滑动按钮
1. 创建一个类SlideButton继承View
2.实现带有两个参数的构造器(获取两个位图)
public SlideButton(Context context,AttributeSet attrs) {
super(context, attrs);
initPaint();
initBmp();
}
private void initPaint() {
mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
}
private void initBmp() {
mBackgroundBmp =BitmapFactory.decodeResource(getResources(),
R.drawable.switch_background);
mSlideBmp =BitmapFactory.decodeResource(getResources(),
R.drawable.slide_button_background);
}
3. 实现onMeasure()设置控件大小为底部位图的大小
@Override
protected void onMeasure(int widthMeasureSpec,int heightMeasureSpec) {
setMeasuredDimension(mBackgroundBmp.getWidth(),
mBackgroundBmp.getHeight());
}
4. 实现onDraw() 绘制默认的图片
@Override
protected void onDraw(Canvas canvas) {
canvas.drawBitmap(mBackgroundBmp, 0, 0,mPaint);
canvas.drawBitmap(mSlideBmp, 0, 0,mPaint);
}
5. 实现onTouchEvent() 滑动的时候控制滑块的位置 注意设置滑块的范围
private float mSlideLeft=0;
@Override
protected void onDraw(Canvas canvas) {
canvas.drawBitmap(mBackgroundBmp, 0, 0,mPaint);
if (mSlideLeft<0) {
canvas.drawBitmap(mSlideBmp, 0, 0,mPaint);
}else if(mSlideLeft>mBackgroundBmp.getWidth()-mSlideBmp.getWidth()) {
canvas.drawBitmap(mSlideBmp,mBackgroundBmp.getWidth()-
mSlideBmp.getWidth(),0, mPaint);
}else {
canvas.drawBitmap(mSlideBmp,mSlideLeft, 0, mPaint);
}
}
@Override
public boolean onTouchEvent(MotionEvent event){
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
break;
case MotionEvent.ACTION_MOVE:
float touchX=event.getX();
mSlideLeft=touchX-mSlideBmp.getWidth()/2;
break;
case MotionEvent.ACTION_UP:
floatslideHalf=mSlideLeft+mSlideBmp.getWidth()/2;
floatbackgroundHalf=mBackgroundBmp.getWidth()/2;
if (slideHalf>backgroundHalf) {
mSlideLeft=mBackgroundBmp.getWidth()-mSlideBmp.getWidth();
}else {
mSlideLeft=0;
}
break;
}
//刷新界⾯面 让系统调⽤用onDraw()
invalidate();
return true;
}
6. 在onDraw()中根据最后的界面决定当前控件的状态
@Override
protected void onDraw(Canvas canvas) {
...
//根据当前的状态决定开关
if (mSlideLeft==0&&mIsOpen) {
mIsOpen=false;
..
}elseif(mSlideLeft==mBackgroundBmp.getWidth()-
mSlideBmp.getWidth()&&!mIsOpen){
mIsOpen=true;
..
}
}
7. 创建开关的回调接口
public interface ISlideButtonChangeListener{
public void onButtonStateChanged(booleanflag);
}
public class SlideButton extends View {
private ISlideButtonChangeListenermListener;
public voidsetmListener(ISlideButtonChangeListener mListener) {
this.mListener = mListener;
}
@Override
protected void onDraw(Canvas canvas) {
...
//根据当前的状态决定开关
if (mSlideLeft==0&&mIsOpen) {
mIsOpen=false;
if (mListener!=null) {
mListener.onButtonStateChanged(mIsOpen);
}
}elseif(mSlideLeft==mBackgroundBmp.getWidth()-
mSlideBmp.getWidth()&&!mIsOpen){
mIsOpen=true;
if (mListener!=null) {
mListener.onButtonStateChanged(mIsOpen);
}
}
}
}
