Canvas isn't updating with the changes, even though repeatedly called

Question

This is my Code to the java class wherein I draw three towers onto which I place certain amount of rings. In the onTouchEvent function, I notice activity and increase the number of moves accordingly, which is, in turn being displayed on the screen. But it doesn't update until I go to the previous activity and come back.

Number.java

package com.syncnlink.myapplication;

public class Number {
public static int tower1[] = new int[10];
public static int tower2[] = new int[10];
public static int tower3[] = new int[10];


public static void initialize() {
    for (int i = 0; i < 10; i++)
    {
        tower1[i] = i+1;
        tower2[i] = -1;
        tower3[i] = -1;
    }
}
public static int numelements(int arr[]) {
    int count = 0;
    for (int i = 0; i < 10; i++)
    {
        if (arr[i] > 0)
            count++;
        else
            continue;
    }
    return count;
}

public static void setit(int arr[], int a)
{
    arr[a]=-1;
}

public static void setit1(int a)
{
    tower1[a]=-1;
}

public static boolean isEmpty(int arr[])
{
    for(int i=0;i<5;i++)
        if(arr[i]>-1)
        {
            return false;
        }
    return true;
}

}

NewGame Activity

package com.syncnlink.myapplication;

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class NewGame extends Activity {

public CustomRectangle cr;
static float x,y,width, height;
public static int moves =0;
private static Bitmap background;
static Canvas canvas;
public int ff=0,initialized=0;
public static int t1,t2,t3;


@Override
protected void onCreate(Bundle savedInstanceState) {
    background =    BitmapFactory.decodeResource(getResources(),R.drawable.background);
    super.onCreate(savedInstanceState);
    CustomRectangle cr = new CustomRectangle(this);
    setContentView(cr);
    Number.initialize();


    t1 = Number.numelements(Number.tower1);
    t2 = Number.numelements(Number.tower2);
    t3 = Number.numelements(Number.tower3);
}

public static class CustomRectangle extends View {

    CustomRectangle(Context c) {
        super(c);
        invalidate();
    }

    public void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        NewGame n = new NewGame();
        if(n.initialized == 0)
        {
            Number.initialize();
        }
        Paint p[]= new Paint[11];
        for(int i=0;i<11;i++)
            p[i] = new Paint();
        p[0].setColor(Color.YELLOW);
        p[1].setColor(Color.BLUE);
        p[2].setColor(Color.CYAN);
        p[3].setColor(Color.RED);
        p[4].setColor(Color.GRAY);
        p[5].setColor(Color.MAGENTA);
        p[6].setColor(Color.BLUE);
        p[7].setColor(Color.CYAN);
        p[8].setColor(Color.RED);
        p[9].setColor(Color.GRAY);
        p[10].setColor(Color.MAGENTA);
        canvas.drawBitmap(background,0,0,null);

        p[0].setStrokeWidth(24);

        height = getHeight();
        width = getWidth();
        float w = width/1794;
        float h = height/1008;

        canvas.drawLine(100*(width/1794),1000*(height/1008),500*(width/1794),1000*(height/1008),p[0]);
        canvas.drawLine(300*(width/1794),1000*(height/1008),300*(width/1794),400,p[0]);
        canvas.drawLine((100+600)*(width/1794),1000*(height/1008),(500+600)*(width/1794),1000*(height/1008),p[0]);
        canvas.drawLine((300+600)*(width/1794),1000*(height/1008),(300+600)*(width/1794),400*(height/1008),p[0]);
        canvas.drawLine((100+1200)*(width/1794),1000*(height/1008),(500+1200)*(width/1794),1000*(height/1008),p[0]);
        canvas.drawLine((300+1200)*(width/1794),1000*(height/1008),(300+1200)*(width/1794),400*(height/1008),p[0]);

        int j=0;
        for (int i = 0; i < 10; i++) {
            if(Number.tower1[i]<0)
            continue;
            else {
                canvas.drawRect((150 + (i * 14))*w, (942 - (j * 44))*h, (450 - (i * 14))*w, (987 - (j * 44))*h, p[i + 1]);
                j++;
            }
        }

        j=0;
        for (int i = 0; i < 10; i++) {
            if(Number.tower2[i]<0)
                continue;
            else {
                canvas.drawRect((150 + (i * 14) + 600)*w, (942 - (i * 44))*h, (450 + 600 - (i * 14))*w, (987 - (i * 44))*h, p[i + 1]);
                j++;
            }
        }

        j=0;
        for (int i = 0; i < 10; i++) {
            if(Number.tower3[i]<0)
                continue;
            else {
                canvas.drawRect((150 + 1200 + (i * 14))*w, (942 - (i * 44))*h, (450 + 1200 - (i * 14))*w, (987 - (i * 44))*h, p[i + 1]);
                j++;
            }
        }

        p[0].setTextSize(48);
        canvas.drawText(" No. of Moves  " + moves ,100,40,p[0]);
    }
}

