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Full screen image using canvas and bitmap

I am tryin to set an image in full screen using canvas and bitmap but whenever I load the app the image gets zoomed in and only displays half of what it's supposed to. How would I do this? I have attached my code snippet and i have tried updating the canvas.drawbitmap line of code inside the onDraw method but it doesn't help, the image still appears zoomed in. Some help would greatly be appreciated thank you in advance...
public class Fish extends View {
private Bitmap fish [] =new Bitmap[2];
private int fishX=10;
private int fishY;
private int fishSpeed;
private int canvasWidth, canvasHeight;
private int yellowX, yellowY, yellowSpeed=16;
private Paint yellowPaint=new Paint();
private int greenX, greenY, greenSpeed=20;
private Paint greenPaint=new Paint();
private int redX, redY, redSpeed=25;
private Paint redPaint=new Paint();
private int score, lifeCountOfLife;
private boolean touch=false;
private Bitmap backgroundImage;
private Paint scorePaint= new Paint();
private Bitmap life[]=new Bitmap[2];
//updates the background
public Fish(Context context) {
super(context);
fish [0]=BitmapFactory.decodeResource(getResources(),R.drawable.fish1);
fish [1]=BitmapFactory.decodeResource(getResources(),R.drawable.fish2);
//updates the bg
backgroundImage=BitmapFactory.decodeResource(getResources(),R.drawable.mn);
//creates the ball/foood color
yellowPaint.setColor(Color.YELLOW);
yellowPaint.setAntiAlias(false);
greenPaint.setColor(Color.GREEN);
greenPaint.setAntiAlias(false);
redPaint.setColor(Color.RED);
redPaint.setAntiAlias(false);
// updates score
scorePaint.setColor(Color.WHITE);
scorePaint.setTextSize(70);
scorePaint.setTypeface(Typeface.DEFAULT_BOLD);
scorePaint.setAntiAlias(true);
//displays the heart and life
life[0]=BitmapFactory.decodeResource(getResources(),R.drawable.heartts);
life[1]=BitmapFactory.decodeResource(getResources(),R.drawable.greyheart);
fishY=550;
score=0;
lifeCountOfLife=3;
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvasWidth=canvas.getWidth();
canvasHeight=canvas.getHeight();
//displays it to the main actiivty
canvas.drawBitmap(backgroundImage,canvasWidth,canvasHeight,null);
int minFish= fish[0].getHeight();
int maxFishY=canvasHeight-fish[0].getHeight() *3;
fishY=fishY+fishSpeed;
if(fishY<minFish){
fishY=minFish;
}
if(fishY> maxFishY){
fishY=maxFishY;
}
fishSpeed=fishSpeed+2;
if(touch){
canvas.drawBitmap(fish[1], fishX,fishY, null);
touch=false;
}else{
canvas.drawBitmap(fish[0],fishX,fishY,null);
}
yellowX=yellowX-yellowSpeed;
//updates the score if the ball is collected
if(hitBallChecker(yellowX,yellowY)){
score=score+10;
yellowX=-100;
}
if(yellowX<0){
yellowX=canvasWidth+21;
yellowY=(int) Math.floor(Math.random() * (maxFishY-minFish))+ minFish;
}
//increases size of ball
canvas.drawCircle(yellowX, yellowY, 25, yellowPaint);
//Green ball
greenX=greenX-greenSpeed;
if(hitBallChecker(greenX,greenY)){
score=score+20;
greenX=-100;
}
if(greenX<0){
greenX=canvasWidth+21;
greenY=(int) Math.floor(Math.random() * (maxFishY-minFish))+ minFish;
}
//increases size of ball
canvas.drawCircle(greenX, greenY, 25, greenPaint);
//red ball
//if the ball gets hit
redX=redX-redSpeed;
if(hitBallChecker(redX,redY)){
redX=-100;
lifeCountOfLife--;
if(lifeCountOfLife==0){
Intent gameOverIntent= new Intent(getContext(), GameOverActivity.class);
gameOverIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);
gameOverIntent.putExtra("score", score);
getContext().startActivity(gameOverIntent);
}
}
//increases size of ball
if(redX<0){
redX=canvasWidth+21;
redY=(int) Math.floor(Math.random() * (maxFishY-minFish))+ minFish;
}
canvas.drawCircle(redX, redY, 30, redPaint);
canvas.drawText("Score: " +score, 20, 60, scorePaint);
for(int i=0; i<3; i++){
int x=(int) (580+life[0].getWidth() * 1.5 * i);
int y=30;
if(i<lifeCountOfLife){
canvas.drawBitmap(life[0], x,y, null);
}else{
canvas.drawBitmap(life[1], x,y, scorePaint);
}
}
}
public boolean hitBallChecker(int x, int y){
if(fishX< x && x<(fishX+fish[0].getWidth()) &&fishY<y &&y<(fishY+ fish[0].getHeight())){
return true;
}
return false;
}
//updates fish speed
#Override
public boolean onTouchEvent(MotionEvent event) {
if(event.getAction()==MotionEvent.ACTION_DOWN){
touch=true;
fishSpeed=-22;
}
return true;
}
}

