diff --git a/libs/renderengine/ExternalTexture.cpp b/libs/renderengine/ExternalTexture.cpp
index eabff58..84771c0 100644
--- a/libs/renderengine/ExternalTexture.cpp
+++ b/libs/renderengine/ExternalTexture.cpp
@@ -14,30 +14,32 @@
  * limitations under the License.
  */
 
-#include <renderengine/ExternalTexture.h>
 #include <renderengine/RenderEngine.h>
+#include <renderengine/impl/ExternalTexture.h>
 #include <ui/GraphicBuffer.h>
 
 #include "log/log_main.h"
 
-namespace android::renderengine {
+namespace android::renderengine::impl {
 
-ExternalTexture::ExternalTexture(const sp<GraphicBuffer>& buffer, RenderEngine& renderEngine,
-                                 uint32_t usage)
+ExternalTexture::ExternalTexture(const sp<GraphicBuffer>& buffer,
+                                 renderengine::RenderEngine& renderEngine, uint32_t usage)
       : mBuffer(buffer), mRenderEngine(renderEngine) {
     LOG_ALWAYS_FATAL_IF(buffer == nullptr,
                         "Attempted to bind a null buffer to an external texture!");
     // GLESRenderEngine has a separate texture cache for output buffers,
-    if (usage == Usage::WRITEABLE &&
-        (mRenderEngine.getRenderEngineType() == RenderEngine::RenderEngineType::GLES ||
-         mRenderEngine.getRenderEngineType() == RenderEngine::RenderEngineType::THREADED)) {
+    if (usage == WRITEABLE &&
+        (mRenderEngine.getRenderEngineType() ==
+                 renderengine::RenderEngine::RenderEngineType::GLES ||
+         mRenderEngine.getRenderEngineType() ==
+                 renderengine::RenderEngine::RenderEngineType::THREADED)) {
         return;
     }
-    mRenderEngine.mapExternalTextureBuffer(mBuffer, usage & Usage::WRITEABLE);
+    mRenderEngine.mapExternalTextureBuffer(mBuffer, usage & WRITEABLE);
 }
 
 ExternalTexture::~ExternalTexture() {
     mRenderEngine.unmapExternalTextureBuffer(mBuffer);
 }
 
-} // namespace android::renderengine
+} // namespace android::renderengine::impl
diff --git a/libs/renderengine/benchmark/RenderEngineBench.cpp b/libs/renderengine/benchmark/RenderEngineBench.cpp
index 6c8f8e8..ead97cf 100644
--- a/libs/renderengine/benchmark/RenderEngineBench.cpp
+++ b/libs/renderengine/benchmark/RenderEngineBench.cpp
@@ -22,6 +22,7 @@
 #include <renderengine/ExternalTexture.h>
 #include <renderengine/LayerSettings.h>
 #include <renderengine/RenderEngine.h>
+#include <renderengine/impl/ExternalTexture.h>
 
 #include <mutex>
 
@@ -115,15 +116,15 @@
                                                        uint32_t height,
                                                        uint64_t extraUsageFlags = 0,
                                                        std::string name = "output") {
-    return std::make_shared<ExternalTexture>(new GraphicBuffer(width, height,
-                                                               HAL_PIXEL_FORMAT_RGBA_8888, 1,
-                                                               GRALLOC_USAGE_HW_RENDER |
-                                                                       GRALLOC_USAGE_HW_TEXTURE |
-                                                                       extraUsageFlags,
-                                                               std::move(name)),
-                                             re,
-                                             ExternalTexture::Usage::READABLE |
-                                                     ExternalTexture::Usage::WRITEABLE);
+    return std::make_shared<
+            impl::ExternalTexture>(new GraphicBuffer(width, height, HAL_PIXEL_FORMAT_RGBA_8888, 1,
+                                                     GRALLOC_USAGE_HW_RENDER |
+                                                             GRALLOC_USAGE_HW_TEXTURE |
+                                                             extraUsageFlags,
+                                                     std::move(name)),
+                                   re,
+                                   impl::ExternalTexture::Usage::READABLE |
+                                           impl::ExternalTexture::Usage::WRITEABLE);
 }
 
 static std::shared_ptr<ExternalTexture> copyBuffer(RenderEngine& re,
diff --git a/libs/renderengine/include/renderengine/ExternalTexture.h b/libs/renderengine/include/renderengine/ExternalTexture.h
index 07f0833..621a209 100644
--- a/libs/renderengine/include/renderengine/ExternalTexture.h
+++ b/libs/renderengine/include/renderengine/ExternalTexture.h
@@ -33,28 +33,22 @@
  */
 class ExternalTexture {
 public:
-    // Usage specifies the rendering intent for the buffer.
-    enum Usage : uint32_t {
-        // When a buffer is not READABLE but is WRITEABLE, then GLESRenderEngine will use that as a
-        // hint to load the buffer into a separate cache
-        READABLE = 1 << 0,
+    ExternalTexture() = default;
+    virtual ~ExternalTexture() = default;
 
