MyRatingBar

 解决官方RatingBar无法自由调整宽高的问题
 可选则适应宽度或者高度

 我的简书  

   

##只设置了常用的几个属性  
base_of_width_or_height 以宽度为准或已高度为准
step 滑动间距
rating 当前星值
stars 星星总数

<declare-styleable name="MyRatingBar">
    <attr name="base_of_width_or_height" format="enum">
        <enum name="width" value="0"/>
        <enum name="height" value="1"/>
    </attr>
    <attr name="step" format="float"/>
    <attr name="rating" format="float"/>
    <attr name="stars" format="integer"/>
</declare-styleable>

   根布局添加 xmlns:app="http://schemas.android.com/apk/res-auto"

<com.zjd.myratingbar.MyRatingBar
    app:base_of_width_or_height="width"
    app:stars="15"
    app:step="1"
    app:rating="10"
    android:layout_gravity="center"
    android:layout_width="300dp"
    android:layout_height="30dp" />

核心部分 (根据手指在X轴的滑动画Bitmap)

private void drawStars(Canvas canvas) {
    Bitmap bitmap=((BitmapDrawable)getResources().getDrawable(R.drawable.icon_star_yellow_128)).getBitmap();
    stepWidth=step*starWidth;
    int stepNum=(int)(currentX/stepWidth);
    rating=round((double)stepNum*step,2);
    for (int i = 0; i < stepNum*stepWidth/starWidth; i++) {
        int leftX=starWidth*i;
        int rightX=starWidth*(i+1);
        int x=(int)(stepNum*stepWidth-starWidth*i);
        if(currentX>leftX&&currentX<rightX){
            canvas.drawBitmap(bitmap,new Rect(0,0,bitmap.getWidth()*x/starWidth,bitmap.getHeight()),new Rect(leftX,0,x+i*starWidth,starWidth),paint);
        }else{
            if(stepNum*stepWidth/starWidth<i+1){
                canvas.drawBitmap(bitmap,new Rect(0,0,bitmap.getWidth()*x/starWidth,bitmap.getHeight()),new Rect(leftX,0,x+i*starWidth,starWidth),paint);
            }else {
                canvas.drawBitmap(bitmap,new Rect(0,0,bitmap.getWidth(),bitmap.getHeight()),new Rect(leftX,0,rightX,starWidth),paint);
            }
        }
    }
}