Android實(shí)現(xiàn)拍照及圖片顯示效果

<uses-feature android:name="android.hardware.camera2"
    <!-- required為false時(shí)，不強(qiáng)制要求設(shè)備支持該功能 -->
    <!-- 如果不設(shè)置該值，一旦設(shè)備不支持camera，就不能安裝該應(yīng)用-->
    android:required="false"/>

public File getPhotoFile(Crime crime) {
  //獲取應(yīng)用對(duì)應(yīng)的存儲(chǔ)照片的外部存儲(chǔ)路徑
  File externalFilesDir = mContext
      .getExternalFilesDir(Environment.DIRECTORY_PICTURES);

  if (externalFilesDir == null) {
    return null;
  }

  //創(chuàng)建指向文件的File對(duì)象
  return new File(externalFilesDir, crime.getPhotoFilename());
}
.............
//每個(gè)crime對(duì)應(yīng)的文件名
public String getPhotoFilename() {
  return "IMG_" + getId().toString() + ".jpg";
}

mPhotoButton = (ImageButton) v.findViewById(R.id.crime_camera);

//隱式Intent觸發(fā)相機(jī)拍照
final Intent captureImageIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

//mPhotoFile保存著上文創(chuàng)建的指向指定地址的File
//此處判斷是否有能夠處理隱式Intent的組件
boolean canTakePhoto = mPhotoFile != null
    && captureImageIntent.resolveActivity(packageManager) != null;
mPhotoButton.setEnabled(canTakePhoto);

if (canTakePhoto) {
  //得到File文件對(duì)應(yīng)的Uri地址
  Uri uri = Uri.fromFile(mPhotoFile);

  //將Uri地址存入到Intent中，相機(jī)拍照得到的圖像將會(huì)存入到該Uri地址對(duì)應(yīng)的File里
  captureImageIntent.putExtra(MediaStore.EXTRA_OUTPUT, uri);
}

mPhotoButton.setOnClickListener(new View.OnClickListener() {
  @Override
  public void onClick(View v) {
    startActivityForResult(captureImageIntent, REQUEST_PHOTO);
  }
});

@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
  .........
  } else if (requestCode == REQUEST_PHOTO) {
    updatePhotoView();
  }
  .........
}

private void updatePhotoView() {
  if (mPhotoFile == null || !mPhotoFile.exists()) {
    mPhotoView.setImageDrawable(null);
  } else {
    //加載圖片對(duì)應(yīng)的縮略圖
    Bitmap bitmap = PictureUtils.getScaledBitmap(mPhotoFile.getPath(), getActivity());
    mPhotoView.setImageBitmap(bitmap);
  }
}

//在具體視圖未加載前，無(wú)法得到視圖的實(shí)際大小
//因此根據(jù)屏幕尺寸，使用估算值進(jìn)行縮放
public static Bitmap getScaledBitmap(String path, Activity activity) {
  Point size = new Point();
  activity.getWindowManager().getDefaultDisplay().getSize(size);

  return getScaledBitmap(path, size.x, size.y);
}

public static Bitmap getScaledBitmap(String path, int destWidth, int destHeight) {
  BitmapFactory.Options options = new BitmapFactory.Options();
  options.inJustDecodeBounds = true;

  //按照正常尺寸解析文件
  BitmapFactory.decodeFile(path, options);

  //得到原始文件的寬和高
  float srcWidth = options.outWidth;
  float srcHeight = options.outHeight;

  //inSampleSize表示水平/豎直抽樣比
  //例如，inSampleSize為2時(shí)，水平和數(shù)值均在原始基礎(chǔ)上，每2個(gè)點(diǎn)抽取1個(gè)點(diǎn)
  //于是，新圖的大小變?yōu)樵瓉?lái)的1/4
  int inSampleSize = 1;
  if (srcHeight > destHeight || srcWidth > destWidth) {
    if (srcWidth > srcHeight) {
      inSampleSize = Math.round(srcHeight / destHeight);
    } else {
      inSampleSize = Math.round(srcWidth / destWidth);
    }
   }

  options = new BitmapFactory.Options();
  options.inSampleSize = inSampleSize;

  //按新的抽樣比，重新解析文件
  return BitmapFactory.decodeFile(path, options);
}