Question

I have a code that get the coordinate of image view, and i want to draw a line when the user touch 2 times in the imageview. The imageview has a bitmap from drawable. for more detail this is my code :

public class MainActivity extends Activity implements OnTouchListener {
   ImageView tampil;
   Matrix matrix = new Matrix();
   Matrix savedMatrix = new Matrix();
   private static final String TAG = "Touch";
   static final int NONE = 0;
   static final int DRAG = 1;
   static final int ZOOM = 2;
   int mode = NONE;

   // Remember some things for zooming
   PointF start = new PointF();
   PointF mid = new PointF();
   float oldDist = 1f;
   float x1, y1, x2, y2;
   Bitmap bmp;
   int i = 1;



@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    tampil = (ImageView)findViewById(R.id.imageView1);
    tampil.setOnTouchListener(this);
    Drawable d = getResources().getDrawable(R.drawable.enigma);
    bmp = ((BitmapDrawable)d).getBitmap();
    tampil.setImageBitmap(bmp);
}

@Override
public boolean onTouch(View v, MotionEvent event) {
    // TODO Auto-generated method stub
    //ImageView view = (ImageView) v;

      // Handle touch events here...
      switch (event.getAction() & MotionEvent.ACTION_MASK) {
      case MotionEvent.ACTION_DOWN:
         savedMatrix.set(matrix);
         start.set(event.getX(), event.getY());
         Log.d(TAG, "mode=DRAG");
         mode = DRAG;
         Log.i(TAG, "("+String.valueOf((int)event.getX())+","+String.valueOf((int)event.getY())+")");
         if (i==1){
             x1 = event.getX();
             y1 = event.getY();
             i = 2;
             Log.i(TAG, "coordinate x1 : "+String.valueOf(x1)+" y1 : "+String.valueOf(y1));
         } else if (i==2){
             x2 = event.getX();
             y2 = event.getY();
             i = 3;
             Log.i(TAG, "coordinate x2 : "+String.valueOf(x2)+" y2 : "+String.valueOf(y2));
             onDraw();
         } 
        break;
      }
    return true;
}

public void onDraw(){
    Bitmap tes = Bitmap.createBitmap(bmp.getWidth(), bmp.getHeight(), Bitmap.Config.RGB_565);
    tes = bmp;
    Canvas cvs = new Canvas(tes);
    Paint pnt = new Paint();
    pnt.setColor(Color.RED);
    Log.i(TAG, "draw line");
    cvs.drawLine(x1, y1, x2, y2, pnt);
    i=1;
    tampil.setImageBitmap(tes);
}
}

but when the user touch 2 time, the aplication has not draw the line.. anyone can give a solution

this is the log cat say :

10-17 12:08:21.082: I/ActivityManager(70): Displayed com.example.tesontouch/.MainActivity: +3s139ms
  10-17 12:08:24.103: D/Touch(796): mode=DRAG
  10-17 12:08:24.103: I/Touch(796): (113,145)
  10-17 12:08:24.123: I/Touch(796): coordinate x1 : 113.26723 y1 : 145.2766
  10-17 12:08:26.243: D/dalvikvm(264): GC_EXPLICIT freed 8K, 55% free 2595K/5703K, external 1625K/2137K, paused 88ms
  10-17 12:08:26.323: D/Touch(796): mode=DRAG
  10-17 12:08:26.323: I/Touch(796): (306,284)
  10-17 12:08:26.343: I/Touch(796): coordinate x2 : 306.67017 y2 : 284.45056
  10-17 12:08:26.423: D/dalvikvm(796): GC_EXTERNAL_ALLOC freed 4K, 53% free 2559K/5379K, external 3064K/4342K, paused 81ms
  10-17 12:08:26.473: I/Touch(796): draw line
  10-17 12:08:31.413: D/dalvikvm(473): GC_EXPLICIT freed 6K, 52% free 2697K/5511K, external 3502K/4752K, paused 183ms

Answer 1

this is the correct working code 🙂

package com.example.stackdrawline;

import android.os.Bundle;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.PointF;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.ImageView;

public class StackActivity extends Activity implements OnTouchListener {
ImageView tampil;
   Matrix matrix = new Matrix();
   Matrix savedMatrix = new Matrix();
   private static final String TAG = "Touch";
   static final int NONE = 0;
   static final int DRAG = 1;
   static final int ZOOM = 2;
   int mode = NONE;

   // Remember some things for zooming
   PointF start = new PointF();
   PointF mid = new PointF();
   float oldDist = 1f;
   float x1, y1, x2, y2;
   Bitmap bmp;
   int i = 1;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_stack);
    tampil = (ImageView)findViewById(R.id.imageView1);
    tampil.setOnTouchListener(this);
    Drawable d = getResources().getDrawable(R.drawable. enigma);
    bmp = ((BitmapDrawable)d).getBitmap();
    tampil.setImageBitmap(bmp);

}

@Override
public boolean onTouch(View v, MotionEvent event) {
    // TODO Auto-generated method stub
    switch (event.getAction() & MotionEvent.ACTION_MASK) {
      case MotionEvent.ACTION_DOWN:
         savedMatrix.set(matrix);
         start.set(event.getX(), event.getY());
         Log.d(TAG, "mode=DRAG");
         mode = DRAG;
         Log.i(TAG, "("+String.valueOf((int)event.getX())+","+String.valueOf((int)event.getY())+")");
         if (i==1){
             x1 = event.getX();
             y1 = event.getY();
             i = 2;
             Log.i(TAG, "coordinate x1 : "+String.valueOf(x1)+" y1 : "+String.valueOf(y1));
         } else if (i==2){
             x2 = event.getX();
             y2 = event.getY();
             i = 3;
             Log.i(TAG, "coordinate x2 : "+String.valueOf(x2)+" y2 : "+String.valueOf(y2));
             onDraw();
         } 
        break;
      }
    return true;
}
public void onDraw(){
    bmp = Bitmap.createBitmap(tampil.getWidth(), tampil.getHeight(), Config.ARGB_8888);
    Canvas c = new Canvas(bmp);
    tampil.draw(c);

    Paint pnt = new Paint();
    pnt.setColor(Color.RED);
    c.drawLine(x1, y1, x2, y2, pnt);
    tampil.setImageBitmap(bmp);
    i = 1;
}

}