Upstream support for iOS Simulator.

Originally authored in the WebKit repository:
https://bugs.webkit.org/show_bug.cgi?id=205618

Has been tested with WebKit's WebGL backend on top of ANGLE inside the
iOS Simulator. TODOs will be addressed in forthcoming CLs.

Bug: angleproject:4263
Change-Id: Ic879866aaee5f933599d956b0646d0c01db55d0d
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1995824
Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Jonah Ryan-Davis <jonahr@google.com>
Commit-Queue: Kenneth Russell <kbr@chromium.org>

extensions/EGL_ANGLE_iosurface_client_buffer.txt

@@ -21,7 +21,7 @@ Status
     Draft
 
 Version
-    Version 3, Aug 13, 2019
+    Version 4, Dec 28, 2019
 
 Number
 
@@ -53,6 +53,7 @@ New Tokens
         EGL_TEXTURE_RECTANGLE_ANGLE    0x345B
         EGL_TEXTURE_TYPE_ANGLE         0x345C
         EGL_TEXTURE_INTERNAL_FORMAT_ANGLE 0x345D
+        EGL_IOSURFACE_USAGE_HINT_ANGLE 0x348A
 
 Additions to Chapter 3 of the EGL 1.4 Specification (EGL Functions and Errors)
 
@@ -80,7 +81,8 @@ Additions to Chapter 3 of the EGL 1.4 Specification (EGL Functions and Errors)
       - EGL_TEXTURE_FORMAT with a value of EGL_TEXTURE_RGBA
       - EGL_WIDTH with a value between 1 and the width of <buffer>.
       - EGL_HEIGHT with a value between 1 and the height of <buffer>.
-      - EGL_TEXTURE_TARGET with a value of EGL_TEXTURE_RECTANGLE_ANGLE
+      - EGL_TEXTURE_TARGET with a value of EGL_TEXTURE_RECTANGLE_ANGLE (macOS)
+        or EGL_TEXTURE_2D (iOS)
       - EGL_IOSURFACE_PLANE_ANGLE with a value between 0 and the number of
     planes of <buffer> (exclusive).
 
@@ -88,7 +90,15 @@ Additions to Chapter 3 of the EGL 1.4 Specification (EGL Functions and Errors)
     EGL_TEXTURE_INTERNAL_FORMAT_ANGLE attributes must be one of the
     combinations listed in table egl.iosurface.formats or an
     EGL_BAD_PARAMETER is generated. The combination must also be a valid
-    combinations for glTexImage2D or EGL_BAD_PARAMETER is generated."
+    combinations for glTexImage2D or EGL_BAD_PARAMETER is generated.
+
+    The attribute EGL_IOSURFACE_USAGE_HINT_ANGLE may optionally be specified as
+    a combination of the bits EGL_IOSURFACE_READ_HINT_ANGLE and
+    EGL_IOSURFACE_WRITE_HINT_ANGLE. On the iOS Simulator platform, where
+    IOSurface support is incomplete, these hints indicate whether the intent is
+    to read from the IOSurface, write to it, or both. Explicitly passing 0 for
+    this attribute is equivalent to setting both the read and write usage
+    bits. This attribute is ignored on other platforms."
 
     ---------------------------------------------------------------------------
     Texture Type               Texture Internal Format
@@ -122,3 +132,5 @@ Revision History
     Version 1, 2017/12/06 - first draft.
     Version 2, 2019/04/01 - Allow MakeCurrent.
     Version 3, 2019/08/13 - Allow RGB internal formats
+    Version 4, 2019/12/28 - Add usage hint; require TEXTURE_RECTANGLE on macOS
+                            and TEXTURE_2D on iOS

include/EGL/eglext_angle.h

@@ -194,6 +194,9 @@ EGLAPI EGLint EGLAPIENTRY eglProgramCacheResizeANGLE(EGLDisplay dpy, EGLint limi
 #define EGL_TEXTURE_RECTANGLE_ANGLE 0x345B
 #define EGL_TEXTURE_TYPE_ANGLE 0x345C
 #define EGL_TEXTURE_INTERNAL_FORMAT_ANGLE 0x345D
+#define EGL_IOSURFACE_USAGE_HINT_ANGLE 0x348A
+#define EGL_IOSURFACE_READ_HINT_ANGLE 0x0001
+#define EGL_IOSURFACE_WRITE_HINT_ANGLE 0x0002
 #endif /* EGL_ANGLE_iosurface_client_buffer */
 
