Develop Reference

Animate ImageView's Bitmap Position

I have an ImageView with width = 1080 and height = 1920
I have a bitmap with width = 3340 and height = 1920
I set the scale type of the imageView to MATRIX. So that the bitmap is not scaled to the imageView
imageView.setScaleType(ImageView.ScaleType.MATRIX);
I would like to animate the bitmap from left to right and vice versa.
Is it possible to be done? Any thoughts?

please create following Custom view class into your project
package com.company.xyz;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
import android.widget.ImageView;
/**
* Created by rohitp on 12/10/2015.
*/
public class CustomImageView extends View {
Bitmap bm;
int x, y;
boolean flag = true;
public CustomImageView(Context context) {
super(context);
}
public CustomImageView(Context context, AttributeSet attrs) {
super(context, attrs);
try{
int src_resource = attrs.getAttributeResourceValue("http://schemas.android.com/apk/res/android", "src", 0);
bm = getDrawable(getResources(),src_resource);
}catch (Exception e){
}
}
public static Bitmap getDrawable(Resources res, int id){
return BitmapFactory.decodeResource(res, id);
}
public void setBm(Bitmap bm) {
this.bm = bm;
}
#Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
super.onDraw(canvas);
if(bm != null){
if(flag){
if (x < (getMeasuredWidth()-bm.getWidth())) {
x += 10;
Log.e("Custom",x+""+getMeasuredWidth());
}
else {
Log.e("Custom",x+" false");
flag = false;
}
}else{
if (x >0 ) {
x -= 10;
Log.e("Custom",x+" -");
}
else {
flag = true;
Log.e("Custom",x+" true");
}
}
canvas.drawBitmap(bm, x, y, new Paint());
}
invalidate();//calls this method again and again
}
}
create an layout xml with following
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<com.company.xyz.CustomImageView
android:layout_width="match_parent"
android:layout_height="100dp"
android:id="#+id/animate_pic"
android:src="#drawable/test">
</com.company.xyz.CustomImageView>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="New Button"
android:id="#+id/button"
android:layout_gravity="bottom"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true" />
</RelativeLayout>
And you can also change bitmap through code at runtime
((CustomImageView) findViewById(R.id.animate_pic)).setBm(bm)

As per an example in this link http://www.sanfoundry.com/java-android-program-animante-bitmap/ you need to move the image using canvas inside onDraw(). So, follow this link, may be this will help you. And let me know for any issues.

draw a line on an image (ImageView)

I have an app that shows an image (ImageView). I want that when I touch the screen on the image, it draws a line in the same point where I touched.
With this code I can't do it but i think that it has a logical thought.
Could you help me please?
Thanks
import android.app.Activity;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.os.Bundle;
import android.view.MotionEvent;
import android.widget.Toast;
public class Cronograma extends Activity{
public boolean touched=false;
public float touched_x=0, touched_y=0;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.cronograma);
}
public void onDraw(Canvas canvas){
Paint pincel = new Paint();
pincel.setColor(Color.BLUE);
pincel.setStrokeWidth(8);
pincel.setStyle(Style.STROKE);
if (touched==true)
canvas.drawLine(touched_x, touched_y, touched_x+5, touched_y, pincel);
}
public boolean onTouchEvent (MotionEvent event){
touched_x = event.getX();
touched_y = event.getY();
int action = event.getAction();
switch (action){
case MotionEvent.ACTION_DOWN:
Toast toast = Toast.makeText(getApplicationContext(), "La coordenada x es " + touched_x + " y la coordenada y es " + touched_y , Toast.LENGTH_SHORT);
toast.show();
touched=true;
break;
}
return false;
}
}

How to add Color Picker in Application?

