83 lines
2.8 KiB
Markdown
83 lines
2.8 KiB
Markdown
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<!--
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Copyright (C) 2022 The Android Open Source Project
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License
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-->
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# car-evs-helper-lib
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This directory contains two modules that are used by other apps to process
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CarEvsBufferDescriptor and render its contents to the display with EGL.
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* `car-evs-helper-lib:` This library contains `CarEvsGLSurfaceView` and
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`CarEvsBufferRenderer` classes.
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* `libcarevsglrenderer_jni`: This is a JNI library `CarEvsBufferRenderer` uses
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to render the contents of `CarEvsBufferDescriptor` with EGL.
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## How to use
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Please follow below instructions to delegate a `CarEvsBufferDescriptor` rendering
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to this library. A reference implementation is also available at
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`packages/services/Car/tests/CarEvsCameraPreviewApp`.
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1. Make the application refer to `car-evs-helper-lib` and
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`libcarevsglrenderer_jni` libraries by adding below lines to `Android.bp`.
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```
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static_libs: ["car-evs-helper-lib"],
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jni_libs: ["libcarevsglrenderer_jni"],
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```
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2. Implement `CarEvsGLSurfaceView.Callback` interface. For example,
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```
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/**
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* This method is called by the renderer to fetch a new frame to draw.
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*/
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@Override
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public CarEvsBufferDescriptor getNewFrame() {
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synchronized(mLock) {
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// Return a buffer to render.
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return mBufferToRender;
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}
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}
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/**
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* This method is called by the renderer when it is done with a passed
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* CarEvsBufferDescriptor object.
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*/
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@Override
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public void returnBuffer(CarEvsBufferDescriptor buffer) {
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// Return a buffer to CarEvsService.
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try {
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mEvsManager.returnFrameBuffer(buffer);
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} catch (Exception e) {
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...
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}
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...
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}
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```
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3. Create `CarEvsGLSurfaceView` with the application context,
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`CarEvsGLSurfaceView.Callback` object, and, optionally, a desired in-plane
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rotation angle.
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```
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private CarEvsGLSurfaceView mView;
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@Override
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protected void onCreate(Bundle savedInstanceState) {
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...
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mView = CarEvsGLSurfaceView(getAppliation(), this, /* angleInDegree= */ 0);
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...
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}
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```
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4. Start a video stream and update wheneven new frame buffer arrives. For
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example,
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```
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private final CarEvsManager.CarEvsStreamCallback mStreamHandler =
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new CarEvsManager.CarEvsStreamCallback() {
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...
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@Override
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public void onNewFrame(CarEvsBufferDescriptor buffer) {
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synchronized(mLock) {
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mBufferToRender = buffer;
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}
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}
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}
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```
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