From 368a7a51c652fe39a130ec6f09315df4f7260e53 Mon Sep 17 00:00:00 2001
From: Leon Scroggins III <scroggo@google.com>
Date: Fri, 20 Nov 2020 12:23:27 -0500
Subject: [PATCH] ImageDecoder: use kYes_ZeroInitialized memory

Bug: 183115528
Test: (A)ImageDecoderTest(s) (verify correctness)
Test: monitor showmap_pss_bytes dashboards (verify memory impact)

This lets the decoder leave zero initialized memory untouched. An
Android feature makes untouched zero initialized memory cheaper, and
BitmapFactory takes advantage of it. Do the same for ImageDecoder.

This feature was originally brought up in b/10016979. ImageDecoder saved
memory in other ways, and as I understand it, Android has shifted
towards using (Animated)VectorDrawables. Both of these may have
contributed to us not noticing when we switched from BitmapFactory to
ImageDecoder.

Change-Id: Iecfd1bbfdcc38e1f0bf380b4f4ea5b861cfcf08a
---
 libs/hwui/hwui/ImageDecoder.cpp | 11 ++++++++++-
 libs/hwui/hwui/ImageDecoder.h   |  4 ++--
 libs/hwui/jni/ImageDecoder.cpp  |  3 ++-
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/libs/hwui/hwui/ImageDecoder.cpp b/libs/hwui/hwui/ImageDecoder.cpp
index ade63e5b832c8..5d9fad5b676e1 100644
--- a/libs/hwui/hwui/ImageDecoder.cpp
+++ b/libs/hwui/hwui/ImageDecoder.cpp
@@ -45,7 +45,8 @@ sk_sp<SkColorSpace> ImageDecoder::getDefaultColorSpace() const {
     return SkColorSpace::MakeSRGB();
 }
 
-ImageDecoder::ImageDecoder(std::unique_ptr<SkAndroidCodec> codec, sk_sp<SkPngChunkReader> peeker)
+ImageDecoder::ImageDecoder(std::unique_ptr<SkAndroidCodec> codec, sk_sp<SkPngChunkReader> peeker,
+                           SkCodec::ZeroInitialized zeroInit)
     : mCodec(std::move(codec))
     , mPeeker(std::move(peeker))
     , mDecodeSize(mCodec->codec()->dimensions())
@@ -57,6 +58,7 @@ ImageDecoder::ImageDecoder(std::unique_ptr<SkAndroidCodec> codec, sk_sp<SkPngChu
     mTargetSize = swapWidthHeight() ? SkISize { mDecodeSize.height(), mDecodeSize.width() }
                                     : mDecodeSize;
     this->rewind();
+    mOptions.fZeroInitialized = zeroInit;
 }
 
 ImageDecoder::~ImageDecoder() = default;
@@ -446,10 +448,17 @@ SkCodec::Result ImageDecoder::decode(void* pixels, size_t rowBytes) {
                 ALOGE("Failed to invert matrix!");
             }
         }
+
+        // Even if the client did not provide zero initialized memory, the
+        // memory we decode into is.
+        mOptions.fZeroInitialized = SkCodec::kYes_ZeroInitialized;
     }
 
     auto result = mCodec->getAndroidPixels(decodeInfo, decodePixels, decodeRowBytes, &mOptions);
 
+    // The next call to decode() may not provide zero initialized memory.
+    mOptions.fZeroInitialized = SkCodec::kNo_ZeroInitialized;
+
     if (scale || handleOrigin || mCropRect) {
         SkBitmap scaledBm;
         if (!scaledBm.installPixels(outputInfo, pixels, rowBytes)) {
diff --git a/libs/hwui/hwui/ImageDecoder.h b/libs/hwui/hwui/ImageDecoder.h
index cbfffd5e9291d..cef2233fc3715 100644
--- a/libs/hwui/hwui/ImageDecoder.h
+++ b/libs/hwui/hwui/ImageDecoder.h
@@ -34,8 +34,8 @@ public:
     std::unique_ptr<SkAndroidCodec> mCodec;
     sk_sp<SkPngChunkReader> mPeeker;
 
-    ImageDecoder(std::unique_ptr<SkAndroidCodec> codec,
-                 sk_sp<SkPngChunkReader> peeker = nullptr);
+    ImageDecoder(std::unique_ptr<SkAndroidCodec> codec, sk_sp<SkPngChunkReader> peeker = nullptr,
+                 SkCodec::ZeroInitialized zeroInit = SkCodec::kNo_ZeroInitialized);
     ~ImageDecoder();
 
     SkISize getSampledDimensions(int sampleSize) const;
diff --git a/libs/hwui/jni/ImageDecoder.cpp b/libs/hwui/jni/ImageDecoder.cpp
index ad7741b61e9f4..f7b8c014be6e4 100644
--- a/libs/hwui/jni/ImageDecoder.cpp
+++ b/libs/hwui/jni/ImageDecoder.cpp
@@ -141,7 +141,8 @@ static jobject native_create(JNIEnv* env, std::unique_ptr<SkStream> stream,
     }
 
     const bool isNinePatch = peeker->mPatch != nullptr;
-    ImageDecoder* decoder = new ImageDecoder(std::move(androidCodec), std::move(peeker));
+    ImageDecoder* decoder = new ImageDecoder(std::move(androidCodec), std::move(peeker),
+                                             SkCodec::kYes_ZeroInitialized);
     return env->NewObject(gImageDecoder_class, gImageDecoder_constructorMethodID,
                           reinterpret_cast<jlong>(decoder), decoder->width(), decoder->height(),
                           animated, isNinePatch);