在MediaCodec里面可以看到 Configure 和 SetSurface 都是接收一个 sp<Surface> 入参的,而回归到 NDK 侧,则可以发现,传递给 AMediaCodec_Configure 和 AMediaCodec_SetSurface 的确是 ANativeWindow 指针,因此 ndk 里面必然进行了某种转换。
cpp
EXPORT
media_status_t AMediaCodec_configure(
AMediaCodec *mData,
const AMediaFormat* format,
ANativeWindow* window,
AMediaCrypto *crypto,
uint32_t flags) {
sp<AMessage> nativeFormat;
AMediaFormat_getFormat(format, &nativeFormat);
// create our shallow copy, so we aren't victim to any later changes.
sp<AMessage> dupNativeFormat = nativeFormat->dup();
ALOGV("configure with format: %s", dupNativeFormat->debugString(0).c_str());
sp<Surface> surface = NULL;
if (window != NULL) {
surface = (Surface*) window;
}
status_t err = mData->mCodec->configure(dupNativeFormat, surface,
crypto ? crypto->mCrypto : NULL, flags);
if (err != OK) {
ALOGE("configure: err(%d), failed with format: %s",
err, dupNativeFormat->debugString(0).c_str());
}
return translate_error(err);
}
cpp
//prebuilts/vndk/v32/arm64/include/frameworks/native/libs/gui/include/gui/Surface.h
/*
* An implementation of ANativeWindow that feeds graphics buffers into a
* BufferQueue.
*
* This is typically used by programs that want to render frames through
* some means (maybe OpenGL, a software renderer, or a hardware decoder)
* and have the frames they create forwarded to SurfaceFlinger for
* compositing. For example, a video decoder could render a frame and call
* eglSwapBuffers(), which invokes ANativeWindow callbacks defined by
* Surface. Surface then forwards the buffers through Binder IPC
* to the BufferQueue's producer interface, providing the new frame to a
* consumer such as GLConsumer.
*/
class Surface
: public ANativeObjectBase<ANativeWindow, Surface, RefBase>
由此可见, Surface 类是 ANativeWindow 的子类。