Android 图片缩放实例详解

<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=".mainactivity" >

  <imageview
    android:id="@+id/iv_1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    />

  <imageview
    android:id="@+id/iv_2"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
     />

</linearlayout>

public class mainactivity extends activity {

  private imageview iv1;
  private imageview iv2;

  @override
  protected void oncreate(bundle savedinstancestate) {
    super.oncreate(savedinstancestate);
    setcontentview(r.layout.activity_main);

    iv1 = (imageview) findviewbyid(r.id.iv_1);
    iv2 = (imageview) findviewbyid(r.id.iv_2);

    // 设置第一个bitmap的图标
    bitmap bitmap1 = bitmapfactory.decoderesource(getresources(),
        r.drawable.ic_launcher);

    iv1.setimagebitmap(bitmap1);

    // 新建一个bitmap
    bitmap alterbitmap = bitmap.createbitmap(bitmap1.getwidth(),
        bitmap1.getheight(), bitmap1.getconfig());

    // 以alterbitmap为模板新建画布
    canvas canvas = new canvas(alterbitmap);
    // 新建画笔并设置属性
    paint paint = new paint();
    paint.setcolor(color.black);
    
    //新建矩阵并设置缩放值
    matrix matrix = new matrix();
    matrix.setvalues(new float[] { 
        0.5f, 0, 0, 
        0, 1, 0, 
        0, 0, 1 
    });
    //设置画布
    canvas.drawbitmap(bitmap1, matrix, paint);
    iv2.setimagebitmap(alterbitmap);
  }

}