-        // The buffer needs to be mapped as a 2D texture if set, otherwise must be mapped as an
-        // external texture
-        WRITEABLE = 1 << 1,
-    };
-    // Creates an ExternalTexture for the provided buffer and RenderEngine instance, with the given
-    // usage hint of type Usage.
-    ExternalTexture(const sp<GraphicBuffer>& buffer, RenderEngine& renderEngine, uint32_t usage);
-
-    ~ExternalTexture();
+    virtual bool hasSameBuffer(const ExternalTexture& other) const = 0;
+    virtual uint32_t getWidth() const = 0;
+    virtual uint32_t getHeight() const = 0;
+    virtual uint64_t getId() const = 0;
+    virtual PixelFormat getPixelFormat() const = 0;
+    virtual uint64_t getUsage() const = 0;
 
     // Retrieves the buffer that is bound to this texture.
-    const sp<GraphicBuffer>& getBuffer() const { return mBuffer; }
+    virtual const sp<GraphicBuffer>& getBuffer() const = 0;
 
-private:
-    sp<GraphicBuffer> mBuffer;
-    RenderEngine& mRenderEngine;
+    Rect getBounds() const {
+        return {0, 0, static_cast<int32_t>(getWidth()), static_cast<int32_t>(getHeight())};
+    }
     DISALLOW_COPY_AND_ASSIGN(ExternalTexture);
 };
 
diff --git a/libs/renderengine/include/renderengine/RenderEngine.h b/libs/renderengine/include/renderengine/RenderEngine.h
index d646756..faa84fc 100644
--- a/libs/renderengine/include/renderengine/RenderEngine.h
+++ b/libs/renderengine/include/renderengine/RenderEngine.h
@@ -76,6 +76,7 @@
 
 namespace impl {
 class RenderEngine;
+class ExternalTexture;
 }
 
 enum class Protection {
@@ -228,7 +229,7 @@
     // avoid any thread synchronization that may be required by directly calling postRenderCleanup.
     virtual bool canSkipPostRenderCleanup() const = 0;
 
