From 0ec8a19a34e6943d9dca04e944dcc5ce6cd59747 Mon Sep 17 00:00:00 2001
From: Luke Wilde <lukew@serenityos.org>
Date: Sun, 19 Jun 2022 19:45:33 +0100
Subject: [PATCH] LibWeb/WebGL: Forward the render context ref count to
 HTMLCanvasElement

This allows HTMLCanvasElement and WebGL rendering contexts to share
their lifetime, as JS allows them to arbitrarily access them at any
time and WebGLRCB.canvas expects a non-null return value.
---
 .../LibWeb/WebGL/WebGLRenderingContextBase.cpp | 18 +++++++++++++-----
 .../LibWeb/WebGL/WebGLRenderingContextBase.h   |  9 +++++----
 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/Userland/Libraries/LibWeb/WebGL/WebGLRenderingContextBase.cpp b/Userland/Libraries/LibWeb/WebGL/WebGLRenderingContextBase.cpp
index a486ded3b2..da0d132571 100644
--- a/Userland/Libraries/LibWeb/WebGL/WebGLRenderingContextBase.cpp
+++ b/Userland/Libraries/LibWeb/WebGL/WebGLRenderingContextBase.cpp
@@ -12,7 +12,7 @@
 namespace Web::WebGL {
 
 WebGLRenderingContextBase::WebGLRenderingContextBase(HTML::HTMLCanvasElement& canvas_element, NonnullOwnPtr<GL::GLContext> context, WebGLContextAttributes context_creation_parameters, WebGLContextAttributes actual_context_parameters)
-    : m_canvas_element(canvas_element)
+    : RefCountForwarder(canvas_element)
     , m_context(move(context))
     , m_context_creation_parameters(move(context_creation_parameters))
     , m_actual_context_parameters(move(actual_context_parameters))
@@ -67,15 +67,23 @@ void WebGLRenderingContextBase::present()
     }
 }
 
+HTML::HTMLCanvasElement& WebGLRenderingContextBase::canvas_element()
+{
+    return ref_count_target();
+}
+
+HTML::HTMLCanvasElement const& WebGLRenderingContextBase::canvas_element() const
+{
+    return ref_count_target();
+}
+
 void WebGLRenderingContextBase::needs_to_present()
 {
     m_should_present = true;
 
-    if (!m_canvas_element)
+    if (!canvas_element().layout_node())
         return;
-    if (!m_canvas_element->layout_node())
-        return;
-    m_canvas_element->layout_node()->set_needs_display();
+    canvas_element().layout_node()->set_needs_display();
 }
 
 void WebGLRenderingContextBase::set_error(GLenum error)
diff --git a/Userland/Libraries/LibWeb/WebGL/WebGLRenderingContextBase.h b/Userland/Libraries/LibWeb/WebGL/WebGLRenderingContextBase.h
index 4bf1e26a64..5a5914b7cc 100644
--- a/Userland/Libraries/LibWeb/WebGL/WebGLRenderingContextBase.h
+++ b/Userland/Libraries/LibWeb/WebGL/WebGLRenderingContextBase.h
@@ -6,7 +6,7 @@
 
 #pragma once
 
-#include <AK/RefCounted.h>
+#include <AK/RefCountForwarder.h>
 #include <AK/WeakPtr.h>
 #include <AK/Weakable.h>
 #include <LibGL/GLContext.h>
@@ -16,7 +16,7 @@
 namespace Web::WebGL {
 
 class WebGLRenderingContextBase
-    : public RefCounted<WebGLRenderingContextBase>
+    : public RefCountForwarder<HTML::HTMLCanvasElement>
     , public Weakable<WebGLRenderingContextBase> {
 public:
     virtual ~WebGLRenderingContextBase();
@@ -63,8 +63,6 @@ protected:
     WebGLRenderingContextBase(HTML::HTMLCanvasElement& canvas_element, NonnullOwnPtr<GL::GLContext> context, WebGLContextAttributes context_creation_parameters, WebGLContextAttributes actual_context_parameters);
 
 private:
-    WeakPtr<HTML::HTMLCanvasElement> m_canvas_element;
-
     NonnullOwnPtr<GL::GLContext> m_context;
 
     // https://www.khronos.org/registry/webgl/specs/latest/1.0/#context-creation-parameters
@@ -87,6 +85,9 @@ private:
 
     GLenum m_error { GL_NO_ERROR };
 
+    HTML::HTMLCanvasElement& canvas_element();
+    HTML::HTMLCanvasElement const& canvas_element() const;
+
     void needs_to_present();
     void set_error(GLenum error);
 };