public void drawBitmap (Bitmap bitmap,
float left,
float top,
Paint paint)
In drawBitmap left and top define the (x,y) of the top left corner of the image, which in your case should be (0,0).
If you want to draw a canvas sized backgound it would probably be best to use:
public void drawBitmap (Bitmap bitmap,
Rect src,
Rect dst,
Paint paint)
Where src is the Rect that defines the subset of the Bitmap that you want to draw (you can leave it at null to draw the entire Bitmap), and dst is the destination Rect that will automatically be filled with the Bitmap.
You are going to need to define the destination Rect:
Rect backgroundRect = new Rect(0, 0, canvas.getWidth(), canvas.getHeight());
You can now call
canvas.drawBitmap(backgroundImage,null,backgroundRect,null);

How to draw different points with canvas in Android

I'm developing an Android application, I have to implement a function that allow me to draw different point in an activity.
This is my code:
public class MainActivity extends AppCompatActivity {
public Paint paint;
public List<Point> coords;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new DrawingView(this));
paint = new Paint();
coords = new ArrayList();
ImageView iv = new ImageView(getApplicationContext());
iv.setImageResource(R.drawable.car);
iv.setScaleType(ImageView.ScaleType.CENTER_INSIDE);
LinearLayout.LayoutParams parms = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT,LinearLayout.LayoutParams.MATCH_PARENT);
iv.setLayoutParams(parms);
}
class DrawingView extends SurfaceView {
private final SurfaceHolder surfaceHolder;
private final Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
public DrawingView(Context context) {
super(context);
surfaceHolder = getHolder();
paint.setColor(Color.BLACK);
paint.setStyle(Paint.Style.FILL);
}
#Override
public boolean onTouchEvent(MotionEvent event) {
if(event.getAction() == MotionEvent.ACTION_DOWN) {
addpoint(event.getX(), event.getY());
}
return false;
}
public void addpoint(float x, float y){
Point point = new Point();
point.x = Math.round(x);
point.y = Math.round(y);
coords.add(point);
for(int i = 0; i< coords.size(); i++) {
Canvas canvas = surfaceHolder.lockCanvas();
canvas.drawColor(Color.WHITE);
canvas.drawCircle(coords.get(i).x, coords.get(i).y, 20, paint);
surfaceHolder.unlockCanvasAndPost(canvas);
}
}
}
}
Everytime that I touch the screen I get and save the coordinates in a list, then I try to draw the list of point, but only one point remain on the screen, I don't understand why.
So how I can draw different point on the screen (and save it) ?
Another question: how I can show a background image ?

