我想将imageview更改为黑白，而不是drawable。这样做的原因是因为用户拍照并在图像视图中显示如果你知道如何做到这一点，我很感激，谢谢。
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.graphics.Color;
import android.graphics.ColorMatrix;
import android.graphics.ColorMatrixColorFilter;
import android.graphics.drawable.Drawable;
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 };
{
ImageView imageView = (ImageView)findViewById(R.id.imageView1);
ColorMatrix matrix = new ColorMatrix();
matrix.setSaturation(0);
ColorMatrixColorFilter filter = new ColorMatrixColorFilter(matrix);
imageView.setColorFilter(filter);
}
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());
}
}
}
}
}
logcat的：
05-22 10:26:07.156: D/AndroidRuntime(24617): Shutting down VM
05-22 10:26:07.156: W/dalvikvm(24617): threadid=1: thread exiting with uncaught exception (group=0x41cac700)
05-22 10:26:07.156: E/AndroidRuntime(24617): FATAL EXCEPTION: main
05-22 10:26:07.156: E/AndroidRuntime(24617): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.triptych4/com.example.triptych4.MainActivity}: java.lang.NullPointerException
05-22 10:26:07.156: E/AndroidRuntime(24617): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2219)
05-22 10:26:07.156: E/AndroidRuntime(24617): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2349)
05-22 10:26:07.156: E/AndroidRuntime(24617): at android.app.ActivityThread.access$700(ActivityThread.java:159)
05-22 10:26:07.156: E/AndroidRuntime(24617): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1316)
05-22 10:26:07.156: E/AndroidRuntime(24617): at android.os.Handler.dispatchMessage(Handler.java:99)
05-22 10:26:07.156: E/AndroidRuntime(24617): at android.os.Looper.loop(Looper.java:137)
05-22 10:26:07.156: E/AndroidRuntime(24617): at android.app.ActivityThread.main(ActivityThread.java:5419)
05-22 10:26:07.156: E/AndroidRuntime(24617): at java.lang.reflect.Method.invokeNative(Native Method)
05-22 10:26:07.156: E/AndroidRuntime(24617): at java.lang.reflect.Method.invoke(Method.java:525)
05-22 10:26:07.156: E/AndroidRuntime(24617): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1209)
05-22 10:26:07.156: E/AndroidRuntime(24617): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1025)
05-22 10:26:07.156: E/AndroidRuntime(24617): at dalvik.system.NativeStart.main(Native Method)
05-22 10:26:07.156: E/AndroidRuntime(24617): Caused by: java.lang.NullPointerException
05-22 10:26:07.156: E/AndroidRuntime(24617): at android.app.Activity.findViewById(Activity.java:1914)
05-22 10:26:07.156: E/AndroidRuntime(24617): at com.example.triptych4.MainActivity.<init>(MainActivity.java:47)
05-22 10:26:07.156: E/AndroidRuntime(24617): at java.lang.Class.newInstanceImpl(Native Method)
05-22 10:26:07.156: E/AndroidRuntime(24617): at java.lang.Class.newInstance(Class.java:1130)
05-22 10:26:07.156: E/AndroidRuntime(24617): at android.app.Instrumentation.newActivity(Instrumentation.java:1078)
05-22 10:26:07.156: E/AndroidRuntime(24617): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2210)
05-22 10:26:07.156: E/AndroidRuntime(24617): ... 11 more
答案 0 :(得分：8)
您可以使用ColorMatrix并将饱和度设置为零，从而转动
你的形象变成黑白。然后，您使用ColorMatrix作为过滤器
为您的imageView。
ImageView imageView = (ImageView)findViewById(R.id.imageView);
...
ColorMatrix matrix = new ColorMatrix();
matrix.setSaturation(0);
ColorMatrixColorFilter filter = new ColorMatrixColorFilter(matrix);
imageView.setColorFilter(filter);