顾名思义，Android ScaleDrawable实现一个drawable的缩放。写一个例子。

一个线性布局，垂直放几个ImageView，然后依次缩放若干个ScaleDrawable。

布局文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="zhangphil.app.MainActivity">

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:id="@+id/imageView1" />

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:id="@+id/imageView2" />

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:id="@+id/imageView3" />

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:id="@+id/imageView4" />

</LinearLayout>

Java代码：

package zhangphil.app;

import android.graphics.Color;
import android.graphics.drawable.ColorDrawable;
import android.graphics.drawable.ScaleDrawable;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Gravity;
import android.widget.ImageView;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ColorDrawable drawable1=new ColorDrawable(Color.RED);
        drawable1.setLevel(1);
        ImageView image1= (ImageView) findViewById(R.id.imageView1);
        image1.setImageDrawable(drawable1);

        ColorDrawable drawable2=new ColorDrawable(Color.YELLOW);
        drawable2.setLevel(1);
        ScaleDrawable sd2 = new ScaleDrawable(drawable2, Gravity.LEFT,0.1f,0.0f);
        ImageView image2= (ImageView) findViewById(R.id.imageView2);
        image2.setImageDrawable(sd2);

        ColorDrawable drawable3=new ColorDrawable(Color.BLUE);
        drawable3.setLevel(1);
        ScaleDrawable sd3 = new ScaleDrawable(drawable3, Gravity.LEFT,0.2f,0.0f);
        ImageView image3= (ImageView) findViewById(R.id.imageView3);
        image3.setImageDrawable(sd3);

        ColorDrawable drawable4=new ColorDrawable(Color.GREEN);
        drawable4.setLevel(1);
        ScaleDrawable sd4 = new ScaleDrawable(drawable4, Gravity.LEFT,0.3f,0.0f);
        ImageView image4= (ImageView) findViewById(R.id.imageView4);
        image4.setImageDrawable(sd4);
    }
}

代码运行结果：

以上ScaleDrawable没有让drawable的高度缩放，只缩放宽度。

附录：
1，《Android ImageView的setImageLevel和level-list使用简介》链接：http://blog.csdn.net/zhangphil/article/details/48936209