Android(安卓)API之ImageView.ScaleType代码演示

原文地址：AndroidAPI之ImageView.ScaleType代码演示 作者：易智

为了全面演示ImageView.ScaleType的八种类型即CENTER，CENTER_CROP，CENTER_INSIDE，FIT_CENTER，FIT_START，FIT_END，FIT_XY，MATRIX，我在这里通过一个GridView进行显示，可通过点击每一种类型的ImageButton进行详细查看、比较。

背景图片为一个像素宽度（443px）×高度（500px），大于默认的Android模拟器320×480，这样可以清晰的看出ImageView是否做了比例缩放，及所处位置的差异。

（1）AndroidManifest.xml添加各种ScaleType的Activity

（2）res/layout/main.xmlGridView主视图布局

<GridView

android:id="@+id/gridView"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:numColumns="auto_fit"

android:verticalSpacing="10dp"

android:horizontalSpacing="10dp"

android:columnWidth="90dp"

android:stretchMode="columnWidth"

android:gravity="center"

（3）res/layout/image.xml ScaleType视图布局

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:orientation="vertical"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

<ImageView

android:id="@+id/imageView1"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

</LinearLayout>

（4）ImageAdapter.java 继承BaseAdapter，并载入GridView的图片资源

public class ImageAdapter extends BaseAdapter

{

// 定义Context

private ContextmContext;

// 定义整型数组即图片资源

private Integer[] mImageIds =

{

R.drawable.center,

R.drawable.centercrop,

R.drawable.centerinside,

R.drawable.fitcenter,

R.drawable.fitstart,

R.drawable.fitend,

R.drawable.fitxy,

R.drawable.matrix,

};

public ImageAdapter(Context c)

{

mContext = c;

}

// 获取图片的个数

public int getCount()

{

return mImageIds.length;

}

// 获取图片在库中的位置

public Object getItem(int position)

{

return position;

}

// 获取图片ID

public long getItemId(int position)

{

return position;

}

public View getView(int position, View convertView, ViewGroupparent)

{

ImageView imageView;

if(convertView ==null)

{

// 给ImageView设置资源

imageView = new ImageView(mContext);

// 设置布局图片显示

imageView.setLayoutParams(new GridView.LayoutParams(85,85));

// 设置显示比例类型

imageView.setScaleType(ImageView.ScaleType.FIT_CENTER);

}

else

{

imageView = (ImageView) convertView;

}

imageView.setImageResource(mImageIds[position]);

return imageView;

}

（5）MainActivity.java GridView主视图类

public class MainActivity extends Activity {

private GridView gridView;

@Override

public void onCreate(Bundle savedInstanceState){

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

gridView=(GridView)findViewById(R.id.gridView);

gridView.setAdapter(newImageAdapter(this));

gridView.setBackgroundResource(R.drawable.image);

gridView.setOnItemClickListener(new AdapterView.OnItemClickListener(){

@Override

public void onItemClick(AdapterView<?>arg0, View arg1, int arg2,

long arg3) {

// TODO Auto-generated method stub

Intent intent=new Intent();

switch(arg2){

//GridView第一个ID，对应CENTER

case 0:

intent.setClass(MainActivity.this,ImageViewScaleTypeDemo1.class);

startActivity(intent);

MainActivity.this.finish();

break;

//GridView第二个ID，对应CENTER_CROP

case 1:

intent.setClass(MainActivity.this,ImageViewScaleTypeDemo2.class);

startActivity(intent);

MainActivity.this.finish();

break;

case 2:

intent.setClass(MainActivity.this,ImageViewScaleTypeDemo3.class);

startActivity(intent);

MainActivity.this.finish();

break;

case 3:

intent.setClass(MainActivity.this,ImageViewScaleTypeDemo4.class);

startActivity(intent);

MainActivity.this.finish();

break;

case 4:

intent.setClass(MainActivity.this,ImageViewScaleTypeDemo5.class);

startActivity(intent);

MainActivity.this.finish();

break;

case 5:

intent.setClass(MainActivity.this,ImageViewScaleTypeDemo6.class);

startActivity(intent);

MainActivity.this.finish();

break;

case 6:

intent.setClass(MainActivity.this,ImageViewScaleTypeDemo7.class);

startActivity(intent);

MainActivity.this.finish();

break;

case 7:

intent.setClass(MainActivity.this,ImageViewScaleTypeDemo8.class);

startActivity(intent);

MainActivity.this.finish();

break;

}

});

}

（6）ImageViewScaleTypeDemo1.java显示imageView1显示类型为CENTER，其它ImageViewScaleTypeDemo2-8分别为CENTER_CROP，CENTER_INSIDE，FIT_CENTER，FIT_START，FIT_END，FIT_XY，MATRIX，此处略去代码

public class ImageViewScaleTypeDemo1extends Activity {

private ImageView imageView1;

@Override

public void onCreate(Bundle savedInstanceState){

super.onCreate(savedInstanceState);

setContentView(R.layout.image);

//显示imageView1

imageView1=(ImageView)findViewById(R.id.imageView1);

//设置imageView1背景资源

imageView1.setImageResource(R.drawable.image);

//设置imageView1显示类型为CENTER

imageView1.setScaleType(ImageView.ScaleType.CENTER);

}

@Override

public boolean onKeyDown(int keyCode, KeyEvent event) {

// TODO Auto-generated method stub

//响应返回按键，退出到主界面

if(keyCode==KeyEvent.KEYCODE_BACK){

Intent intent=new Intent();

intent.setClass(ImageViewScaleTypeDemo1.this, MainActivity.class);

startActivity(intent);

ImageViewScaleTypeDemo1.this.finish();

}

return super.onKeyDown(keyCode,event);

}

(7) 效果截图：

主界面：