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 69707fb246fe37280a178e29f955d4af52f87d7a..511558d5efb966470659243a77d6eb46fb74e48d 100644
--- a/Source/core/html/canvas/WebGL2RenderingContextBase.cpp
+++ b/Source/core/html/canvas/WebGL2RenderingContextBase.cpp
@@ -1461,6 +1461,108 @@ 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) {

[Ken Russell (switch to Gerrit), 2015/04/28 05:43:23]

Please make sure that this code eventually uses the new validation function from
 https://codereview.chromium.org/1099853002/ .

[yunchao, 2015/04/29 11:13:11]

Done.

+        synthesizeGLError(GL_INVALID_ENUM, functionName, "invalid target");
+        return false;
+    }
+    ASSERT(m_framebufferBinding || drawingBuffer());
+    if (!m_framebufferBinding) {
+    // for the default framebuffer
+        switch (attachment) {
+        case GL_BACK:
+        case GL_DEPTH:
+        case GL_STENCIL:
+            break;
+        default:
+            synthesizeGLError(GL_INVALID_ENUM, functionName, "invalid attachment");
+            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_ENUM, functionName, "invalid attachment");
+            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());

[Ken Russell (switch to Gerrit), 2015/04/28 05:43:23]

target can be either GL_READ_FRAMEBUFFER or GL_DRAW_FRAMEBUFFER.
m_framebufferBinding is only the DRAW_FRAMEBUFFER. As in
https://codereview.chromium.org/1099853002/ , this code needs to be updated to
handle both binding points.

[yunchao, 2015/04/29 11:13:11]

Done.

+
+    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) {
+            ASSERT(!m_framebufferBinding);
+            return WebGLAny(scriptState, GL_FRAMEBUFFER_DEFAULT);
+        }
+        ASSERT(attachmentObject->isTexture() || attachmentObject->isRenderbuffer());
+        if (attachmentObject->isTexture())
+            return WebGLAny(scriptState, GL_TEXTURE);
+        if (attachmentObject->isRenderbuffer())
+            return WebGLAny(scriptState, GL_RENDERBUFFER);
+        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);

[Ken Russell (switch to Gerrit), 2015/04/28 05:43:23]

This will return an incorrect answer if the DrawingBuffer's FBO (which is
WebGL's default framebuffer) is bound. The code needs to be updated to handle
that case.

[yunchao, 2015/04/29 11:13:11]

Agreed. The latest patch set has updated bindFramebuffer. If binding to the
default Framebuffer, the latest patch set would bind to DrawingBuffer's FBO for
the given target, so the query would be correct.

+            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)
 {
     visitor->trace(m_readFramebufferBinding);