android实现自定义SwichButton

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());
}
}

<span style="white-space:pre">        </span>//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);
// 如果开关开着向左滑动，或者开关关着向右滑动（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;
}
}

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;
}
}

<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>