Develop Reference

Getting surfaceview's height and width while implementing runnable

I've read many threads here which discuss how to get view size at runtime yet none of the solutions have worked for me.
GameScreen.java
public class GameScreen extends AppCompatActivity{
// Declare an instance of SnakeView
GameView snakeView;
SurfaceHolder surface;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_game_screen);
snakeView = (GameView) findViewById(R.id.GameView);
surface = snakeView.getHolder();
snakeView = new GameView(this, surface);
}
where GameView is a view class extending surfaceview. The following is a simplified version of my code detailing the issue. I've omitted the run() method and many others to avoid confusion.
GameView.java
public class GameView extends SurfaceView implements Runnable {
public GameView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}
public GameView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public GameView(Context context, SurfaceHolder surfaceholder) {
super(context);
init();
m_context = context;
// Initialize the drawing objects
m_Holder = surfaceholder;
m_Paint = new Paint();
}
private void init(){
surfaceHolder = getHolder();
surfaceHolder.addCallback(new SurfaceHolder.Callback() {
#Override
public void surfaceCreated(SurfaceHolder holder) {
}
#Override
public void surfaceChanged(SurfaceHolder holder,
int format, int width, int height) {
m_Screenheight = height;
m_Screenwidth = width;
}
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub
}
});
}
However calling getWidth() and getHeight() causes the app to crash.
I know that you have to wait for the view to layout but I've tried all the suggestions but I've tried all the suggestions from other threads to no avail.
My main lack of understanding comes from the fact that I am using implements Runnable in my custom class so I'm not sure where I am allowed to use getWidth or a similar method. I'm new to android in general so please be explicit in your solution.
EDIT:
I should mention that I am using the width and height to form a grid to draw in the surfaceview.
EDIT 2:
See revised code.

If your surface is full screen, you can get the screen sizes.
public GameView(Context context, SurfaceHolder surfaceholder) {
super(context);
init();
m_context = context;
// Initialize the drawing objects
m_Holder = surfaceholder;
m_Paint = new Paint();
DisplayMetrics displayMetrics = new DisplayMetrics();
((Activity)context).getWindowManager()
.getDefaultDisplay()
.getMetrics(displayMetrics);
int height = displayMetrics.heightPixels;
int width = displayMetrics.widthPixels;
m_ScreenHeight= height;
m_ScreenWidth= width;
}

Can't set view params to WRAP_CONTENT programatically

I am trying to set a custom view to wrap_content in both height and width programatically. The problem is that no matter what i do it is always presented as match_parent.
This is the view
public class Circle extends View
{
public Circle(Context context) {
super(context);
}
public Circle(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
}
public Circle(Context context, AttributeSet attrs) {
super(context, attrs);
}
protected void onDraw(Canvas canvas)
{
super.onDraw(canvas);
Paint paint = new Paint();
paint.setColor(0xffff0000);
canvas.drawCircle(mmToPx(4), mmToPx(4), mmToPx(4), paint);
}
public float mmToPx(int mm) {
DisplayMetrics displayMetrics = this.getResources().getDisplayMetrics();
return mm * displayMetrics.xdpi * (1.0f/25.4f);
}
this is the main code
public void addCircle()
{
Circle circle = new Circle(this);
Random r = new Random();
FrameLayout.LayoutParams cParams = new FrameLayout.LayoutParams(-1, -2);
cParams.setMargins(r.nextInt((int) (w - (mmToPx(diam)))), r.nextInt((int) (h - (mmToPx(diam)))), 0, 0);
circle.setLayoutParams(cParams);
circle.setBackgroundColor(0xff00ff00);
Log.v("sd", circle.getLayoutParams().width + "");
circle.setId(R.id.circle);
circle.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
count++; scoreTv.setText("Score:\n"+count);
frame.removeView(findViewById(R.id.circle));
addCircle();
}
});
frame.addView(circle);
}
Thank you for help :)

First- NEVER use magic numbers like -2. Use ViewGroup.LayoutParams.WRAP_CONTENT. Otherwise your code becomes difficult to read and may contain bugs (for example, if they changed the value).
Second- you aren't actually using cParams anywhere. You want to use the version of addView that takes the view and the layout params. Otherwise how will it know to use those layout params with that view.
Third- you don't have an onMeasure function in your view. Without that, how will it know how big your view is so it can actually wrap content on it? You'll need to define onMeasure so it can get the width and height of your view.

try this:
view.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT))