From the official Javadocs:
drawColor(int color) Fill the entire canvas' bitmap (restricted to the
current clip) with the specified color, using srcover porterduff mode.
So every time you draw a circle, first you clear the whole canvas with white color. So after a draw, the circle drawed before is cleared.
So one option is to save the current state of the background, and always draw it on top of the white, or try not using drawColor

for(int i = 0; i< coords.size(); i++) {
Canvas canvas = surfaceHolder.lockCanvas();
canvas.drawColor(Color.WHITE);
canvas.drawCircle(coords.get(i).x, coords.get(i).y, 20, paint);
surfaceHolder.unlockCanvasAndPost(canvas);
}
should be
Canvas canvas = surfaceHolder.lockCanvas();
canvas.drawColor(Color.WHITE);
for(int i = 0; i< coords.size(); i++) {
canvas.drawCircle(coords.get(i).x, coords.get(i).y, 20, paint);
}
surfaceHolder.unlockCanvasAndPost(canvas);
canvas.drawColor(Color.WHITE); Everytime ereases all the canvas and surfaceHolder.unlockCanvasAndPost(canvas); shows only the last added Circle

How to erase image with finger in Android

I'm developing an app that need the feature in object.
I have an Image A that cover an Image B. With finger I need to erase the Image A to show the Image B.
Erase must follow your finger flowing image A
I'm trying some code but still I couldn't erase the image A. this is the code that i'm using to draw a line on image (_imageToErase is Image A):
Canvas canvas;
Paint paint;
float downx = 0, downy = 0, upx = 0, upy = 0;
ImageView _imageToErase;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.g_layout);
_imageToErase = (ImageView) findViewById(R.id.image_to_erase);
_imageToErase.setOnTouchListener(this);
}
#Override
public void onWindowFocusChanged(boolean hasFocus){
int width = _imageToErase.getWidth();
int height = _imageToErase.getHeight();
Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
canvas = new Canvas(bitmap);
paint = new Paint();
paint.setColor(Color.WHITE);
paint.setStrokeWidth(25);
paint.setAntiAlias(true);
_imageToErase.setImageBitmap(bitmap);
}
public boolean onTouch(View v, MotionEvent event) {
int action = event.getAction();
switch (action){
case MotionEvent.ACTION_DOWN:
downx = event.getX();
downy = event.getY();
break;
case MotionEvent.ACTION_MOVE:
upx = event.getX();
upy = event.getY();
canvas.drawLine(downx, downy, upx, upy, paint);
_imageToErase.invalidate();
downx = upx;
downy = upy;
break;
case MotionEvent.ACTION_UP:
break;
case MotionEvent.ACTION_CANCEL:
break;
default:
break;
}
return true;
}
This code produce only a line that follow the finger but not erase the image.
How to modify this code to erase the image? Thanks
EDIT
The link suggested in comments not solved my problem. Simply add this line:
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_OUT));
not work for me.