-    friend class ExternalTexture;
+    friend class impl::ExternalTexture;
     friend class threaded::RenderEngineThreaded;
     friend class RenderEngineTest_cleanupPostRender_cleansUpOnce_Test;
     const RenderEngineType mRenderEngineType;
diff --git a/libs/renderengine/include/renderengine/impl/ExternalTexture.h b/libs/renderengine/include/renderengine/impl/ExternalTexture.h
new file mode 100644
index 0000000..c0e24f0
--- /dev/null
+++ b/libs/renderengine/include/renderengine/impl/ExternalTexture.h
@@ -0,0 +1,60 @@
+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <android-base/macros.h>
+#include <renderengine/ExternalTexture.h>
+#include <ui/GraphicBuffer.h>
+
+namespace android::renderengine::impl {
+
+class RenderEngine;
+
+class ExternalTexture : public android::renderengine::ExternalTexture {
+public:
+    // Usage specifies the rendering intent for the buffer.
+    enum Usage : uint32_t {
+        // When a buffer is not READABLE but is WRITEABLE, then GLESRenderEngine will use that as a
+        // hint to load the buffer into a separate cache
+        READABLE = 1 << 0,
+
+        // The buffer needs to be mapped as a 2D texture if set, otherwise must be mapped as an
+        // external texture
+        WRITEABLE = 1 << 1,
+    };
+
+    // Creates an ExternalTexture for the provided buffer and RenderEngine instance, with the given
+    // usage hint of type Usage.
+    ExternalTexture(const sp<GraphicBuffer>& buffer,
+                    android::renderengine::RenderEngine& renderEngine, uint32_t usage);
+    ~ExternalTexture();
+    const sp<GraphicBuffer>& getBuffer() const override { return mBuffer; };
+    uint32_t getWidth() const override { return getBuffer()->getWidth(); }
+    uint32_t getHeight() const override { return getBuffer()->getHeight(); }
+    uint64_t getId() const override { return getBuffer()->getId(); }
+    PixelFormat getPixelFormat() const override { return getBuffer()->getPixelFormat(); }
+    uint64_t getUsage() const override { return getBuffer()->getUsage(); }
+    bool hasSameBuffer(const renderengine::ExternalTexture& other) const override {
+        return getBuffer() == other.getBuffer();
+    }
+
+private:
+    sp<GraphicBuffer> mBuffer;
+    android::renderengine::RenderEngine& mRenderEngine;
+};
+
+} // namespace android::renderengine::impl
diff --git a/libs/renderengine/include/renderengine/mock/FakeExternalTexture.h b/libs/renderengine/include/renderengine/mock/FakeExternalTexture.h
new file mode 100644
index 0000000..974e0fd
--- /dev/null
+++ b/libs/renderengine/include/renderengine/mock/FakeExternalTexture.h
@@ -0,0 +1,51 @@
+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <renderengine/ExternalTexture.h>
+
+namespace android {
+namespace renderengine {
+namespace mock {
+
+class FakeExternalTexture : public renderengine::ExternalTexture {
+    const sp<GraphicBuffer> mNullBuffer = nullptr;
+    uint32_t mWidth;
+    uint32_t mHeight;
+    uint64_t mId;
+    PixelFormat mPixelFormat;
+    uint64_t mUsage;
+
+public:
+    FakeExternalTexture(uint32_t width, uint32_t height, uint64_t id, PixelFormat pixelFormat,
+                        uint64_t usage)
+          : mWidth(width), mHeight(height), mId(id), mPixelFormat(pixelFormat), mUsage(usage) {}
+    const sp<GraphicBuffer>& getBuffer() const { return mNullBuffer; }
+    bool hasSameBuffer(const renderengine::ExternalTexture& other) const override {
+        return getId() == other.getId();
+    }
+    uint32_t getWidth() const override { return mWidth; }
+    uint32_t getHeight() const override { return mHeight; }
+    uint64_t getId() const override { return mId; }
+    PixelFormat getPixelFormat() const override { return mPixelFormat; }
+    uint64_t getUsage() const override { return mUsage; }
+    ~FakeExternalTexture() = default;
+};
+
+} // namespace mock
+} // namespace renderengine
+} // namespace android
diff --git a/libs/renderengine/skia/Cache.cpp b/libs/renderengine/skia/Cache.cpp
index b18a872..a3a1969 100644
--- a/libs/renderengine/skia/Cache.cpp
+++ b/libs/renderengine/skia/Cache.cpp
@@ -19,6 +19,7 @@
 #include "android-base/unique_fd.h"
 #include "renderengine/DisplaySettings.h"
 #include "renderengine/LayerSettings.h"
+#include "renderengine/impl/ExternalTexture.h"
 #include "ui/GraphicBuffer.h"
 #include "ui/GraphicTypes.h"
 #include "ui/PixelFormat.h"
@@ -365,8 +366,8 @@
                                   1, usage, "primeShaderCache_dst");
 
         const auto dstTexture =
-                std::make_shared<ExternalTexture>(dstBuffer, *renderengine,
-                                                  ExternalTexture::Usage::WRITEABLE);
+                std::make_shared<impl::ExternalTexture>(dstBuffer, *renderengine,
+                                                        impl::ExternalTexture::Usage::WRITEABLE);
         // This buffer will be the source for the call to drawImageLayers. Draw
         // something to it as a placeholder for what an app draws. We should draw
         // something, but the details are not important. Make use of the shadow layer drawing step
@@ -375,10 +376,10 @@
                 new GraphicBuffer(displayRect.width(), displayRect.height(), PIXEL_FORMAT_RGBA_8888,
                                   1, usage, "drawImageLayer_src");
 
-        const auto srcTexture =
-                std::make_shared<ExternalTexture>(srcBuffer, *renderengine,
-                                                  ExternalTexture::Usage::READABLE |
-                                                          ExternalTexture::Usage::WRITEABLE);
+        const auto srcTexture = std::make_shared<
+                impl::ExternalTexture>(srcBuffer, *renderengine,
+                                       impl::ExternalTexture::Usage::READABLE |
+                                               impl::ExternalTexture::Usage::WRITEABLE);
         drawHolePunchLayer(renderengine, display, dstTexture);
         drawSolidLayers(renderengine, display, dstTexture);
 
