自定义View之Switch

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思路：
定义类继承view，重写几个用到的方法
1.三个构造方法
2. onMeasure测量
onLayout布局
onDrow绘图
3.onTouchEvent触摸事件方法
invalidate();可以高频度的调用onDraw()
定义一个外部接口，将开关状态传出去
添加设置接口对象的方法，外部进行调用

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;/** * Created by maker_huige on 2016/12/26. */public class ToggleView extends View {    boolean isTouchMode = false;    Bitmap bitmap_switch_background;    Bitmap bitmap_slide_button;    boolean mSwitchState = true;    float currentX;    private OnSwitchStateUpdateListener onSwitchStateUpdateListener;    public ToggleView(Context context) {        super(context);        init(null);    }    public ToggleView(Context context, AttributeSet attrs) {        super(context, attrs);        init(attrs);    }    public ToggleView(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        init(attrs);    }    private void init(AttributeSet attrs) {        String namespace = "http://schemas.android.com/apk/res-auto";        int switch_background = attrs.getAttributeResourceValue(namespace, "switch_background", -1);        int slide_button = attrs.getAttributeResourceValue(namespace, "slide_button", -1);        mSwitchState =attrs.getAttributeBooleanValue(namespace,"switch_state",false);        setSwitchBackgroundResource(switch_background);        setSlideButtonResource(slide_button);    }    /**     * 自定义组件的三个方法,执行onResum后执行     * onMeasure测量     * onLayout布局     * onDrow绘图     * view需要两个     * viewGrowp需要三个     */    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        setMeasuredDimension(bitmap_switch_background.getWidth(),bitmap_switch_background.getHeight());    }    @Override    protected void onDraw(Canvas canvas) {        Paint paint = new Paint();        canvas.drawBitmap(bitmap_switch_background,0,0,paint);        if(isTouchMode){            //当用户触摸到位置画滑块            float newLeft = currentX;            newLeft = currentX -bitmap_slide_button.getWidth() / 2.0f;            float maxLeft = bitmap_switch_background.getWidth()-bitmap_slide_button.getWidth();            if(newLeft < 0){                newLeft = 0;            }else {                newLeft = maxLeft;            }            canvas.drawBitmap(bitmap_slide_button,newLeft,0,paint);        }else {            if(mSwitchState){                canvas.drawBitmap(bitmap_slide_button,                        bitmap_switch_background.getWidth()-bitmap_slide_button.getWidth(),                        0,paint);            }else{                canvas.drawBitmap(bitmap_slide_button,0,0,paint);            }        }    }    @Override    public boolean onTouchEvent(MotionEvent event) {        switch (event.getAction()){            case MotionEvent.ACTION_MOVE:                currentX = event.getX();                break;            case MotionEvent.ACTION_DOWN:                isTouchMode = true;                currentX = event.getX();                break;            case MotionEvent.ACTION_UP:                currentX = event.getX();                isTouchMode = false;                boolean state = currentX > bitmap_switch_background.getWidth() / 2.0f;                if(state != mSwitchState && onSwitchStateUpdateListener !=null){                    onSwitchStateUpdateListener.onStateUpdate(state);                }                mSwitchState = state;                break;            }        invalidate();        return true;    }    //    声明接口对象    public interface OnSwitchStateUpdateListener{        void onStateUpdate(boolean state);    }//    添加设置接口对象的方法，外部进行调用    public void setOnSwitchStateUpdateListener(OnSwitchStateUpdateListener onSwitchStateUpdateListener) {        this.onSwitchStateUpdateListener = onSwitchStateUpdateListener;    }    public void setSwitchBackgroundResource(int switch_background) {        bitmap_switch_background = BitmapFactory.decodeResource(getResources(), switch_background);    }    public void setSlideButtonResource(int slide_button) {        bitmap_slide_button = BitmapFactory.decodeResource(getResources(), slide_button);    }}

在Activity中设置事件监听器，通过匿名内部类的方式并将state状态打印出来

public class ToggleActivity extends Activity {    ToggleView toggleView;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_toggle);        initUI();        toggleView.setOnSwitchStateUpdateListener(new ToggleView.OnSwitchStateUpdateListener() {            @Override            public void onStateUpdate(boolean state) {                Toast.makeText(getApplicationContext(),"state:" + state,Toast.LENGTH_SHORT).show();            }        });    }    private void initUI() {        toggleView = (ToggleView) findViewById(R.id.toggleview);        //用自定义属替代了        /*toggleView.setSwitchBackgroundResource(R.mipmap.switch_background);        toggleView.setSlideButtonResource(R.mipmap.slide_button);*/    }}

xml

<?xml version="1.0" encoding="utf-8"?><RelativeLayout    xmlns:itheima="http://schemas.android.com/apk/res-auto"    xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent" android:layout_height="match_parent">    <com.maker_huige.ui.ToggleView        itheima:switch_background="@mipmap/switch_background"        itheima:slide_button="@mipmap/slide_button"        itheima:switch_state="true"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_centerInParent="true"        android:id="@+id/toggleview"        /></RelativeLayout>

自定义属性的xml

<?xml version="1.0" encoding="utf-8"?><resources>    <declare-styleable name="ToggleView">        <attr name="switch_background" format="reference"/>        <attr name="slide_button" format="reference"/>        <attr name="switch_state" format="boolean"/>    </declare-styleable></resources>

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