Make cross-process CALayers work on Mac

content/common/gpu/image_transport_surface_calayer_mac.mm

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/common/gpu/image_transport_surface_calayer_mac.h"
+
+#include "base/mac/sdk_forward_declarations.h"
+#include "content/common/gpu/surface_handle_types_mac.h"
+#include "ui/base/cocoa/animation_utils.h"
+#include "ui/gfx/geometry/size_conversions.h"
+
+@interface ImageTransportLayer (Private) {
+}
+@end
+
+@implementation ImageTransportLayer
+
+- (id)initWithContext:(CGLContextObj)context
+          withTexture:(GLuint)texture
+        withPixelSize:(gfx::Size)pixelSize
+      withScaleFactor:(float)scaleFactor {
+  if (self = [super init]) {
+    shareContext_.reset(CGLRetainContext(context));
+    texture_ = texture;
+    pixelSize_ = pixelSize;
+
+    gfx::Size dipSize(gfx::ToFlooredSize(gfx::ScaleSize(
+        pixelSize_, 1.0f / scaleFactor)));
+    [self setContentsScale:scaleFactor];
+    [self setFrame:CGRectMake(0, 0, dipSize.width(), dipSize.height())];
+  }
+  return self;
+}
+
+- (CGLPixelFormatObj)copyCGLPixelFormatForDisplayMask:(uint32_t)mask {
+  return CGLRetainPixelFormat(CGLGetPixelFormat(shareContext_));
+}
+
+- (CGLContextObj)copyCGLContextForPixelFormat:(CGLPixelFormatObj)pixelFormat {
+  CGLContextObj context = NULL;
+  CGLError error = CGLCreateContext(pixelFormat, shareContext_, &context);
+  if (error != kCGLNoError)
+    DLOG(ERROR) << "CGLCreateContext failed with CGL error: " << error;
+  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 {
+  glClearColor(1, 0, 1, 1);
+  glClear(GL_COLOR_BUFFER_BIT);
+
+  GLint viewport[4] = {0, 0, 0, 0};
+  glGetIntegerv(GL_VIEWPORT, viewport);
+  gfx::Size viewportSize(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];
+}
+
+@end
+
+namespace content {
+
+CALayerStorageProvider::CALayerStorageProvider() {
+  base::scoped_nsobject<NSDictionary> dict([[NSDictionary alloc] init]);
+  CGSConnectionID connection_id = CGSMainConnectionID();
+  context_.reset([CAContext contextWithCGSConnection:connection_id
+                                             options:dict]);
+  [context_ retain];
+}
+
+CALayerStorageProvider::~CALayerStorageProvider() {
+}
+
+gfx::Size CALayerStorageProvider::GetRoundedSize(gfx::Size size) {
+  return size;
+}
+
+bool CALayerStorageProvider::AllocateColorBufferStorage(
+    CGLContextObj context, gfx::Size pixel_size, float scale_factor) {
+  // Allocate an ordinary OpenGL texture to back the FBO.
+  GLenum error = glGetError();

[piman, 2014/06/19 21:51:02]

note: there can be a stack of GL errors. If you want to be thorough and get rid
of all errors you need a while loop. See e.g. ErrorStateImpl::ClearRealGLErrors

[ccameron, 2014/06/19 23:56:41]

Done.

+  if (error != GL_NO_ERROR) {
+    DLOG(ERROR) << "Error found (and ignored) before allocating buffer "
+                << "storage: " << error;
+  }
+  glTexImage2D(GL_TEXTURE_RECTANGLE_ARB,
+               0,
+               GL_RGBA,
+               pixel_size.width(),
+               pixel_size.height(),
+               0,
+               GL_RGBA,
+               GL_UNSIGNED_BYTE,
+               NULL);
+  error = glGetError();
+  if (error != GL_NO_ERROR) {
+    DLOG(ERROR) << "glTexImage failed with GL error: " << error;
+    return false;
+  }
+  glFlush();
+
+  GLuint texture = 0;
+  glGetIntegerv(GL_TEXTURE_BINDING_RECTANGLE_ARB,
+                reinterpret_cast<GLint*>(&texture));

[piman, 2014/06/19 21:51:02]

How about passing the texture id to the function? The caller has it.

[ccameron, 2014/06/19 23:56:41]

Umm, that's a good point. Somehow that eluded me. Done.

+
+  // Disable the fade-in animation as the layer is changed.
+  ScopedCAActionDisabler disabler;
+
+  // Resize the CAOpenGLLayer to match the size needed, and change it to be the
+  // hosted layer.
+  layer_.reset([[ImageTransportLayer alloc] initWithContext:context
+                                                withTexture:texture
+                                              withPixelSize:pixel_size
+                                            withScaleFactor:scale_factor]);
+  return true;
+}
+
+void CALayerStorageProvider::FreeColorBufferStorage() {
+  [context_ setLayer:nil];
+  layer_.reset();
+}
+
+uint64 CALayerStorageProvider::GetSurfaceHandle() const {
+  return SurfaceHandleFromCAContextID([context_ contextId]);
+}
+
+void CALayerStorageProvider::WillSwapBuffers() {
+  // Don't add the layer to the CAContext until a SwapBuffers is going to be
+  // called, because the texture does not have any content until the
+  // SwapBuffers call is about to be made.
+  if ([context_ layer] != layer_.get())
+    [context_ setLayer:layer_];
+
+  // TODO(ccameron): Use the isAsynchronous property to ensure smooth
+  // animation.
+  [layer_ setNeedsDisplay];
+}
+
+}  //  namespace content