Develop Reference

How to change a textview from a custom view's class

Let's say I have a custom view inside an activity and a TextView just below that custom view. I would like to change the TextView's text once the custom view was clicked but I seem to get a null pointer when I use findViewById(), so how can I do that?
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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: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="com.yuvaleliav1gmail.quoridor_ye.MainActivity"
android:background="#dd7d23">
<com.yuvaleliav1gmail.quoridor_ye.ComBoardView
android:layout_width="900px"
android:layout_height="900px"
android:id="#+id/bview"
android:background="#drawable/game_board"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true" />
<RadioGroup
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/radioGroup"
android:layout_below="#+id/bview"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true">
<RadioButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Move Pawn"
android:id="#+id/radioPawn"
android:checked="true"
android:onClick="radioButtonClick"/>
<RadioButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Set VERTICAL Wall"
android:id="#+id/verticalRdio"
android:checked="false"
android:onClick="radioButtonClick"/>
<RadioButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Set HORIZONTAL Wall"
android:id="#+id/horizontalRdio"
android:checked="false"
android:onClick="radioButtonClick"/>
</RadioGroup>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Your turn"
android:id="#+id/turnText34"
android:layout_gravity="center_horizontal"
android:layout_below="#+id/radioGroup"
android:layout_alignLeft="#+id/bview"
android:layout_alignStart="#+id/bview" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Your walls left: "
android:id="#+id/yourWallsText"
android:layout_gravity="center_horizontal"
android:layout_below="#+id/turnText34"
android:layout_alignLeft="#+id/turnText34"
android:layout_alignStart="#+id/turnText34" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="10"
android:id="#+id/yourNumText"
android:layout_gravity="center_horizontal"
android:layout_alignTop="#+id/yourWallsText"
android:layout_toRightOf="#+id/yourWallsText"
android:layout_toEndOf="#+id/yourWallsText" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Opponent&apos;s walls left:"
android:id="#+id/opWallsText"
android:layout_gravity="center_horizontal"
android:layout_below="#+id/yourWallsText"
android:layout_alignLeft="#+id/yourWallsText"
android:layout_alignStart="#+id/yourWallsText" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="10"
android:id="#+id/opNumText"
android:layout_gravity="center_horizontal"
android:layout_alignTop="#+id/opWallsText"
android:layout_toRightOf="#+id/opWallsText"
android:layout_toEndOf="#+id/opWallsText" />
</RelativeLayout>
comBoardView is the custom view's class
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Point;
import android.os.CountDownTimer;
import android.os.Handler;
import android.util.AttributeSet;
import android.view.Display;
import android.view.MotionEvent;
import android.view.View;
import android.view.WindowManager;
import android.widget.TextView;
import android.widget.Toast;
public class ComBoardView extends View {
private static final int ROWS = 9;
private static final int COLUMNS = 9;
public static Context con;
Paint paint;
GameService game;
TextView turns;
public static Point size = new Point();
/*
* constructor
*/
public ComBoardView(Context context, AttributeSet attrs) {
super(context, attrs);
con = context;
paint = new Paint();
WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
Display display = wm.getDefaultDisplay();
display.getSize(size);
turns = (TextView) findViewById(R.id.turnText34);
}
/*
*/
public boolean onTouchEvent( MotionEvent event ) {
game = GameService.getInstance();
int x = (int)event.getX() / 100;
int y = (int)event.getY() / 100;
if ( event.getAction() != MotionEvent.ACTION_UP )
return true;
if(game.movePawn){
if(game.turn % 2 == 0){
if(game.isLegalMove(game.ai.MyLocation , y * ROWS + x)){
game.board.ClrPlayer(game.ai);
game.ai.MyLocation = y * ROWS + x;
game.board.SetPlayer(game.ai);
if(turns != null){
turns.setText("white's turn");
}
game.turn++;
}
}
else{
if(game.isLegalMove(game.player.MyLocation , y * ROWS + x)){
game.board.ClrPlayer(game.player);
game.player.MyLocation = y * ROWS + x;
game.board.SetPlayer(game.player);
if(turns != null){
turns.setText("black's turn");
}
game.turn++;
}
}
}
else {
if(((int)event.getX() % 100) < 50) x--;
if(((int)event.getY() % 100) < 50) y--;
if(game.setHWall){
game.board.SetHWall(y,x);
game.turn++;
}
else{
game.board.SetVWall(y,x);
game.turn++;
}
}
return true;
}
public void RestartTimer() {
new CountDownTimer(3500, 1000) {
public void onTick(long millisUntilFinished) {
final Toast toast = Toast.makeText(con, "restarting in: " + millisUntilFinished / 1000, Toast.LENGTH_LONG);
toast.show();
new Handler().postDelayed(new Runnable() {
#Override
public void run() {
toast.cancel();
}
}, 1000);
}
public void onFinish() {
}
}.start();
}
protected void onDraw(Canvas canvas) {
paint.setAntiAlias(true);
paint.setColor(Color.BLACK);
GameService.getInstance().onDraw(canvas, paint);
}
}
and game is the activity's class
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.RadioButton;
import java.util.Timer;
public class Game extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_game);
Timer timer = new Timer();
GameUpdateTimer ut = new GameUpdateTimer();
ut.boardView = (ComBoardView)this.findViewById(R.id.bview);
timer.schedule(ut, 200, 200);
RadioButton pawn = (RadioButton)findViewById(R.id.radioPawn);
RadioButton hWall = (RadioButton)findViewById(R.id.horizontalRdio);
RadioButton vWall = (RadioButton)findViewById(R.id.verticalRdio);
final GameService g = GameService.getInstance();
pawn.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
g.movePawn = true;
g.setHWall = false;
}});
hWall.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
g.movePawn = false;
g.setHWall = true;
}
});
vWall.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
g.movePawn = false;
g.setHWall = false;
}
});
}
}