 #ifndef EGL_ANGLE_create_context_extensions_enabled

src/libANGLE/renderer/gl/eagl/DisplayEAGL.mm

@@ -29,8 +29,6 @@
 
 #    define GLES_SILENCE_DEPRECATION
 
-#    if !defined(ANGLE_PLATFORM_IOS_SIMULATOR)
-
 namespace
 {
 
@@ -38,8 +36,6 @@ const char *kOpenGLESDylibName = "/System/Library/Frameworks/OpenGLES.framework/
 
 }
 
-#    endif
-
 namespace rx
 {
 
@@ -69,10 +65,6 @@ egl::Error DisplayEAGL::initialize(egl::Display *display)
 {
     mEGLDisplay = display;
 
-#    if defined(ANGLE_PLATFORM_IOS_SIMULATOR)
-    return egl::EglNotInitialized()
-           << "ANGLE with EAGL not supported on iOS Simulator due to lack of IOSurface support.";
-#    else
     angle::SystemInfo info;
     if (!angle::GetSystemInfo(&info))
     {
@@ -105,7 +97,6 @@ egl::Error DisplayEAGL::initialize(egl::Display *display)
     }
 
     return DisplayGL::initialize(display);
-#    endif
 }
 
 void DisplayEAGL::terminate()

src/libANGLE/renderer/gl/eagl/IOSurfaceSurfaceEAGL.h

@@ -10,8 +10,7 @@
 #include "libANGLE/renderer/gl/SurfaceGL.h"
 #include "libANGLE/renderer/gl/eagl/DisplayEAGL.h"
 
-struct __IOSurface;
-typedef __IOSurface *IOSurfaceRef;
+#include <IOSurface/IOSurfaceRef.h>
 
 namespace egl
 {
@@ -66,6 +65,10 @@ class IOSurfaceSurfaceEAGL : public SurfaceGL
   private:
     angle::Result initializeAlphaChannel(const gl::Context *context, GLuint texture);
 
+#if defined(ANGLE_PLATFORM_IOS_SIMULATOR)
+    IOSurfaceLockOptions getIOSurfaceLockOptions() const;
+#endif
+
     EAGLContextObj mEAGLContext;
     IOSurfaceRef mIOSurface;
     int mWidth;
@@ -74,6 +77,11 @@ class IOSurfaceSurfaceEAGL : public SurfaceGL
     int mFormatIndex;
 
     bool mAlphaInitialized;
+#if defined(ANGLE_PLATFORM_IOS_SIMULATOR)
+    GLuint mBoundTextureID;
+    bool mUploadFromIOSurface;
+    bool mReadbackToIOSurface;
+#endif
 };
 
 }  // namespace rx

src/libANGLE/renderer/gl/eagl/IOSurfaceSurfaceEAGL.mm

@@ -102,6 +102,15 @@ IOSurfaceSurfaceEAGL::IOSurfaceSurfaceEAGL(const egl::SurfaceState &state,
     ASSERT(mFormatIndex >= 0);
 
     mAlphaInitialized = !hasEmulatedAlphaChannel();
+
+#    if defined(ANGLE_PLATFORM_IOS_SIMULATOR)
+    mBoundTextureID = 0;
+    EGLAttrib usageHint =
+        attribs.get(EGL_IOSURFACE_USAGE_HINT_ANGLE,
+                    EGL_IOSURFACE_READ_HINT_ANGLE | EGL_IOSURFACE_WRITE_HINT_ANGLE);
+    mUploadFromIOSurface = ((usageHint & EGL_IOSURFACE_READ_HINT_ANGLE) != 0);
+    mReadbackToIOSurface = ((usageHint & EGL_IOSURFACE_WRITE_HINT_ANGLE) != 0);
+#    endif
 }
 
