vo_gpu: add android opengl backend

At the moment, rendering on Android requires ``--vo=opengl-cb`` and
a lot of java<->c++ bridging code to receive the receive and react to
the render callback in java. Performance also suffers with opengl-cb,
due to the overhead of context switching in JNI.

With this patch, Android can render using ``--vo=gpu --gpu-context=android``
(after setting ``--wid`` to point to an android.view.Surface on-screen).

DOCS/man/options.rst

@@ -2483,7 +2483,8 @@ Window
 
     On Android, the ID is interpreted as ``android.view.Surface``. Pass it as a
     value cast to ``intptr_t``. Use with ``--vo=mediacodec_embed`` and
-    ``--hwdec=mediacodec`` for direct rendering using MediaCodec.
+    ``--hwdec=mediacodec`` for direct rendering using MediaCodec, or with
+    ``--vo=gpu --gpu-context=android`` (with or without ``--hwdec=mediacodec-copy``).
 
 ``--no-window-dragging``
     Don't move the window when clicking on it and moving the mouse pointer.
@@ -4637,6 +4638,8 @@ The following video options are currently all specific to ``--vo=gpu`` and
         DRM/EGL
     x11egl
         X11/EGL
+    android
+	Android/EGL. Requires ``--wid`` be set to an ``android.view.Surface``.
     mali-fbdev
         Direct fbdev/EGL support on some ARM/MALI devices.
     vdpauglx

DOCS/man/vo.rst

@@ -512,3 +512,6 @@ Available video output drivers are:
     Since this video output driver uses native decoding and rendering routines,
     many of mpv's features (subtitle rendering, OSD/OSC, video filters, etc)
     are not available with this driver.
+
+    To use hardware decoding with ``--vo-gpu`` instead, use
+    ``--hwdec=mediacodec-copy`` along with ``--gpu-context=android``.

