Getting the Pixel Color of Image using a Button in Android?

问题

I'm still learning Android programming, and right now I'm writing an app to detect colors in a picture uploaded from the gallery. So far, using a tutorial, the app can upload a picture from the gallery into imageview, but I'm not sure how to get the second part working. I want the user to be able to simply press a button and display the color of the image (right now I'm using single color images). How would I go about doing this? Here's my source code so far:

package com.example.testrunvday;

import com.example.testrunvday.R;
import android.app.Activity;
import android.content.Intent;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;

public class MainActivity extends Activity {

    int test = 0; //will give 1 if red is detected, 0 if not

    private static final int SELECT_PICTURE = 1;

    private String selectedImagePath;
    private ImageView img;
    private Button pixel;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        img = (ImageView)findViewById(R.id.ImageView01);

        ((Button) findViewById(R.id.Button01))
                .setOnClickListener(new OnClickListener() {
                    public void onClick(View arg0) {
                        Intent intent = new Intent();
                        intent.setType("image/*");
                        intent.setAction(Intent.ACTION_GET_CONTENT);
                        startActivityForResult(Intent.createChooser(intent,"Select Picture"), SELECT_PICTURE);
                    }
                });

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


            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub


                //so far everything I've written here hasn't worked)



            }







        });
    }

    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (resultCode == RESULT_OK) {
            if (requestCode == SELECT_PICTURE) {
                Uri selectedImageUri = data.getData();
                selectedImagePath = getPath(selectedImageUri);
                System.out.println("Image Path : " + selectedImagePath);
                img.setImageURI(selectedImageUri);
            }
        }
    }

    public String getPath(Uri uri) {
        String[] projection = { MediaStore.Images.Media.DATA };
        Cursor cursor = managedQuery(uri, projection, null, null, null);
        int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA);
        cursor.moveToFirst();
        return cursor.getString(column_index);
    }
}

XML:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
<TextView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"

    />

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="TextView" />

<Button
    android:id="@+id/pixel"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="pixel" />

<Button
    android:id="@+id/Button01"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Browse gallery" />

<ImageView android:id="@+id/ImageView01"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content">
</ImageView>
</LinearLayout>

回答1:

get imageview's bitmap:

Bitmap bitmap = ((BitmapDrawable)image.getDrawable()).getBitmap();

get color of pixel at location:

int pixel = bitmap.getPixel(x,y);

split in RGB:

int redValue = Color.red(pixel);
int blueValue = Color.blue(pixel);
int greenValue = Color.green(pixel);

there you have your color for a specific pixel.

回答2:

ImageView imageView = (ImageView)findViewById(R.id.ImageView01);
Bitmap bitmapImageView = ((BitmapDrawable)imageView.getDrawable()).getBitmap();
int pixel = bitmapImageView.getPixel(x,y);

来源：https://stackoverflow.com/questions/21779371/getting-the-pixel-color-of-image-using-a-button-in-android