Canvas is not working on Android latest version 4+

I want create layer on top of the activity layout and I need make hole like rectangle or circle, something like the attached image. I did this by using SurfaceView and its working fine on lower version on android but not on version 4+
[Sample screen shot] (https://docs.google.com/file/d/0B3yZokwUGKFgTkM1ek1nZHNyZ2s/edit?usp=sharing)
My code is
public class SurfacePanel extends SurfaceView implements SurfaceHolder.Callback{
public SurfacePanel(Context context) {
super(context);
init();
}
public SurfacePanel(Context context, AttributeSet attrs) {
super(context, attrs);
this.CommonInit();
}
private void init() {
setZOrderOnTop(true); //necessary
getHolder().setFormat(PixelFormat.TRANSPARENT);
getHolder().addCallback(this);
setBackgroundColor(Color.TRANSPARENT);
}
public void onDraw(Canvas canvas){
Path path = new Path();
path.moveTo(10, 10);
path.lineTo(115, 10);
path.lineTo(115, 260);
path.lineTo(10, 260);
path.close();
canvas.clipPath(path, Region.Op.DIFFERENCE);
canvas.clipRect(150, 30, 200, 100, Region.Op.DIFFERENCE);
canvas.drawARGB(180, 0, 0, 0);
super.onDraw(canvas);
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
}
#Override
public void surfaceCreated(SurfaceHolder holder) {
}
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
}
}
Someone please help me out of this.
Thanks in advance.

This is probably because ICS+ defaults hardware acceleration to true, and some of your drawing calls on the canvas aren't supported in hardware mode, check the following:
http://developer.android.com/guide/topics/graphics/hardware-accel.html
You can turn it off in your application tag in your manifest, per activity in your manifest, or on the view itself with setLayerType

Canvas Clip function bug on Galaxy Nexus

I'm making a application it's picture cropping.
But Galaxy nexus has some problem.
Region.Op.DIFFERENCE is not works.
Desire(2.3.3) and GalaxyNexus(4.1) Emulator works well.
But not works only on GalaxyNexus Real Phone
Please see the code...
It's a onDraw overrided method it's extended imageview
#override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
//all rectangle
getDrawingRect(viewRect);
//small rectangle
getDrawingRect(smallRect);
smallRect.left += 100;
smallRect.right -= 100;
smallRect.bottom -= 200;
smallRect.top += 200;
// paint color setting to transparency black
mNoFocusPaint.setARGB(150, 50, 50, 50);
// All Rectangle clipping
canvas.clipRect(viewRect);
// Small Rectangle clipping
canvas.clipRect(smallRect, Region.Op.DIFFERENCE);
// Draw All Rectangle transparency black color it's except small rectangle
canvas.drawRect(viewRect, mNoFocusPaint);
}

solved!
add this code in manifest
android:hardwareAccelerated="false"
: )

JuHyun's answer is great! In my case however I didn't want to remove hardware acceleration for my entire app across all SDK versions. The issue with hardware-accelerated canvas clipping seems to be confined to 4.1.1, so I took the route of disabling hardware acceleration for the specific view in which I was performing the clipping operation.
Custom view class (in this case, a RecyclerView):
public class ClippableRecyclerView extends RecyclerView {
private final CanvasClipper clipper = new CanvasClipper();
public ClippableRecyclerView(Context context) {
super(context);
configureHardwareAcceleration();
}
public ClippableRecyclerView(Context context, AttributeSet attrs) {
super(context, attrs);
configureHardwareAcceleration();
}
public ClippableRecyclerView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
configureHardwareAcceleration();
}
public void configureHardwareAcceleration() {
if (Build.VERSION.SDK_INT == Build.VERSION_CODES.JELLY_BEAN) {
setLayerType(View.LAYER_TYPE_SOFTWARE, null);
}
}
/**
* Remove the region from the current clip using a difference operation
* #param rect
*/
public void removeFromClipBounds(Rect rect) {
clipper.removeFromClipBounds(rect);
invalidate();
}
public void resetClipBounds() {
clipper.resetClipBounds();
invalidate();
}
#Override
public void onDraw(Canvas c) {
super.onDraw(c);
clipper.clipCanvas(c);
}
}
Canvas clipper class:
public class CanvasClipper {
private final ArrayList<Rect> clipRegions = new ArrayList<>();
/**
* Remove the region from the current clip using a difference operation
* #param rect
*/
public void removeFromClipBounds(Rect rect) {
clipRegions.add(rect);
}
public void resetClipBounds() {
clipRegions.clear();
}
public void clipCanvas(Canvas c) {
if (!clipRegions.isEmpty()) {
for (Rect clipRegion : clipRegions) {
c.clipRect(clipRegion, Region.Op.DIFFERENCE);
}
}
}
}