video/out/opengl/context_android.c

@@ -0,0 +1,151 @@
+/*
+ * This file is part of mpv.
+ *
+ * mpv is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * mpv is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with mpv.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <EGL/egl.h>
+#include <EGL/eglext.h>
+#include <libavcodec/jni.h>
+#include <android/native_window_jni.h>
+
+#include "egl_helpers.h"
+
+#include "common/common.h"
+#include "options/m_config.h"
+#include "context.h"
+
+struct priv {
+    struct GL gl;
+    EGLDisplay egl_display;
+    EGLConfig egl_config;
+    EGLContext egl_context;
+    EGLSurface egl_surface;
+    ANativeWindow *native_window;
+    int w, h;
+};
+
+static void android_swap_buffers(struct ra_ctx *ctx)
+{
+    struct priv *p = ctx->priv;
+    eglSwapBuffers(p->egl_display, p->egl_surface);
+}
+
+static void android_uninit(struct ra_ctx *ctx)
+{
+    struct priv *p = ctx->priv;
+    ra_gl_ctx_uninit(ctx);
+
+    if (p->egl_surface) {
+        eglMakeCurrent(p->egl_display, EGL_NO_SURFACE, EGL_NO_SURFACE,
+                       EGL_NO_CONTEXT);
+        eglDestroySurface(p->egl_display, p->egl_surface);
+    }
+    if (p->egl_context)
+        eglDestroyContext(p->egl_display, p->egl_context);
+
+    if (p->native_window) {
+        ANativeWindow_release(p->native_window);
+        p->native_window = NULL;
+    }
+}
+
+static bool android_init(struct ra_ctx *ctx)
+{
+    struct priv *p = ctx->priv = talloc_zero(ctx, struct priv);
+
+    jobject surface = (jobject)(intptr_t)ctx->vo->opts->WinID;
+    JavaVM *vm = (JavaVM *)av_jni_get_java_vm(NULL);
+    JNIEnv *env;
+    int ret = (*vm)->GetEnv(vm, (void**)&env, JNI_VERSION_1_6);
+    if (ret == JNI_EDETACHED) {
+        if ((*vm)->AttachCurrentThread(vm, &env, NULL) != 0) {
+            MP_FATAL(ctx, "Could not attach java VM.\n");
+            goto fail;
+        }
+    }
+    p->native_window = ANativeWindow_fromSurface(env, surface);
+    (*vm)->DetachCurrentThread(vm);
+
+    p->egl_display = eglGetDisplay(EGL_DEFAULT_DISPLAY);
+    if (!eglInitialize(p->egl_display, NULL, NULL)) {
+        MP_FATAL(ctx, "EGL failed to initialize.\n");
+        goto fail;
+    }
+
+    EGLConfig config;
+    if (!mpegl_create_context(ctx, p->egl_display, &p->egl_context, &config))
+        goto fail;
+
+    EGLint format;
+    eglGetConfigAttrib(p->egl_display, config, EGL_NATIVE_VISUAL_ID, &format);
+    ANativeWindow_setBuffersGeometry(p->native_window, 0, 0, format);
+
+    p->egl_surface = eglCreateWindowSurface(p->egl_display, config,
+                                    (EGLNativeWindowType)p->native_window, NULL);
+
+    if (p->egl_surface == EGL_NO_SURFACE) {
+        MP_FATAL(ctx, "Could not create EGL surface!\n");
+        goto fail;
+    }
+
+    if (!eglMakeCurrent(p->egl_display, p->egl_surface, p->egl_surface,
+                        p->egl_context)) {
+        MP_FATAL(ctx, "Failed to set context!\n");
+        goto fail;
+    }
+
+    if (!eglQuerySurface(p->egl_display, p->egl_surface, EGL_WIDTH, &p->w) ||
+        !eglQuerySurface(p->egl_display, p->egl_surface, EGL_HEIGHT, &p->h)) {
+        MP_FATAL(ctx, "Failed to get height and width!\n");
+        goto fail;
+    }
+
+    mpegl_load_functions(&p->gl, ctx->log);
+
+    struct ra_gl_ctx_params params = {
+        .swap_buffers = android_swap_buffers,
+    };
+
+    if (!ra_gl_ctx_init(ctx, &p->gl, params))
+        goto fail;
+
+    return true;
+fail:
+    android_uninit(ctx);
+    return false;
+}
+
+static bool android_reconfig(struct ra_ctx *ctx)
+{
+    struct priv *p = ctx->priv;
+    ctx->vo->dwidth = p->w;
+    ctx->vo->dheight = p->h;
+    ra_gl_ctx_resize(ctx->swapchain, p->w, p->h, 0);
+    return true;
+}
+
+static int android_control(struct ra_ctx *ctx, int *events, int request, void *arg)
+{
+    return VO_NOTIMPL;
+}
+
+const struct ra_ctx_fns ra_ctx_android = {
+    .type           = "opengl",
+    .name           = "android",
+    .reconfig       = android_reconfig,
+    .control        = android_control,
+    .init           = android_init,
+    .uninit         = android_uninit,
+};

wscript

@@ -153,7 +153,10 @@ main_dependencies = [
     }, {
         'name': '--android',
         'desc': 'Android environment',
-        'func': check_statement('android/api-level.h', '(void)__ANDROID__'),  # arbitrary android-specific header
+        'func': compose_checks(
+            check_statement('android/api-level.h', '(void)__ANDROID__'),  # arbitrary android-specific header
+            check_cc(lib="android"),
+        )
     }, {
         'name': 'posix-or-mingw',
         'desc': 'development environment',
@@ -817,7 +820,7 @@ video_output_features = [
         'name': 'egl-helpers',
         'desc': 'EGL helper functions',
         'deps': 'egl-x11 || mali-fbdev || rpi || gl-wayland || egl-drm || ' +
-                'egl-angle-win32',
+                'egl-angle-win32 || android',
         'func': check_true
     }
 ]

wscript_build.py

@@ -425,6 +425,7 @@ def build(ctx):
         ( "video/out/opengl/context_drm_egl.c",  "egl-drm" ),
         ( "video/out/opengl/context_dxinterop.c","gl-dxinterop" ),
         ( "video/out/opengl/context_mali_fbdev.c","mali-fbdev" ),
+        ( "video/out/opengl/context_android.c",  "android" ),
         ( "video/out/opengl/context_rpi.c",      "rpi" ),
         ( "video/out/opengl/context_vdpau.c",    "vdpau-gl-x11" ),
         ( "video/out/opengl/context_wayland.c",  "gl-wayland" ),