@@ -398,8 +399,8 @@
                 new GraphicBuffer(displayRect.width(), displayRect.height(), PIXEL_FORMAT_RGBA_8888,
                                   1, usageExternal, "primeShaderCache_external");
         const auto externalTexture =
-                std::make_shared<ExternalTexture>(externalBuffer, *renderengine,
-                                                  ExternalTexture::Usage::READABLE);
+                std::make_shared<impl::ExternalTexture>(externalBuffer, *renderengine,
+                                                        impl::ExternalTexture::Usage::READABLE);
         std::vector<const std::shared_ptr<ExternalTexture>> textures =
             {srcTexture, externalTexture};
 
@@ -412,8 +413,8 @@
         status_t error = f16ExternalBuffer->initCheck();
         if (!error) {
             const auto f16ExternalTexture =
-                std::make_shared<ExternalTexture>(f16ExternalBuffer, *renderengine,
-                                                  ExternalTexture::Usage::READABLE);
+                    std::make_shared<impl::ExternalTexture>(f16ExternalBuffer, *renderengine,
+                                                            impl::ExternalTexture::Usage::READABLE);
             textures.push_back(f16ExternalTexture);
         }
 
diff --git a/libs/renderengine/tests/RenderEngineTest.cpp b/libs/renderengine/tests/RenderEngineTest.cpp
index eb2b2dc..2a25b0b 100644
--- a/libs/renderengine/tests/RenderEngineTest.cpp
+++ b/libs/renderengine/tests/RenderEngineTest.cpp
@@ -26,6 +26,7 @@
 #include <gtest/gtest.h>
 #include <renderengine/ExternalTexture.h>
 #include <renderengine/RenderEngine.h>
+#include <renderengine/impl/ExternalTexture.h>
 #include <sync/sync.h>
 #include <system/graphics-base-v1.0.h>
 #include <tonemap/tonemap.h>
@@ -178,7 +179,7 @@
 public:
     std::shared_ptr<renderengine::ExternalTexture> allocateDefaultBuffer() {
         return std::make_shared<
-                renderengine::
+                renderengine::impl::
                         ExternalTexture>(new GraphicBuffer(DEFAULT_DISPLAY_WIDTH,
                                                            DEFAULT_DISPLAY_HEIGHT,
                                                            HAL_PIXEL_FORMAT_RGBA_8888, 1,
@@ -188,15 +189,16 @@
                                                                    GRALLOC_USAGE_HW_TEXTURE,
                                                            "output"),
                                          *mRE,
-                                         renderengine::ExternalTexture::Usage::READABLE |
-                                                 renderengine::ExternalTexture::Usage::WRITEABLE);
+                                         renderengine::impl::ExternalTexture::Usage::READABLE |
+                                                 renderengine::impl::ExternalTexture::Usage::
+                                                         WRITEABLE);
     }
 
     // Allocates a 1x1 buffer to fill with a solid color
     std::shared_ptr<renderengine::ExternalTexture> allocateSourceBuffer(uint32_t width,
                                                                         uint32_t height) {
         return std::make_shared<
-                renderengine::
+                renderengine::impl::
                         ExternalTexture>(new GraphicBuffer(width, height,
                                                            HAL_PIXEL_FORMAT_RGBA_8888, 1,
                                                            GRALLOC_USAGE_SW_READ_OFTEN |
@@ -204,8 +206,9 @@
                                                                    GRALLOC_USAGE_HW_TEXTURE,
                                                            "input"),
                                          *mRE,
-                                         renderengine::ExternalTexture::Usage::READABLE |
-                                                 renderengine::ExternalTexture::Usage::WRITEABLE);
+                                         renderengine::impl::ExternalTexture::Usage::READABLE |
+                                                 renderengine::impl::ExternalTexture::Usage::
+                                                         WRITEABLE);
     }
 
     std::shared_ptr<renderengine::ExternalTexture> allocateAndFillSourceBuffer(uint32_t width,
@@ -2439,16 +2442,17 @@
     };
 