I have developed an Application , which uses screen as a Slate and finger as a Chalk, which is working properly. But I want to use different color types for chalk.
Here is my Code:
MyDemo.java
package com.example.mydemo;
import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;
public class MyDemo extends Activity {
private LinearLayout root;
private Button btnReset;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my_demo);
root = (LinearLayout) findViewById(R.id.root);
btnReset = (Button) findViewById(R.id.reset);
final MyImageView view = new MyImageView(this);
view.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.FILL_PARENT, LinearLayout.LayoutParams.FILL_PARENT));
root.addView(view);
btnReset.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
view.reset();
}
});
}
}
MyImageView.java
package com.example.mydemo;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PointF;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;
import java.util.ArrayList;
import java.util.List;
public class MyImageView extends ImageView implements View.OnTouchListener {
private int id = -1;
private Path path;
private List<Path> paths = new ArrayList<Path>();
private List<PointF> points = new ArrayList<PointF>();
boolean multiTouch = false;
public MyImageView(Context context) {
super(context);
this.setOnTouchListener(this);
}
public void reset() {
paths.clear();
points.clear();
path = null;
id = -1;
invalidate();
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
Paint paint = createPen(Color.BLACK);
paint.setStyle(Paint.Style.STROKE);
for (Path path : paths) {
canvas.drawPath(path, paint);
}
for (int i = 0; i < points.size(); i++) {
PointF p = points.get(i);
canvas.drawText("" + p.x, p.y, i, createPen(Color.WHITE));
}
}
private PointF copy(PointF p) {
PointF copy = new PointF();
copy.set(p);
return copy;
}
public boolean onTouch(View v, MotionEvent event) {
int action = event.getAction();
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
multiTouch = false;
id = event.getPointerId(0);
PointF p = getPoint(event, id);
path = new Path();
path.moveTo(p.x, p.y);
paths.add(path);
points.add(copy(p));
break;
case MotionEvent.ACTION_POINTER_DOWN:
multiTouch = true;
for (int i = 0; i < event.getPointerCount(); i++) {
int tId = event.getPointerId(i);
if (tId != id) {
points.add(getPoint(event,i));
}
}
break;
case MotionEvent.ACTION_MOVE:
if (!multiTouch) {
p =getPoint(event, id);
path.lineTo(p.x, p.y);
}
break;
}
invalidate();
return true;
}
private PointF getPoint(MotionEvent event, int i) {
int index = 0;
return new PointF(event.getX(index), event.getY(index));
}
private Paint createPen(int color) {
Paint pen = new Paint();
pen.setColor(color);
float width = 3;
pen.setStrokeWidth(width);
return pen;
}
}
activity_my_demo.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout android:id="#+id/root" xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<Button android:id="#+id/reset" android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Reset"
/>
</LinearLayout>
Can any one tell me what should be added or changed in my code so that I can use different colors for Chalk?

You can take the sample in your android folder's..
For the color picker go to in this folder:
android/samples/android-YOURS_VERSION/ApiDemos

