显示成果
背景
在利用的开发过程中，咱们防止不了要应用Opengl共享context的技术。比方咱们须要在预览的同时还要将预览的画面传递给MediaCodec进行编码。有的敌人会说Camera2能够设置多个surface，这样就能够把预览的surface和MediaCodec的surface同时传递给Camera2。这种只是实现比较简单的录制性能。当初少数有录制性能的利用都反对滤镜性能，能够把你拍得更丑陋。因为退出了滤镜的性能，所以咱们要通过Opengl技术来实现。
当咱们退出opengl的滤镜性能后就有一个须要解决的问题，如何让预览和MediaCo dec同时利用滤镜。这时共享 context技术就派上用场了，通过共享context使创立在不同线程的texture id能够互相共享。通常共享的texture id绑定的是一个frame buffer，滤镜成果都绘制在这个frame buffer上，而后将frame buffer别离绘制在预览和MediaCodec。这里不对共享context的实现进行具体的介绍，这里重点关注的是有没有其余的计划来实现这个性能。
对于Camera2的思考（SurfaceTextureRenderer）
大家都晓得Camera2是反对设置多个surface的，那么他是如何把camera数据绘制到这些surface上的呢？实现形式就在SurfaceTextureRenderer中，通过查看这个文件咱们理解到他结构了一个opengl环境用于绘制camera数据。在构建opengl环境的过程中创立了EGLDisplay、EGLContext、EGLSurface。这里对于EGLSurface的创立有些非凡，咱们能够看到代码中创立了多个EGLSurface。每个EGLSurface都与一个surface进行绑定。
private void configureEGLOutputSurfaces(Collection<EGLSurfaceHolder> surfaces) { if (surfaces == null || surfaces.size() == 0) { throw new IllegalStateException("No Surfaces were provided to draw to"); } int[] surfaceAttribs = { EGL14.EGL_NONE }; for (EGLSurfaceHolder holder : surfaces) { holder.eglSurface = EGL14.eglCreateWindowSurface(mEGLDisplay, mConfigs, holder.surface, surfaceAttribs, /*offset*/ 0); checkEglError("eglCreateWindowSurface"); } }上面的代码是绘制camera数据到各个EGLSurface上，具体绘制到哪个EGLSurface上是通过 makeCurrent办法管制的。看到这里大家大略就明确了，通过EGL14.eglMakeCurrent办法就能够实现绘制内容到不同的surface上。当然在切换surface的时候要注意绘制的viewport大小也会发送变动，所以mvp matrix也要进行相应的更新。
public void drawIntoSurfaces(CaptureCollector targetCollector) { ... for (EGLSurfaceHolder holder : mSurfaces) { if (LegacyCameraDevice.containsSurfaceId(holder.surface, targetSurfaceIds)) { try{ LegacyCameraDevice.setSurfaceDimens(holder.surface, holder.width, holder.height); makeCurrent(holder.eglSurface); LegacyCameraDevice.setNextTimestamp(holder.surface, captureHolder.second); drawFrame(mSurfaceTexture, holder.width, holder.height, (mFacing == CameraCharacteristics.LENS_FACING_FRONT) ? FLIP_TYPE_HORIZONTAL : FLIP_TYPE_NONE); swapBuffers(holder.eglSurface); } catch (LegacyExceptionUtils.BufferQueueAbandonedException e) { Log.w(TAG, "Surface abandoned, dropping frame. ", e); request.setOutputAbandoned(); } } } ... } ｝ private void makeCurrent(EGLSurface surface) throws LegacyExceptionUtils.BufferQueueAbandonedException { EGL14.eglMakeCurrent(mEGLDisplay, surface, surface, mEGLContext); checkEglDrawError("makeCurrent"); }通过增加两个SurfaceView验证计划
这里咱们创立两个surfaceview用于验证结构多个eglsurface的计划。
surfaceView1.holder.addCallback(object:SurfaceHolder.Callback{ override fun surfaceCreated(holder: SurfaceHolder?) { } override fun surfaceChanged(holder: SurfaceHolder?, format: Int, width: Int, height: Int) { if (eglSurfaceHolder1 == null) { eglSurfaceHolder1 = EGLCore.EGLSurfaceHolder(holder!!.surface, width.toFloat(), height.toFloat()) renderScope.addSurfaceHolder(eglSurfaceHolder1) } } override fun surfaceDestroyed(holder: SurfaceHolder?) { renderScope.removeSurfaceHolder(eglSurfaceHolder1) eglSurfaceHolder1 = null } }) surfaceView2.holder.addCallback(object:SurfaceHolder.Callback{ override fun surfaceCreated(holder: SurfaceHolder?) { } override fun surfaceChanged(holder: SurfaceHolder?, format: Int, width: Int, height: Int) { if (eglSurfaceHolder2 == null) { eglSurfaceHolder2 = EGLCore.EGLSurfaceHolder(holder!!.surface, width.toFloat(), height.toFloat()) renderScope.addSurfaceHolder(eglSurfaceHolder2) } } override fun surfaceDestroyed(holder: SurfaceHolder?) { renderScope.removeSurfaceHolder(eglSurfaceHolder2) eglSurfaceHolder2 = null } })这里把两个surface都增加到RenderScope中，RenderScope创立opengl线程环境，opengl描绘都是产生在这个线程的。
