root/remoting/android/java/src/org/chromium/chromoting/DesktopView.java

DEFINITIONS

1. isAnimationRunning
2. startAnimation
3. render
4. setDesktop
5. requestRepaint
6. onScreenConfigurationChanged
7. paint
8. processAnimation
9. surfaceChanged
10. surfaceCreated
11. surfaceDestroyed
12. onCreateInputConnection
13. onTouchEvent
14. injectMouseEvent
15. injectMouseWheelDeltaEvent
16. showLongPressFeedback
17. showActionBar
18. showKeyboard
19. transformationChanged
20. setAnimationEnabled

// 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.

package org.chromium.chromoting;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Point;
import android.graphics.RadialGradient;
import android.graphics.Shader;
import android.os.Looper;
import android.os.SystemClock;
import android.text.InputType;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.inputmethod.EditorInfo;
import android.view.inputmethod.InputConnection;
import android.view.inputmethod.InputMethodManager;

import org.chromium.chromoting.jni.JniInterface;

/**
 * The user interface for viewing and interacting with a specific remote host.
 * It provides a canvas onto which the video feed is rendered, handles
 * multitouch pan and zoom gestures, and collects and forwards input events.
 */
/** GUI element that holds the drawing canvas. */
public class DesktopView extends SurfaceView implements DesktopViewInterface,
        SurfaceHolder.Callback {
    private RenderData mRenderData;
    private TouchInputHandler mInputHandler;

    /** The parent Desktop activity. */
    private Desktop mDesktop;

    // Flag to prevent multiple repaint requests from being backed up. Requests for repainting will
    // be dropped if this is already set to true. This is used by the main thread and the painting
    // thread, so the access should be synchronized on |mRenderData|.
    private boolean mRepaintPending;

    // Flag used to ensure that the SurfaceView is only painted between calls to surfaceCreated()
    // and surfaceDestroyed(). Accessed on main thread and display thread, so this should be
    // synchronized on |mRenderData|.
    private boolean mSurfaceCreated = false;

    /** Helper class for displaying the long-press feedback animation. This class is thread-safe. */
    private static class FeedbackAnimator {
        /** Total duration of the animation, in milliseconds. */
        private static final float TOTAL_DURATION_MS = 220;

        /** Start time of the animation, from {@link SystemClock#uptimeMillis()}. */
        private long mStartTime = 0;

        private boolean mRunning = false;

        /** Lock to allow multithreaded access to {@link #mStartTime} and {@link #mRunning}. */
        private Object mLock = new Object();

        private Paint mPaint = new Paint();

        public boolean isAnimationRunning() {
            synchronized (mLock) {
                return mRunning;
            }
        }

        /**
         * Begins a new animation sequence. After calling this method, the caller should
         * call {@link #render(Canvas, float, float, float)} periodically whilst
         * {@link #isAnimationRunning()} returns true.
         */
        public void startAnimation() {
            synchronized (mLock) {
                mRunning = true;
                mStartTime = SystemClock.uptimeMillis();
            }
        }

        public void render(Canvas canvas, float x, float y, float size) {
            // |progress| is 0 at the beginning, 1 at the end.
            float progress;
            synchronized (mLock) {
                progress = (SystemClock.uptimeMillis() - mStartTime) / TOTAL_DURATION_MS;
                if (progress >= 1) {
                    mRunning = false;
                    return;
                }
            }

            // Animation grows from 0 to |size|, and goes from fully opaque to transparent for a
            // seamless fading-out effect. The animation needs to have more than one color so it's
            // visible over any background color.
            float radius = size * progress;
            int alpha = (int)((1 - progress) * 0xff);

            int transparentBlack = Color.argb(0, 0, 0, 0);
            int white = Color.argb(alpha, 0xff, 0xff, 0xff);
            int black = Color.argb(alpha, 0, 0, 0);
            mPaint.setShader(new RadialGradient(x, y, radius,
                    new int[] {transparentBlack, white, black, transparentBlack},
                    new float[] {0.0f, 0.8f, 0.9f, 1.0f}, Shader.TileMode.CLAMP));
            canvas.drawCircle(x, y, radius, mPaint);
        }
    }

    private FeedbackAnimator mFeedbackAnimator = new FeedbackAnimator();

    // Variables to control animation by the TouchInputHandler.

