public class SwitchButton extends View implements OnClickListener, OnTouchListener {
private Context mContext;
private Bitmap mSwitchBottom, mSwitchThumb, mSwitchFrame, mSwitchMask;
private float mCurrentX = 0;
/**开关状态*/
private boolean mSwitchOn = true;
/**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;
/**移动的偏移量*/
private int mDeltX = 0;
private Paint mPaint = null;
private OnChangeListener mListener = null;
private boolean mFlag = false;
public SwitchButton(Context context) {
this(context, null);
}
public SwitchButton(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public SwitchButton(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
this.mContext = context;
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 = ((BitmapDrawable) getResources().getDrawable(R.drawable.switch_mask)).getBitmap();//两种方式都行
mMoveLength = mSwitchBottom.getWidth() - mSwitchFrame.getWidth();
mSrc = new Rect();
mDest = new Rect(0, 0, mSwitchFrame.getWidth(), mSwitchFrame.getHeight());
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setAlpha(255);
mPaint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
setOnClickListener(this);
setOnTouchListener(this);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {//这里的大小是写死的，所以布局中任何宽高的设置都是无效的！
setMeasuredDimension(mSwitchFrame.getWidth(), mSwitchFrame.getHeight());
}
@Override
protected void onDraw(Canvas canvas) {
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
//onTouchListener的onTouch优先级比onTouchEvent高，会先触发。若onTouch返回false会接着触发onTouchEvent，反之onTouchEvent方法不会被调用！
public boolean onTouch(View paramView, MotionEvent paramMotionEvent) {
return false;//内置诸如click事件的实现等等都基于onTouchEvent，假如onTouch返回true，这些事件将不会被触发
}
@Override
public boolean onTouchEvent(MotionEvent event) {
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);
}
@Override
public void onClick(View v) {
mDeltX = mSwitchOn ? mMoveLength : -mMoveLength;
mSwitchOn = !mSwitchOn;
if (mListener != null) mListener.onChange(this, mSwitchOn);
invalidate();
mDeltX = 0;
}
//自定义的回调
public interface OnChangeListener {
public void onChange(SwitchButton sb, boolean state);
}
public void setOnChangeListener(OnChangeListener listener) {
mListener = listener;
}
}
