近日使用了一个滑动开关,使用的是xiaanming的WiperSwitch,地址在
http://blog.csdn.net/xiaanming/article/details/8842453
确实是个好东西,很容易就移植到app中,果然是没有版本不兼容问题。
可是在使用过程中,发现有些小问题,然后进行了改进。改进有如下几点:
1,支持控件的缩放;
2,解决有时开关会卡在中间的问题;
3,更换了图片;
4,解决滑动冲突问题;
5,onDraw 中不new;
先上个改进后的效果图:
下面分别对改进点进行说明:
1、支持控件的缩放
就是重写了onMeasure,根据设定的宽高值进行缩放。缩放时,为了美观,保持了view的宽高的比例;
设置缩放上下限:不能太大、太小,都没有意义,此处,我是限定上下限为 1/3 – 3倍;
2、解决有时开关会卡在中间的问题
运行时会遇到中间的滑动按钮卡在中间的情况,后来上网一顿查找,才知道是触摸事件onTouch()的处理中,有一种动作没有处理到,是MotionEvent.ACTION_CANCEL:
当保持按下操作,并从滑动开关转移到外层控件时,会触发MotionEvent.ACTION_CANCEL。
中onTouch()中添加上,并与MotionEvent.ACTION_UP做同样的处理,ok。
3、更换了图片
更换图片有些地方需要注意:
滑块的高度与背景图片的高度保持一致,滑块外缘是透明部分,通过透明部分来衬托出外边缘。
另外,说句题外话,做安卓开发,学习点PhotoShop也挺不错的。
4、解决滑动冲突问题
我在实际项目使用中,遇到将滑块滑动到中间部分时,突然跳转到另一头的情况。通过跟踪信息,发现竟然执行了MotionEvent.ACTION_CANCEL,原来是滑动事件被上层的布局给抢走了(我在外层使用了一个侧滑菜单,从而出现了滑动冲突)。
解决方法:
在ACTION_DOWN时禁止父ViewGroup的滑动监听:
getParent().requestDisallowInterceptTouchEvent(true);
在ACTION_CANCEL与ACTION_UP时恢复父ViewGroup的滑动监听:
getParent().requestDisallowInterceptTouchEvent(false);
5、onDraw 中不new
根据Lint的提示,View 的 onDraw() 方法会被频繁的调用,因此不建议在onDraw()函数体内进行对象分配。如果在其中有需要用到的对象,就把这些对象的分配放在别处。
6、下面是具体实现
package com.customview.view;
import com.customview.LogUtil;
import com.customview.R;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
/**
*
* @author xiaanming,lintax
*
*/
public class WiperSwitch extends View implements OnTouchListener{
private Bitmap bg_on, bg_off, slipper_btn;
/**
* 按下时的x和当前的x
*/
private float downX=0, nowX=0;
/**
* 记录用户是否在滑动
*/
private boolean onSlip = false;
/**
* 当前的状态
*/
private boolean nowStatus = false;
/**
* 监听接口
*/
private OnChangedListener listener;
Paint paint = null;//画笔
float x = 0;//滑动块的x位置
public WiperSwitch(Context context) {
super(context);
init();
}
public WiperSwitch(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public void init(){
LogUtil.logWithMethod(new Exception(),"init");
//载入图片资源
bg_on = BitmapFactory.decodeResource(getResources(), R.drawable.switch_open);
bg_off = BitmapFactory.decodeResource(getResources(), R.drawable.switch_close);
slipper_btn = BitmapFactory.decodeResource(getResources(), R.drawable.switch_btn);
x = 0;
paint = new Paint();
setOnTouchListener(this);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
{
int widthMode = MeasureSpec.getMode(widthMeasureSpec);
int widthSize = MeasureSpec.getSize(widthMeasureSpec);
int heightMode = MeasureSpec.getMode(heightMeasureSpec);
int heightSize = MeasureSpec.getSize(heightMeasureSpec);
int width;
int height ;
boolean flagExactly=false;
float viewWidth = (float)bg_on.getWidth();
float viewHeight = (float)bg_on.getHeight();
if (widthMode == MeasureSpec.EXACTLY)
{
width = widthSize;
flagExactly = true;
} else
{
width = (int) (viewWidth );
}
if (heightMode == MeasureSpec.EXACTLY)
{
height = heightSize;
flagExactly = true;
} else
{
height = (int) ( viewHeight );
}
//如果是指定大小,且宽高值确实不一致了,要重新调整图片的大小
if( flagExactly && ( (width!=viewWidth) || (height!=viewHeight) )){
//限制调整的范围:最大3倍,比例需要保持(要调比例,换原始图片)
//按比例,取小值
float ratio = Math.min(width/viewWidth, height/viewHeight);
if(ratio > 3){
ratio = 3;
} else if(ratio < 1/3){
ratio = 1/3;
}
width=(int)(viewWidth*ratio);
height=(int)(viewHeight*ratio);
LogUtil.logWithMethod(new Exception(),"after change: width="+width+" height="+height);
bg_on = Bitmap.createScaledBitmap(bg_on, width, height, false);
bg_off = Bitmap.createScaledBitmap(bg_off, width, height, false);
slipper_btn = Bitmap.createScaledBitmap(slipper_btn, height, height, false);
}
setMeasuredDimension(width, height);
}
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
x = 0;
if(isInEditMode()){
return;
}
//根据nowStatus设置背景,开或者关状态
if(nowStatus){
canvas.drawBitmap(bg_on, 0, 0, paint);
}else{
canvas.drawBitmap(bg_off, 0, 0, paint);
}
if (onSlip) {//是否是在滑动状态,
if(nowX >= bg_on.getWidth())//是否划出指定范围,不能让滑块跑到外头,必须做这个判断
x = bg_on.getWidth() - slipper_btn.getWidth()/2;//减去滑块1/2的长度
else
x = nowX - slipper_btn.getWidth()/2;
}else {
if(nowStatus){//根据当前的状态设置滑块的x值,若不在滑动状态,非左即右!