    /** Protects mInputAnimationRunning. */
    private Object mAnimationLock = new Object();

    /** Whether the TouchInputHandler has requested animation to be performed. */
    private boolean mInputAnimationRunning = false;

    public DesktopView(Context context, AttributeSet attributes) {
        super(context, attributes);

        // Give this view keyboard focus, allowing us to customize the soft keyboard's settings.
        setFocusableInTouchMode(true);

        mRenderData = new RenderData();
        mInputHandler = new TrackingInputHandler(this, context, mRenderData);
        mRepaintPending = false;

        getHolder().addCallback(this);
    }

    public void setDesktop(Desktop desktop) {
        mDesktop = desktop;
    }

    /** Request repainting of the desktop view. */
    void requestRepaint() {
        synchronized (mRenderData) {
            if (mRepaintPending) {
                return;
            }
            mRepaintPending = true;
        }
        JniInterface.redrawGraphics();
    }

    /** Called whenever the screen configuration is changed. */
    public void onScreenConfigurationChanged() {
        mInputHandler.onScreenConfigurationChanged();
    }

    /**
     * Redraws the canvas. This should be done on a non-UI thread or it could
     * cause the UI to lag. Specifically, it is currently invoked on the native
     * graphics thread using a JNI.
     */
    public void paint() {
        long startTimeMs = SystemClock.uptimeMillis();

        if (Looper.myLooper() == Looper.getMainLooper()) {
            Log.w("deskview", "Canvas being redrawn on UI thread");
        }

        Bitmap image = JniInterface.getVideoFrame();
        if (image == null) {
            // This can happen if the client is connected, but a complete video frame has not yet
            // been decoded.
            return;
        }

        int width = image.getWidth();
        int height = image.getHeight();
        boolean sizeChanged = false;
        synchronized (mRenderData) {
            if (mRenderData.imageWidth != width || mRenderData.imageHeight != height) {
                // TODO(lambroslambrou): Move this code into a sizeChanged() callback, to be
                // triggered from JniInterface (on the display thread) when the remote screen size
                // changes.
                mRenderData.imageWidth = width;
                mRenderData.imageHeight = height;
                sizeChanged = true;
            }
        }
        if (sizeChanged) {
            mInputHandler.onHostSizeChanged(width, height);
        }

        Canvas canvas;
        int x, y;
        synchronized (mRenderData) {
            mRepaintPending = false;
            // Don't try to lock the canvas before it is ready, as the implementation of
            // lockCanvas() may throttle these calls to a slow rate in order to avoid consuming CPU.
            // Note that a successful call to lockCanvas() will prevent the framework from
            // destroying the Surface until it is unlocked.
            if (!mSurfaceCreated) {
                return;
            }
            canvas = getHolder().lockCanvas();
            if (canvas == null) {
                return;
            }
            canvas.setMatrix(mRenderData.transform);
            x = mRenderData.cursorPosition.x;
            y = mRenderData.cursorPosition.y;
        }

        canvas.drawColor(Color.BLACK);
        canvas.drawBitmap(image, 0, 0, new Paint());

        boolean feedbackAnimationRunning = mFeedbackAnimator.isAnimationRunning();
        if (feedbackAnimationRunning) {
            float scaleFactor;
            synchronized (mRenderData) {
                scaleFactor = mRenderData.transform.mapRadius(1);
            }
            mFeedbackAnimator.render(canvas, x, y, 40 / scaleFactor);
        }

        Bitmap cursorBitmap = JniInterface.getCursorBitmap();
        if (cursorBitmap != null) {
            Point hotspot = JniInterface.getCursorHotspot();
            canvas.drawBitmap(cursorBitmap, x - hotspot.x, y - hotspot.y, new Paint());
        }

        getHolder().unlockCanvasAndPost(canvas);

        synchronized (mAnimationLock) {
            if (mInputAnimationRunning || feedbackAnimationRunning) {
                getHandler().postAtTime(new Runnable() {
                    @Override
                    public void run() {
                        processAnimation();
                    }
                }, startTimeMs + 30);
            }
        };
    }

    private void processAnimation() {
        boolean running;
        synchronized (mAnimationLock) {
            running = mInputAnimationRunning;
        }
        if (running) {
            mInputHandler.processAnimation();
        }
        running |= mFeedbackAnimator.isAnimationRunning();
        if (running) {
            requestRepaint();
        }
    }

