Android 自定义实现switch开关按钮
原文地址：http://blog.csdn.net/swust_chenpeng/article/details/19967501
前几天在看蘑菇街上有个开关按钮：
就在想是怎样实现的，于是反编译了它的源码，但是这时得到了下面的几张图片：
图片对应的名称：
无色长条:switch_frame;
白色圆点:switch_btn_pressed;
左白右红的长条:switch_bottom;
黑色长条:switch_mask.
那我们就用这几张图片来实现类似的效果吧。
代码：
SwitchButton类：
package com.example.switchbutton;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.PorterDuff.Mode;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
public class SwitchButton extends View implements
android.view.View.OnClickListener {
private Bitmap mSwitchBottom, mSwitchThumb, mSwitchFrame, mSwitchMask;
private float mCurrentX = 0;
private boolean mSwitchOn = true;// 开关默认是开着的
private int mMoveLength;// 最大移动距离
private float mLastX = 0;// 第一次按下的有效区域
private Rect mDest = null;// 绘制的目标区域大小
private Rect mSrc = null;// 截取源图片的大小
private int mDeltX = 0;// 移动的偏移量
private Paint mPaint = null;
private OnChangeListener mListener = null;
private boolean mFlag = false;
public SwitchButton(Context context) {
this(context, null);
// TODO Auto-generated constructor stub
}
public SwitchButton(Context context, AttributeSet attrs) {
this(context, attrs, 0);
// TODO Auto-generated constructor stub
}
public SwitchButton(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
// TODO Auto-generated constructor stub
init();
}
/**
* 初始化相关资源
*/
public void init() {
mSwitchBottom = BitmapFactory.decodeResource(getResources(),
R.drawable.switch_bottom);
mSwitchThumb = BitmapFactory.decodeResource(getResources(),
R.drawable.switch_btn_pressed);
mSwitchFrame = BitmapFactory.decodeResource(getResources(),
R.drawable.switch_frame);
mSwitchMask = BitmapFactory.decodeResource(getResources(),
R.drawable.switch_mask);
setOnClickListener(this);
setOnTouchListener(new OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
// TODO Auto-generated method stub
return false;
}
});
mMoveLength = mSwitchBottom.getWidth() - mSwitchFrame.getWidth();
mDest = new Rect(0, 0, mSwitchFrame.getWidth(),
mSwitchFrame.getHeight());
mSrc = new Rect();
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setAlpha(255);
mPaint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
// TODO Auto-generated method stub
setMeasuredDimension(mSwitchFrame.getWidth(), mSwitchFrame.getHeight());
}
@Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
super.onDraw(canvas);
if (mDeltX > 0 || mDeltX == 0 && !mSwitchOn) {
if (mSrc != null) {
mSrc.set(mMoveLength - mDeltX, 0, mSwitchBottom.getWidth()
- mDeltX, mSwitchFrame.getHeight());
}
} else if (mDeltX < 0 || mDeltX == 0 && mSwitchOn) {
if (mSrc != null) {
mSrc.set(-mDeltX, 0, mSwitchFrame.getWidth() - mDeltX,
mSwitchFrame.getHeight());
}
}
// 这儿是离屏缓冲，自己感觉类似双缓冲机制吧
int count = canvas.saveLayer(new RectF(mDest), null,
Canvas.MATRIX_SAVE_FLAG | Canvas.CLIP_SAVE_FLAG
| Canvas.HAS_ALPHA_LAYER_SAVE_FLAG
| Canvas.FULL_COLOR_LAYER_SAVE_FLAG
| Canvas.CLIP_TO_LAYER_SAVE_FLAG);
canvas.drawBitmap(mSwitchBottom, mSrc, mDest, null);
canvas.drawBitmap(mSwitchThumb, mSrc, mDest, null);
canvas.drawBitmap(mSwitchFrame, 0, 0, null);
canvas.drawBitmap(mSwitchMask, 0, 0, mPaint);
canvas.restoreToCount(count);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
// TODO Auto-generated method stub
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
mLastX = event.getX();
break;
case MotionEvent.ACTION_MOVE:
mCurrentX = event.getX();
mDeltX = (int) (mCurrentX - mLastX);
// 如果开关关着向左滑动，或者开关开着向右滑动（这时候是不需要处理的）
if ((mSwitchOn && mDeltX > 0) || (!mSwitchOn && mDeltX < 0)) {
mFlag = true;
mDeltX = 0;
}
if (Math.abs(mDeltX) > mMoveLength) {
mDeltX = mDeltX > 0 ? mMoveLength : -mMoveLength;
}
invalidate();
return true;
case MotionEvent.ACTION_UP:
if (Math.abs(mDeltX) > 0 && Math.abs(mDeltX) < mMoveLength / 2) {
mDeltX = 0;
invalidate();
return true;
} else if (Math.abs(mDeltX) > mMoveLength / 2
&& Math.abs(mDeltX) <= mMoveLength) {
mDeltX = mDeltX > 0 ? mMoveLength : -mMoveLength;
mSwitchOn = !mSwitchOn;
if (mListener != null) {
mListener.onChange(this, mSwitchOn);
}
invalidate();
mDeltX = 0;
return true;
} else if (mDeltX == 0 && mFlag) {
// 这时候得到的是不需要进行处理的，因为已经move过了
mDeltX = 0;
mFlag = false;
return true;
}
return super.onTouchEvent(event);
default:
break;
}
invalidate();
return super.onTouchEvent(event);
}
public void setOnChangeListener(OnChangeListener listener) {
mListener = listener;
}
public interface OnChangeListener {
public void onChange(SwitchButton sb, boolean state);
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
mDeltX = mSwitchOn ? mMoveLength : -mMoveLength;
mSwitchOn = !mSwitchOn;
if (mListener != null) {
mListener.onChange(this, mSwitchOn);
}
invalidate();
mDeltX = 0;
}
MainActivity：
package com.example.switchbutton;
import com.example.switchbutton.SwitchButton.OnChangeListener;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.widget.Toast;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
SwitchButton sb = (SwitchButton) findViewById(R.id.wiperSwitch1);
sb.setOnChangeListener(new OnChangeListener() {
@Override
public void onChange(SwitchButton sb, boolean state) {
// TODO Auto-generated method stub
Log.d("switchButton", state ? "开":"关");
Toast.makeText(MainActivity.this, state ? "开":"关", Toast.LENGTH_SHORT).show();
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
activity_main.xml:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" > <ImageView android:id="@+id/imageView" android:layout_width="wrap_content" android:layout_height="wrap_content" /> <com.example.switchbutton.SwitchButton android:id="@+id/wiperSwitch1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginLeft="100dip" /> </LinearLayout>主要的代码在switchbutton类中，代码有什么不足还希望大家多提提意见，自己很少写。
参考：http://stackoverflow.com/questions/11838022/how-to-paint-with-alpha
http://blog.csdn.net/zenip/article/details/8766263
PS：以下为自己补充内容，如果想自己手动设置打开或者关闭状态，可以在SwitchButton中加上以下代码，调用即可。
public void setChecked(boolean checked){
mSwitchOn = checked;
invalidate();
}