Use this, review this code. than your problem will be solve
package com.example.changecolor;
import android.app.Activity;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.graphics.Color;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;
public class MainActivity extends Activity
implements View.OnClickListener, UberColorPickerDialog.OnColorChangedListener {
private int mColor = 0xFFFF0000;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Write the version number
PackageManager pm = getPackageManager();
String versionName = "";
try {
PackageInfo pi = pm.getPackageInfo("com.keithwiley.android.ubercolorpickerdemo", 0);
versionName = pi.versionName;
}
catch (Exception e) {
}
TextView textView = (TextView) findViewById(R.id.version);
textView.setText(versionName);
//Initialize the sample
((LinearLayout) findViewById(R.id.LinearLayout)).setBackgroundColor(mColor);
float hsv[] = new float[3];
Color.colorToHSV(mColor, hsv);
if (UberColorPickerDialog.isGray(mColor))
hsv[1] = 0;
if (hsv[2] < .5)
((TextView) findViewById(R.id.sample)).setTextColor(Color.WHITE);
else ((TextView) findViewById(R.id.sample)).setTextColor(Color.BLACK);
//Set up the buttons
Button button = (Button) findViewById(R.id.colorPickerWithTitle);
button.setOnClickListener(this);
button = (Button) findViewById(R.id.colorPickerWithToast);
button.setOnClickListener(this);
}
protected void onPause() {
super.onPause();
}
protected void onResume() {
super.onResume();
}
public boolean onCreateOptionsMenu(Menu menu) {
super.onCreateOptionsMenu(menu);
return true;
}
public boolean onPrepareOptionsMenu(Menu menu) {
super.onPrepareOptionsMenu(menu);
return true;
}
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
}
return super.onOptionsItemSelected(item);
}
public void onClick(View v) {
if (v.getId() == R.id.colorPickerWithTitle)
new UberColorPickerDialog(this, this, mColor, true).show();
if (v.getId() == R.id.colorPickerWithToast)
new UberColorPickerDialog(this, this, mColor, false).show();
}
public void colorChanged(int color) {
((LinearLayout) findViewById(R.id.LinearLayout)).setBackgroundColor(mColor=color);
float hsv[] = new float[3];
Color.colorToHSV(mColor, hsv);
//if (UberColorPickerDialog.isGray(mColor))
// hsv[1] = 0;
if (hsv[2] < .5)
((TextView) findViewById(R.id.sample)).setTextColor(Color.WHITE);
else ((TextView) findViewById(R.id.sample)).setTextColor(Color.BLACK);
}
}
And use the color picker class

How to Draw something with your finger in an Android App.... And save it to the web

**THIS QUESTION WAS SUCCESSFULLY ANSWERED AND HAS BECOME A BLOG POST <- click **
Hi I am a PHP developer I want to do a simple thing - I want to draw something drawn on a blank page on an Android Phone (with a finger with a largeish "emulated pen nib") and store the bitmap as a jpeg on a server by http post.
Here is what I have so far but this is taken from a tutorial that is involved with writing sprites for a game.. And I cant' adapt it
package com.my.example;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.View.OnTouchListener;
public class DrawCapture extends Activity implements OnTouchListener{
OurView v;
Bitmap ball;
float x,y;
#Override
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.draw_capture);
v = new OurView(this);
v.setOnTouchListener(this);
ball = BitmapFactory.decodeResource(getResources(), R.drawable.blueball);
x = y = 0;
setContentView(v);
}
#Override
protected void onPause(){
super.onPause();
v.pause();
}
protected void onResume(){
super.onResume();
v.resume();
}
public class OurView extends SurfaceView implements Runnable{
Thread t = null;
SurfaceHolder holder;
boolean isItOK = false;
public OurView(Context context) {
super(context);
holder = getHolder();
}
public void run() {
while (isItOK == true){
try {
Thread.sleep(50);
} catch (InterruptedException e) {
e.printStackTrace();
}
//perform canvas drawing
if (!holder.getSurface().isValid()){
continue;
}
Canvas c = holder.lockCanvas();
onDraw(c);
holder.unlockCanvasAndPost(c);
}
}
public void onDraw(Canvas c){
c.drawARGB(255, 210, 210, 210);
c.drawBitmap(ball, x - (ball.getWidth()/2), y - (ball.getHeight()/2), null);
}
public void pause(){
isItOK = false;
while(true){
try{
t.join();
} catch(InterruptedException e){
e.printStackTrace();
}
break;
}
t = null;
}
public void resume(){
isItOK = true;
t = new Thread(this);
t.start();
}
}
public boolean onTouch(View v, MotionEvent me){
switch (me.getAction()){
case MotionEvent.ACTION_DOWN :
x = me.getX();
y = me.getY();
break;
case MotionEvent.ACTION_UP :
x = me.getX();
y = me.getY();
break;
case MotionEvent.ACTION_MOVE :
x = me.getX();
y = me.getY();
break;
}
return true;
}
}
and here is the XML
<?xml version="1.0" encoding="utf-8"?>
<SurfaceView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
</SurfaceView>
Can someone please help me? I feel I am close - I use the blueball as a pen nib I just want to "save" this and possibly I'll need to have a button (or menu) on the XML page to do this ? I know it's a bit of a beg but there are a lot of people online asking how to draw with your finger and save something to the "cloud" if people could respond with examples of the code (not references) I promise I will compile this into a proper tutorial piece of code for the eventual benefit of all. Including the PHP server side code that I already am really happy with.

