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.view.View;
23import android.widget.ImageView;
24
25/**
26 * A button designed to be used for the on-screen shutter button.
27 * It's currently an {@code ImageView} that can call a delegate when the
28 * pressed state changes.
29 */
30public class ShutterButton extends ImageView {
31
32    private boolean mTouchEnabled = true;
33
34    /**
35     * A callback to be invoked when a ShutterButton's pressed state changes.
36     */
37    public interface OnShutterButtonListener {
38        /**
39         * Called when a ShutterButton has been pressed.
40         *
41         * @param pressed The ShutterButton that was pressed.
42         */
43        void onShutterButtonFocus(boolean pressed);
44        void onShutterButtonClick();
45    }
46
47    private OnShutterButtonListener mListener;
48    private boolean mOldPressed;
49
50    public ShutterButton(Context context, AttributeSet attrs) {
51        super(context, attrs);
52    }
53
54    public void setOnShutterButtonListener(OnShutterButtonListener listener) {
55        mListener = listener;
56    }
57
58    @Override
59    public boolean dispatchTouchEvent(MotionEvent m) {
60        if (mTouchEnabled) {
61            return super.dispatchTouchEvent(m);
62        } else {
63            return false;
64        }
65    }
66
67    public void enableTouch(boolean enable) {
68        mTouchEnabled = enable;
69    }
70
71    /**
72     * Hook into the drawable state changing to get changes to isPressed -- the
73     * onPressed listener doesn't always get called when the pressed state
74     * changes.
75     */
76    @Override
77    protected void drawableStateChanged() {
78        super.drawableStateChanged();
79        final boolean pressed = isPressed();
80        if (pressed != mOldPressed) {
81            if (!pressed) {
82                // When pressing the physical camera button the sequence of
83                // events is:
84                //    focus pressed, optional camera pressed, focus released.
85                // We want to emulate this sequence of events with the shutter
86                // button. When clicking using a trackball button, the view
87                // system changes the drawable state before posting click
88                // notification, so the sequence of events is:
89                //    pressed(true), optional click, pressed(false)
90                // When clicking using touch events, the view system changes the
91                // drawable state after posting click notification, so the
92                // sequence of events is:
93                //    pressed(true), pressed(false), optional click
94                // Since we're emulating the physical camera button, we want to
95                // have the same order of events. So we want the optional click
96                // callback to be delivered before the pressed(false) callback.
97                //
98                // To do this, we delay the posting of the pressed(false) event
99                // slightly by pushing it on the event queue. This moves it
100                // after the optional click notification, so our client always
101                // sees events in this sequence:
102                //     pressed(true), optional click, pressed(false)
103                post(new Runnable() {
104                    @Override
105                    public void run() {
106                        callShutterButtonFocus(pressed);
107                    }
108                });
109            } else {
110                callShutterButtonFocus(pressed);
111            }
112            mOldPressed = pressed;
113        }
114    }
115
116    private void callShutterButtonFocus(boolean pressed) {
117        if (mListener != null) {
118            mListener.onShutterButtonFocus(pressed);
119        }
120    }
121
122    @Override
123    public boolean performClick() {
124        boolean result = super.performClick();
125        if (mListener != null && getVisibility() == View.VISIBLE) {
126            mListener.onShutterButtonClick();
127        }
128        return result;
129    }
130}
131