[gtk/wip/chergert/quartz4u: 114/116] macos: stub out a GL layer

[Christian Hergert <chergert src gnome org>]

commit 284bcabd7a4602725590ed649b31174ae7f980f8
Author: Christian Hergert <chergert redhat com>
Date:   Tue Jun 23 18:24:02 2020 -0700

    macos: stub out a GL layer
    
    The goal here, currently, would be to use an FBO and a texture
    so that the GL context can render out of sync to the FBO and the
    layer can render contents when requested by core animation using
    the texture.
    
    All still tbd of course.

 gdk/macos/GdkMacosGLLayer.c | 157 ++++++++++++++++++++++++++++++++++++++++++++
 gdk/macos/GdkMacosGLLayer.h |  40 +++++++++++
 gdk/macos/meson.build       |   2 +
 3 files changed, 199 insertions(+)
---
diff --git a/gdk/macos/GdkMacosGLLayer.c b/gdk/macos/GdkMacosGLLayer.c
new file mode 100644
index 0000000000..a1ab55a4dc
--- /dev/null
+++ b/gdk/macos/GdkMacosGLLayer.c
@@ -0,0 +1,157 @@
+/* GdkMacosGLLayer.c
+ *
+ * Copyright © 2020 Red Hat, Inc.
+ *
+ * This library 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 of the License, or (at your option) any later version.
+ *
+ * This library 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 this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ */
+
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//    * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//    * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//    * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+/* Based on Chromium image_transport_surface_calayer_mac.mm
+ * See the BSD-style license above.
+ */
+
+#include "config.h"
+
+#include <OpenGL/gl.h>
+
+#import "GdkMacosGLLayer.h"
+
+@implementation GdkMacosGLLayer
+
+G_GNUC_BEGIN_IGNORE_DEPRECATIONS
+
+-(id)initWithContext:(NSOpenGLContext *)shared
+{
+  [super init];
+  _shared = [shared retain];
+  return self;
+}
+
+-(void)dealloc
+{
+  [_shared release];
+  _shared = nil;
+
+  [super dealloc];
+}
+
+-(void)setContentsRect:(NSRect)bounds
+{
+  _pixelSize = bounds.size;
+  [super setContentsRect:bounds];
+}
+
+-(CGLPixelFormatObj)copyCGLPixelFormatForDisplayMask:(uint32_t)mask
+{
+  return CGLRetainPixelFormat ([[_shared pixelFormat] CGLPixelFormatObj]);
+}
+
+-(CGLContextObj)copyCGLContextForPixelFormat:(CGLPixelFormatObj)pixelFormat
+{
+  CGLContextObj context = NULL;
+  CGLCreateContext (pixelFormat, [_shared CGLContextObj], &context);
+  return context;
+}
+
+-(BOOL)canDrawInCGLContext:(CGLContextObj)glContext
+               pixelFormat:(CGLPixelFormatObj)pixelFormat
+              forLayerTime:(CFTimeInterval)timeInterval
+               displayTime:(const CVTimeStamp*)timeStamp
+{
+  return YES;
+}
+
+-(void)drawInCGLContext:(CGLContextObj)glContext
+            pixelFormat:(CGLPixelFormatObj)pixelFormat
+           forLayerTime:(CFTimeInterval)timeInterval
+            displayTime:(const CVTimeStamp*)timeStamp
+{
+  if (_texture == 0)
+    return;
+
+  glClearColor (1, 0, 1, 1);
+  glClear (GL_COLOR_BUFFER_BIT);
+  GLint viewport[4] = {0, 0, 0, 0};
+  glGetIntegerv (GL_VIEWPORT, viewport);
+  NSSize viewportSize = NSMakeSize (viewport[2], viewport[3]);
+
+  /* Set the coordinate system to be one-to-one with pixels. */
+  glMatrixMode (GL_PROJECTION);
+  glLoadIdentity ();
+  glOrtho (0, viewportSize.width, 0, viewportSize.height, -1, 1);
+  glMatrixMode (GL_MODELVIEW);
+  glLoadIdentity ();
+
+  /* Draw a fullscreen quad. */
+  glColor4f (1, 1, 1, 1);
+  glEnable (GL_TEXTURE_RECTANGLE_ARB);
+  glBindTexture (GL_TEXTURE_RECTANGLE_ARB, _texture);
+  glBegin (GL_QUADS);
+  {
+    glTexCoord2f (0, 0);
+    glVertex2f (0, 0);
+    glTexCoord2f (0, _pixelSize.height);
+    glVertex2f (0, _pixelSize.height);
+    glTexCoord2f (_pixelSize.width, _pixelSize.height);
+    glVertex2f (_pixelSize.width, _pixelSize.height);
+    glTexCoord2f (_pixelSize.width, 0);
+    glVertex2f (_pixelSize.width, 0);
+  }
+  glEnd ();
+  glBindTexture (0, _texture);
+  glDisable (GL_TEXTURE_RECTANGLE_ARB);
+  [super drawInCGLContext:glContext
+              pixelFormat:pixelFormat
+             forLayerTime:timeInterval
+              displayTime:timeStamp];
+}
+
+-(void)setTexture:(GLuint)texture
+{
+  _texture = texture;
+  [self setNeedsDisplay];
+}
+
+G_GNUC_END_IGNORE_DEPRECATIONS
+
+@end
diff --git a/gdk/macos/GdkMacosGLLayer.h b/gdk/macos/GdkMacosGLLayer.h
new file mode 100644
index 0000000000..dd90c1ca08
--- /dev/null
+++ b/gdk/macos/GdkMacosGLLayer.h
@@ -0,0 +1,40 @@
+/* GdkMacosGLLayer.h
+ *
+ * Copyright © 2020 Red Hat, Inc.
+ *
+ * This library 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 of the License, or (at your option) any later version.
+ *
+ * This library 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 this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ */
+
+#include <AppKit/AppKit.h>
+#include <glib.h>
+
+#define GDK_IS_MACOS_GL_LAYER(obj) ((obj) && [obj isKindOfClass:[GdkMacosGLLayer class]])
+
+G_GNUC_BEGIN_IGNORE_DEPRECATIONS
+
+@interface GdkMacosGLLayer : CAOpenGLLayer
+{
+  NSOpenGLContext *_shared;
+  GLuint _texture;
+  NSSize _pixelSize;
+}
+
+-(id)initWithContext:(NSOpenGLContext *)shared;
+-(void)setTexture:(GLuint)texture;
+
+@end
+
+G_GNUC_END_IGNORE_DEPRECATIONS
diff --git a/gdk/macos/meson.build b/gdk/macos/meson.build
index 4d6362f8cb..072e695d6d 100644
--- a/gdk/macos/meson.build
+++ b/gdk/macos/meson.build
@@ -22,6 +22,7 @@ gdk_macos_sources = files([
   'GdkMacosBaseView.c',
   'GdkMacosCairoView.c',
   'GdkMacosCairoSubview.c',
+  'GdkMacosGLLayer.c',
   'GdkMacosWindow.c',
 ])
 
@@ -40,6 +41,7 @@ gdk_macos_frameworks = [
   'Carbon',
   'CoreVideo',
   'CoreServices',
+  'OpenGL',
 ]
 
 gdk_macos_deps = [