PaintView.java
public class PaintView extends View implements View.OnTouchListener {
private static final String TAG = "PaintView";
Bitmap Bitmap1, Bitmap2;
Bitmap Transparent;
int X = -100;
int Y = -100;
Canvas c2;
private boolean isTouched = false;
Paint paint = new Paint();
Path drawPath = new Path();
public PaintView(Context context) {
super(context);
setFocusable(true);
setFocusableInTouchMode(true);
this.setOnTouchListener(this);
DisplayMetrics metrics = context.getResources().getDisplayMetrics();
int width = metrics.widthPixels;
int height = metrics.heightPixels;
Transparent = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
Bitmap1 = BitmapFactory.decodeResource(getResources(), R.drawable.cake1);
Bitmap2 = BitmapFactory.decodeResource(getResources(), R.drawable.cake2);
c2 = new Canvas();
c2.setBitmap(Transparent);
c2.drawBitmap(Bitmap2, 0, 0, paint);
paint.setAlpha(0);
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeJoin(Paint.Join.ROUND);
paint.setStrokeCap(Paint.Cap.ROUND);
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
paint.setAntiAlias(true);
}
private static Point getDisplaySize(final Display display) {
final Point point = new Point();
point.x = display.getWidth();
point.y = display.getHeight();
return point;
}
#Override
protected void onDraw(Canvas canvas) {
System.out.println("onDraw");
if(isTouched)
{
canvas.drawBitmap(Bitmap1, 0, 0, null);
}
canvas.drawBitmap(Transparent, 0, 0, null);
}
#Override
public boolean onTouch(View v, MotionEvent event) {
isTouched = true;
X = (int) event.getX();
Y = (int) event.getY();
paint.setStrokeWidth(60);
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
drawPath.moveTo(X, Y);
c2.drawPath(drawPath, paint);
break;
case MotionEvent.ACTION_MOVE:
drawPath.lineTo(X, Y);
c2.drawPath(drawPath, paint);
break;
case MotionEvent.ACTION_UP:
drawPath.lineTo(X, Y);
c2.drawPath(drawPath, paint);
drawPath.reset();
count=0;
break;
default:
return false;
}
invalidate();
return true;}}class Point {
float x, y;
#Override
public String toString() {
return x + ", " + y;
}}
MainActivity.java
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new PaintView(this));
}}

Finally I found a library that works very well for me and implementation is pretty simple
https://github.com/winsontan520/Android-WScratchView
Import library in your project and then in layout.xml
<com.winsontan520.WScratchView
android:layout_width="287dp"
android:layout_height="212dp"
android:layout_centerHorizontal="true"
android:layout_marginTop="80dp"
android:adjustViewBounds="true"
android:scaleType="centerInside"
android:id="#+id/image_to_erase"/>
in onCreate:
_imageToErase = (WScratchView) findViewById(R.id.image_to_erase);
Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.img_erase);
_imageToErase.setScratchBitmap(bitmap);
_imageToErase.setOnScratchCallback(new WScratchView.OnScratchCallback() {
#Override
public void onScratch(float percentage) {
updatePercentage(percentage);
}
#Override
public void onDetach(boolean fingerDetach) {
if (mPercentage > 40) {
_imageToErase.setScratchAll(true);
updatePercentage(100);
}
}
});
and
private void updatePercentage(float percentage) {
mPercentage = percentage;
// System.out.println("percentage = "+percentage);
}
Thanks everybody

How to extract the Bitmap out of the onDraw() method of a View?

How can I extract a Bitmap object out of my onDraw() routine in my CustomView?
Here is my code:
public class DrawView extends View {
private Paint paint = new Paint();
private Point point;
private LinkedList<Point> listaPontos;
private static Context context;
class Point {
public Point(float x, float y) {
this.x = x;
this.y = y;
}
float x = 0;
float y = 0;
}
public DrawView(Context context) {
super(context);
this.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,ViewGroup.LayoutParams.MATCH_PARENT));
this.context = context;
paint.setColor(Color.YELLOW);
this.listaPontos = new LinkedList<Point>();
}
#Override
public void onDraw(Canvas canvas) {
if(listaPontos.size() != 0){
for(Point point : listaPontos){
canvas.drawCircle(point.x, point.y, 25, paint);
}
}
calculateAmount(canvas);
}
private void calculateAmount(Canvas canvas) {
LinkedList<Integer> colors = new LinkedList<Integer>();
for(int i = 0 ; i != canvas.getWidth(); i++)
{
for(int j = 0; j != canvas.getHeight(); j++){
int color = BITMAP.getPixel(i,j); //How can I get the bitmap generated on onDraw ?
colors.add(color);
}
}
int yellow = 0;
int white = 0;
for(Integer cor : colors) {
if(cor == Color.WHITE) {
white++;
}
if(cor == Color.YELLOW) {
yellow++;
}
}
}
#Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_MOVE:
listaPontos.add(new Point(event.getX(), event.getY()));
break;
}
invalidate();
return true;
}
}
Thanks alot in advance ;)
EDIT: The bitmap thing is to calculate each pixel color, how can I add a background image to my DrawView ? I tested this.setBackgroundResource(R.drawable.a); at constructor but didn't work, thanks again ;)

