Android自定义Rating Bar

Android自定义Rating Bar

一、效果图

二、代码实现

package com.example.layoutdemo.widget;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;

import androidx.annotation.Nullable;

import com.example.layoutdemo.R;


public class RatingBar extends View {
    private Bitmap mNormalStar;
    private Bitmap mSelectedStar;
    private int mCurrentStep = 0;
    private static final int NUM = 5;
    public RatingBar(Context context) {
        this(context,null);
    }

    public RatingBar(Context context, @Nullable AttributeSet attrs) {
        this(context,attrs,0);
    }

    public RatingBar(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        mNormalStar = BitmapFactory.decodeResource(context.getResources(), R.mipmap.star_normal);
        mSelectedStar = BitmapFactory.decodeResource(context.getResources(),R.mipmap.star_selected);
    }

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

    @Override
    protected void onDraw(Canvas canvas) {
       for (int i = 0;i <= NUM;i++) {
           if (mCurrentStep > i) {
               canvas.drawBitmap(mSelectedStar,i * mSelectedStar.getWidth(),0,null);
           } else {
               canvas.drawBitmap(mNormalStar,i * mNormalStar.getWidth(),0,null);
           }

       }
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                Log.d("TAG","MotionEvent.ACTION_DOWN");
            case MotionEvent.ACTION_MOVE:
                int currentStep  = (int)(event.getX()/mNormalStar.getWidth() + 1);
                Log.d("TAG","currentStep:" + currentStep);
                if (currentStep < 0) {
                    mCurrentStep = 0;
                }
                if (currentStep >NUM) {
                    mCurrentStep = NUM;
                }
                if (currentStep == mCurrentStep) {
                    return true;
                }
                mCurrentStep = currentStep;
                invalidate();
                break;
            case MotionEvent.ACTION_UP:
                Log.d("TAG","MotionEvent.ACTION_UP");
                break;
        }
        return true;
    }
}

三、使用控件

<com.example.layoutdemo.widget.RatingBar
        android:layout_marginStart="20dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

四、源码下载地址

Android自定义View