1 files changed, 59 insertions, 0 deletions
diff --git a/gfx/layers/mlgpu/MLGPUScreenshotGrabber.h b/gfx/layers/mlgpu/MLGPUScreenshotGrabber.h
new file mode 100644
index 0000000000..1be5c0f0fb
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+++ b/gfx/layers/mlgpu/MLGPUScreenshotGrabber.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_layers_MLGPUScreenshotGrabber_h
+#define mozilla_layers_MLGPUScreenshotGrabber_h
+
+#include "mozilla/UniquePtr.h"
+#include "mozilla/layers/MLGDevice.h"
+
+namespace mozilla {
+namespace layers {
+
+class MLGPUScreenshotGrabberImpl;
+
+/**
+ * Used by LayerManagerComposite to grab snapshots from the compositor and
+ * submit them to the Gecko profiler.
+ * Doesn't do any work if the profiler is not running or the "screenshots"
+ * feature is not enabled.
+ * Screenshots are scaled down to fit within a fixed size, and read back to
+ * main memory using async readback. Scaling is done in multiple scale-by-0.5x
+ * steps using CompositingRenderTargets and Compositor::BlitFromRenderTarget,
+ * and readback is done using AsyncReadbackBuffers.
+ */
+class MLGPUScreenshotGrabber final {
+ public:
+  MLGPUScreenshotGrabber();
+  ~MLGPUScreenshotGrabber();
+
+  // Scale the contents of aTexture into an appropriately sized MLGTexture
+  // and read its contents into an AsyncReadbackBuffer. The AsyncReadbackBuffer
+  // is not mapped into main memory until the second call to
+  // MaybeProcessQueue() after this call to MaybeGrabScreenshot().
+  void MaybeGrabScreenshot(MLGDevice* aDevice, MLGTexture* aTexture);
+
+  // Map the contents of any outstanding AsyncReadbackBuffers from previous
+  // composites into main memory and submit each screenshot to the profiler.
+  void MaybeProcessQueue();
+
+  // Insert a special profiler marker for a composite that didn't do any actual
+  // compositing, so that the profiler knows why no screenshot was taken for
+  // this frame.
+  void NotifyEmptyFrame();
+
+  // Destroy all Compositor-related resources that this class is holding on to.
+  void Destroy();
+
+ private:
+  // non-null while ProfilerScreenshots::IsEnabled() returns true
+  UniquePtr<MLGPUScreenshotGrabberImpl> mImpl;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif  // mozilla_layers_MLGPUScreenshotGrabber_h