You can't call turns = (TextView) findViewById(R.id.turnText34); from your custom view, it will always return Null because TextView exist in the activity xml and not in ComBoardView.
What you can do, is to instantiate your TextView in the activity, then add a clickListener to your ComBoardView.
TextView turns;
#Override
protected void onCreate(Bundle savedInstanceState) {
//...
turns = (TextView) findViewById(R.id.turnText34);
ut.boardView.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
turns.setText("ComBoardView was clicked!");
}});
//...
}

Switch between activities in Android?

I want to switch between my Main Actvity and my second Activity, but whenever I do it the app shuts down.
So after i click the button1 "Neues Feld", the App should switch to the second activity: feldlayout.class with the layout: feldlayout.xml! The activities are liested in the Android_MAnifest, that's also not the problem...
Thank you for the help! It's working now! I made a new View class, added it to the layout and then it worked fine!
Main Class
package com.example.volleyballapp;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.content.res.Resources;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.drawable.Drawable;
import android.view.Menu;
import android.view.MotionEvent;
import android.view.View;
import android.view.Window;
import android.widget.Button;
public class Main_Layout extends Activity {
Button b1;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.main_layout);
b1 = (Button) findViewById(R.id.button1);
b1.setOnClickListener(myhandler);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main__layout, menu);
return true;
}
View.OnClickListener myhandler = new View.OnClickListener(){
public void onClick(View v) {
if(v==b1){
Intent i = new Intent(Main_Layout.this, feldlayout.class);
startActivity(i);
}
}
};}
Main Layout
<RelativeLayout 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:background="#drawable/background2"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
android:orientation="vertical"
tools:context=".Main_Layout" >
<TextView
android:id="#+id/textView"
android:layout_width="fill_parent"
android:layout_height="250dp"
android:layout_alignParentTop="true"
android:layout_marginLeft="10sp"
android:layout_marginRight="10sp"
android:text=" "
android:textAppearance="?android:attr/textAppearanceLarge"
android:textColor="#color/farbe" />
<Button
android:id="#+id/button1"
style="#style/ButtonText"
android:layout_below="#id/textView"
android:layout_centerHorizontal="true"
android:background="#drawable/bnt_black"
android:onClick="NeuesFeldClick"
android:text="Neues Feld" />
<TextView
android:layout_width="fill_parent"
android:layout_height="100dp"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text=" "
android:id="#+id/textView2"
android:textColor="#color/farbe"
android:layout_below="#id/button1"/>
<Button
android:id="#+id/button2"
style="#style/ButtonText"
android:layout_below="#id/textView2"
android:layout_centerHorizontal="true"
android:background="#drawable/bnt_black"
android:onClick="LetztesFeldClick"
android:text="Letztes Feld" />
<TextView
android:layout_width="fill_parent"
android:layout_height="100dp"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text=" "
android:id="#+id/textView3"
android:textColor="#color/farbe"
android:layout_below="#id/button2"/>
<Button
android:id="#+id/button3"
style="#style/ButtonText"
android:layout_below="#id/textView3"
android:layout_centerHorizontal="true"
android:background="#drawable/bnt_black"
android:onClick="SavesClick"
android:text="Gespeicherte Felder" />
</RelativeLayout>
Second Activity
package com.example.volleyballapp;
import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.Menu;
import android.view.MotionEvent;
import android.view.View;
public class feldlayout extends Activity{
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.feldlayout);
}
private Paint paint = new Paint();
private Path path = new Path();
int count = 1;
public feldlayout(Context context, AttributeSet attrs) {
super();
paint.setAntiAlias(true);
paint.setStrokeWidth(6f); //Breite des Strichs
paint.setColor(Color.BLACK); //Farbe des Strichs
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeJoin(Paint.Join.ROUND);
}
protected void onDraw(Canvas canvas) {
if ((count%2 != 0)){
canvas.drawPath(path, paint);}
}
#Override
public boolean onTouchEvent(MotionEvent event) {
float eventX = event.getX();
float eventY = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
count++;
if(count%2 != 1){
path.moveTo(eventX, eventY);
return true;
}
if(count%2 != 0){
path.lineTo(eventX, eventY);
break;
}
case MotionEvent.ACTION_MOVE:
break;
case MotionEvent.ACTION_UP:
// nothing to do
break;
default:
return false;
}
// Schedules a repaint.
invalidate();
return true;
}
private void invalidate() {
// TODO Auto-generated method stub
}
}

It's just i tried. your code is working. The problem is you call Constructor in the second Activity. Below one.
public feldlayout(Context context, AttributeSet attrs) {
super();
paint.setAntiAlias(true);
paint.setStrokeWidth(6f); //Breite des Strichs
paint.setColor(Color.BLACK); //Farbe des Strichs
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeJoin(Paint.Join.ROUND);
}
Please remove this constructor and try again.
Note
Just create a separate class and call the constructor there.

how to use colorpicker with my application?