 IOSurfaceSurfaceEAGL::~IOSurfaceSurfaceEAGL()
@@ -154,7 +163,6 @@ egl::Error IOSurfaceSurfaceEAGL::bindTexImage(const gl::Context *context,
                                               gl::Texture *texture,
                                               EGLint)
 {
-#    if !defined(ANGLE_PLATFORM_IOS_SIMULATOR)
     StateManagerGL *stateManager = GetStateManagerGL(context);
 
     const TextureGL *textureGL = GetImplAs<TextureGL>(texture);
@@ -162,6 +170,7 @@ egl::Error IOSurfaceSurfaceEAGL::bindTexImage(const gl::Context *context,
     stateManager->bindTexture(gl::TextureType::_2D, textureID);
     const auto &format = kIOSurfaceFormats[mFormatIndex];
 
+#    if !defined(ANGLE_PLATFORM_IOS_SIMULATOR)
     if (![mEAGLContext texImageIOSurface:mIOSurface
                                   target:GL_TEXTURE_2D
                           internalFormat:format.nativeInternalFormat
@@ -178,17 +187,58 @@ egl::Error IOSurfaceSurfaceEAGL::bindTexImage(const gl::Context *context,
     {
         return egl::EglContextLost() << "Failed to initialize IOSurface alpha channel.";
     }
+#    else   // !defined(ANGLE_PLATFORM_IOS_SIMULATOR)
+    const FunctionsGL *functions = GetFunctionsGL(context);
+
+    IOSurfaceLock(mIOSurface, getIOSurfaceLockOptions(), nullptr);
+    void *textureData = nullptr;
+    if (mUploadFromIOSurface)
+    {
+        // TODO(kbr): possibly more state to be set here, including setting any
+        // pixel unpack buffer to 0 when using ES 3.0 contexts.
+        gl::PixelUnpackState defaultUnpackState;
+        stateManager->setPixelUnpackState(defaultUnpackState);
+        textureData = IOSurfaceGetBaseAddress(mIOSurface);
+    }
+
+    // TODO(kbr): consider trying to optimize away texture reallocations by
+    // keeping track of which textures have already been allocated.
+    functions->texImage2D(GL_TEXTURE_2D, 0, format.nativeInternalFormat, mWidth, mHeight, 0,
+                          format.nativeFormat, format.nativeType, textureData);
+
+    mBoundTextureID = textureID;
+#    endif  // !defined(ANGLE_PLATFORM_IOS_SIMULATOR)
 
     return egl::NoError();
-#    else
-    return egl::EglContextLost() << "EAGLContext IOSurface not supported in the simulator.";
-#    endif
 }
 
 egl::Error IOSurfaceSurfaceEAGL::releaseTexImage(const gl::Context *context, EGLint buffer)
 {
     const FunctionsGL *functions = GetFunctionsGL(context);
+#    if !defined(ANGLE_PLATFORM_IOS_SIMULATOR)
     functions->flush();
+#    else   // !defined(ANGLE_PLATFORM_IOS_SIMULATOR)
+    if (mReadbackToIOSurface)
+    {
+        StateManagerGL *stateManager = GetStateManagerGL(context);
+        GLuint tempFBO               = 0;
+        functions->genFramebuffers(1, &tempFBO);
+        stateManager->bindFramebuffer(GL_FRAMEBUFFER, tempFBO);
+        functions->framebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D,
+                                        mBoundTextureID, 0);
+        gl::PixelPackState state;
+        state.alignment = 1;
+        stateManager->setPixelPackState(state);
+        // TODO(kbr): possibly more state to be set here, including setting any
+        // pixel pack buffer to 0 when using ES 3.0 contexts.
+        const auto &format = kIOSurfaceFormats[mFormatIndex];
+        functions->readPixels(0, 0, mWidth, mHeight, format.nativeFormat, format.nativeType,
+                              IOSurfaceGetBaseAddress(mIOSurface));
+    }
+
+    IOSurfaceUnlock(mIOSurface, getIOSurfaceLockOptions(), nullptr);
+#    endif  // !defined(ANGLE_PLATFORM_IOS_SIMULATOR)
+
     return egl::NoError();
 }
 