There is no way to extract a Bitmap out of a Canvas. At least not directly.
However, it is possible to draw on a Bitmap with the Canvas and then use the Bitmap.
Bitmap mDrawBitmap;
Canvas mBitmapCanvas;
Paint drawPaint = new Paint();
#Override
public void onDraw(Canvas canvas) {
drawPaint.setColor(Color.RED);
if (mDrawBitmap == null) {
mDrawBitmap = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_8888);
mBitmapCanvas = new Canvas(mDrawBitmap);
}
// clear previously drawn stuff
mBitmapCanvas.drawColor(Color.WHITE);
// draw on the btimapCanvas
mBitmapCanvas.drawStuff(...);
//... and more
// after drawing with the bitmapcanvas,
//all drawn information is stored in the Bitmap
// draw everything to the screen
canvas.drawBitmap(mDrawBitmap, 0, 0, drawPaint);
}
After the onDraw() method has finished, all drawn information will be drawn on the screen (by calling canvas.drawBitmap(...), and also be stored in your Bitmap object (because all draw operations have been done on the Canvas that was created with the Bitmap).

How to make black background and red color for drawing?

I have been developing the application for drawing. I have following code for main activity:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
Display display = getWindow().getWindowManager().getDefaultDisplay();
mMainView = new MyView(this, display.getWidth(), display.getHeight());
setContentView(mMainView);
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);
mEmboss = new EmbossMaskFilter(new float[] { 1, 1, 1 }, 0.4f, 6, 3.5f);
mBlur = new BlurMaskFilter(8, BlurMaskFilter.Blur.NORMAL);
}
And code for my custom view for drawing:
public class MyView extends View {
private static final float TOUCH_TOLERANCE = 4;
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;
private float mX, mY;
public MyView(Context context, int width, int height) {
super(context);
this.setDrawingCacheEnabled(true);
mBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
mCanvas = new Canvas(mBitmap);
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);
}
#Override
protected void onDraw(Canvas canvas) {
canvas.drawColor(0xFF000000);
canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
canvas.drawPath(mPath, mPaint);
}
public void clearView() {
mBitmap.eraseColor(Color.TRANSPARENT);
}
public Bitmap getState() {
return mBitmap;
}
private void touchStart(float x, float y) {
mPath.reset();
mPath.moveTo(x, y);
mX = x;
mY = y;
}
private void touchMove(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 touchUp() {
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:
touchStart(x, y);
invalidate();
break;
case MotionEvent.ACTION_MOVE:
touchMove(x, y);
invalidate();
break;
case MotionEvent.ACTION_UP:
touchUp();
invalidate();
break;
}
return true;
}
}
So, because if I try to save resulted bitmap as jpeg file using bitmap compress then all is good, but if I try to save as png file I will get file with transparent background (white) and red picture. I need that I can save using JPEG/PNG with black background and red picture. Code for saving is good, don't worry. Thank you.

you can draw a black rectangle on the bitmap, like so:
Bitmap myBitmap = Bitmap.createBitmap(width, height, ...);
Canvas mCanvas = new Canvas(myBitmap);
// create a black rectangle
final int color = 0xffffffff;
final Paint p1 = new Paint();
final Rect rect = new Rect(0, 0, width, height);
final RectF rectF = new RectF(rect);
// draw it to the canvas
mCanvas.drawARGB(0, 0, 0, 0);
p1.setColor(color);
mCanvas.drawRect(rectF, p1);
That should force a black background, and you can overlay additional bitmaps on the canvas, and finally use myBitmap to export as png.
I think the black background you have now is a jpeg default, since it does not have transparency.