Draw Rubber Band Line With An Ontouchevent

Ok, I'm trying to make a program that utilizes a linedrawview. When the user starts a touch event(action DOWN), it gets the current x and y and stores them in variables. Then whe

Solution 1:

Okay, I found out: Make sure to set the start position x and y, like this:

currentXExample = event.getX(); currentYExample = event.getY();

exampleStartX = currentXExample; exampleStartY = currentYExample;

exampleEndX = currentXExample;

exampleEndY = currentYExample;

You can leave it out of the Up event, but never leave it out of the MOVE event or it will not work.

LineDrawView.java

// Project:         Java2Lab// File:            LineDrawView.java// Date:            4/9/13// Author:          Joshua Lefelhocz// Description:     custom view to draw lines onpackage com.lcc.java2lab11lefelhocz;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.MotionEvent;
import android.view.View;

// Notice this class extends ViewpublicclassLineDrawViewextendsView 
{
      // This view's boundsprivateintxMin=0;          
privateint xMax;
privateintyMin=0;
privateint yMax;
privatefloat currentX;
privatefloat currentY;
privatefloat startX;
privatefloat endX;
privatefloat startY;
privatefloat endY;
// Paint objectprivate Paint paintFill;

// constructorpublicLineDrawView(Context context) 
{
    // call the super class constructorsuper(context);

    // The Paint class holds the style and color information about how to draw geometries, text and bitmaps.// For efficiency create the paint objects in the constructor, not in draw// paint.setStrokeWidth(10); // works on lines// You can change the color of Paint without effecting objects already drawn// You can NOT change the style of Paint without effecting objects already drawn// The Style, TextSize apply to all objects drawn with the paint.// Create a default Paint object Style=Fill
    paintFill = newPaint();

    // set the background color when the view is createdthis.setBackgroundColor(Color.LTGRAY);  
}

// Called to draw the view. Also called by invalidate().@OverrideprotectedvoidonDraw(Canvas canvas) 
{
   //canvas.drawColor(Color.LTGRAY); // this works in onDraw to set the background color// Draw a Red Diagonal line from upper left corner to bottom right corner

    paintFill.setColor(Color.BLACK);
    canvas.drawLine(startX, startY, endX, endY, paintFill);

}

// Called when the view is first created or its size changes.@OverridepublicvoidonSizeChanged(int width, int height, int oldWidth, int oldHeight) 
{
    // Set the view bounds
    xMax = width-1;
    yMax = height-1;
}

publicbooleanonTouchEvent(MotionEvent event)
{
    currentX = event.getX();
    currentY = event.getY();



    switch(event.getAction())
    {   
    case MotionEvent.ACTION_DOWN:
        startX = currentX;
        startY = currentY;
        returntrue;
    case MotionEvent.ACTION_MOVE:
    endX = currentX;
    endY = currentY;
    invalidate();
        returntrue;
    case MotionEvent.ACTION_UP:


        returntrue;
    }
    returnsuper.onTouchEvent(event);
     }
}