Android Multiple SurfaceViews

I'm trying to work with 3 SurfaceViews on one screen, one on top half (BoardView), one on bottom half (StatusView), and the last one as an extra layer above the top half (TileView) (see main.xml).
I created a class MySurfaceView, which is extended by BoardView, StatusView and TileView.
I've got multiple problems with this.
Let me first give the code.
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:background="#color/main_background">
<com.niek.test.BoardView
android:id="#+id/boardview"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
<FrameLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_below="#+id/boardview">
<com.niek.test.StatusView
android:id="#+id/statusview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#F0931E"
android:layout_below="#+id/boardview" />
<com.niek.test.TileView
android:id="#+id/tileview"
android:layout_width="180dip"
android:layout_height="60dip"
android:layout_gravity="bottom"/>
</FrameLayout>
</RelativeLayout>
MainActivity.java:
package com.niek.test;
public class MainActivity extends Activity {
private Board board;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
board = new Board();
BoardView boardView = (BoardView) findViewById(R.id.boardview);
boardView.setBoard(board);
StatusView statusView = (StatusView) findViewById(R.id.statusview);
statusView.setBoard(board);
}
}
MySurfaceView.java
package com.niek.test;
public class MySurfaceView extends SurfaceView implements SurfaceHolder.Callback {
protected DrawThread drawThread;
public MyView(Context context, AttributeSet attrs) {
super(context, attrs);
getHolder().addCallback(this);
setFocusable(true);
drawThread = new DrawThread(getHolder());
}
#Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
// TODO Auto-generated method stub
}
#Override
public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub
drawThread.setRunning(true);
drawThread.start();
}
#Override
public void surfaceDestroyed(SurfaceHolder holder) {
// we have to tell thread to shut down & wait for it to finish, or else
// it might touch the Surface after we return and explode
boolean retry = true;
drawThread.setRunning(false);
while (retry) {
try {
drawThread.join();
retry = false;
} catch (InterruptedException e) {
// we will try it again and again...
}
}
}
protected class DrawThread extends Thread {
private SurfaceHolder surfaceHolder;
private boolean isRunning;
public DrawThread(SurfaceHolder surfaceHolder) {
this.surfaceHolder = surfaceHolder;
isRunning = false;
}
public void setRunning(boolean run) {
isRunning = run;
}
public void run() {
Canvas c;
while (isRunning) {
try {
Thread.sleep(100);
} catch (Exception e) {
// TODO: handle exception
}
c = null;
try {
c = surfaceHolder.lockCanvas(null);
synchronized (surfaceHolder) {
onDraw(c);
postInvalidate();
}
} finally {
// do this in a finally so that if an exception is thrown
// during the above, we don't leave the Surface in an
// inconsistent state
if (c != null) {
surfaceHolder.unlockCanvasAndPost(c);
}
}
}
}
}
}
These three classes extend MySurfaceView:
BoardView.java
package com.niek.test;
public class BoardView extends MySurfaceView {
private int squareSize, marginX, marginY;
private Board board;
Paint boardBorder;
public BoardView(Context context, AttributeSet attrs) {
super(context, attrs);
board = null;
}
public void setBoard(Board board) {
this.board = board;
}
private void init(SurfaceHolder holder) {
Canvas canvas = null;
try {
canvas = holder.lockCanvas();
/* Initialize the board */
squareSize = canvas.getWidth() / Board.GRIDSIZE;
/* Size the view */
LayoutParams lp = getLayoutParams();
lp.height = (squareSize * Board.GRIDSIZE) + 4;
setLayoutParams(lp);
/* Place the board neatly in the center */
marginX = (canvas.getWidth() - (squareSize * Board.GRIDSIZE)) / 2;
marginY = 1;
} finally {
holder.unlockCanvasAndPost(canvas);
}
boardBorder = new Paint();
boardBorder.setColor(Color.RED);
boardBorder.setStyle(Style.STROKE);
}
#Override
public void onDraw(Canvas canvas) {
drawBoard(board, canvas);
}
#Override
public void surfaceCreated(SurfaceHolder holder) {
init(holder);
super.surfaceCreated(holder);
}
private void drawBoard(Board board, Canvas canvas) {
synchronized (board) {
if (board != null) {
for (Square[] ys : board.getSquares()) {
for (Square xs : ys) {
xs.onDraw(canvas, squareSize, squareSize, marginX, marginY);
}
}
}
canvas.drawRect(marginX - 1, marginY - 1, marginX + squareSize * Board.GRIDSIZE + 1, marginY + squareSize * Board.GRIDSIZE + 1, boardBorder);
}
}
}
StatusView.java
package com.niek.test;
public class StatusView extends MySurfaceView {
private Board board;
private Paint textPaint;
public StatusView(Context context, AttributeSet attrs) {
super(context, attrs);
board = null;
textPaint = new Paint();
textPaint.setColor(Color.BLACK);
textPaint.setTextSize(20);
textPaint.setTypeface(Typeface.DEFAULT_BOLD);
}
public void setBoard(Board board) {
this.board = board;
}
int tmp=0;
#Override
public void onDraw(Canvas c) {
if (board != null) {
c.drawText(tmp+"", 10, 20, textPaint);
tmp++;
System.out.println(tmp);
}
}
}
TileView.java
package com.niek.test;
public class TileView extends MySurfaceView {
public TileView(Context context, AttributeSet attrs) {
super(context, attrs);
System.out.println(0);
}
int tmp =0;
#Override
public void onDraw(Canvas c) {
System.out.println(2);
Paint p= new Paint();
p.setColor(Color.RED);
c.drawColor(Color.RED);
c.drawText(tmp+"",10,10,p);
tmp++;
}
}
Now what are my problems?
First off, as you can see in MySurfaceView I've got this:
try {
c = surfaceHolder.lockCanvas(null);
synchronized (surfaceHolder) {
onDraw(c);
postInvalidate();
}
}
When I only use onDraw(c), only the BoardView gets drawn, the StatusView doesn't get drawn, but the tmp increments in the onDraw of StatusView are being executed.
When I only use postInvalidate(), same story, but only StatusView gets drawn, BoardView doesn't.
So that's why I use both methods, and both Views get drawn.
Then there's TileView, the System.out(2) is being shown in logcat, but the view doesn't get drawn. It is a black square instead of the red square I ask it to be in the onDraw method.
When I turn the screen off and then on again, the TileView does get drawn, and the tmp increments are shown.
Who can help me?
For clarity, I've created this based on this tutorial.

