1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.camera;
18
19import android.content.Context;
20import android.util.AttributeSet;
21import android.view.MotionEvent;
22import android.widget.ImageView;
23
24/**
25 * A button designed to be used for the on-screen shutter button.
26 * It's currently an {@code ImageView} that can call a delegate when the
27 * pressed state changes.
28 */
29public class ShutterButton extends ImageView {
30
31    private boolean mTouchEnabled = true;
32
33    /**
34     * A callback to be invoked when a ShutterButton's pressed state changes.
35     */
36    public interface OnShutterButtonListener {
37        /**
38         * Called when a ShutterButton has been pressed.
39         *
40         * @param pressed The ShutterButton that was pressed.
41         */
42        void onShutterButtonFocus(boolean pressed);
43        void onShutterButtonClick();
44    }
45
46    private OnShutterButtonListener mListener;
47    private boolean mOldPressed;
48
49    public ShutterButton(Context context, AttributeSet attrs) {
50        super(context, attrs);
51    }
52
53    public void setOnShutterButtonListener(OnShutterButtonListener listener) {
54        mListener = listener;
55    }
56
57    @Override
58    public boolean dispatchTouchEvent(MotionEvent m) {
59        if (mTouchEnabled) {
60            return super.dispatchTouchEvent(m);
61        } else {
62            return false;
63        }
64    }
65
66    public void enableTouch(boolean enable) {
67        mTouchEnabled = enable;
68    }
69
70    /**
71     * Hook into the drawable state changing to get changes to isPressed -- the
72     * onPressed listener doesn't always get called when the pressed state
73     * changes.
74     */
75    @Override
76    protected void drawableStateChanged() {
77        super.drawableStateChanged();
78        final boolean pressed = isPressed();
79        if (pressed != mOldPressed) {
80            if (!pressed) {
81                // When pressing the physical camera button the sequence of
82                // events is:
83                //    focus pressed, optional camera pressed, focus released.
84                // We want to emulate this sequence of events with the shutter
85                // button. When clicking using a trackball button, the view
86                // system changes the drawable state before posting click
87                // notification, so the sequence of events is:
88                //    pressed(true), optional click, pressed(false)
89                // When clicking using touch events, the view system changes the
90                // drawable state after posting click notification, so the
91                // sequence of events is:
92                //    pressed(true), pressed(false), optional click
93                // Since we're emulating the physical camera button, we want to
94                // have the same order of events. So we want the optional click
95                // callback to be delivered before the pressed(false) callback.
96                //
97                // To do this, we delay the posting of the pressed(false) event
98                // slightly by pushing it on the event queue. This moves it
99                // after the optional click notification, so our client always
100                // sees events in this sequence:
101                //     pressed(true), optional click, pressed(false)
102                post(new Runnable() {
103                    @Override
104                    public void run() {
105                        callShutterButtonFocus(pressed);
106                    }
107                });
108            } else {
109                callShutterButtonFocus(pressed);
110            }
111            mOldPressed = pressed;
112        }
113    }
114
115    private void callShutterButtonFocus(boolean pressed) {
116        if (mListener != null) {
117            mListener.onShutterButtonFocus(pressed);
118        }
119    }
120
121    @Override
122    public boolean performClick() {
123        boolean result = super.performClick();
124        if (mListener != null) {
125            mListener.onShutterButtonClick();
126        }
127        return result;
128    }
129}
130