I have made a simple android drawing application,In that i have taken different buttons for different colors,Now i want is that when i click on red button my pen color should be chaned to red.same as for diffrent colors..My code is as below,Please suggest me friends..
SingleTouch.java
package com.example.singletouch;
import java.util.AbstractMap;
import java.util.Map;
import java.util.concurrent.ConcurrentLinkedQueue;
import android.R.color;
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.PorterDuff;
import android.graphics.PorterDuff.Mode;
import android.graphics.PorterDuffXfermode;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;
import android.widget.Switch;
import android.widget.Toast;
public class SingleTouchView extends View {
public static int width;
public int height;
public Bitmap mBitmap;
public Canvas mCanvas;
public Path mPath;
public Paint mBitmapPaint;
Context context;
public Paint mPaint;
public Paint circlePaint;
public Path circlePath;
public enum DrawingPens {
PEN_1(6), PEN_2(4), PEN_3(2), PEN_4(1);
public Paint mPaint;
private DrawingPens(final int width) {
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setStrokeWidth(width);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
}
Paint getPaint() {
return mPaint;
}
}
public enum DrawingColors{
Black(Color.parseColor("#000000")),Blue(Color.parseColor("#0000FF")),Cofee(Color.parseColor("#D2691E")),Cyan(Color.parseColor("#00FFFF"))
,Fuchiya(Color.parseColor("#FF00FF")),Gray(Color.parseColor("#808080")),Green(Color.parseColor("#00FF00")),Indigo(Color.parseColor("#4B0082")),
Khaki(Color.parseColor("#F0E68C")),Lavendar(Color.parseColor("#E6E6FA")),Magenta(Color.parseColor("#FF00FF")),Mango(Color.parseColor("#FF8C00"))
,Maroon(Color.parseColor("#800000")),Orange(Color.parseColor("#FFA500")),Pink(Color.parseColor("#FFC0CB")),Pista(Color.parseColor("#9ACD32")),
Purple(Color.parseColor("#800080")),Red(Color.parseColor("#FF0000")),Tan(Color.parseColor("#0000A0")),Yellow(Color.parseColor("#FFD801"));
public Paint mPaint;
private DrawingColors(final int color) {
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setStrokeWidth(width);
mPaint.setColor(color);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
}
Paint getPaint() {
return mPaint;
}
}
public SingleTouchView(final Context context) {
super(context);
init(context);
}
public SingleTouchView(final Context context, final AttributeSet attrs) {
super(context, attrs);
init(context);
mBitmap = Bitmap.createBitmap(400, 400, Bitmap.Config.ARGB_8888);
mCanvas = new Canvas(mBitmap);
mPath = new Path();
mBitmapPaint = new Paint(Paint.DITHER_FLAG);
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(12);
}
public SingleTouchView(final Context context, final AttributeSet attrs,
final int defStyle) {
super(context, attrs, defStyle);
init(context);
}
private ConcurrentLinkedQueue<Map.Entry<Path, DrawingPens>> mPaths = new ConcurrentLinkedQueue<Map.Entry<Path, DrawingPens>>();
private Path mCurrentPath;
private Path mCurrentPath1;
private void init(final Context context) {
setPen(DrawingPens.PEN_1);
}
#Override
public void onDraw(Canvas canvas) {
super.onDraw(canvas);
for (Map.Entry<Path, DrawingPens> entry : mPaths) {
canvas.drawPath(entry.getKey(), entry.getValue().getPaint());
}
}
#Override
public boolean onTouchEvent(MotionEvent me) {
float eventX = me.getX();
float eventY = me.getY();
switch (me.getAction()) {
case MotionEvent.ACTION_DOWN:
mCurrentPath.moveTo(eventX, eventY);
return true;
case MotionEvent.ACTION_MOVE:
mCurrentPath.lineTo(eventX, eventY);
break;
case MotionEvent.ACTION_UP:
break;
}
invalidate();
return true;
}
public void setPen(final DrawingPens pen) {
mCurrentPath = new Path();
mPaths.add(new AbstractMap.SimpleImmutableEntry<Path, DrawingPens>(
mCurrentPath, pen));
}
public void eraser() {
// TODO Auto-generated method stub
mPaint = new Paint();
/* Toast.makeText(getContext(), "eraser", Toast.LENGTH_LONG).show();