You can have multiple SurfaceViewsin one layout. The "Multi-surface test" activity in Grafika has three.
The first post cited in #nonsleepr's answer was followed up 9 months later with this post by the same author, which mentioned the existence of SurfaceView#setZOrderMediaOverlay().
The key thing to understand is that SurfaceView is not a regular view. When your app comes to the foreground it gets a surface to draw on. Everything in your app's UI is rendered onto the app's surface by the app, and then that surface is composited with other surfaces (like the status bar and navigation bar) by the system compositor. When you create a SurfaceView, it's actually creating an entirely new surface that is composited by the system, not by your app.
You can control the Z-ordering (i.e. "depth") of the SurfaceView surface very loosely. There are four positions, from top to bottom:
SurfaceView + ZOrderOnTop
(app UI goes here)
SurfaceView + ZOrderMediaOverlay
SurfaceView (default)
If you have two SurfaceViews at the same depth, and they overlap, the results are undefined -- one will "win", but you can't control which.
The system compositor on modern devices is very efficient when you have N surfaces. At N+1 surfaces you hit a performance cliff. So while you can have three SurfaceViews, you're generally better off keeping the number down. The value of N varies from device to device.
Update: if you really want to understand how SurfaceView works, see the Android System-Level Graphics doc.

It looks like you are not supposed to create multiple SurfaceViews on one Layout.
According to this two posts written by Android framework engineer:
The way surface view is implemented is that a separate surface is created and Z-ordered behind its containing window, and transparent pixels drawn into the rectangle where the SurfaceView is so you can see the surface behind. We never intended to allow for multiple surface view.
and
you should effectively think of SurfaceView as an overlay you embed inside your window,
giving you an area in which you can directly draw independently of the normal view update system.
So, what you can do, is use one SurfaceView to draw all the graphics you want.

It sounds like the SurfaceViews are being drawn, but transparency is not enabled for whichever one is on top. In your MySurfaceView class in the surfaceCreated() method, make sure you are calling holder.setFormat(PixelFormat.TRANSPARENT);