR;
+}
+
+status_t TrustedPresentationListener::readFromParcel(const Parcel* parcel) {
+    sp<IBinder> tmpBinder = nullptr;
+    SAFE_PARCEL(parcel->readNullableStrongBinder, &tmpBinder);
+    if (tmpBinder) {
+        callbackInterface = checked_interface_cast<ITransactionCompletedListener>(tmpBinder);
+    }
+    SAFE_PARCEL(parcel->readInt32, &callbackId);
+    return NO_ERROR;
+}
+
 }; // namespace android
-- 
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