问题描述

如何调整gallery中的图像大小？

第一个文件允许用户从gallery中选择一个图片，然后把图片传到一个activity中处理。问题是图像相对于手机屏幕来说太大了，所以只能看见图像的左上角，就像图像是被放大的。

Button useGallery = (Button)findViewById(R.id.loadfromgallery);
        useGallery.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {

                Intent photoPickerIntent = new Intent(Intent.ACTION_PICK);
                photoPickerIntent.setType("image/*");
                startActivityForResult(photoPickerIntent, SELECT_PHOTO);
            }}) ;

 @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent imageReturnedIntent) {
        super.onActivityResult(requestCode, resultCode, imageReturnedIntent); 

        switch(requestCode) {
        case SELECT_PHOTO:
            if(resultCode == RESULT_OK){
                Uri selectedImage = imageReturnedIntent.getData();
                InputStream imageStream = null;
                try {
                    imageStream = getContentResolver().openInputStream(selectedImage);
                } catch (FileNotFoundException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                Bitmap yourSelectedImage = BitmapFactory.decodeStream(imageStream);
                Intent intent = new Intent(mContext, DisplayUndistortedBitmapFromGalleryActivity.class);
                intent.setData(selectedImage);
                startActivity(intent);

                if(yourSelectedImage != null){
                Log.e(TAG,"pic ok");
                }else{
                     Log.e(TAG,"pic not ok");
                }
            }
        }

第二个文件是activity，从intent中接收到图片图像数据，然后把它放置在一个包含bitmap的URI中。

public class DisplayUndistortedBitmapFromGalleryActivity extends Activity {

    private static final String TAG = "*********DUBFGActivity";
    private Context mContext = this;
    Uri uri;
    private Bitmap mbitmap = null;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                WindowManager.LayoutParams.FLAG_FULLSCREEN);

         uri = getIntent().getData();
        if(uri != null){
            Log.e(TAG, "uri ok");
        }else {
            Log.e(TAG, "uri not ok");
        }

        try {
              mbitmap = Media.getBitmap(getContentResolver(), uri);
             //setMbitmap(bitmap);
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

第三个文件是activity的customview。下面这一行从activity中检索出bitmap并显示它。是否有精简bitmap的方法，让它符合屏幕的大小？

Bitmap bm = ((DisplayUndistortedBitmapFromGalleryActivity)getContext()).getMbitmap();

解决方案

我用过的一个最简单的方法：

public class bitmaptest extends Activity {
@Override
public void onCreate(Bundle icicle) {
    super.onCreate(icicle);
    LinearLayout linLayout = new LinearLayout(this);

    // load the origial BitMap (500 x 500 px)
    Bitmap bitmapOrg = BitmapFactory.decodeResource(getResources(),
           R.drawable.android);

    int width = bitmapOrg.width();
    int height = bitmapOrg.height();
    int newWidth = 200;
    int newHeight = 200;

    // calculate the scale - in this case = 0.4f
    float scaleWidth = ((float) newWidth) / width;
    float scaleHeight = ((float) newHeight) / height;

    // createa matrix for the manipulation
    Matrix matrix = new Matrix();
    // resize the bit map
    matrix.postScale(scaleWidth, scaleHeight);
    // rotate the Bitmap

    // recreate the new Bitmap
    Bitmap resizedBitmap = Bitmap.createBitmap(bitmapOrg, 0, 0,
                      width, height, matrix, true);

    // make a Drawable from Bitmap to allow to set the BitMap
    // to the ImageView, ImageButton or what ever
    BitmapDrawable bmd = new BitmapDrawable