     auto buf = std::make_shared<
-            renderengine::ExternalTexture>(new GraphicBuffer(kGreyLevels, 1,
-                                                             HAL_PIXEL_FORMAT_RGBA_8888, 1,
-                                                             GRALLOC_USAGE_SW_READ_OFTEN |
-                                                                     GRALLOC_USAGE_SW_WRITE_OFTEN |
-                                                                     GRALLOC_USAGE_HW_RENDER |
-                                                                     GRALLOC_USAGE_HW_TEXTURE,
-                                                             "input"),
-                                           *mRE,
-                                           renderengine::ExternalTexture::Usage::READABLE |
-                                                   renderengine::ExternalTexture::Usage::WRITEABLE);
+            renderengine::impl::
+                    ExternalTexture>(new GraphicBuffer(kGreyLevels, 1, HAL_PIXEL_FORMAT_RGBA_8888,
+                                                       1,
+                                                       GRALLOC_USAGE_SW_READ_OFTEN |
+                                                               GRALLOC_USAGE_SW_WRITE_OFTEN |
+                                                               GRALLOC_USAGE_HW_RENDER |
+                                                               GRALLOC_USAGE_HW_TEXTURE,
+                                                       "input"),
+                                     *mRE,
+                                     renderengine::impl::ExternalTexture::Usage::READABLE |
+                                             renderengine::impl::ExternalTexture::Usage::WRITEABLE);
     ASSERT_EQ(0, buf->getBuffer()->initCheck());
 
     {
@@ -2472,16 +2476,17 @@
     }
 
     mBuffer = std::make_shared<
-            renderengine::ExternalTexture>(new GraphicBuffer(kGreyLevels, 1,
-                                                             HAL_PIXEL_FORMAT_RGBA_8888, 1,
-                                                             GRALLOC_USAGE_SW_READ_OFTEN |
-                                                                     GRALLOC_USAGE_SW_WRITE_OFTEN |
-                                                                     GRALLOC_USAGE_HW_RENDER |
-                                                                     GRALLOC_USAGE_HW_TEXTURE,
-                                                             "output"),
-                                           *mRE,
-                                           renderengine::ExternalTexture::Usage::READABLE |
-                                                   renderengine::ExternalTexture::Usage::WRITEABLE);
+            renderengine::impl::
+                    ExternalTexture>(new GraphicBuffer(kGreyLevels, 1, HAL_PIXEL_FORMAT_RGBA_8888,
+                                                       1,
+                                                       GRALLOC_USAGE_SW_READ_OFTEN |
+                                                               GRALLOC_USAGE_SW_WRITE_OFTEN |
+                                                               GRALLOC_USAGE_HW_RENDER |
+                                                               GRALLOC_USAGE_HW_TEXTURE,
+                                                       "output"),
+                                     *mRE,
+                                     renderengine::impl::ExternalTexture::Usage::READABLE |
+                                             renderengine::impl::ExternalTexture::Usage::WRITEABLE);
     ASSERT_EQ(0, mBuffer->getBuffer()->initCheck());
 
     const renderengine::LayerSettings layer{
diff --git a/libs/renderengine/tests/RenderEngineThreadedTest.cpp b/libs/renderengine/tests/RenderEngineThreadedTest.cpp
index db7e12b..9685189 100644
--- a/libs/renderengine/tests/RenderEngineThreadedTest.cpp
+++ b/libs/renderengine/tests/RenderEngineThreadedTest.cpp
@@ -17,6 +17,7 @@
 #include <cutils/properties.h>
 #include <gmock/gmock.h>
 #include <gtest/gtest.h>
+#include <renderengine/impl/ExternalTexture.h>
 #include <renderengine/mock/RenderEngine.h>
 #include "../threaded/RenderEngineThreaded.h"
 
@@ -174,9 +175,10 @@
     renderengine::DisplaySettings settings;
     std::vector<renderengine::LayerSettings> layers;
     std::shared_ptr<renderengine::ExternalTexture> buffer = std::make_shared<
-            renderengine::ExternalTexture>(new GraphicBuffer(), *mRenderEngine,
-                                           renderengine::ExternalTexture::Usage::READABLE |
-                                                   renderengine::ExternalTexture::Usage::WRITEABLE);
+            renderengine::impl::
+                    ExternalTexture>(new GraphicBuffer(), *mRenderEngine,
+                                     renderengine::impl::ExternalTexture::Usage::READABLE |
+                                             renderengine::impl::ExternalTexture::Usage::WRITEABLE);
 
     base::unique_fd bufferFence;