    /**
     * Called after the canvas is initially created, then after every subsequent resize, as when
     * the display is rotated.
     */
    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        synchronized (mRenderData) {
            mRenderData.screenWidth = width;
            mRenderData.screenHeight = height;
        }

        JniInterface.provideRedrawCallback(new Runnable() {
            @Override
            public void run() {
                paint();
            }
        });
        mInputHandler.onClientSizeChanged(width, height);
        requestRepaint();
    }

    /** Called when the canvas is first created. */
    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        synchronized (mRenderData) {
            mSurfaceCreated = true;
        }
    }

    /**
     * Called when the canvas is finally destroyed. Marks the canvas as needing a redraw so that it
     * will not be blank if the user later switches back to our window.
     */
    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        // Stop this canvas from being redrawn.
        JniInterface.provideRedrawCallback(null);

        synchronized (mRenderData) {
            mSurfaceCreated = false;
        }
    }

    /** Called when a software keyboard is requested, and specifies its options. */
    @Override
    public InputConnection onCreateInputConnection(EditorInfo outAttrs) {
        // Disables rich input support and instead requests simple key events.
        outAttrs.inputType = InputType.TYPE_NULL;

        // Prevents most third-party IMEs from ignoring our Activity's adjustResize preference.
        outAttrs.imeOptions |= EditorInfo.IME_FLAG_NO_FULLSCREEN;

        // Ensures that keyboards will not decide to hide the remote desktop on small displays.
        outAttrs.imeOptions |= EditorInfo.IME_FLAG_NO_EXTRACT_UI;

        // Stops software keyboards from closing as soon as the enter key is pressed.
        outAttrs.imeOptions |= EditorInfo.IME_MASK_ACTION | EditorInfo.IME_FLAG_NO_ENTER_ACTION;

        return null;
    }

    /** Called whenever the user attempts to touch the canvas. */
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        return mInputHandler.onTouchEvent(event);
    }

    @Override
    public void injectMouseEvent(int x, int y, int button, boolean pressed) {
        boolean cursorMoved = false;
        synchronized (mRenderData) {
            // Test if the cursor actually moved, which requires repainting the cursor. This
            // requires that the TouchInputHandler doesn't mutate |mRenderData.cursorPosition|
            // directly.
            if (x != mRenderData.cursorPosition.x) {
                mRenderData.cursorPosition.x = x;
                cursorMoved = true;
            }
            if (y != mRenderData.cursorPosition.y) {
                mRenderData.cursorPosition.y = y;
                cursorMoved = true;
            }
        }

        if (button == TouchInputHandler.BUTTON_UNDEFINED && !cursorMoved) {
            // No need to inject anything or repaint.
            return;
        }

        JniInterface.sendMouseEvent(x, y, button, pressed);
        if (cursorMoved) {
            // TODO(lambroslambrou): Optimize this by only repainting the affected areas.
            requestRepaint();
        }
    }

    @Override
    public void injectMouseWheelDeltaEvent(int deltaX, int deltaY) {
        JniInterface.sendMouseWheelEvent(deltaX, deltaY);
    }

    @Override
    public void showLongPressFeedback() {
        mFeedbackAnimator.startAnimation();
        requestRepaint();
    }

    @Override
    public void showActionBar() {
        mDesktop.showActionBar();
    }

    @Override
    public void showKeyboard() {
        InputMethodManager inputManager =
                (InputMethodManager)getContext().getSystemService(Context.INPUT_METHOD_SERVICE);
        inputManager.showSoftInput(this, 0);
    }

    @Override
    public void transformationChanged() {
        requestRepaint();
    }

    @Override
    public void setAnimationEnabled(boolean enabled) {
        synchronized (mAnimationLock) {
            if (enabled && !mInputAnimationRunning) {
                requestRepaint();
            }
            mInputAnimationRunning = enabled;
        }
    }
}