mPaint.setXfermode(null);
mPaint.setAlpha(0x00FFFFFF);
mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));*/
// invalidate();
}
public void setColor(final DrawingColors color){
mCurrentPath = new Path();
mPaths.add(new AbstractMap.SimpleImmutableEntry<Path, DrawingColors>(
mCurrentPath, color));
}
}
main.java
package com.example.singletouch;
import android.os.Bundle;
import android.app.Activity;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.HorizontalScrollView;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
public class MainActivity extends Activity {
ImageView pen, color;
SingleTouchView mDrawView;
RelativeLayout layout, layout1;
ImageView remove;
ImageView eraser;
LinearLayout pens;
HorizontalScrollView myplate;
private Path mPath;
public Canvas mCanvas;
LinearLayout pen1, pen2, pen3, pen4;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mDrawView = (SingleTouchView) findViewById(R.id.myview);
layout1 = (RelativeLayout) findViewById(R.id.layout1);
layout = (RelativeLayout) findViewById(R.id.layout);
pen = (ImageView) findViewById(R.id.pen);
pens = (LinearLayout) findViewById(R.id.linear);
pens.setVisibility(View.GONE);
pen1 = (LinearLayout) findViewById(R.id.pen1);
pen2 = (LinearLayout) findViewById(R.id.pen2);
pen3 = (LinearLayout) findViewById(R.id.pen3);
pen4 = (LinearLayout) findViewById(R.id.pen4);
color = (ImageView) findViewById(R.id.color);
myplate = (HorizontalScrollView) findViewById(R.id.myplate);
eraser = (ImageView) findViewById(R.id.eraser);
remove = (ImageView) findViewById(R.id.remove);
/*
* pen1.setOnClickListener(this); pen2.setOnClickListener(this);
* pen3.setOnClickListener(this); pen4.setOnClickListener(this);
*/
pen.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
// layout.addView(mDrawView);
pens.setVisibility(View.VISIBLE);
}
});
pens.setVisibility(View.GONE);
pen1.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
mDrawView.setPen(SingleTouchView.DrawingPens.PEN_1);
pens.setVisibility(View.GONE);
}
});
pen2.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
mDrawView.setPen(SingleTouchView.DrawingPens.PEN_2);
pens.setVisibility(View.GONE);
}
});
pen3.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
pens.setVisibility(View.GONE);
mDrawView.setPen(SingleTouchView.DrawingPens.PEN_3);
}
});
pen4.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
pens.setVisibility(View.GONE);
mDrawView.setPen(SingleTouchView.DrawingPens.PEN_4);
}
});
remove.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
layout.removeView(mDrawView);
mDrawView = new SingleTouchView(MainActivity.this);
layout.addView(mDrawView);
}
});
eraser.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
}
});
color.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
}
});
}
}
main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
tools:context=".MainActivity" >
<RelativeLayout
android:id="#+id/layout1"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#ffffff" >
</RelativeLayout>
<RelativeLayout
android:id="#+id/layout"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_above="#+id/linearLayout1" >
<com.example.singletouch.SingleTouchView
android:id="#+id/myview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_above="#+id/pen" />
</RelativeLayout>
<HorizontalScrollView
android:id="#+id/myplate"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="#+id/linearLayout1"
android:visibility="gone" >
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
>
<!-- > -->
<Button
android:id="#+id/red"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/red"
android:padding="15dp" />
<Button
android:id="#+id/green"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/green"
android:padding="15dp" />
<Button
android:id="#+id/blue"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/blue"
android:padding="15dp" />
<Button
android:id="#+id/cyan"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/cyan"
android:padding="15dp" />
<Button
