update getFramebufferAttachmentParameter for WebGL 2

Source/core/html/canvas/WebGL2RenderingContextBase.cpp

Index: Source/core/html/canvas/WebGL2RenderingContextBase.cpp
diff --git a/Source/core/html/canvas/WebGL2RenderingContextBase.cpp b/Source/core/html/canvas/WebGL2RenderingContextBase.cpp
index b6f57f87ac8c23137bcad0062f63a038e1dc62b6..aed4b39e18a30e39eb926dad19470ad1b0e27b37 100644
--- a/Source/core/html/canvas/WebGL2RenderingContextBase.cpp
+++ b/Source/core/html/canvas/WebGL2RenderingContextBase.cpp
@@ -1196,6 +1196,105 @@ bool WebGL2RenderingContextBase::validateAndUpdateBufferBindTarget(const char* f
     return true;
 }
 
+bool WebGL2RenderingContextBase::validateGetFramebufferAttachmentParameterFunc(const char* functionName, GLenum target, GLenum attachment)
+{
+    if (target != GL_FRAMEBUFFER && target != GL_READ_FRAMEBUFFER && target != GL_DRAW_FRAMEBUFFER) {
+        synthesizeGLError(GL_INVALID_ENUM, functionName, "invalid target");
+        return false;
+    }
+    ASSERT(!m_framebufferBinding && !drawingBuffer());

[Zhenyao Mo, 2015/03/09 18:39:19]

OK, let me explain again.  I understand your intention, but your assertion is
incorrect.  It's the same as !(m_framebufferBinding || drawingBuffer()), which
is always false.  You should assert the opposite.

[yunchao, 2015/03/10 15:34:54]

Yeah. I got it. Thank you, @zmo.

+    if (!m_framebufferBinding) {
+    // for the default framebuffer
+        switch (attachment) {
+        case GL_BACK:
+        case GL_DEPTH:
+        case GL_STENCIL:
+            break;
+        default:
+            synthesizeGLError(GL_INVALID_OPERATION, functionName, "invalid attachment");

[Zhenyao Mo, 2015/03/09 18:39:19]

Although the man page of this function says INVALID_OPERATION, but the es3 spec
doesn't say anything about INVALID_OPERATION in this situation.  Same as in the
es2 spec.

In ES2/WebGL1, we generate an INVALID_ENUM.  I feel we should be consistent
here.

[yunchao, 2015/03/10 15:34:53]

Done.

+            return false;
+        }
+    } else {
+    // for the FBO
+        switch (attachment) {
+        case GL_COLOR_ATTACHMENT0:
+        case GL_DEPTH_ATTACHMENT:
+        case GL_STENCIL_ATTACHMENT:
+            break;
+        case GL_DEPTH_STENCIL_ATTACHMENT:
+            if (m_framebufferBinding->getAttachmentObject(GL_DEPTH_STENCIL_ATTACHMENT) || (m_framebufferBinding->getAttachmentObject(GL_DEPTH_ATTACHMENT) == m_framebufferBinding->getAttachmentObject(GL_STENCIL_ATTACHMENT)))
+                break;
+        default:
+            if (attachment > GL_COLOR_ATTACHMENT0
+                && attachment < static_cast<GLenum>(GL_COLOR_ATTACHMENT0 + maxColorAttachments()))
+                break;
+            synthesizeGLError(GL_INVALID_OPERATION, functionName, "invalid attachment");

[Zhenyao Mo, 2015/03/09 18:39:19]

Same here, maybe INVALID_ENUM.

[yunchao, 2015/03/10 15:34:53]

Done.

+            return false;
+        }
+    }
+    return true;
+}
+
+ScriptValue WebGL2RenderingContextBase::getFramebufferAttachmentParameter(ScriptState* scriptState, GLenum target, GLenum attachment, GLenum pname)
+{
+    if (isContextLost() || !validateGetFramebufferAttachmentParameterFunc("getFramebufferAttachmentParameter", target, attachment))
+        return ScriptValue::createNull(scriptState);
+
+    ASSERT(m_framebufferBinding && !m_framebufferBinding->object());
+
+    WebGLSharedObject* attachmentObject = m_framebufferBinding ? m_framebufferBinding->getAttachmentObject(attachment) : 0;
+    if (m_framebufferBinding && !attachmentObject) {
+        if (pname == GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE)
+            return WebGLAny(scriptState, GL_NONE);
+        if (pname == GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME)
+            return WebGLAny(scriptState, 0);
+        synthesizeGLError(GL_INVALID_OPERATION, "getFramebufferAttachmentParameter", "invalid parameter name");
+        return ScriptValue::createNull(scriptState);
+    }
+
+    switch (pname) {
+    case GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE:
+        if (!attachmentObject)

[Zhenyao Mo, 2015/03/09 18:39:19]

nit: add ASSERT(!m_framebufferBinding) here to make code easier to read.

[yunchao, 2015/03/10 15:34:54]

Done.

+            return WebGLAny(scriptState, GL_FRAMEBUFFER_DEFAULT);
+        if (attachmentObject->isTexture())
+            return WebGLAny(scriptState, GL_TEXTURE);
+        if (attachmentObject->isRenderbuffer())
+            return WebGLAny(scriptState, GL_RENDERBUFFER);

[Zhenyao Mo, 2015/03/09 18:39:19]

nit: ASSERT(attachmentObject->isTexture() || attachmentObject->isRenderbuffer())
here or above.

[yunchao, 2015/03/10 15:34:54]

Done.

+        break;
+    case GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME:
+        if (!attachmentObject)
+            break;
+        return WebGLAny(scriptState, PassRefPtrWillBeRawPtr<WebGLObject>(attachmentObject));
+    case GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_CUBE_MAP_FACE:
+    case GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER:
+    case GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_LEVEL:
+        if (!attachmentObject || !attachmentObject->isTexture())
+            break;
+    case GL_FRAMEBUFFER_ATTACHMENT_RED_SIZE:
+    case GL_FRAMEBUFFER_ATTACHMENT_GREEN_SIZE:
+    case GL_FRAMEBUFFER_ATTACHMENT_BLUE_SIZE:
+    case GL_FRAMEBUFFER_ATTACHMENT_ALPHA_SIZE:
+    case GL_FRAMEBUFFER_ATTACHMENT_DEPTH_SIZE:
+    case GL_FRAMEBUFFER_ATTACHMENT_STENCIL_SIZE:
+        {
+            GLint value = 0;
+            webContext()->getFramebufferAttachmentParameteriv(target, attachment, pname, &value);
+            return WebGLAny(scriptState, value);
+        }
+    case GL_FRAMEBUFFER_ATTACHMENT_COMPONENT_TYPE:
+    case GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING:
+        {
+            GLint value = 0;
+            webContext()->getFramebufferAttachmentParameteriv(target, attachment, pname, &value);
+            return WebGLAny(scriptState, static_cast<unsigned>(value));
+        }
+    default:
+        break;
+    }
+    synthesizeGLError(GL_INVALID_ENUM, "getFramebufferAttachmentParameter", "invalid parameter name");
+    return ScriptValue::createNull(scriptState);
+}
+
 DEFINE_TRACE(WebGL2RenderingContextBase)
 {
     WebGLRenderingContextBase::trace(visitor);