Android自定义开关

一、效果:

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二、解析:

(1)自定义类继承View

/**
 * 自定义开关
 * Created by Sean on 2017/1/30.
 */

public class ToggleView extends View {

    private Bitmap switchBackgroundBitmap; //背景图片
    private Bitmap slideButtonBitmap;//滑块背景图
    private Paint paint;
    private boolean mSwitchState = false;//开关状态一开始为关
    private float currentX;
    private boolean isTouchMode;

    public ToggleView(Context context) {
        super(context);
        init();
    }



    public ToggleView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }


    public ToggleView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    /**
     * 初始化画笔
     */
    private void init() {
        paint = new Paint();
    }
}

(2)自定义属性，拷贝包名的全路径到xml文件中

<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>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:sean="http://schemas.android.com/apk/res/com.project.codingma.customedswitch"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity">

    <com.project.codingma.customedswitch.ToggleView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/toggleView"
        android:layout_centerInParent="true"
        sean:switch_background="@drawable/switch_background"
        sean:switch_state="false"
        sean:slide_button="@drawable/slide_button"/>
RelativeLayout>

(3)找到相关控件，初始化信息

public ToggleView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();

        //获取配置的自定义属性
        String namespace = "http://schemas.android.com/apk/res/com.project.codingma.customedswitch";
        int switchBackgroundRescource = attrs.getAttributeResourceValue(namespace,"switch_background",-1);
        int slideButtonResource = attrs.getAttributeResourceValue(namespace,"slide_button",-1);
        mSwitchState = attrs.getAttributeBooleanValue(namespace,"switch_state",false);
        setSwitchBackgroundResource(switchBackgroundRescource);
        setSlideButtonResource(slideButtonResource);
    }

/**
     * 设置滑块图片
     * @param slideButtonResource 滑块背景图
     */
    private void setSlideButtonResource(int slideButtonResource) {
        slideButtonBitmap= BitmapFactory.decodeResource(getResources(),slideButtonResource);
    }

    /**
     * 设置背景图
     * @param switchBackgroundRescource 背景图资源
     */
    private void setSwitchBackgroundResource(int switchBackgroundRescource) {
        switchBackgroundBitmap = BitmapFactory.decodeResource(getResources(),switchBackgroundRescource);
    }

(4)测量自定义控件的大小

@Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        setMeasuredDimension(switchBackgroundBitmap.getWidth(),switchBackgroundBitmap.getHeight());
    }

(5)绘制图像

@Override
    protected void onDraw(Canvas canvas) {

        //绘制背景
        canvas.drawBitmap(switchBackgroundBitmap,0,0,paint);

        //绘制滑块
        if(isTouchMode){
            // 根据当前用户触摸到的位置画滑块

            // 让滑块向左移动自身一半大小的位置
            float newLeft = currentX - slideButtonBitmap.getWidth() / 2.0f;

            int maxLeft = switchBackgroundBitmap.getWidth() - slideButtonBitmap.getWidth();

            // 限定滑块范围
            if(newLeft < 0){
                newLeft = 0; // 左边范围
            }else if (newLeft > maxLeft) {
                newLeft = maxLeft; // 右边范围
            }

            canvas.drawBitmap(slideButtonBitmap, newLeft, 0, paint);
        }else {
            // 根据开关状态boolean, 直接设置图片位置
            if(mSwitchState){// 开
                int newLeft = switchBackgroundBitmap.getWidth() - slideButtonBitmap.getWidth();
                canvas.drawBitmap(slideButtonBitmap, newLeft, 0, paint);
            }else {// 关
                canvas.drawBitmap(slideButtonBitmap, 0, 0, paint);
            }
        }

(6)设置触摸事件

 @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()){
            case MotionEvent.ACTION_DOWN:
                isTouchMode=true;
                currentX=event.getX();
                break;
            case MotionEvent.ACTION_MOVE:
                currentX=event.getX();
                break;
            case MotionEvent.ACTION_UP:
                isTouchMode=false;
                currentX=event.getX();

                float center = switchBackgroundBitmap.getWidth()/2.0f;

                //当前的位置同中心位置比较，决定状态
                boolean state = currentX>center;
                mSwitchState = state;
                break;

            default:
                break;

        }
        invalidate();
        return true;

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源码地址:https://github.com/codingma/CustomizedSwitch