Develop Reference

How to draw an audio waveform on Android

I have a custom view that I want to use to display the amplitude of audio coming in through the microphone in a line graph.
Getting the amplitude and all that I have no problem with, and drawing the lines is not really a problem either.
What I want to do is show the amplitude starting at the far right edge, moving left. So with each new sample I want to translate the bitmap to the left, then draw a line from the last point to the new point. I'm not sure what the easiest way to achieve this is. I originally was able to do it by drawing Paths and just adding a new point to the path with each sample, the problem was that after like a minute the path was too big to be drawn. So I thought about it and wanted to switch to using a cached bitmap, translate that on each iteration, and draw from the last point to the new point. However this is tricky to do as (after experimentation). When I translate the bitmap it doesn't move the far left pixels off the bitmap, it just moves the entire bitmap in the canvas and I have no way to write pixels to the right side.
Below is a description of what I'm trying to do:
Given this:
I want to translate that to the left:
Then draw a line to a new point the space space on the right
Of course, step 2 and 3 should happen at essentially the same time.
How can I achieve this? I'm open to new ideas altogether, like perhaps saving all the points for up to 1 screen worth and drawing them out on each onDraw call. I'd prefer to just save them in a bitmap and do some kind of translation/clipping etc to achieve the same thing with perhaps less overhead.
private static final int MAX_AMPLITUDE = 32767;
float lx, ly;
private Paint mPaint;
private Bitmap mBitmap;
private Canvas mCanvas;
private void init() {
mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeWidth(5);
mPaint.setColor(Color.Black);
}
#Override
public void onSizeChanged(int w, int h, int oldw, int oldh) {
if (mBitmap != null) {
mBitmap.recycle();
}
mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
mCanvas = new Canvas(mBitmap);
height = h;
width = w;
ly = height;
lx = width;
amplitudeDivisor = ((float) MAX_AMPLITUDE / (float) height);
}
#Override
public void onDraw(Canvas canvas) {
mAmplitude = (float)(MAX_AMPLITUDE * Math.random());
float dx = width - delta;
float dy = height - (mAmplitude / amplitudeDivisor);
mCanvas.drawLine(lx, ly, dx, dy, mPaint);
mCanvas.translate(-delta, 0);
canvas.drawBitmap(mBitmap, 0, 0, mPaint);
lx = dx;
ly = dy;
delta+=10;
postInvalidateDelayed(200);
}
The above is just a sample, I'm just using a random value for the amplitude to simplify for now. I've tried a bunch of things with no luck. Any help would be greatly appreciated.

I ended up getting this working by saving the points to an array. I draw a white line before the recording starts. Note that I use an EvictingQueue from the Guava library as a circular buffer of points to render on a line. To use this, once a recording starts call start() and when it ends call stop. From your activity you will need to send MediaRecorder getMaxAmplitude() values to the updateAmplitude() method of this class, and do so at an interval of say 50 ms. The view also supports rotation.
public class AmplitudeWaveFormView extends View {
private static final String TAG = AmplitudeWaveFormView.class.getSimpleName();
private static final int MAX_AMPLITUDE = 32767;
private static final int SAMPLES_PER_SCREEN = 100;
private float mAmplitude = 0;
private Paint mRecordingPaint, mNotRecordingPaint;
private int height = -1;
private int width = -1;
private boolean mIsStarted;
private float[] lastPoints;
private int oldWidth = -1, oldHeight = -1;
private int mCurrentSample;
private float amplitudeDivisor = 1;
private float lx,ly, deltaX;
private EvictingQueue<Float> mPointQueue;
private int recordColor;
private int notRecordingColor;
public AmplitudeWaveFormView(Context context) {
super(context);
init();
}
public AmplitudeWaveFormView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public AmplitudeWaveFormView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
public void start() {
mIsStarted = true;
}
public void stop() {
mIsStarted = false;
}
public void updateAmplitude(float amplitude) {
mAmplitude = amplitude;
postInvalidate();
}
private void init() {
recordColor = getResources().getColor(R.color.mint);
notRecordingColor = getResources().getColor(R.color.alpine);
mRecordingPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mRecordingPaint.setStyle(Paint.Style.STROKE);
mRecordingPaint.setStrokeWidth(5);
mRecordingPaint.setColor(recordColor);
mNotRecordingPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mNotRecordingPaint.setStyle(Paint.Style.STROKE);
mNotRecordingPaint.setStrokeWidth(5);
mNotRecordingPaint.setColor(notRecordingColor);
}
#Override
public void onSizeChanged(int w, int h, int oldw, int oldh) {
height = h;
width = w;
ly = height;
lx = width;
deltaX = (float)width / (float)SAMPLES_PER_SCREEN;
amplitudeDivisor = ((float) MAX_AMPLITUDE / (float) height);
mPointQueue = EvictingQueue.create(SAMPLES_PER_SCREEN * 4);
if (lastPoints != null && lastPoints.length > 0) {
float xScale = (float) width/oldWidth;
float yScale = (float) height/oldHeight;
Matrix matrix = new Matrix();
matrix.setScale(xScale, yScale);
matrix.mapPoints(lastPoints);
mPointQueue.addAll(Floats.asList(lastPoints));
ly = lastPoints[lastPoints.length-1];
lx= lastPoints[lastPoints.length -2];
lastPoints = null;
}
}
#Override
public void onRestoreInstanceState(Parcelable state) {
if (state instanceof Bundle) {
Bundle bundle = (Bundle) state;
mCurrentSample = bundle.getInt("sample");
lastPoints = bundle.getFloatArray("lines");
oldWidth = bundle.getInt("oldWidth");
oldHeight = bundle.getInt("oldHeight");
state = ((Bundle) state).getParcelable("parent");
}
super.onRestoreInstanceState(state);
}
#Override
public Parcelable onSaveInstanceState() {
Bundle bundle = new Bundle();
bundle.putFloatArray("lines", Floats.toArray(mPointQueue));
bundle.putInt("sample", mCurrentSample);
bundle.putParcelable("parent", super.onSaveInstanceState());
bundle.putInt("oldWidth", width);
bundle.putInt("oldHeight", height);
return bundle;
}
#Override
public void onDraw(Canvas canvas) {
if (mIsStarted) {
float x = lx + deltaX;
float y = height - (mAmplitude / amplitudeDivisor);
mPointQueue.add(lx);
mPointQueue.add(ly);
mPointQueue.add(x);
mPointQueue.add(y);
lastPoints = Floats.toArray(mPointQueue);
lx = x;
ly = y;
}
if (lastPoints != null && lastPoints.length > 0) {
int len = mPointQueue.size() / 4 >= SAMPLES_PER_SCREEN ? SAMPLES_PER_SCREEN * 4 : mPointQueue.size();
float translateX = width - lastPoints[lastPoints.length - 2];
canvas.translate(translateX, 0);
canvas.drawLines(lastPoints, 0, len, mRecordingPaint);
}
if (mCurrentSample <= SAMPLES_PER_SCREEN) {
drawNotRecordingLine(canvas);
}
mCurrentSample++;
}
private void drawNotRecordingLine(Canvas canvas) {
canvas.drawLine(0,height, width, height, mNotRecordingPaint);
}
}

