Android-从相册中选择图片显示出来

来源：互联网发布：旋转秋千知乎编辑：程序博客网时间：2024/06/05 11:24

一、选择图片

定义Intent跳转到特定图库的Uri下挑选，然后将挑选结果返回给Activity

用到startActivityForResult

Intent intent = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);startActivityForResult(intent, RESULT);

然后在onActivityForResult保存

二、图片缩放

这里讲的很详细

http://blog.csdn.net/lincyang/article/details/6651582

照它所说有3种方法：

第一种是BitmapFactory和BitmapFactory.Options，同比例缩放，但是效率高

第二种是使用Bitmap加Matrix来缩放，能够不同比例，但是效率低

第三种是用2.2新加的类ThumbnailUtils来做，这方法不懂，好复杂。。

我用第一种，将图片放在Imageview中

  private void showPhoto(ImageView photo){        String picturePath = target.getInfo(Target.TargetPhotoPath);// 图片的uri        if(picturePath.equals(""))            return;        // 缩放图片, width, height 按相同比例缩放图片        BitmapFactory.Options options = new BitmapFactory.Options();        // options 设为true时，构造出的bitmap没有图片，只有一些长宽等配置信息，但比较快，设为false时，才有图片        options.inJustDecodeBounds = true;        Bitmap bitmap = BitmapFactory.decodeFile(picturePath, options);        int scale = (int)( options.outWidth / (float)300);        if(scale <= 0)            scale = 1;        options.inSampleSize = scale;        options.inJustDecodeBounds = false;        bitmap = BitmapFactory.decodeFile(picturePath, options);        photo.setImageBitmap(bitmap);        photo.setMaxHeight(350);    }

三、代码

public class RemindActivity extends Activity {    private ImageView photo;    private static final int RESULT = 1;    Target target;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_remind);        photo = (ImageView)findViewById(R.id.photo);        target = new Target(this);        showPhoto(photo);        photo.setOnClickListener(new OnClickListener(){            @Override            public void onClick(View arg0) {                // TODO Auto-generated method stub                Dialog dialog = new AlertDialog.Builder(RemindActivity.this)                .setTitle("从图库里选择照片").setMessage("确定要更换照片？").setPositiveButton("确定",                         new DialogInterface.OnClickListener() {                            @Override                            public void onClick(DialogInterface dialog, int which) {                                // TODO Auto-generated method stub                                Intent intent = new Intent(Intent.ACTION_PICK, android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);                                startActivityForResult(intent, RESULT);                            }                        }).setNegativeButton("取消", new DialogInterface.OnClickListener() {                            @Override                            public void onClick(DialogInterface dialog, int which) {                                // TODO Auto-generated method stub                                dialog.cancel();                            }                        }).create();                dialog.show();            }        });    }    @Override    protected void onActivityResult(int requestCode, int resultCode, Intent data) {        // TODO Auto-generated method stub        super.onActivityResult(requestCode, resultCode, data);        if(requestCode == RESULT && resultCode == RESULT_OK && data != null){            Uri selectedImage = data.getData();            String[] filePathColumn = { MediaStore.Images.Media.DATA };            Cursor cursor = getContentResolver().query(selectedImage,                    filePathColumn, null, null, null);            cursor.moveToFirst();            int columnIndex = cursor.getColumnIndex(filePathColumn[0]);            String picturePath = cursor.getString(columnIndex);            cursor.close();            target.setInfo(Target.TargetPhotoPath, picturePath);            showPhoto(photo);        }    }    private void showPhoto(ImageView photo){        String picturePath = target.getInfo(Target.TargetPhotoPath);        if(picturePath.equals(""))            return;        // 缩放图片, width, height 按相同比例缩放图片        BitmapFactory.Options options = new BitmapFactory.Options();        // options 设为true时，构造出的bitmap没有图片，只有一些长宽等配置信息，但比较快，设为false时，才有图片        options.inJustDecodeBounds = true;        Bitmap bitmap = BitmapFactory.decodeFile(picturePath, options);        int scale = (int)( options.outWidth / (float)300);        if(scale <= 0)            scale = 1;        options.inSampleSize = scale;        options.inJustDecodeBounds = false;        bitmap = BitmapFactory.decodeFile(picturePath, options);        photo.setImageBitmap(bitmap);        photo.setMaxHeight(350);    }}

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