You can try to use the Gesture Object proposed by Google, try to execute my following code :
Activity1 xml :
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#FFFFFF" >
<android.gesture.GestureOverlayView
android:id="#+id/gestures"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:fadeEnabled="false"
android:fadeOffset="5000000000"
android:gestureColor="#000000"
android:gestureStrokeType="multiple"
android:gestureStrokeWidth="1"
android:uncertainGestureColor="#000000"
android:layout_above="#+id/save_button" />
<Button
android:id="#id/save_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="20sp"
android:paddingLeft="20sp"
android:paddingRight="20sp"
android:text="Save"
android:textSize="22sp" />
</RelativeLayout>
Activity1 java :
package com.testandroidproject;
import java.io.ByteArrayOutputStream;
import android.app.Activity;
import android.content.Intent;
import android.gesture.GestureOverlayView;
import android.graphics.Bitmap;
import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;
public class Activity1 extends Activity {
private Button button_save;
private GestureOverlayView gesture;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
gesture = (GestureOverlayView) findViewById(R.id.gestures);
button_save = (Button) findViewById(R.id.save_button);
button_save.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
try {
Bitmap gestureImg = gesture.getGesture().toBitmap(100, 100,
8, Color.BLACK);
ByteArrayOutputStream bos = new ByteArrayOutputStream();
gestureImg.compress(Bitmap.CompressFormat.PNG, 100, bos);
byte[] bArray = bos.toByteArray();
Intent intent = new Intent(Activity1.this, Activity2.class);
intent.putExtra("draw", bArray);
startActivity(intent);
} catch (Exception e) {
e.printStackTrace();
Toast.makeText(Activity1.this, "No draw on the string",
3000).show();
}
}
});
}
}
Activity2 xml :
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#FFFFFF"
android:orientation="vertical" >
<ImageView
android:id="#+id/image_saved"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal" />
</LinearLayout>
Activity2 java :
package com.testandroidproject;
import java.io.ByteArrayInputStream;
import android.app.Activity;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.widget.ImageView;
public class Activity2 extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.display_image);
ImageView image = (ImageView) findViewById(R.id.image_saved);
ByteArrayInputStream imageStreamClient = new ByteArrayInputStream(
getIntent().getExtras().getByteArray("draw"));
image.setImageBitmap(BitmapFactory.decodeStream(imageStreamClient));
}
}
Hope you will find this helpful.

I'm not sure what part of the "save" you are trying to accomplish, but I'll assume you're asking how to store what you've drawn on the canvas to a bitmap.
First, make yourself a bitmap to draw into. Say, canvasBitmap. Then:
c.setBitmap(canvasBitmap);
This will store everything that has been drawn into 'canvasBitmap.' Then, when the user presses a button to save:
savedBitmap = Bitmap.copy(canvasBitmap.getConfig(), true);
Now, take savedBitmap and fire it off into the cloud. Hope that helps.

How to clear canvas in a surface view?

