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      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 
     17 package com.android.camera;
     18 
     19 import android.content.Context;
     20 import android.util.AttributeSet;
     21 import android.view.View;
     22 import 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  */
     29 public class ShutterButton extends ImageView implements View.OnLongClickListener {
     30     /**
     31      * A callback to be invoked when a ShutterButton's pressed state changes.
     32      */
     33     public interface OnShutterButtonListener {
     34         /**
     35          * Called when a ShutterButton has been pressed.
     36          *
     37          * @param pressed The ShutterButton that was pressed.
     38          */
     39         void onShutterButtonFocus(boolean pressed);
     40         void onShutterButtonClick();
     41     }
     42 
     43     /**
     44      * A callback to be invoked when a ShutterButton's long pressed.
     45      */
     46     public interface OnShutterButtonLongPressListener {
     47         void onShutterButtonLongPressed();
     48     }
     49 
     50     private OnShutterButtonListener mListener;
     51     private OnShutterButtonLongPressListener mLongPressListener;
     52     private boolean mOldPressed;
     53 
     54     public ShutterButton(Context context, AttributeSet attrs) {
     55         super(context, attrs);
     56         setOnLongClickListener(this);
     57     }
     58 
     59     public void setOnShutterButtonListener(OnShutterButtonListener listener) {
     60         mListener = listener;
     61     }
     62 
     63     public void setOnShutterButtonLongPressListener(OnShutterButtonLongPressListener listener) {
     64         mLongPressListener = listener;
     65     }
     66 
     67     /**
     68      * Hook into the drawable state changing to get changes to isPressed -- the
     69      * onPressed listener doesn't always get called when the pressed state
     70      * changes.
     71      */
     72     @Override
     73     protected void drawableStateChanged() {
     74         super.drawableStateChanged();
     75         final boolean pressed = isPressed();
     76         if (pressed != mOldPressed) {
     77             if (!pressed) {
     78                 // When pressing the physical camera button the sequence of
     79                 // events is:
     80                 //    focus pressed, optional camera pressed, focus released.
     81                 // We want to emulate this sequence of events with the shutter
     82                 // button. When clicking using a trackball button, the view
     83                 // system changes the the drawable state before posting click
     84                 // notification, so the sequence of events is:
     85                 //    pressed(true), optional click, pressed(false)
     86                 // When clicking using touch events, the view system changes the
     87                 // drawable state after posting click notification, so the
     88                 // sequence of events is:
     89                 //    pressed(true), pressed(false), optional click
     90                 // Since we're emulating the physical camera button, we want to
     91                 // have the same order of events. So we want the optional click
     92                 // callback to be delivered before the pressed(false) callback.
     93                 //
     94                 // To do this, we delay the posting of the pressed(false) event
     95                 // slightly by pushing it on the event queue. This moves it
     96                 // after the optional click notification, so our client always
     97                 // sees events in this sequence:
     98                 //     pressed(true), optional click, pressed(false)
     99                 post(new Runnable() {
    100                     public void run() {
    101                         callShutterButtonFocus(pressed);
    102                     }
    103                 });
    104             } else {
    105                 callShutterButtonFocus(pressed);
    106             }
    107             mOldPressed = pressed;
    108         }
    109     }
    110 
    111     private void callShutterButtonFocus(boolean pressed) {
    112         if (mListener != null) {
    113             mListener.onShutterButtonFocus(pressed);
    114         }
    115     }
    116 
    117     @Override
    118     public boolean performClick() {
    119         boolean result = super.performClick();
    120         if (mListener != null) {
    121             mListener.onShutterButtonClick();
    122         }
    123         return result;
    124     }
    125 
    126     @Override
    127     public boolean onLongClick(View v) {
    128         if (mLongPressListener != null) {
    129             mLongPressListener.onShutterButtonLongPressed();
    130         }
    131         return false;
    132     }
    133 }
    134