@Override
public boolean onTouchEvent( MotionEvent event1) {
    try {

        switch (event1.getAction()) {
            case MotionEvent.ACTION_DOWN: {
                x=event1.getX();
                y=event1.getY();

                if(x<width/3)
                {

                    if(!Number.isEmpty(Number.tower1)) {
                        Toast.makeText(this, "Pop Tower1   " + t1--, Toast.LENGTH_SHORT).show();
                        ff=0;
                        moves++;
                        Number.setit1(t1);
                        cr.invalidate();
                    }
                    else {
                        Toast.makeText(this, "Empty! Nothing to Pop", Toast.LENGTH_SHORT).show();
                        ff = 1;
                    }
                }
                else
                if(x<width*2/3) {
                    if (!Number.isEmpty(Number.tower2)) {
                        Toast.makeText(this, "Pop Tower2   " + t2--, Toast.LENGTH_SHORT).show();
                        Number.setit(Number.tower2, t2);
                        ff=0;
                        moves++;
                        cr.invalidate();

                    } else {
                        ff = 1;
                        Toast.makeText(this, "Empty! Nothing to Pop", Toast.LENGTH_SHORT).show();
                    }
                }
                else
                {
                    if(!Number.isEmpty(Number.tower3)) {
                        Number.setit(Number.tower3, t3);
                        Toast.makeText(this, "Pop Tower3   " + t3--, Toast.LENGTH_SHORT).show();
                        moves++;
                        cr.invalidate();
                        ff=0;
                    }
                    else {
                        Toast.makeText(this, "Empty! Nothing to Pop", Toast.LENGTH_SHORT).show();
                        ff = 1;
                    }
                }
                break;
            }
            case MotionEvent.ACTION_UP: {
                x=event1.getX();
                y=event1.getY();
                if(x<width/3)
                {
                    if(ff==0)
                    {
                    Number.setit2(Number.tower1,++t1);
                    Toast.makeText(this, "Push Tower1    " + t1, Toast.LENGTH_SHORT).show();
                }
                }
                else
                if(x<width*2/3)
                {
                    if(ff==0)
                    {
                    Number.setit2(Number.tower2,++t2);
                    Toast.makeText(this, "Push Tower2    " + t2, Toast.LENGTH_SHORT).show();
                }
                }

                else
                {
                    if(ff==0) {
                        Number.setit2(Number.tower3, ++t3);
                        Toast.makeText(this, "Push Tower3    " + t3, Toast.LENGTH_SHORT).show();
                    }
                }

                break;
            }

        }
    }
    catch(Exception e)
    {

    }
    return true;
}
}

So, I can see all the Toasts on the screen and also if I put up a toast in onDraw(), I can see that being called several times, but it isn't updating the information or not redrawing the new canvas on top of the previous one. Any help is welcome. Been stuck at it for a few days now

http://stackoverflow.com/q/2865315/5733853 – VahidHoseini Sep 04 '16 at 07:12 — VahidHoseini, Sep 04 '16 at 07:12

score 0 · Answer 1 · answered Jul 14 '16 at 08:18

0

I think you need create some setters on your CustomRectangle.class

public void setSomething(Arguments)
{
    // do your changes here 
    invalidate();
}

and call the setters to change the state of your draws inside the onTounch.

case:MotionEvent.ACTION_DOWN:
    cr.setSomething(Arguments);
....
....

when you call the setters they will update the states of you canvas after the call invalidate.

i hope this help you !

answered Jul 14 '16 at 08:18

Adliano Alves

311
2
6

I have already used the setters in the "onTouchEvent" function. So I guess it should have updated the states if my canvas after invalidate call.? Is it necessary to do it in CustomRectangle class? @AdrianoAlves – Karan Asthana Jul 14 '16 at 08:55
Dis you call invalidate() inside your setters ? It must case it will be last line of your setter – Adliano Alves Jul 14 '16 at 17:31

score 0 · Answer 2 · answered Jul 14 '16 at 08:42

you can fix it by threading your invalidate in your constructor that will be fix by changing it to :

   CustomRectangle(Context c) {
            super(c);
            Thread thread = new Thread(new Runnable() {
                @Override
                public void run() {
                    while(true) {
                        try {
                            Thread.sleep(1000);
                            postInvalidate();
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }

                    }
                }
            });

        thread.start();
        }

Canvas isn't updating with the changes, even though repeatedly called

2 Answers2