我想将ImageView的图像更改为黑白。唯一的事情是我的代码允许用户拍摄照片，该照片被放置在imageview中。我希望那张照片是黑白的。如果有人知道我该怎么做，我将不胜感激。
主要 Activity :
package com.example.triptych4;
import java.io.File;
import android.app.Activity;
import android.content.ContentResolver;
import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.Gallery;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.Toast;
public class MainActivity extends Activity {
// label our logs "CameraApp3"
private static String logtag = "CameraApp3";
// tells us which camera to take a picture from
private static int TAKE_PICTURE = 1;
// empty variable to hold our image Uri once we store it
private Uri imageUri;
private Integer[] pics = { R.drawable.android, R.drawable.android3d,
R.drawable.background3 };
private ImageView imageView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Gallery gallery = (Gallery) findViewById(R.id.gallery1);
gallery.setAdapter(new ImageAdapter(this));
imageView = (ImageView) findViewById(R.id.imageView1);
gallery.setOnItemClickListener( new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
Toast.makeText(getApplicationContext(), "pic:" + arg2,
Toast.LENGTH_SHORT).show();
imageView.setImageResource(pics[arg2]);
}
});
// look for the button we set in the view
ImageButton cameraButton = (ImageButton)
findViewById(R.id.button_camera);
// set a listener on the button
cameraButton.setOnClickListener(cameraListener);
}
// set a new listener
private OnClickListener cameraListener = new OnClickListener() {
public void onClick(View v) {
// open the camera and pass in the current view
takePhoto(v);
}
};
public void takePhoto(View v) {
// tell the phone we want to use the camera
Intent intent = new Intent("android.media.action.IMAGE_CAPTURE");
// create a new temp file called pic.jpg in the "pictures" storage area of the phone
File photo = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), "pic.jpg");
// take the return data and store it in the temp file "pic.jpg"
intent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(photo));
// stor the temp photo uri so we can find it later
imageUri = Uri.fromFile(photo);
// start the camera
startActivityForResult(intent, TAKE_PICTURE);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
public class ImageAdapter extends BaseAdapter{
private Context context;
int imageBackground;
public ImageAdapter(Context context){
this.context = context;
}
@Override
public int getCount() {
// TODO Auto-generated method stub
return pics.length;
}
@Override
public Object getItem(int arg0) {
// TODO Auto-generated method stub
return arg0;
}
@Override
public long getItemId(int arg0) {
// TODO Auto-generated method stub
return arg0;
}
@Override
public View getView(int arg0, View arg1, ViewGroup arg2) {
// TODO Auto-generated method stub
ImageView imageView =new ImageView(context);
imageView.setImageResource(pics[arg0]);
return imageView;
}
}
// override the original activity result function
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
// call the parent
super.onActivityResult(requestCode, resultCode, data);
switch(requestCode) {
// if the requestCode was equal to our camera code (1) then...
case 1:
// if the user took a photo and selected the photo to use
if(resultCode == Activity.RESULT_OK) {
// get the image uri from earlier
Uri selectedImage = imageUri;
// notify any apps of any changes we make
getContentResolver().notifyChange(selectedImage, null);
// get the imageView we set in our view earlier
ImageButton imageButton = (ImageButton)findViewById(R.id.button_camera);
// create a content resolver object which will allow us to access the image file at the uri above
ContentResolver cr = getContentResolver();
// create an empty bitmap object
Bitmap bitmap;
try {
// get the bitmap from the image uri using the content resolver api to get the image
bitmap = android.provider.MediaStore.Images.Media.getBitmap(cr, selectedImage);
// set the bitmap to the image view
imageButton.setImageBitmap(bitmap);
// notify the user
Toast.makeText(MainActivity.this, selectedImage.toString(), Toast.LENGTH_LONG).show();
} catch(Exception e) {
// notify the user
Toast.makeText(MainActivity.this, "failed to load", Toast.LENGTH_LONG).show();
Log.e(logtag, e.toString());
}
}
}
}
}
布局:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.triptych5.MainActivity" >
<ImageView
android:id="@+id/imageView1"
android:layout_width="200dp"
android:layout_height="200dp"
android:scaleType="fitXY"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_alignParentRight="true"
android:layout_alignTop="@+id/button_camera"/>
<ImageButton
android:id="@+id/button_camera"
android:layout_width="230dp"
android:layout_height="235dp"
android:scaleType="fitXY"
android:rotation="-90"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:background="@drawable/middle4" />
<Gallery
android:id="@+id/gallery1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_above="@+id/imageView1"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true" />
</RelativeLayout>
最佳答案
您可以通过执行以下操作简单地实现此目的:
ImageView imageview = (ImageView) findViewById(R.id.imageView1);
ColorMatrix matrix = new ColorMatrix();
matrix.setSaturation(0);
ColorMatrixColorFilter filter = new ColorMatrixColorFilter(matrix);
imageview.setColorFilter(filter);