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/*
* Copyright (C) 2008 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.camera;
import android.content.Context;
import android.util.AttributeSet;
import android.widget.ImageView;
/**
* A button designed to be used for the on-screen shutter button.
* It's currently an {@code ImageView} that can call a delegate when the
* pressed state changes.
*/
public class ShutterButton extends ImageView {
/**
* A callback to be invoked when a ShutterButton's pressed state changes.
*/
public interface OnShutterButtonListener {
/**
* Called when a ShutterButton has been pressed.
*
* @param b The ShutterButton that was pressed.
*/
void onShutterButtonFocus(ShutterButton b, boolean pressed);
void onShutterButtonClick(ShutterButton b);
}
private OnShutterButtonListener mListener;
private boolean mOldPressed;
public ShutterButton(Context context) {
super(context);
}
public ShutterButton(Context context, AttributeSet attrs) {
super(context, attrs);
}
public ShutterButton(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public void setOnShutterButtonListener(OnShutterButtonListener listener) {
mListener = listener;
}
/**
* Hook into the drawable state changing to get changes to isPressed -- the
* onPressed listener doesn't always get called when the pressed state
* changes.
*/
@Override
protected void drawableStateChanged() {
super.drawableStateChanged();
final boolean pressed = isPressed();
if (pressed != mOldPressed) {
if (!pressed) {
// When pressing the physical camera button the sequence of
// events is:
// focus pressed, optional camera pressed, focus released.
// We want to emulate this sequence of events with the shutter
// button. When clicking using a trackball button, the view
// system changes the the drawable state before posting click
// notification, so the sequence of events is:
// pressed(true), optional click, pressed(false)
// When clicking using touch events, the view system changes the
// drawable state after posting click notification, so the
// sequence of events is:
// pressed(true), pressed(false), optional click
// Since we're emulating the physical camera button, we want to
// have the same order of events. So we want the optional click
// callback to be delivered before the pressed(false) callback.
//
// To do this, we delay the posting of the pressed(false) event
// slightly by pushing it on the event queue. This moves it
// after the optional click notification, so our client always
// sees events in this sequence:
// pressed(true), optional click, pressed(false)
post(new Runnable() {
public void run() {
callShutterButtonFocus(pressed);
}
});
} else {
callShutterButtonFocus(pressed);
}
mOldPressed = pressed;
}
}
private void callShutterButtonFocus(boolean pressed) {
if (mListener != null) {
mListener.onShutterButtonFocus(this, pressed);
}
}
@Override
public boolean performClick() {
boolean result = super.performClick();
if (mListener != null) {
mListener.onShutterButtonClick(this);
}
return result;
}
}
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