android:id="#+id/yellow"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/yellow"
android:padding="15dp" />
<Button
android:id="#+id/orange"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/orange"
android:padding="15dp" />
<Button
android:id="#+id/black"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/black"
android:padding="15dp" />
<Button
android:id="#+id/cofee"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/cofee"
android:padding="15dp" />
<Button
android:id="#+id/fuchiya"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/fuchiya"
android:padding="15dp" />
<Button
android:id="#+id/gray"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/gray"
android:padding="15dp" />
<Button
android:id="#+id/indigo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/indigo"
android:padding="15dp" />
<Button
android:id="#+id/khaki"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/khaki"
android:padding="15dp" />
<Button
android:id="#+id/lavendar"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/lavendar"
android:padding="15dp" />
<Button
android:id="#+id/magenta"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/magenta"
android:padding="15dp" />
<Button
android:id="#+id/mango"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/mango"
android:padding="15dp" />
<Button
android:id="#+id/maroon"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/maroon"
android:padding="15dp" />
<Button
android:id="#+id/pista"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/pista"
android:padding="15dp" />
<Button
android:id="#+id/pink"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/pink"
android:padding="15dp" />
<Button
android:id="#+id/purple"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/purple"
android:padding="15dp" />
</LinearLayout>
</HorizontalScrollView>
<LinearLayout
android:id="#+id/linearLayout1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:background="#drawable/menubar"
android:padding="2dp"
android:weightSum="4" >
<ImageView
android:id="#+id/pen"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_alignParentBottom="true"
android:layout_weight="1"
android:gravity="center"
android:src="#drawable/pen" />
<ImageView
android:id="#+id/eraser"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_alignParentBottom="true"
android:layout_weight="1"
android:src="#drawable/eraser" />
<ImageView
android:id="#+id/color"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_alignParentBottom="true"
android:layout_weight="1"
android:src="#drawable/color" />
<ImageView
android:id="#+id/remove"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_alignParentBottom="true"
android:layout_weight="1"
android:src="#drawable/remove" />
</LinearLayout>
<LinearLayout
android:id="#+id/linear"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_above="#+id/linearLayout1"
android:layout_alignParentLeft="true"
android:background="#eeeeee"
android:orientation="horizontal"
android:visibility="gone"
android:weightSum="4" >
<LinearLayout
android:id="#+id/pen1"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_weight="1"
android:gravity="center" >
<ImageView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:src="#drawable/pen1" />
</LinearLayout>
<LinearLayout
android:id="#+id/pen2"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_weight="1"
android:gravity="center" >
<ImageView
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:src="#drawable/pen2" />
</LinearLayout>
<LinearLayout
android:id="#+id/pen3"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_weight="1"
android:gravity="center" >
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:src="#drawable/pen3" />
</LinearLayout>
<LinearLayout
android:id="#+id/pen4"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_weight="1"
android:gravity="center" >
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:src="#drawable/pen4" />
</LinearLayout>
</LinearLayout>
</RelativeLayout>