@@ -223,7 +273,6 @@ EGLint IOSurfaceSurfaceEAGL::getSwapBehavior() const
 bool IOSurfaceSurfaceEAGL::validateAttributes(EGLClientBuffer buffer,
                                               const egl::AttributeMap &attribs)
 {
-#    if !defined(ANGLE_PLATFORM_IOS_SIMULATOR)
     IOSurfaceRef ioSurface = reinterpret_cast<IOSurfaceRef>(buffer);
 
     // The plane must exist for this IOSurface. IOSurfaceGetPlaneCount can return 0 for non-planar
@@ -264,9 +313,6 @@ bool IOSurfaceSurfaceEAGL::validateAttributes(EGLClientBuffer buffer,
     }
 
     return true;
-#    else
-    return false;
-#    endif
 }
 
 // Wraps a FramebufferGL to hook the destroy function to delete the texture associated with the
@@ -316,9 +362,9 @@ FramebufferImpl *IOSurfaceSurfaceEAGL::createDefaultFramebuffer(const gl::Contex
         ERR() << "[EAGLContext texImageIOSurface] failed";
         return nullptr;
     }
-#    else
-    ERR() << "IOSurfaces not supported on iOS Simulator";
-#    endif
+#    else   // !defined(ANGLE_PLATFORM_IOS_SIMULATOR)
+    ERR() << "IOSurfaces with OpenGL ES not supported on iOS Simulator";
+#    endif  // !defined(ANGLE_PLATFORM_IOS_SIMULATOR)
 
     if (IsError(initializeAlphaChannel(context, texture)))
     {
@@ -357,6 +403,18 @@ bool IOSurfaceSurfaceEAGL::hasEmulatedAlphaChannel() const
     return format.internalFormat == GL_RGB;
 }
 
+#    if defined(ANGLE_PLATFORM_IOS_SIMULATOR)
+IOSurfaceLockOptions IOSurfaceSurfaceEAGL::getIOSurfaceLockOptions() const
+{
+    IOSurfaceLockOptions options = 0;
+    if (!mReadbackToIOSurface)
+    {
+        options |= kIOSurfaceLockReadOnly;
+    }
+    return options;
+}
+#    endif  // defined(ANGLE_PLATFORM_IOS_SIMULATOR)
+
 }  // namespace rx
 
 #endif  // defined(ANGLE_PLATFORM_IOS)

src/libANGLE/validationEGL.cpp

@@ -1775,6 +1775,13 @@ Error ValidateCreatePbufferFromClientBuffer(Display *display,
                     return EglBadAttribute() << "<buftype> doesn't support setting GL colorspace";
                 }
                 break;
+            case EGL_IOSURFACE_USAGE_HINT_ANGLE:
+                if (value & ~(EGL_IOSURFACE_READ_HINT_ANGLE | EGL_IOSURFACE_WRITE_HINT_ANGLE))
+                {
+                    return EglBadAttribute()
+                           << "IOSurface usage hint must only contain READ or WRITE";
+                }
+                break;
             default:
                 return EglBadAttribute();
         }
@@ -1834,10 +1841,18 @@ Error ValidateCreatePbufferFromClientBuffer(Display *display,
 
     if (buftype == EGL_IOSURFACE_ANGLE)
     {
+#if ANGLE_PLATFORM_MACOS || ANGLE_PLATFORM_MACCATALYST
         if (textureTarget != EGL_TEXTURE_RECTANGLE_ANGLE)
         {
-            return EglBadAttribute() << "EGL_IOSURFACE requires the EGL_TEXTURE_RECTANGLE target";
+            return EglBadAttribute()
+                   << "EGL_IOSURFACE requires the EGL_TEXTURE_RECTANGLE target on desktop macOS";
         }
+#else   // ANGLE_PLATFORM_MACOS || ANGLE_PLATFORM_MACCATALYST
+        if (textureTarget != EGL_TEXTURE_2D)
+        {
+            return EglBadAttribute() << "EGL_IOSURFACE requires the EGL_TEXTURE_2D target on iOS";
+        }
+#endif  // ANGLE_PLATFORM_MACOS || ANGLE_PLATFORM_MACCATALYST
 
         if (textureFormat != EGL_TEXTURE_RGBA)
         {