How to draw a line in android

Question

Can anybody tell how to draw a line in Android, perhaps with an example?

Answer 1

You can draw multiple straight lines on view using Finger paint example which is in Developer android. example link

Just comment: mPath.quadTo(mX, mY, (x + mX)/2, (y + mY)/2); You will be able to draw straight lines.

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Point;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.ImageView;

public class JoinPointsActivity extends Activity  {
    /** Called when the activity is first created. */
    Paint mPaint;
    float Mx1,My1;
    float x,y;
    @Override

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
       // setContentView(R.layout.main);
        MyView view1 =new MyView(this);
        view1.setBackgroundResource(R.drawable.image_0031_layer_1);
        setContentView(view1);


        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setDither(true);
        mPaint.setColor(0xFFFF0000);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeJoin(Paint.Join.ROUND);
       // mPaint.setStrokeCap(Paint.Cap.ROUND);
        mPaint.setStrokeWidth(10);

    }

    public class MyView extends View {

        private static final float MINP = 0.25f;
        private static final float MAXP = 0.75f;

      private Bitmap  mBitmap;
        private Canvas  mCanvas;
        private Path    mPath;
       private Paint   mBitmapPaint;

        public MyView(Context c) {
            super(c);

            mPath = new Path();
          mBitmapPaint = new Paint(Paint.DITHER_FLAG);
        }

        @Override
       protected void onSizeChanged(int w, int h, int oldw, int oldh) {
            super.onSizeChanged(w, h, oldw, oldh);
            mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
            mCanvas = new Canvas(mBitmap);
        }

        @Override
        protected void onDraw(Canvas canvas) {
            canvas.drawColor(0xFFAAAAAA);
           // canvas.drawLine(mX, mY, Mx1, My1, mPaint);
           // canvas.drawLine(mX, mY, x, y, mPaint);
            canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
            canvas.drawPath(mPath, mPaint);

        }

        private float mX, mY;
        private static final float TOUCH_TOLERANCE = 4;

        private void touch_start(float x, float y) {
            mPath.reset();
            mPath.moveTo(x, y);
            mX = x;
            mY = y;
        }
        private void touch_move(float x, float y) {
            float dx = Math.abs(x - mX);
            float dy = Math.abs(y - mY);
            if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
               // mPath.quadTo(mX, mY, (x + mX)/2, (y + mY)/2);
                mX = x;
                mY = y;
            }
        }
        private void touch_up() {
            mPath.lineTo(mX, mY);
            // commit the path to our offscreen
            mCanvas.drawPath(mPath, mPaint);
            // kill this so we don't double draw
            mPath.reset();
        }

        @Override
        public boolean onTouchEvent(MotionEvent event) {
            float x = event.getX();
            float y = event.getY();

            switch (event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    touch_start(x, y);
                    invalidate();
                    break;
                case MotionEvent.ACTION_MOVE:
                    touch_move(x, y);
                    invalidate();
                    break;
                case MotionEvent.ACTION_UP:
                    touch_up();
               //   Mx1=(int) event.getX();
                 //  My1= (int) event.getY();
                   invalidate();
                    break;
            }
            return true;
        }
    }

}