Draw the mouse cursor in Chromoting Android client

remoting/client/jni/chromoting_jni_runtime.cc

 // Copyright 2013 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 "remoting/client/jni/chromoting_jni_runtime.h"
 
 #include "base/android/base_jni_registrar.h"
 #include "base/android/jni_android.h"
+#include "base/android/scoped_java_ref.h"
 #include "base/memory/singleton.h"
+#include "base/stl_util.h"
 #include "base/synchronization/waitable_event.h"
 #include "media/base/yuv_convert.h"
 #include "net/android/net_jni_registrar.h"
 #include "remoting/base/url_request_context.h"
 
+namespace {
+
 // Class and package name of the Java class supporting the methods we call.
 const char* const kJavaClass = "org/chromium/chromoting/jni/JniInterface";
 
+const int kBytesPerPixel = 4;
+
+}  // namespace
+
 namespace remoting {
 
 // static
 ChromotingJniRuntime* ChromotingJniRuntime::GetInstance() {
   return Singleton<ChromotingJniRuntime>::get();
 }
 
 ChromotingJniRuntime::ChromotingJniRuntime() {
   // Obtain a reference to the Java environment. (Future calls to this function
   // made from the same thread return the same stored reference instead of
@@ skipping 146 matching lines @@
   env->SetStaticIntField(
       class_,
       env->GetStaticFieldID(class_, "sHeight", "I"),
       height);
   env->SetStaticObjectField(
       class_,
       env->GetStaticFieldID(class_, "sBuffer", "Ljava/nio/ByteBuffer;"),
       buffer);
 }
 
+void ChromotingJniRuntime::UpdateCursorShape(
+    const protocol::CursorShapeInfo& cursor_shape) {
+  DCHECK(display_task_runner_->BelongsToCurrentThread());
+
+  // const_cast<> is safe as long as the Java updateCursorShape() method copies
+  // the data out of the buffer without mutating it, and doesn't keep any
+  // reference to the buffer afterwards. Unfortunately, there seems to be no way
+  // to create a read-only ByteBuffer from a pointer-to-const.
+  char* data = string_as_array(const_cast<std::string*>(&cursor_shape.data()));
+  int cursor_total_bytes =
+      cursor_shape.width() * cursor_shape.height() * kBytesPerPixel;
+
+  JNIEnv* env = base::android::AttachCurrentThread();
+  base::android::ScopedJavaLocalRef<jobject> buffer(env,
+      env->NewDirectByteBuffer(data, cursor_total_bytes));
+  env->CallStaticVoidMethod(
+      class_,
+      env->GetStaticMethodID(
+          class_,
+          "updateCursorShape",
+          "(IIIILjava/nio/ByteBuffer;)V"),
+      cursor_shape.width(),
+      cursor_shape.height(),
+      cursor_shape.hotspot_x(),
+      cursor_shape.hotspot_y(),
+      buffer.obj());
+}
+
 void ChromotingJniRuntime::RedrawCanvas() {
   DCHECK(display_task_runner_->BelongsToCurrentThread());
 
   JNIEnv* env = base::android::AttachCurrentThread();
   env->CallStaticVoidMethod(
       class_,
       env->GetStaticMethodID(class_, "redrawGraphicsInternal", "()V"));
 }
 
 void ChromotingJniRuntime::DetachFromVmAndSignal(base::WaitableEvent* waiter) {
   base::android::DetachFromVM();
   waiter->Signal();
 }
 
 }  // namespace remoting