Android 自定义简单控件--星级评价

效果图

实现

package com.easypass.carstong.view;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.support.annotation.AttrRes;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.util.AttributeSet;
import android.view.View;

import com.easypass.carstong.R;

/**
* Created by huangbo on 2017/8/1.
*/

public class ViewStar extends View {
public static final int MAX_STAR = 5;

public ViewStar(@NonNull Context context) {
this(context, null);
}

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

public ViewStar(@NonNull Context context, @Nullable AttributeSet attrs, @AttrRes int defStyleAttr) {
super(context, attrs, defStyleAttr);
TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.StarView);
mRating = typedArray.getFloat(R.styleable.StarView_rating, 0);
typedArray.recycle();
init();
}

Paint paint;
Bitmap starYellow;
Bitmap starGray;
float mRating;
int starWidth;
int starHeight;
int gap;

private void init() {
paint = new Paint();
starYellow = BitmapFactory.decodeResource(getResources(), R.mipmap.rating_star_yellow);
starGray = BitmapFactory.decodeResource(getResources(), R.mipmap.rating_star);
starWidth = starYellow.getWidth();
starHeight = starYellow.getHeight();
gap = 5;
invalidate();
}

public void setRating(float rating) {
this.mRating = rating;
invalidate();
}

public void setGrayStar(int resId, int alpha) {
starGray = BitmapFactory.decodeResource(getResources(), resId);
invalidate();
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int widthMode = MeasureSpec.getMode(widthMeasureSpec);
int widthSize = MeasureSpec.getSize(widthMeasureSpec);
int heightMode = MeasureSpec.getMode(heightMeasureSpec);
int heightSize = MeasureSpec.getSize(heightMeasureSpec);
int width = (getPaddingLeft() + (starWidth + gap) * MAX_STAR + getPaddingRight());
int height = (getPaddingTop() + starHeight + getPaddingBottom());
setMeasuredDimension(widthMode == MeasureSpec.EXACTLY ? widthSize : width,
heightMode == MeasureSpec.EXACTLY ? heightSize : height);

}

@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
float currentRating = mRating < 0 ? 0 : (mRating > MAX_STAR ? MAX_STAR : mRating);
int mLeft = 0;
int mTop = 0;
int full = (int) currentRating;/*整个星星的数量*/
/**
* 画黄色的整颗星
*/
for (int i = 0; i < full; i++) {
canvas.drawBitmap(starYellow, mLeft, mTop, paint);
mLeft = mLeft + starWidth + gap;
}

if (currentRating == MAX_STAR) {
return;
}
/**
* 画灰色的整颗星
*/
for (int i = full; i < MAX_STAR; i++) {
canvas.drawBitmap(starGray, mLeft, mTop, paint);
mLeft = mLeft + starWidth + gap;
}

/**
* 画小数点部分的星
*/
float part = mRating - full;
if (part > 0) {
int w = (int) (part * starWidth);
Bitmap partBitmap = Bitmap.createBitmap(starYellow, 0, 0, w, starYellow.getHeight());
canvas.drawBitmap(partBitmap, full * (starWidth + gap), mTop, paint);
}

}
}

使用方法

<your.package.name.ViewStar
android:layout_width="wrap_content"
app:rating="2.5"
android:layout_height="wrap_content"/>

ViewStar star=new ViewStar(this);
star.setRating(1.5);