Mus version of GLHelper

components/mus/gles2/gl_helper.cc

Index: components/mus/gles2/gl_helper.cc
diff --git a/components/mus/gles2/gl_helper.cc b/components/mus/gles2/gl_helper.cc
new file mode 100644
index 0000000000000000000000000000000000000000..bbfef3f8807e5dd59b4b40551f7c547671db6ccb
--- /dev/null
+++ b/components/mus/gles2/gl_helper.cc
@@ -0,0 +1,108 @@
+// Copyright (c) 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "components/mus/gles2/gl_helper.h"
+
+#include "base/macros.h"
+#include "third_party/skia/include/core/SkRect.h"
+#include "third_party/skia/include/core/SkRegion.h"
+
+namespace mus {
+
+namespace {
+
+class ScopedGLuint {
+ public:
+  typedef void (gpu::gles2::GLES2Interface::*GenFunc)(GLsizei n, GLuint* ids);
+  typedef void (gpu::gles2::GLES2Interface::*DeleteFunc)(GLsizei n,
+                                                         const GLuint* ids);
+  ScopedGLuint(gpu::gles2::GLES2Interface* gl,
+               GenFunc gen_func,
+               DeleteFunc delete_func)
+      : gl_(gl), id_(0u), delete_func_(delete_func) {
+    (gl_->*gen_func)(1, &id_);
+  }
+
+  operator GLuint() const { return id_; }
+
+  GLuint id() const { return id_; }
+
+  ~ScopedGLuint() {
+    if (id_ != 0) {
+      (gl_->*delete_func_)(1, &id_);
+    }
+  }
+
+ private:
+  gpu::gles2::GLES2Interface* gl_;
+  GLuint id_;
+  DeleteFunc delete_func_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedGLuint);
+};
+
+class ScopedFramebuffer : public ScopedGLuint {
+ public:
+  explicit ScopedFramebuffer(gpu::gles2::GLES2Interface* gl)
+      : ScopedGLuint(gl,
+                     &gpu::gles2::GLES2Interface::GenFramebuffers,
+                     &gpu::gles2::GLES2Interface::DeleteFramebuffers) {}
+};
+
+template <GLenum Target>
+class ScopedBinder {
+ public:
+  typedef void (gpu::gles2::GLES2Interface::*BindFunc)(GLenum target,
+                                                       GLuint id);
+  ScopedBinder(gpu::gles2::GLES2Interface* gl, GLuint id, BindFunc bind_func)
+      : gl_(gl), bind_func_(bind_func) {
+    (gl_->*bind_func_)(Target, id);
+  }
+
+  virtual ~ScopedBinder() { (gl_->*bind_func_)(Target, 0); }
+
+ private:
+  gpu::gles2::GLES2Interface* gl_;
+  BindFunc bind_func_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedBinder);
+};
+
+template <GLenum Target>
+class ScopedFramebufferBinder : ScopedBinder<Target> {
+ public:
+  ScopedFramebufferBinder(gpu::gles2::GLES2Interface* gl, GLuint id)
+      : ScopedBinder<Target>(gl,
+                             id,
+                             &gpu::gles2::GLES2Interface::BindFramebuffer) {}
+};
+
+}  // namespace
+
+// Cribbed from content/common/gpu/client/gl_helper.cc
+void GLCopySubBufferDamage(gpu::gles2::GLES2Interface* gl,
+                           GLenum target,
+                           GLuint texture,
+                           GLuint previous_texture,
+                           const SkRegion& new_damage,
+                           const SkRegion& old_damage) {
+  SkRegion region(old_damage);
+  if (region.op(new_damage, SkRegion::kDifference_Op)) {
+    ScopedFramebuffer dst_framebuffer(gl);
+    ScopedFramebufferBinder<GL_FRAMEBUFFER> framebuffer_binder(gl,
+                                                               dst_framebuffer);
+    gl->BindTexture(target, texture);
+    gl->FramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, target,
+                             previous_texture, 0);
+    for (SkRegion::Iterator it(region); !it.done(); it.next()) {
+      const SkIRect& rect = it.rect();
+      gl->CopyTexSubImage2D(target, 0, rect.x(), rect.y(), rect.x(), rect.y(),
+                            rect.width(), rect.height());
+    }
+    gl->BindTexture(target, 0);
+    gl->Flush();
+  }
+}
+
+}  // namespace mus