I am developing an Android Digital signature app in which user can sign and i have to save this file as image.i am using SurfaceView for drawing. DigitalSignatureActivity has two Buttons Save,Clear.
1.Save Button to save file as image
2.Clear Button to clear surface.
But i am unable to clear the surface.i tried drawingSurface.setBackgroundColor(Color.BLACK); still previous sign is retained and canvas.drawColor(Color.BLACK); has no effect and
i am able to save file but its not storing signature perfectly(Some contents are missing) please help.
My code is:
DigitalSignatureActivity.java
package com.pop.digitalsign;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.os.Bundle;
import android.os.Environment;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Toast;
public class DigitalSignatureActivity extends Activity implements
View.OnTouchListener {
private DrawingSurface drawingSurface;
private DrawingPath currentDrawingPath;
private Paint currentPaint;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
setCurrentPaint();
drawingSurface = (DrawingSurface) findViewById(R.id.drawingSurface);
drawingSurface.setOnTouchListener(this);
}
private void setCurrentPaint() {
currentPaint = new Paint();
currentPaint.setDither(true);
currentPaint.setColor(Color.WHITE);
currentPaint.setStyle(Paint.Style.STROKE);
currentPaint.setStrokeJoin(Paint.Join.ROUND);
currentPaint.setStrokeCap(Paint.Cap.ROUND);
currentPaint.setStrokeWidth(2);
}
public boolean onTouch(View view, MotionEvent motionEvent) {
if (motionEvent.getAction() == MotionEvent.ACTION_DOWN) {
drawingSurface.setBackgroundColor(0);
currentDrawingPath = new DrawingPath();
currentDrawingPath.paint = currentPaint;
currentDrawingPath.path = new Path();
currentDrawingPath.path.moveTo(motionEvent.getX(),
motionEvent.getY());
currentDrawingPath.path.lineTo(motionEvent.getX(),
motionEvent.getY());
} else if (motionEvent.getAction() == MotionEvent.ACTION_MOVE) {
currentDrawingPath.path.lineTo(motionEvent.getX(),motionEvent.getY());
drawingSurface.addDrawingPath(currentDrawingPath);
} else if (motionEvent.getAction() == MotionEvent.ACTION_UP) {
currentDrawingPath.path.lineTo(motionEvent.getX(),motionEvent.getY());
}
return true;
}
//To save file as Image
public void saveDrawing(View v) throws IOException {
File mediaStorageDir = new File(
Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES),
"MySignatures");
Bitmap nBitmap = drawingSurface.getBitmap();
try {
if (!mediaStorageDir.exists()) {
mediaStorageDir.mkdirs();
}
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss")
.format(new Date());
File mediaFile = new File(mediaStorageDir.getPath()
+ File.separator + "SIGN_" + timeStamp + ".png");
FileOutputStream out = new FileOutputStream(mediaFile);
nBitmap.compress(Bitmap.CompressFormat.PNG, 90, out);
out.flush();
out.close();
Toast.makeText(this, "Signature saved to " + mediaFile,
Toast.LENGTH_LONG).show();
} catch (Exception e) {
e.printStackTrace();
Toast.makeText(getApplicationContext(), "Not saved",
Toast.LENGTH_SHORT).show();
}
}
//To clear Surface
public void clearScreen(View v) {
//drawingSurface.setBackgroundColor(Color.BLACK);
drawingSurface.clear();
}
}
DrawingSurface.java
package com.pop.digitalsign;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.PorterDuff;
import android.util.AttributeSet;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
public class DrawingSurface extends SurfaceView implements SurfaceHolder.Callback {
private Boolean _run;
protected DrawThread thread;
private Bitmap mBitmap;
Canvas canvas;
private CommandManager commandManager;
public DrawingSurface(Context context, AttributeSet attrs) {
super(context, attrs);
getHolder().addCallback(this);
commandManager = new CommandManager();
thread = new DrawThread(getHolder());
}
class DrawThread extends Thread{
public SurfaceHolder mSurfaceHolder;
public DrawThread(SurfaceHolder surfaceHolder){
mSurfaceHolder = surfaceHolder;
}
public DrawThread() {
