Get bitmap color on touched position in ImageView

Last exercise demonstrate "How to detect touch event and position on ImageView". It's modified to get bitmap color on the touched position.

package com.example.androiddrawbitmap;

import java.io.FileNotFoundException;

import android.R.color;
import android.net.Uri;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnTouchListener;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

public class MainActivity extends Activity {
 
 Button btnLoadImage;
 TextView textSource, textInfo;
 ImageView imageResult;
 
 final int RQS_IMAGE1 = 1;

 Uri source;
 Bitmap bitmapMaster;
 Canvas canvasMaster;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
  
  btnLoadImage = (Button)findViewById(R.id.loadimage);
  textSource = (TextView)findViewById(R.id.sourceuri);
  imageResult = (ImageView)findViewById(R.id.result);
  
  btnLoadImage.setOnClickListener(new OnClickListener(){

   @Override
   public void onClick(View arg0) {
    Intent intent = new Intent(Intent.ACTION_PICK,
      android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);
    startActivityForResult(intent, RQS_IMAGE1);
   }});
  
  imageResult.setOnTouchListener(new OnTouchListener(){

   @Override
   public boolean onTouch(View v, MotionEvent event) {
    
    int action = event.getAction();
    int x = (int) event.getX();
    int y = (int) event.getY();
    switch(action){
    case MotionEvent.ACTION_DOWN:
     textSource.setText("ACTION_DOWN- " + x + " : " + y);
     textSource.setBackgroundColor(
       getProjectedColor((ImageView)v, bitmapMaster, x, y));
     break;
    case MotionEvent.ACTION_MOVE:
     textSource.setText("ACTION_MOVE- " + x + " : " + y);
     textSource.setBackgroundColor(
       getProjectedColor((ImageView)v, bitmapMaster, x, y));
     break;
    case MotionEvent.ACTION_UP:
     textSource.setText("ACTION_UP- " + x + " : " + y);
     textSource.setBackgroundColor(
       getProjectedColor((ImageView)v, bitmapMaster, x, y));
     break;
    }
    /*
     * Return 'true' to indicate that the event have been consumed.
     * If auto-generated 'false', your code can detect ACTION_DOWN only,
     * cannot detect ACTION_MOVE and ACTION_UP.
     */
    return true;
   }});
 }
 
 /*
  * Project position on ImageView to position on Bitmap
  * return the color on the position 
  */
 private int getProjectedColor(ImageView iv, Bitmap bm, int x, int y){
  if(x<0 || y<0 || x > iv.getWidth() || y > iv.getHeight()){
   //outside ImageView
   return color.background_light; 
  }else{
   int projectedX = (int)((double)x * ((double)bm.getWidth()/(double)iv.getWidth()));
   int projectedY = (int)((double)y * ((double)bm.getHeight()/(double)iv.getHeight()));

   textSource.setText(x + ":" + y + "/" + iv.getWidth() + " : " + iv.getHeight() + "\n" +
     projectedX + " : " + projectedY + "/" + bm.getWidth() + " : " + bm.getHeight()
     );
   
     return bm.getPixel(projectedX, projectedY);
  }
 }

 @Override
 protected void onActivityResult(int requestCode, int resultCode, Intent data) {
  super.onActivityResult(requestCode, resultCode, data);
  if(resultCode == RESULT_OK){
   switch (requestCode){
   case RQS_IMAGE1:
    source = data.getData();
    textSource.setText(source.toString());
    
    try {
     bitmapMaster = BitmapFactory.decodeStream(
       getContentResolver().openInputStream(source));
     imageResult.setImageBitmap(bitmapMaster);
    } catch (FileNotFoundException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }
    
    break;
   }
  }
 }

}

Modify android:scaleType and android:adjustViewBounds of ImageView in activity_main.xml. You can also try different setting to see how it affect the ImageView and Bitmap reloation.

<LinearLayout 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"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:autoLink="web"
        android:text="http://android-er.blogspot.com/"
        android:textStyle="bold" />

    <Button
        android:id="@+id/loadimage"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Load Image 1" />

    <TextView
        android:id="@+id/sourceuri"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <ImageView
        android:id="@+id/result"
        android:scaleType="centerInside"
        android:adjustViewBounds="true"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@android:color/background_dark" />

</LinearLayout>

Download the files.

Next: Detect touch and free draw on Bitmap

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more: Something about processing images in Android