Implemented copyTexSubImage3D WebGL2 entry point in Blink

Source/modules/webgl/WebGLRenderingContextBase.h

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 698 matching lines @@
         m_extensions.append(TypedExtensionTracker<T>::create(extensionPtr, flags, prefixes));
     }
 
     bool extensionSupportedAndAllowed(const ExtensionTracker*);
 
     inline bool extensionEnabled(WebGLExtensionName name)
     {
         return m_extensionEnabled[name];
     }
 
+    // ScopedDrawingBufferBinder is used for ReadPixels/CopyTexImage2D/CopySubImage2D to read from
+    // a multisampled DrawingBuffer. In this situation, we need to blit to a single sampled buffer
+    // for reading, during which the bindings could be changed and need to be recovered.
+    class ScopedDrawingBufferBinder {
+        STACK_ALLOCATED();
+    public:
+        ScopedDrawingBufferBinder(DrawingBuffer* drawingBuffer, WebGLFramebuffer* framebufferBinding)
+            : m_drawingBuffer(drawingBuffer)
+            , m_readFramebufferBinding(framebufferBinding)
+        {
+            // Commit DrawingBuffer if needed (e.g., for multisampling)
+            if (!m_readFramebufferBinding && m_drawingBuffer)
+                m_drawingBuffer->commit();
+        }
+
+        ~ScopedDrawingBufferBinder()
+        {
+            // Restore DrawingBuffer if needed
+            if (!m_readFramebufferBinding && m_drawingBuffer)
+                m_drawingBuffer->restoreFramebufferBindings();
+        }
+
+    private:
+        DrawingBuffer* m_drawingBuffer;
+        Member<WebGLFramebuffer> m_readFramebufferBinding;
+    };
+
     // Errors raised by synthesizeGLError() while the context is lost.
     Vector<GLenum> m_lostContextErrors;
 
     bool m_isWebGL2FormatsTypesAdded;
     bool m_isOESTextureFloatFormatsTypesAdded;
     bool m_isOESTextureHalfFloatFormatsTypesAdded;
     bool m_isWebGLDepthTextureFormatsTypesAdded;
     bool m_isEXTsRGBFormatsTypesAdded;
 
     std::set<GLenum> m_supportedInternalFormats;
@@ skipping 53 matching lines @@
 
     // Helper function to get the bound framebuffer's color buffer format.
     virtual GLenum boundFramebufferColorFormat();
 
     // Helper function to verify limits on the length of uniform and attribute locations.
     virtual unsigned getMaxWebGLLocationLength() const { return 256; }
     bool validateLocationLength(const char* functionName, const String&);
 
     // Helper function to check if size is non-negative.
     // Generate GL error and return false for negative inputs; otherwise, return true.
-    bool validateSize(const char* functionName, GLint x, GLint y);
+    bool validateSize(const char* functionName, GLint x, GLint y, GLint z = 0);
 
     // Helper function to check if all characters in the string belong to the
     // ASCII subset as defined in GLSL ES 1.0 spec section 3.1.
     bool validateString(const char* functionName, const String&);
 
     // Helper function to check target and texture bound to the target.
     // Generate GL errors and return 0 if target is invalid or texture bound is
     // null.  Otherwise, return the texture bound to the target.
     virtual WebGLTexture* validateTextureBinding(const char* functionName, GLenum target, bool useSixEnumsForCubeMap);
 
@@ skipping 52 matching lines @@
     enum NullDisposition {
         NullAllowed,
         NullNotAllowed
     };
 
     // Helper function to validate that the given ArrayBufferView
     // is of the correct type and contains enough data for the texImage call.
     // Generates GL error and returns false if parameters are invalid.
     bool validateTexFuncData(const char* functionName, GLint level, GLsizei width, GLsizei height, GLenum internalformat, GLenum format, GLenum type, DOMArrayBufferView* pixels, NullDisposition);
 
+    // Helper function to validate that a copyTexSubImage call is valid.
+    bool validateCopyTexSubImage(const char* functionName, GLenum target, GLint level, GLint xoffset, GLint yoffset, GLint zoffset, GLint x, GLint y, GLsizei width, GLsizei height);
+
     // Helper function to validate a given texture format is settable as in
     // you can supply data to texImage2D, or call texImage2D, copyTexImage2D and
     // copyTexSubImage2D.
     // Generates GL error and returns false if the format is not settable.
     bool validateSettableTexFormat(const char* functionName, GLenum format);
 
     // Helper function to validate compressed texture data is correct size
     // for the given format and dimensions.
     bool validateCompressedTexFuncData(const char* functionName, GLsizei width, GLsizei height, GLenum format, DOMArrayBufferView* pixels);
 
@@ skipping 164 matching lines @@
     static IntSize oldestContextSize();
 };
 
 DEFINE_TYPE_CASTS(WebGLRenderingContextBase, CanvasRenderingContext, context, context->is3d(), context.is3d());
 
 } // namespace blink
 
 WTF_ALLOW_MOVE_INIT_AND_COMPARE_WITH_MEM_FUNCTIONS(blink::WebGLRenderingContextBase::TextureUnitState);
 
 #endif // WebGLRenderingContextBase_h