Android 自定义View实现SlideSwitchView

import com.example.compoundbuttonview.R;

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.util.Log;
import android.view.MotionEvent;
import android.view.View;

public class SlideSwitchView extends View{
/** Switch底部样式图片 */
private Bitmap mSwitchBottom;
/** Switch 当前样式  */
private Bitmap mSwitchThumb;
/** Switch无操作情况下的样式  */
private Bitmap mSwitchThumbNormal;
/** Switch当前手指触摸式的样式  */
private Bitmap mSwitchThumbPressed;
/** Switch 框架  */
private Bitmap mSwitchFrame;
private Bitmap mSwitchMask;
private float mCurrentX = 0;
/** Switch 开关状态，默认是  开：true  */
private boolean mSwitchOn = true;
/** Switch 最大移动距离   */
private int mMoveLength;
/** 第一次按下的有效区域 */
private float mLastX = 0;
/** 绘制的目标区域大小  */
private Rect mDest = null;
/** 截取源图片的大小  */
private Rect mSrc = null;
/** Switch 移动的偏移量  */
private int mMoveDeltX = 0;
/** 画笔工具  */
private Paint mPaint = null;
/** Switch 状态监听接口  */
private OnSwitchChangedListener switchListener = null;
private boolean mFlag = false;
/** enabled 属性 为 true */
private boolean mEnabled = true;
/** 最大透明度，就是不透明 */
private final int MAX_ALPHA = 255;
/** 当前透明度，这里主要用于如果控件的enable属性为false时候设置半透明 ，即不可以点击 */
private int mAlpha = MAX_ALPHA;
/** Switch 判断是否在拖动 */
private boolean mIsScrolled =false;

public SlideSwitchView(Context context) {
this(context, null);
}

public SlideSwitchView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}

public SlideSwitchView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}

/**
* 初始化相关资源
*/
public void init() {
mSwitchThumbPressed = BitmapFactory.decodeResource(getResources(),R.drawable.checkswitch_btn_pressed);
mSwitchThumbNormal = BitmapFactory.decodeResource(getResources(),R.drawable.checkswitch_btn_unpressed);
mSwitchBottom = BitmapFactory.decodeResource(getResources(),R.drawable.checkswitch_bottom);
mSwitchFrame = BitmapFactory.decodeResource(getResources(),R.drawable.checkswitch_frame);
mSwitchMask = BitmapFactory.decodeResource(getResources(),R.drawable.checkswitch_mask);
mSwitchThumb = mSwitchThumbNormal;
mMoveLength = mSwitchBottom.getWidth() - mSwitchFrame.getWidth();
//绘制区域大小
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 (mMoveDeltX > 0 || mMoveDeltX == 0 && mSwitchOn) {
if (mSrc != null) {
mSrc.set(mMoveLength - mMoveDeltX, 0, mSwitchBottom.getWidth()
- mMoveDeltX, mSwitchFrame.getHeight());
}
} else if (mMoveDeltX < 0 || mMoveDeltX == 0 && !mSwitchOn) {
if (mSrc != null) {
mSrc.set(-mMoveDeltX, 0, mSwitchFrame.getWidth() - mMoveDeltX,
mSwitchFrame.getHeight());
}
}
Log.d("mAlpha", "mAlpha:" + mAlpha);
canvas.saveLayerAlpha(new RectF(mDest), mAlpha, 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.restore();
}

@Override
public boolean onTouchEvent(MotionEvent event) {
// TODO Auto-generated method stub
//如果Enabled属性设定为true,触摸效果才有效
if(!mEnabled){
return true;
}
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
mSwitchThumb = mSwitchThumbPressed;
mLastX = event.getX();
break;
case MotionEvent.ACTION_MOVE:
mCurrentX = event.getX();
mMoveDeltX = (int) (mCurrentX - mLastX);
if(mMoveDeltX > 10){
//设置了10这个误差距离，可以更好的实现点击效果
mIsScrolled = true;
}
// 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 && mMoveDeltX < 0) || (!mSwitchOn && mMoveDeltX > 0)) {
mFlag = true;
mMoveDeltX = 0;
}

if (Math.abs(mMoveDeltX) > mMoveLength) {
mMoveDeltX = mMoveDeltX > 0 ? mMoveLength : -mMoveLength;
}
invalidate();
break;
case MotionEvent.ACTION_UP:
mSwitchThumb = mSwitchThumbNormal;
//如果没有滑动过，就看作一次点击事件
if(!mIsScrolled){
mMoveDeltX = mSwitchOn ? mMoveLength : -mMoveLength;
mSwitchOn = !mSwitchOn;
if (switchListener != null) {
switchListener.onSwitchChange(this, mSwitchOn);
}
invalidate();
mMoveDeltX = 0;
break;
}
mIsScrolled = false;
if (Math.abs(mMoveDeltX) > 0 && Math.abs(mMoveDeltX) < mMoveLength / 2) {
mMoveDeltX = 0;
invalidate();
} else if (Math.abs(mMoveDeltX) > mMoveLength / 2
&& Math.abs(mMoveDeltX) <= mMoveLength) {
mMoveDeltX = mMoveDeltX > 0 ? mMoveLength : -mMoveLength;
mSwitchOn = !mSwitchOn;
if (switchListener != null) {
switchListener.onSwitchChange(this, mSwitchOn);
}
invalidate();
mMoveDeltX = 0;
} else if (mMoveDeltX == 0 && mFlag) {
// 这时候得到的是不需要进行处理的，因为已经move过了
mMoveDeltX = 0;
mFlag = false;
}
default:
break;
}
invalidate();
return true;
}
/**
* 设置 switch 状态监听
* */
public void setOnChangeListener(OnSwitchChangedListener listener) {
switchListener = listener;
}
/**
* switch 开关监听接口
*  */
public interface OnSwitchChangedListener{
public void onSwitchChange(SlideSwitchView switchView, boolean isChecked);
}

@Override
public void setEnabled(boolean enabled) {
// TODO Auto-generated method stub
mEnabled = enabled;
mAlpha = enabled ? MAX_ALPHA : MAX_ALPHA/2;
Log.d("enabled",enabled ? "true": "false");
super.setEnabled(enabled);
invalidate();
}

/** 自动判断切换至相反的属性 : true -->false ;false -->true */
public void toggle() {
setChecked(!mSwitchOn);
}

/** 设置选中的状态（选中:true   非选中: false） */
public void setChecked(boolean checked) {
mSwitchOn = checked;
invalidate();
}
}