Move Objective-C video renderers to webrtc/api/objc.

webrtc/api/objc/RTCOpenGLVideoRenderer.h

+/*
+ *  Copyright 2015 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#import <Foundation/Foundation.h>
+#if TARGET_OS_IPHONE
+#import <GLKit/GLKit.h>
+#else
+#import <AppKit/NSOpenGL.h>
+#endif
+
+NS_ASSUME_NONNULL_BEGIN
+
+@class RTCVideoFrame;
+
+// RTCOpenGLVideoRenderer issues appropriate OpenGL commands to draw a frame to
+// the currently bound framebuffer. Supports OpenGL 3.2 and OpenGLES 2.0. OpenGL
+// framebuffer creation and management should be handled elsewhere using the
+// same context used to initialize this class.
+@interface RTCOpenGLVideoRenderer : NSObject
+
+// The last successfully drawn frame. Used to avoid drawing frames unnecessarily
+// hence saving battery life by reducing load.
+@property(nonatomic, readonly) RTCVideoFrame *lastDrawnFrame;
+
+#if TARGET_OS_IPHONE
+- (instancetype)initWithContext:(EAGLContext *)context
+    NS_DESIGNATED_INITIALIZER;
+#else
+- (instancetype)initWithContext:(NSOpenGLContext *)context
+    NS_DESIGNATED_INITIALIZER;
+#endif
+
+// Draws |frame| onto the currently bound OpenGL framebuffer. |setupGL| must be
+// called before this function will succeed.
+- (BOOL)drawFrame:(RTCVideoFrame *)frame;
+
+// The following methods are used to manage OpenGL resources. On iOS
+// applications should release resources when placed in background for use in
+// the foreground application. In fact, attempting to call OpenGLES commands
+// while in background will result in application termination.
+
+// Sets up the OpenGL state needed for rendering.
+- (void)setupGL;
+// Tears down the OpenGL state created by |setupGL|.
+- (void)teardownGL;
+
+- (instancetype)init NS_UNAVAILABLE;
+
+@end
+
+NS_ASSUME_NONNULL_END