If i understand your question you can extend FrameLayout and add to it the Button/ImageView with the pencil draw transparent.
With this you only should to change the FrameLayout background and can make whatever color button with the same View.

How to draw lines over ImageView on Android?

I am trying to develop a simple map application, which will display a map in the screen.
When the user moves the cursor on screen, I want to display 2 perpendicular lines over my map. I had tried many examples to get an idea for that, but unfortunately, didn't succeed.
How can I make this?
And as one previous questionhere I had tried. but didn't get the answer. Can anyone guide me?
My main.xml is as following:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<LinearLayout android:layout_width="wrap_content"
android:layout_height="wrap_content">
<ImageView android:id="#+id/main_imagemap"
android:src="#drawable/worldmap"
android:clickable="true"
android:layout_width="fill_parent"
android:layout_height="wrap_content"/>
</LinearLayout>
</LinearLayout>
And my activity file(i had just started it..)
import android.app.Activity;
import android.os.Bundle;
import android.widget.ImageView;
public class LineMapActivity extends Activity
{
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
ImageView map_image = (ImageView)findViewById(R.id.main_imagemap);
}
}
And as in that link, i had also added MyImageView.
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.widget.ImageView;
public class MyImageView extends ImageView
{
public MyImageView(Context context) {
super(context);
// TODO Auto-generated constructor stub
}
#Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
Paint p = new Paint(Paint.ANTI_ALIAS_FLAG);
canvas.drawLine(0, 0, 20, 20, p);
super.onDraw(canvas);
}
}
Now how can i add this MyImageView to my app?

