[Remoting Android] Create Interfaces for GlDisplay

remoting/android/java/src/org/chromium/chromoting/RenderStub.java

+// Copyright 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.
+
+package org.chromium.chromoting;
+
+import android.graphics.Matrix;
+import android.graphics.PointF;
+
+/**
+ * Interface with a set of functions to control the behavior of the remote host renderer.
+ */
+public interface RenderStub {
+    /** Used to define the animation feedback shown when a user touches the screen. */
+    enum InputFeedbackType {
+        NONE,
+        SHORT_TOUCH_ANIMATION,
+        LONG_TOUCH_ANIMATION,
+        LONG_TRACKPAD_ANIMATION
+    }
+
+    /**
+     * Initializes the stub with |view|. The stub should avoid holding strong reference to |view|.
+     */
+    void setDesktopView(DesktopView view);
+
+    /** Triggers a brief animation to indicate the existence and location of an input event. */
+    void showInputFeedback(InputFeedbackType feedbackToShow, PointF pos);
+
+    /**
+     * Informs the stub that its transformation matrix (for rendering the remote desktop bitmap)
+     * has been changed, which requires repainting.
+     */
+    void setTransformation(Matrix matrix);
+
+    /**
+     * Informs the stub that the cursor position has been moved, which requires repainting.
+     */
+    void moveCursor(PointF pos);
+
+    /**
+     * Informs the stub that the cursor visibility has been changed (for different input mode),
+     * which requires repainting.
+     */
+    void setCursorVisibility(boolean visible);
+
+    /** An {@link Event} triggered when the client size is changed. */
+    Event<SizeChangedEventParameter> onClientSizeChanged();

[Hzj_jie, 2016/08/30 23:15:03]

According to the following implementation, I believe, same as onTouch event,
this event should belong to DesktopView, but not GlDisplay or RenderStub.

[Yuwei, 2016/08/31 00:15:56]

In the future I will have surfaceHolder.addCallback(this) in setDesktopView and
drop the SurfaceHolder.Callback implementation in DesktopView.

onTouch is different since it comes from the View base class.

[Hzj_jie, 2016/08/31 00:31:57]

Any benefit for this change? SurfaceHolder can only be accessed from
View.getHolder().

[Yuwei, 2016/08/31 00:47:40]

GlDisplay needs to be notified when the surface is created/changed/destroyed by
all means. Also onClientSizeChanged() is triggered by the surface holder
callback and onHostSizeChanged() is triggered by the native code. It may look
weird if you don't them in the same interface...

[Hzj_jie, 2016/08/31 00:59:21]

My only concern is SurfaceHolder has a same lifetime as View, listening to a
dead object does not really take effect. I do not have a strong opinion here.

+
+    /**
+     * An {@link Event} triggered when the size of the host desktop is changed.
+     */
+    Event<SizeChangedEventParameter> onHostSizeChanged();
+
+    /**
+     * An {@link} triggered when a frame has been rendered.
+     */
+    Event<Void> onCanvasRendered();
+
+    /**
+     * Helper class for mapping a feedback type to the max radius of the feedback animation.
+     */
+    final class InputFeedbackRadiusMapper {
+        private final int mTinyFeedbackPixelRadius;
+        private final int mSmallFeedbackPixelRadius;
+        private final int mLargeFeedbackPixelRadius;
+
+        public InputFeedbackRadiusMapper(DesktopView view) {
+            mTinyFeedbackPixelRadius = view.getResources()
+                    .getDimensionPixelSize(R.dimen.feedback_animation_radius_tiny);
+
+            mSmallFeedbackPixelRadius = view.getResources()
+                    .getDimensionPixelSize(R.dimen.feedback_animation_radius_small);
+
+            mLargeFeedbackPixelRadius = view.getResources()
+                    .getDimensionPixelSize(R.dimen.feedback_animation_radius_large);
+        }
+
+        /**
+         * Returns the radius of the given feedback type.
+         * 0.0f will be returned if no feedback should be shown.
+         */
+        public float getFeedbackRadius(InputFeedbackType feedbackToShow,
+                                       float scaleFactor) {
+            switch (feedbackToShow) {
+                case NONE:
+                    return 0.0f;
+                case SHORT_TOUCH_ANIMATION:
+                    return mSmallFeedbackPixelRadius / scaleFactor;
+                case LONG_TOUCH_ANIMATION:
+                    return mLargeFeedbackPixelRadius / scaleFactor;
+                case LONG_TRACKPAD_ANIMATION:
+                    // The size of the longpress trackpad animation is supposed to be close to the
+                    // size of the cursor so it doesn't need to be normalized and should be scaled
+                    // with the canvas.
+                    return mTinyFeedbackPixelRadius;
+                default:
+                    // Unreachable, but required by Google Java style and findbugs.
+                    assert false : "Unreached";
+                    return 0.0f;
+            }
+        }
+    }
+}