// TODO Auto-generated constructor stub
}
public void setRunning(boolean run) {
_run = run;
}
#Override
public void run() {
canvas = null;
while (_run){
try{
canvas = mSurfaceHolder.lockCanvas(null);
//canvas.drawColor(Color.WHITE);
if(mBitmap == null){
mBitmap = Bitmap.createBitmap (1, 1, Bitmap.Config.ARGB_8888);;
}
final Canvas c = new Canvas (mBitmap);
c.drawColor(0, PorterDuff.Mode.CLEAR);
commandManager.executeAll(c);
canvas.drawBitmap (mBitmap, 0, 0,null);
} finally {
if(canvas!=null){
mSurfaceHolder.unlockCanvasAndPost(canvas);
}
}
}
}
}
public void addDrawingPath (DrawingPath drawingPath){
commandManager.addCommand(drawingPath);
}
public void clear(){
//Here i want to clear surface
canvas.drawColor(Color.BLACK);//it has no effect
}
public boolean hasMoreUndo(){
return commandManager.hasMoreUndo();
}
public Bitmap getBitmap(){
return mBitmap;
}
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
mBitmap = Bitmap.createBitmap (width, height, Bitmap.Config.ARGB_8888);;
}
public void surfaceCreated(SurfaceHolder holder) {
thread.setRunning(true);
thread.start();
}
public void surfaceDestroyed(SurfaceHolder holder) {
boolean retry = true;
thread.setRunning(false);
while (retry) {
try {
thread.join();
retry = false;
} catch (InterruptedException e) {
}
}
}
}
CommandManager.java
package com.pop.digitalsign;
import android.graphics.Canvas;
import java.util.Iterator;
import java.util.List;
import java.util.Collections;
import java.util.ArrayList;
public class CommandManager {
private List<DrawingPath> currentStack;
public CommandManager(){
currentStack = Collections.synchronizedList(new ArrayList<DrawingPath>());
}
public void addCommand(DrawingPath command){
currentStack.add(command);
}
public void undo (){
final int length = currentStackLength();
if ( length > 0) {
final DrawingPath undoCommand = currentStack.get( length - 1 );
currentStack.remove( length - 1 );
undoCommand.undo();
}
}
public int currentStackLength(){
final int length = currentStack.toArray().length;
return length;
}
public void executeAll( Canvas canvas){
if( currentStack != null ){
synchronized( currentStack ) {
final Iterator<?> i = currentStack.iterator();
while ( i.hasNext() ){
final DrawingPath drawingPath = (DrawingPath) i.next();
drawingPath.draw( canvas );
}
}
}
}
public boolean hasMoreUndo(){
return currentStack.toArray().length > 0;
}
}
DrawingPath.java
package com.pop.digitalsign;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Path;
public class DrawingPath {
public Path path;
public Paint paint;
public void draw(Canvas canvas) {
canvas.drawPath( path, paint );
}
public void undo() {
}
}
main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
android:background="#android:color/white" >
<com.pop.digitalsign.DrawingSurface
android:id="#+id/drawingSurface"
android:layout_width="match_parent"
android:layout_height="match_parent"
/>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:gravity="center" >
<Button
android:id="#+id/saveBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="saveDrawing"
android:text="#string/save" />
<Button
android:id="#+id/clearBtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="clearScreen"
android:text="#string/clear" />
</LinearLayout>
</RelativeLayout>

the best suggestion i have is to use this
if (surfaceHolder.getSurface().isValid()) {
Canvas c = surfaceHolder.lockCanvas();
if (first >= 0) {
c.drawARGB(255, 255, 255, 255);
first--;
}
The value of first is 2 you can use what every name you want.
The reason is that the canvas is double buffered so you need to clear both screen by painting it white.
This stops the flickering

canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR)

In DrawingSurface add this method
public void resetCanvas(){ commandManager.clearAllPath(); }
and call this method, when you need to action for clear..
objectNameofDrawingSurefaceClass.resetCanvas();
add the code in CommandManager
public void clearAllPath(){currentStack.clear(); }
ok..