Finally I figured out a solution. It's a simple program which draws a line over an Image.
Here is my main.xml file (com.ImageDraw.MyImageView is my custom view, code below):
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<LinearLayout android:layout_width="wrap_content"
android:layout_height="wrap_content">
<com.ImageDraw.MyImageView android:id="#+id/main_imagemap"
android:layout_width="fill_parent"
android:layout_height="wrap_content"/>
</LinearLayout>
</LinearLayout>
And here is the main activity:
import android.app.Activity;
import android.os.Bundle;
public class MyActivity extends Activity
{
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
}
and this is my custom image view (MyImageView):
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.util.AttributeSet;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
public class MyImageView extends SurfaceView implements SurfaceHolder.Callback
{
private CanvasThread canvasthread;
public MyImageView(Context context) {
super(context);
getHolder().addCallback(this);
canvasthread = new CanvasThread(getHolder(), this);
setFocusable(true);
}
public MyImageView(Context context, AttributeSet attrs)
{
super(context,attrs);
getHolder().addCallback(this);
canvasthread = new CanvasThread(getHolder(), this);
setFocusable(true);
}
protected void onDraw(Canvas canvas) {
Log.d("ondraw", "ondraw");
Paint p = new Paint();
Bitmap mapImg = BitmapFactory.decodeResource(getResources(), R.drawable.mybitmap);
canvas.drawColor(Color.BLACK);
canvas.drawBitmap(mapImg, 0, 0, null);
p.setColor(Color.RED);
canvas.drawLine(0, 0, 100, 100, p);
}
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
}
public void surfaceCreated(SurfaceHolder holder) {
canvasthread.setRunning(true);
canvasthread.start();
}
public void surfaceDestroyed(SurfaceHolder holder) {
boolean retry = true;
canvasthread.setRunning(false);
while (retry)
{
try
{
canvasthread.join();
retry = false;
}
catch (InterruptedException e) {
// TODO: handle exception
}
}
}
}
And finally here is my CanvasThread:
import android.graphics.Canvas;
import android.view.SurfaceHolder;
public class CanvasThread extends Thread
{
private SurfaceHolder surfaceHolder;
private MyImageView myImageView;
private boolean run = false;
public CanvasThread(SurfaceHolder s, MyImageView m)
{
surfaceHolder = s;
myImageView = m;
}
public void setRunning(boolean r)
{
run = r;
}
public void run()
{
Canvas c;
while(run)
{
c=null;
try
{
c= surfaceHolder.lockCanvas(null);
synchronized (surfaceHolder) {
myImageView.onDraw(c);
}
}
finally
{
if(c!=null)
{
surfaceHolder.unlockCanvasAndPost(c);
}
}
}
}
}
You can find more details in this tutorial

Error you are getting because you are trying to casting ImageView object to MyImageView object.

Just fix the xml to include your object instead of an imageview like so (note that com.your.package.MyImageView should be the full package name of the package containing your class and then the class name)
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<LinearLayout android:layout_width="wrap_content"
android:layout_height="wrap_content">
<com.your.package.MyImageView android:id="#+id/main_imagemap"
android:src="#drawable/worldmap"
android:clickable="true"
android:layout_width="fill_parent"
android:layout_height="wrap_content"/>
</LinearLayout>
</LinearLayout>

