Reland refactor of screenshot code on main thread.

Create helper functions to improve readability of what is scheduled on
the SurfaceFlinger main thread. This will allow for cleaner changes in
reducing the calls on the main thread for screenshots. Changes include
some renaming for better clarity.

Bug: b/294936197
Test: presubmit
Test: atest SurfaceFlinger_test
Change-Id: I3643b27b98e20578c51f90f6ab61d1aa2e3458bb

1 files changed, 54 insertions, 49 deletions

diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index cf5f55d7bd..8847ceea44 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -8063,6 +8063,19 @@ void SurfaceFlinger::captureLayers(const LayerCaptureArgs& args,
                         args.allowProtected, args.grayscale, captureListener);
 }
 
+bool SurfaceFlinger::layersHasProtectedLayer(
+        const std::vector<std::pair<Layer*, sp<LayerFE>>>& layers) const {
+    bool protectedLayerFound = false;
+    for (auto& [_, layerFe] : layers) {
+        protectedLayerFound |=
+                (layerFe->mSnapshot->isVisible && layerFe->mSnapshot->hasProtectedContent);
+        if (protectedLayerFound) {
+            break;
+        }
+    }
+    return protectedLayerFound;
+}
+
 void SurfaceFlinger::captureScreenCommon(RenderAreaFuture renderAreaFuture,
                                          GetLayerSnapshotsFunction getLayerSnapshots,
                                          ui::Size bufferSize, ui::PixelFormat reqPixelFormat,
@@ -8085,18 +8098,9 @@ void SurfaceFlinger::captureScreenCommon(RenderAreaFuture renderAreaFuture,
     const bool supportsProtected = getRenderEngine().supportsProtectedContent();
     bool hasProtectedLayer = false;
     if (allowProtected && supportsProtected) {
-        hasProtectedLayer = mScheduler
-                                    ->schedule([=]() {
-                                        bool protectedLayerFound = false;
-                                        auto layers = getLayerSnapshots();
-                                        for (auto& [_, layerFe] : layers) {
-                                            protectedLayerFound |=
-                                                    (layerFe->mSnapshot->isVisible &&
-                                                     layerFe->mSnapshot->hasProtectedContent);
-                                        }
-                                        return protectedLayerFound;
-                                    })
-                                    .get();
+        // Snapshots must be taken from the main thread.
+        auto layers = mScheduler->schedule([=]() { return getLayerSnapshots(); }).get();
+        hasProtectedLayer = layersHasProtectedLayer(layers);
     }
     const bool isProtected = hasProtectedLayer && allowProtected && supportsProtected;
     const uint32_t usage = GRALLOC_USAGE_HW_COMPOSER | GRALLOC_USAGE_HW_RENDER |
@@ -8121,52 +8125,53 @@ void SurfaceFlinger::captureScreenCommon(RenderAreaFuture renderAreaFuture,
             renderengine::impl::ExternalTexture>(buffer, getRenderEngine(),
                                                  renderengine::impl::ExternalTexture::Usage::
                                                          WRITEABLE);
-    auto fence = captureScreenCommon(std::move(renderAreaFuture), getLayerSnapshots, texture,
-                                     false /* regionSampling */, grayscale, isProtected,
-                                     captureListener);
-    fence.get();
+    auto futureFence =
+            captureScreenshot(std::move(renderAreaFuture), getLayerSnapshots, texture,
+                              false /* regionSampling */, grayscale, isProtected, captureListener);
+    futureFence.get();
 }
 
-ftl::SharedFuture<FenceResult> SurfaceFlinger::captureScreenCommon(
+ftl::SharedFuture<FenceResult> SurfaceFlinger::captureScreenshot(
         RenderAreaFuture renderAreaFuture, GetLayerSnapshotsFunction getLayerSnapshots,
         const std::shared_ptr<renderengine::ExternalTexture>& buffer, bool regionSampling,
         bool grayscale, bool isProtected, const sp<IScreenCaptureListener>& captureListener) {
     ATRACE_CALL();
 
-    auto future = mScheduler->schedule(
-            [=, this, renderAreaFuture = std::move(renderAreaFuture)]() FTL_FAKE_GUARD(
-                    kMainThreadContext) mutable -> ftl::SharedFuture<FenceResult> {
-                ScreenCaptureResults captureResults;
-                std::shared_ptr<RenderArea> renderArea = renderAreaFuture.get();
-                if (!renderArea) {
-                    ALOGW("Skipping screen capture because of invalid render area.");
-                    if (captureListener) {
-                        captureResults.fenceResult = base::unexpected(NO_MEMORY);
-                        captureListener->onScreenCaptureCompleted(captureResults);
-                    }
-                    return ftl::yield<FenceResult>(base::unexpected(NO_ERROR)).share();
-                }
+    auto takeScreenshotFn = [=, this, renderAreaFuture = std::move(renderAreaFuture)]() REQUIRES(
+                                    kMainThreadContext) mutable -> ftl::SharedFuture<FenceResult> {
+        ScreenCaptureResults captureResults;
+        std::shared_ptr<RenderArea> renderArea = renderAreaFuture.get();
+        if (!renderArea) {
+            ALOGW("Skipping screen capture because of invalid render area.");
+            if (captureListener) {
+                captureResults.fenceResult = base::unexpected(NO_MEMORY);
+                captureListener->onScreenCaptureCompleted(captureResults);
+            }
+            return ftl::yield<FenceResult>(base::unexpected(NO_ERROR)).share();
+        }
 
-                ftl::SharedFuture<FenceResult> renderFuture;
-                renderArea->render([&]() FTL_FAKE_GUARD(kMainThreadContext) {
-                    renderFuture =
-                            renderScreenImpl(renderArea, getLayerSnapshots, buffer, regionSampling,
-                                             grayscale, isProtected, captureResults);
-                });
+        ftl::SharedFuture<FenceResult> renderFuture;
+        renderArea->render([&]() FTL_FAKE_GUARD(kMainThreadContext) {
+            renderFuture = renderScreenImpl(renderArea, getLayerSnapshots, buffer, regionSampling,
+                                            grayscale, isProtected, captureResults);
+        });
 
-                if (captureListener) {
-                    // Defer blocking on renderFuture back to the Binder thread.
-                    return ftl::Future(std::move(renderFuture))
-                            .then([captureListener, captureResults = std::move(captureResults)](
-                                          FenceResult fenceResult) mutable -> FenceResult {
-                                captureResults.fenceResult = std::move(fenceResult);
-                                captureListener->onScreenCaptureCompleted(captureResults);
-                                return base::unexpected(NO_ERROR);
-                            })
-                            .share();
-                }
-                return renderFuture;
-            });
+        if (captureListener) {
+            // Defer blocking on renderFuture back to the Binder thread.
+            return ftl::Future(std::move(renderFuture))
+                    .then([captureListener, captureResults = std::move(captureResults)](
+                                  FenceResult fenceResult) mutable -> FenceResult {
+                        captureResults.fenceResult = std::move(fenceResult);
+                        captureListener->onScreenCaptureCompleted(captureResults);
+                        return base::unexpected(NO_ERROR);
+                    })
+                    .share();
+        }
+        return renderFuture;
+    };
+
+    auto future =
+            mScheduler->schedule(FTL_FAKE_GUARD(kMainThreadContext, std::move(takeScreenshotFn)));
 
     // Flatten nested futures.
     auto chain = ftl::Future(std::move(future)).then([](ftl::SharedFuture<FenceResult> future) {