x = bg_on.getWidth() - slipper_btn.getWidth();
}else{
x = 0;
}
}
//对滑块滑动进行异常处理,不能让滑块出界
if (x < 0 ){
x = 0;
}
else if(x > bg_on.getWidth() - slipper_btn.getWidth()){
x = bg_on.getWidth() - slipper_btn.getWidth();
}
//画出滑块
canvas.drawBitmap(slipper_btn, x , 0, paint);
}
@Override
public boolean onTouch(View v, MotionEvent event) {
switch(event.getAction()){
case MotionEvent.ACTION_DOWN:{
LogUtil.logWithMethod(new Exception(), "ACTION_DOWN");
if (event.getX() > bg_off.getWidth() || event.getY() > bg_off.getHeight()){
return false;
}else{
onSlip = true;
downX = event.getX();
nowX = downX;
}
//LogUtil.logWithMethod(new Exception(),"ACTION_DOWN: nowX="+nowX);
getParent().requestDisallowInterceptTouchEvent(true);//禁止父ViewGroup的滑动监听
break;
}
case MotionEvent.ACTION_MOVE:{
nowX = event.getX();
if(event.getX() >= (bg_on.getWidth()/2)){
nowStatus = true;
}else{
nowStatus = false;
}
break;
}
case MotionEvent.ACTION_CANCEL:
//LogUtil.logWithMethod(new Exception(),"ACTION_CANCEL:");
case MotionEvent.ACTION_UP:{
onSlip = false;
if(event.getX() >= (bg_on.getWidth()/2)){
LogUtil.logWithMethod(new Exception(), "ACTION_UP: choseed");
nowStatus = true;
nowX = bg_on.getWidth() - slipper_btn.getWidth();
}else{
LogUtil.logWithMethod(new Exception(), "ACTION_UP: un choseed");
nowStatus = false;
nowX = 0;
}
//LogUtil.logWithMethod(new Exception(),"ACTION_UP: nowX="+nowX);
if(listener != null){
listener.OnChanged(WiperSwitch.this, nowStatus);
}
getParent().requestDisallowInterceptTouchEvent(false);//使能父ViewGroup的滑动监听
break;
}
}
//刷新界面
invalidate();
return true;
}
/**
* 为WiperSwitch设置一个监听,供外部调用的方法
* @param listener
*/
public void setOnChangedListener(OnChangedListener listener){
this.listener = listener;
}
/**
* 设置滑动开关的初始状态,供外部调用
* @param checked
*/
public void setChecked(boolean checked){
if(checked){
nowX = bg_off.getWidth();
}else{
nowX = 0;
}
nowStatus = checked;
invalidate();
}
/**
* 回调接口
* @author len
*
*/
public interface OnChangedListener {
public void OnChanged(WiperSwitch wiperSwitch, boolean checkState);
}
}
7、调用View的布局xml
布局中就只是存放了3个View,演示调用方法:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:custom="http://schemas.android.com/apk/res/com.customview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<com.customview.view.WiperSwitch
android:id="@+id/switch1"
android:layout_width="80dp"
android:layout_height="40dp"
android:layout_marginTop="10dp"
android:layout_gravity="center_horizontal"
/>
<com.customview.view.WiperSwitch
android:id="@+id/switch2"
android:layout_width="120dp"
android:layout_height="40dp"
android:layout_marginTop="10dp"
android:layout_gravity="center_horizontal"
/>
<com.customview.view.WiperSwitch
android:id="@+id/switch3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:layout_gravity="center_horizontal"
/>
</LinearLayout>
8、主Activity
主Activity中访问滑动开关,可以设置初始状态:
switch1.setChecked(true);
以及监控开关的状态变化:
switch1.setOnChangedListener(new OnChangedListener() {
具体实现如下:
package com.customview;
import android.os.Bundle;
import android.view.WindowManager;
import com.customview.view.WiperSwitch;
import com.customview.view.WiperSwitch.OnChangedListener;
import android.app.Activity;
public class MainActivity extends Activity
{
WiperSwitch switch1;
WiperSwitch switch2;
WiperSwitch switch3;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);//去掉信息栏
setContentView(R.layout.activity_main);
LogUtil.logWithMethod(new Exception());
switch1 = (WiperSwitch) findViewById(R.id.switch1);
switch2 = (WiperSwitch) findViewById(R.id.switch2);
switch3 = (WiperSwitch) findViewById(R.id.switch3);
switch1.setChecked(true);
switch2.setChecked(true);
switch3.setChecked(false);
switch1.setOnChangedListener(new OnChangedListener() {
@Override
public void OnChanged(WiperSwitch wiperSwitch, boolean checkState) {
// TODO Auto-generated method stub
LogUtil.logWithMethod(new Exception(),"switch1 checkState="+checkState);
}
});
switch2.setOnChangedListener(new OnChangedListener() {
@Override
public void OnChanged(WiperSwitch wiperSwitch, boolean checkState) {
// TODO Auto-generated method stub
LogUtil.logWithMethod(new Exception(),"switch2 checkState="+checkState);
}
});
switch3.setOnChangedListener(new OnChangedListener() {
@Override
public void OnChanged(WiperSwitch wiperSwitch, boolean checkState) {
// TODO Auto-generated method stub
LogUtil.logWithMethod(new Exception(),"switch3 checkState="+checkState);
}
});
}
}