class RenderScope(private val render: Render) : BackgroundScope by HandlerThreadScope() { private var eglCore: EGLCore? = null init { runInBackground { eglCore = EGLCore() render.onCreate() } } fun addSurfaceHolder(eglSurfaceHolder: EGLCore.EGLSurfaceHolder?) = runInBackground { eglCore?.addSurfaceHolder(eglSurfaceHolder) } fun removeSurfaceHolder(eglSurfaceHolder: EGLCore.EGLSurfaceHolder?) = runInBackground { eglCore?.removeSurfaceHolder(eglSurfaceHolder) } fun removeSurfaceHolder(surface: Surface?) = runInBackground { eglCore?.removeSurfaceHolder(surface) } fun release() = runInBackground { render.onDestroy() eglCore?.releaseEGLContext() eglCore = null quit() } fun requestRender() = runInBackground { eglCore?.render { render.onDrawFrame(it) } } interface Render { fun onCreate() fun onDestroy() fun onDrawFrame(eglSurfaceHolder: EGLCore.EGLSurfaceHolder) }}EGLCore这个类是用来结构opengl环境的，结构的过程这里不细说了。咱们重点关注下addSurfaceHolder这个办法。它是用于增加surface的，通过这个办法增加surface后，渲染过程中就能够把内容绘制到这个surface上。render办法用于渲染应用，看他的实现次要就是通过makecurrent来切换eglsurface，而后调用block 进行描绘。block调用的次数与增加的surface数量雷同。
class EGLCore { private var mEGLDisplay = EGL14.EGL_NO_DISPLAY private var mEGLContext = EGL14.EGL_NO_CONTEXT private var mConfigs: EGLConfig? = null private val mEGLSurfaces = SparseArray<EGLSurfaceHolder>() init { log("initEGLContext") releaseEGLContext() mEGLDisplay = EGL14.eglGetDisplay(EGL14.EGL_DEFAULT_DISPLAY) check(!(mEGLDisplay === EGL14.EGL_NO_DISPLAY)) { "No EGL14 display" } val version = IntArray(2) check(EGL14.eglInitialize(mEGLDisplay, version, /*offset*/0, version, /*offset*/1)) { "Cannot initialize EGL14" } val attributeList = intArrayOf( EGL14.EGL_RED_SIZE, EGL_COLOR_BIT_LENGTH, EGL14.EGL_GREEN_SIZE, EGL_COLOR_BIT_LENGTH, EGL14.EGL_BLUE_SIZE, EGL_COLOR_BIT_LENGTH, EGL14.EGL_RENDERABLE_TYPE, EGL14.EGL_OPENGL_ES2_BIT, EGL_RECORDABLE_ANDROID, 1, EGL14.EGL_SURFACE_TYPE, EGL14.EGL_PBUFFER_BIT or EGL14.EGL_WINDOW_BIT, EGL14.EGL_NONE ) val configs = arrayOfNulls<EGLConfig>(1) val numConfigs = IntArray(1) EGL14.eglChooseConfig( mEGLDisplay, attributeList, /*offset*/0, configs, /*offset*/0, configs.size, numConfigs, /*offset*/0 ) checkEglError("eglCreateContext RGB888+recordable ES2") mConfigs = configs[0] val contextAttributeList = intArrayOf( EGL14.EGL_CONTEXT_CLIENT_VERSION, GLES_VERSION, EGL14.EGL_NONE ) mEGLContext = EGL14.eglCreateContext( mEGLDisplay, configs[0], EGL14.EGL_NO_CONTEXT, contextAttributeList, /*offset*/0 ) checkEglError("eglCreateContext") check(!