Android之从SD卡加载大图片

来源：互联网发布：大英百科全书数据库编辑：程序博客网时间：2024/05/17 23:34

和加载小图片一样，首先要让图片存放于Genymotion的SD卡，上篇已经讲了怎么放了，可以看下上篇，这里就不在说了。。

加载大图片比小图片要复杂一点，要获取屏幕的宽高和图片的宽高，而且大图片放的更清晰了。

代码如下：

布局和上篇的一样

MainActivity：

public class MainActivity extends Activity {/* * 从SD卡里加载图片 */private ImageView iv;public void loadImage(View view) {// TODO Auto-generated method stubif (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {//路径String path=Environment.getExternalStorageDirectory()+"/img_big_1.jpg";//获取屏幕的宽，高WindowManager windowManager=(WindowManager) getSystemService(WINDOW_SERVICE);//int screenWidth=windowManager.getDefaultDisplay().getWidth();//int screenHeight=windowManager.getDefaultDisplay().getHeight();//过时了Display display=windowManager.getDefaultDisplay();Point point=new Point();display.getSize(point);int screenWidth=point.x;int screenHeight=point.y;System.out.println(screenWidth);System.out.println(screenHeight);//获取原图的宽高try {ExifInterface exifInterface=new ExifInterface(path);int imageWidth=exifInterface.getAttributeInt(ExifInterface.TAG_IMAGE_WIDTH, 0);int imageHeight=exifInterface.getAttributeInt(ExifInterface.TAG_IMAGE_LENGTH, 0);int sampleWidth=(int)(imageWidth*1.0f/screenWidth+0.5f);//加0.5就是为了四舍五入int sampleHeight=(int)(imageHeight*1.0f/screenHeight+0.5f);int sample=(int)(Math.sqrt(sampleWidth*sampleWidth+sampleHeight*sampleHeight)+0.5f);Options options=new Options();//设置图片的采样率//options.inSampleSize=4;//原宽*1/4   原高*1/4 options.inSampleSize=sample;//Bitmap bitmap=BitmapFactory.decodeFile(path);//iv.setImageBitmap(bitmap);Bitmap bitmap=BitmapFactory.decodeFile(path,options);iv.setImageBitmap(bitmap);} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);iv=(ImageView) findViewById(R.id.iv);}}

权限：

<uses-permission android:name="android.permission.MEDIA_CONTENT_CONTROL"/>    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

效果图：

要源码的点这儿

0 0