Android: Draw a canvas without obscuring row of buttons

My problem is probably simple - there are many apps out there that accomplish what I am trying to do.
I have a Relative Layout with a row of buttons and then beneath this I want to draw on a canvas.
My problem is that Canvas draws over the buttons or instead of the buttons so all I end up with is a shape.
This is my code:
package com.android.phil.graphtoggle;
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.drawable.ShapeDrawable;
import android.graphics.drawable.shapes.OvalShape;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageButton;
public class MainActivity extends Activity
{
public int graph_toggle = 0;
public int data_toggle=0;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
final ImageButton graph_toggle_button = (ImageButton) findViewById(R.id.graph_toggle);
final ImageButton graph_settings_button = (ImageButton) findViewById(R.id.graph_type);
final ImageButton data_toggle_button = (ImageButton) findViewById(R.id.data_toggle);
CustomDrawableView mCustomDrawableView;
mCustomDrawableView = new CustomDrawableView(this);
setContentView(mCustomDrawableView);
graph_toggle_button.setOnClickListener(new View.OnClickListener()
{
public void onClick(View arg0)
{
if (graph_toggle==2)
{
graph_toggle=0;
}
else
{
graph_toggle++;
}
if (graph_toggle==0)
{
graph_settings_button.setImageResource(R.drawable.close);
}
if (graph_toggle==1)
{
graph_settings_button.setImageResource(R.drawable.ohlc_bars);
}
if(graph_toggle==2)
{
graph_settings_button.setImageResource(R.drawable.candles);
}
}
});
data_toggle_button.setOnClickListener(new View.OnClickListener()
{
public void onClick(View arg0)
{
if (data_toggle==2)
{
data_toggle=0;
}
else
{
data_toggle++;
}
if (data_toggle==0)
{
data_toggle_button.setImageResource(R.drawable.ohlc_bars_daily);
}
if (data_toggle==1)
{
data_toggle_button.setImageResource(R.drawable.ohlc_bars_weekly);
}
if(data_toggle==2)
{
data_toggle_button.setImageResource(R.drawable.ohlc_bars_monthly);
}
}
});
}
public class CustomDrawableView extends View
{
private ShapeDrawable mDrawable;
public CustomDrawableView(Context context)
{
super(context);
int x = 10;
int y = 100;
int width = 300;
int height = 50;
mDrawable = new ShapeDrawable(new OvalShape());
mDrawable.getPaint().setColor(0xff74AC23);
mDrawable.setBounds(x, y, x + width, y + height);
}
protected void onDraw(Canvas canvas)
{
mDrawable.draw(canvas);
}
}
}
This is my xml:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
android:layout_width="fill_parent"
android:id="#+id/relativeLayout1" xmlns:android="http://schemas.android.com/apk/res/android" android:layout_height="fill_parent">
<ImageButton
android:layout_height="40dip"
android:layout_width="40dip"
android:id="#+id/graph_toggle"
android:src="#drawable/graph_toggle"
android:layout_alignParentLeft="true"
></ImageButton>
<ImageButton
android:layout_height="40dip"
android:layout_width="40dip"
android:id="#+id/graph_type"
android:src="#drawable/close"
android:layout_toRightOf="#+id/graph_toggle"
></ImageButton>
<ImageButton
android:layout_height="40dip"
android:layout_width="40dip"
android:id="#+id/data_toggle"
android:src="#drawable/ohlc_bars_daily"
android:layout_toRightOf="#+id/graph_type"
></ImageButton>
<ImageButton
android:layout_height="40dip"
android:layout_width="40dip"
android:id="#+id/data_toggle1"
android:src="#drawable/ohlc_bars_daily"
android:layout_toRightOf="#+id/data_toggle"
></ImageButton>
<ImageButton
android:layout_height="40dip"
android:layout_width="40dip"
android:id="#+id/data_toggle2"
android:src="#drawable/ohlc_bars_daily"
android:layout_toRightOf="#+id/data_toggle1"
></ImageButton>
<ImageButton
android:layout_height="40dip"
android:layout_width="40dip"
android:id="#+id/data_toggle3"
android:src="#drawable/ohlc_bars_daily"
android:layout_toRightOf="#+id/data_toggle2"
></ImageButton>
<ImageButton
android:layout_height="40dip"
android:layout_width="40dip"
android:id="#+id/data_toggle4"
android:src="#drawable/ohlc_bars_daily"
android:layout_toRightOf="#+id/data_toggle3"
></ImageButton>
</RelativeLayout>

You're substituting your whole xml layout with your custom view when you call:
setContentView(mCustomDrawableView);
You should rather add your custom view to the layout, something like:
RelativeLayout mainLayout = (RelativeLayout)findViewById(R.id.relativeLayout1);
RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(/*up to you*/);
// add here other layout params rules to make your
// custom view stay below the buttons
mCustomDrawableView.setLayoutParams(lp);
mainLayout.addView(mCustomDrawableView);
However you should also consider adding to your custom view this kind of constructor:
public CustomDrawableView(Context context, AttributeSet attrs) {
super(context, attrs);
// add other init stuff
}
so that you can use your custom view into the xml, making it easier to specify layout params, because doing it in code can be boring for a RelativeLayout.

create a class which extends the framelayout class and overwrite the onDraw function
there you can draw everything you want and it will behave like any other view