drm_hwcomposer: add compositor interface header

Change-Id: I4b743e442e140f8fe5452fba3dd718995fe77b1b
(cherry picked from commit af3c4ecc830bef9d538333d0bf200fed39ae3649)
diff --git a/compositor.h b/compositor.h
new file mode 100644
index 0000000..b162f4a
--- /dev/null
+++ b/compositor.h
@@ -0,0 +1,99 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+#ifndef DRM_HWCOMPOSER_COMPOSITOR_H_
+#define DRM_HWCOMPOSER_COMPOSITOR_H_
+
+struct hwc_layer_1;
+struct hwc_drm_bo;
+
+namespace android {
+
+class GraphicBuffer;
+template <typename T>
+class sp;
+
+class Targeting {
+ public:
+  // Prepares the given framebuffer for use as output of this compositor. On
+  // success, takes a reference to the given buffer and returns a non- negative
+  // integer that is used as a handle to the prepared target. On failure,
+  // returns a negative integer.
+  virtual int CreateTarget(sp<android::GraphicBuffer> &buffer) = 0;
+
+  // Sets the target framebuffer of all subsequent composite calls. The target
+  // must be an integer previously returned by a successful call to createTarget
+  // of this compositor or the target can be -1 to indicate that no custom
+  // buffer should be used for subsequent calls.
+  virtual void SetTarget(int target) = 0;
+
+  // Releases the reference to the buffer underlying the given target. The given
+  // target will no longer be valid for use for setTarget. Calling this on a
+  // target that was used in the last setTarget call or that is the target of a
+  // composition that has not yet signaled its fence is undefined behavior.
+  virtual void ForgetTarget(int target) = 0;
+
+ protected:
+  ~Targeting();
+};
+
+class Composition {
+ public:
+  // Releases and invalidates the composition.
+  virtual ~Composition();
+
+  // Adds the given layer, whose handle has been imported into the given buffer
+  // object, to the given display of the composition. The layer may be modified
+  // to include a releaseFenceFd. Returns 0 on success.
+  virtual int AddLayer(int display, hwc_layer_1 *layer, hwc_drm_bo *bo) = 0;
+
+  // Gets the number of successful AddLayer calls that can be made on the
+  // composition and display, up to num_needed.
+  virtual unsigned GetRemainingLayers(int display,
+                                      unsigned num_needed) const = 0;
+};
+
+class Compositor {
+ public:
+  virtual ~Compositor();
+
+  // This must be called once before any other methods called. It must be called
+  // on the thread the Compositor is meant to operate on to initialize thread
+  // local variables. Returns 0 on success.
+  virtual int Init() = 0;
+
+  // If this compositor supports targeting to output buffers, this returns a
+  // non-null pointer. Otherwise, returns null.
+  virtual Targeting *targeting() = 0;
+
+  // Starts a fresh composition.
+  virtual Composition *CreateComposition() = 0;
+
+  // On success returns a syncpoint fd that will be signaled when composition is
+  // complete or -1 if compositing was completed by this method's return. On
+  // error returns an integer less than -1. The composition is invalid after
+  // this call.
+  virtual int QueueComposition(Composition *composition) = 0;
+
+  // compositors require that every QueueComposition be paired with a Composite
+  // on a worker thread. Each Composite call handles one composition that was
+  // submitted via QueueComposition in FIFO order. Returns 0 on success.
+  virtual int Composite() = 0;
+};
+
+}  // namespace android
+
+#endif