Wire up utils for lock/unlock.

Author: chinmaygarde

impeller/toolkit/android/hardware_buffer.cc

@@ -25,14 +25,27 @@ static AHardwareBuffer_Desc ToAHardwareBufferDesc(
   ahb_desc.format = ToAHardwareBufferFormat(desc.format);
   ahb_desc.layers = 1u;
   if (desc.usage & HardwareBufferUsageFlags::kFrameBufferAttachment) {
-    ahb_desc.usage |= AHARDWAREBUFFER_USAGE_GPU_FRAMEBUFFER;
+    ahb_desc.usage |= (AHARDWAREBUFFER_USAGE_GPU_FRAMEBUFFER |
+                       AHARDWAREBUFFER_USAGE_GPU_COLOR_OUTPUT);
   }
   if (desc.usage & HardwareBufferUsageFlags::kCompositorOverlay) {
     ahb_desc.usage |= AHARDWAREBUFFER_USAGE_COMPOSER_OVERLAY;
   }
   if (desc.usage & HardwareBufferUsageFlags::kSampledImage) {
     ahb_desc.usage |= AHARDWAREBUFFER_USAGE_GPU_SAMPLED_IMAGE;
   }
+  if (desc.usage & HardwareBufferUsageFlags::kCPUReadRarely) {
+    ahb_desc.usage |= AHARDWAREBUFFER_USAGE_CPU_READ_RARELY;
+  }
+  if (desc.usage & HardwareBufferUsageFlags::kCPUReadOften) {
+    ahb_desc.usage |= AHARDWAREBUFFER_USAGE_CPU_READ_OFTEN;
+  }
+  if (desc.usage & HardwareBufferUsageFlags::kCPUWriteRarely) {
+    ahb_desc.usage |= AHARDWAREBUFFER_USAGE_CPU_WRITE_RARELY;
+  }
+  if (desc.usage & HardwareBufferUsageFlags::kCPUWriteOften) {
+    ahb_desc.usage |= AHARDWAREBUFFER_USAGE_CPU_WRITE_OFTEN;
+  }
   return ahb_desc;
 }
 
@@ -121,4 +134,37 @@ std::optional<AHardwareBuffer_Desc> HardwareBuffer::Describe(
   return desc;
 }
 
+void* HardwareBuffer::Lock(CPUAccessType type) const {
+  if (!is_valid_ || !GetProcTable().AHardwareBuffer_lock) {
+    return nullptr;
+  }
+  uint64_t usage = 0;
+  switch (type) {
+    case CPUAccessType::kRead:
+      usage |= AHARDWAREBUFFER_USAGE_CPU_READ_MASK;
+      break;
+    case CPUAccessType::kWrite:
+      usage |= AHARDWAREBUFFER_USAGE_CPU_WRITE_MASK;
+      break;
+  }
+  void* buffer = nullptr;
+  const auto result = GetProcTable().AHardwareBuffer_lock(  //
+      buffer_.get(),                                        // buffer
+      usage,                                                // usage
+      -1,                                                   // fence
+      nullptr,                                              // rect
+      &buffer                                               // out-addr
+  );
+  return result == 0 ? buffer : nullptr;
+}
+
+bool HardwareBuffer::Unlock() const {
+  if (!is_valid_ || !GetProcTable().AHardwareBuffer_unlock) {
+    return false;
+  }
+  const auto result =
+      GetProcTable().AHardwareBuffer_unlock(buffer_.get(), nullptr);
+  return result == 0;
+}
+
 }  // namespace impeller::android

impeller/toolkit/android/hardware_buffer.h

@@ -7,6 +7,7 @@
 
 #include <optional>
 
+#include "flutter/fml/unique_fd.h"
 #include "flutter/fml/unique_object.h"
 #include "impeller/base/mask.h"
 #include "impeller/geometry/size.h"
@@ -32,6 +33,10 @@ enum class HardwareBufferUsageFlags {
   kFrameBufferAttachment = 1u << 0u,
   kCompositorOverlay = 1u << 1u,
   kSampledImage = 1u << 2u,
+  kCPUReadRarely = 1u << 3u,
+  kCPUReadOften = 1u << 4u,
+  kCPUWriteRarely = 1u << 5u,
+  kCPUWriteOften = 1u << 6u,
 };
 
 using HardwareBufferUsage = Mask<HardwareBufferUsageFlags>;
@@ -127,6 +132,29 @@ class HardwareBuffer {
   ///
   static std::optional<uint64_t> GetSystemUniqueID(AHardwareBuffer* buffer);
 
+  enum class CPUAccessType {
+    kRead,
+    kWrite,
+  };
+  //----------------------------------------------------------------------------
+  /// @brief      Lock the buffer for CPU access. This call may fail if the
+  ///             buffer was not created with one the usages that allow for CPU
+  ///             access.
+  ///
+  /// @param[in]  type  The type
+  ///
+  /// @return     A host-accessible buffer if there was no error related to
+  ///             usage or buffer validity.
+  ///
+  void* Lock(CPUAccessType type) const;
+
+  //----------------------------------------------------------------------------
+  /// @brief      Unlock a mapping previously locked for CPU access.
+  ///
+  /// @return     If the unlock was successful.
+  ///
+  bool Unlock() const;
+
  private:
   struct UniqueAHardwareBufferTraits {
     static AHardwareBuffer* InvalidValue() { return nullptr; }

impeller/toolkit/android/proc_table.h

@@ -44,7 +44,9 @@ namespace impeller::android {
   INVOKE(AHardwareBuffer_fromHardwareBuffer, 26) \
   INVOKE(AHardwareBuffer_getId, 31)              \
   INVOKE(AHardwareBuffer_isSupported, 29)        \
+  INVOKE(AHardwareBuffer_lock, 26)               \
   INVOKE(AHardwareBuffer_release, 26)            \
+  INVOKE(AHardwareBuffer_unlock, 26)             \
   INVOKE(ANativeWindow_acquire, 0)               \
   INVOKE(ANativeWindow_getHeight, 0)             \
   INVOKE(ANativeWindow_getWidth, 0)              \