(mEGLContext === EGL14.EGL_NO_CONTEXT)) { "No EGLContext could be made" } EGL14.eglMakeCurrent(mEGLDisplay, EGL14.EGL_NO_SURFACE, EGL14.EGL_NO_SURFACE, mEGLContext) } fun addSurfaceHolder(eglSurfaceHolder: EGLSurfaceHolder?) { if (mEGLDisplay == EGL14.EGL_NO_DISPLAY) { log("addSurfaceHolder mEGLDisplay == EGL14.EGL_NO_DISPLAY") return } eglSurfaceHolder ?: return check(eglSurfaceHolder.surface.isValid) { "addSurface surface is not valid!!" } val surfaceAttribute = intArrayOf( EGL14.EGL_NONE ) eglSurfaceHolder.eglSurface = EGL14.eglCreateWindowSurface( mEGLDisplay, mConfigs, eglSurfaceHolder.surface, surfaceAttribute, /*offset*/0 ) checkEglError("eglCreateWindowSurface") mEGLSurfaces.put(eglSurfaceHolder.surface.hashCode(), eglSurfaceHolder) } fun removeSurfaceHolder(eglSurfaceHolder: EGLSurfaceHolder?) { if (mEGLDisplay == EGL14.EGL_NO_DISPLAY) { log("removeSurfaceHolder mEGLDisplay == EGL14.EGL_NO_DISPLAY") return } eglSurfaceHolder ?: return mEGLSurfaces[eglSurfaceHolder.surface.hashCode()]?.let { EGL14.eglDestroySurface(mEGLDisplay, it.eglSurface) it.eglSurface = null mEGLSurfaces.remove(it.surface.hashCode()) } } fun removeSurfaceHolder(surface: Surface?) { if (mEGLDisplay == EGL14.EGL_NO_DISPLAY) { log("removeSurfaceHolder mEGLDisplay == EGL14.EGL_NO_DISPLAY") return } surface ?: return mEGLSurfaces[surface.hashCode()]?.let { EGL14.eglDestroySurface(mEGLDisplay, it.eglSurface) it.eglSurface = null mEGLSurfaces.remove(surface.hashCode()) } } fun render(block: (EGLSurfaceHolder) -> Unit) { if (mEGLDisplay == EGL14.EGL_NO_DISPLAY) { log("render mEGLDisplay == EGL14.EGL_NO_DISPLAY") return } mEGLSurfaces.forEach { _, holder -> if (!holder.available) { return@forEach } EGL14.eglMakeCurrent(mEGLDisplay, holder.eglSurface, holder.eglSurface, mEGLContext) checkEglError("makeCurrent") block.invoke(holder) val result = EGL14.eglSwapBuffers(mEGLDisplay, holder.eglSurface) when (val error = EGL14.eglGetError()) { EGL14.EGL_SUCCESS -> result EGL14.EGL_BAD_NATIVE_WINDOW, EGL14.EGL_BAD_SURFACE -> throw IllegalStateException( "swapBuffers: EGL error: 0x" + Integer.toHexString(error) ) else -> throw IllegalStateException( "swapBuffers: EGL error: 0x" + Integer.toHexString(error) ) } } } fun releaseEGLContext() { if (mEGLDisplay !== EGL14.EGL_NO_DISPLAY) { log("releaseEGLContext") EGL14.eglMakeCurrent(mEGLDisplay, EGL14.EGL_NO_SURFACE, EGL14.EGL_NO_SURFACE, EGL14.EGL_NO_CONTEXT) mEGLSurfaces.forEach { _, holder -> if (holder.eglSurface != null) { EGL14.eglDestroySurface(mEGLDisplay, holder.eglSurface) holder.eglSurface = null } } mEGLSurfaces.clear() EGL14.eglDestroyContext(mEGLDisplay, mEGLContext) EGL14.eglReleaseThread() EGL14.eglTerminate(mEGLDisplay) } mConfigs = null mEGLDisplay = EGL14.EGL_NO_DISPLAY mEGLContext = EGL14.EGL_NO_CONTEXT } private fun checkEglError(msg: String) { val error = EGL14.eglGetError() check(error == EGL14.EGL_SUCCESS) { msg + ": EGL error: 0x" + Integer.toHexString(error) } } private fun log(msg: String) { Log.d("EGLCore", msg) } class EGLSurfaceHolder( val surface: Surface, val width: Float, val height: Float ) { var eglSurface: EGLSurface? = null var available = true val mvpMatrix = MVPMatrix().updateViewport(width, height) val viewPortRectF = RectF(0f, 0f, width, height) } companion object { private const val GLES_VERSION = 2 private const val EGL_COLOR_BIT_LENGTH = 8 const val EGL_RECORDABLE_ANDROID = 0x3142 // from EGL/eglext.h }}Git
https://github.com/mjlong1231...