Force redraw of custom view (android)

I just have read similar questions but all answer don't work for me.
I have this custom view:
public class CompassTargetView extends View {
Context mContext;
Bitmap mBmp;
Matrix matrix;
int w, h, bw, bh;
int px = -1, py = -1;
public CompassTargetView(Context context, AttributeSet attrs) {
super(context, attrs);
setWillNotDraw(false);
mContext = context;
Resources res = getResources();
mBmp = BitmapFactory.decodeResource(res, R.drawable.ttriangle);
bw = mBmp.getWidth();
bh = mBmp.getHeight();
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
if(px == -1 && py == -1){
px=w/2-bw/2;
py=h/2-bh/2;
}
if (matrix != null) {
canvas.drawBitmap(mBmp, matrix, null);
matrix = null;
} else {
canvas.drawBitmap(mBmp, px, py, null);
}
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
//registriamo le dimensioni della view
w = MeasureSpec.getSize(widthMeasureSpec);
h = MeasureSpec.getSize(heightMeasureSpec);
setMeasuredDimension(w, h);
}
public void setTrinagleIcon(){
Resources res = getResources();
mBmp = BitmapFactory.decodeResource(res, R.drawable.ttriangle);
bw = mBmp.getWidth();
bh = mBmp.getHeight();
invalidate();
}
public void setCircleIcon(){
Resources res = getResources();
mBmp = BitmapFactory.decodeResource(res, R.drawable.tcircle);
bw = mBmp.getWidth();
bh = mBmp.getHeight();
invalidate();
}
public void setXY(Integer nx, Integer ny){
px = nx - bw/2;
py = ny - bh/2;
invalidate();
}
public void translateIcon(Integer nx, Integer ny){
matrix = new Matrix();
matrix.reset();
matrix.postTranslate(nx, ny);
invalidate();
}
public void rotateIcon(Integer nx, Integer ny, Float ang){
matrix = new Matrix();
matrix.reset();
matrix.postRotate(ang, nx, ny);
invalidate();
}
}
it show a small icon then I want use setXY, translateIcon and rotateIcon to "animate" the icon. However the onDraw method is call only on view create after this if I call setXY, translateIcon and rotateIcon onDraw is not call.
I just use invalidate(); and I have try setWillNotDraw(false); but this don't work.
Any idea?

Displaying a Toast in the onDraw is a very bad idea since it may cause a call to onDraw which will display the Toast and it will call onDraw.... infinite loop.
So replace the Toast by log (and keep the log only during debugging since onDraw is call very very often) and see what append.
The problem is that you are not updating the member matrix. You are creating a new one !
public void translateIcon(Integer nx, Integer ny){
Matrix matrix = new Matrix(); // <-- WRONG
matrix = new Matrix(); // <-- CORRECT
...
invalidate();
}

Rotate an image by 90,180,270 and 360 degrees every time a button is clicked and retain the rotation degree in portrait and landscape mode?

I am making an app in android where in an image has to be rotated whenever rotate button is clicked by 90,180,270 and 360 degrees. The rotation has to be the same in portrait and in landscape mode.
I am a beginner in Android Programming and I have basic knowledge of Java.
Kindly, help me soon.
The code that I have used is as below.I can only rotate it 90 degrees once. How do it continue with it?
btn_rotate = (ImageButton) findViewById(R.id.btn_rotate);
btn_rotate.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Bitmap bmap = BitmapFactory.decodeResource(getResources(), R.drawable.about_us_ipad_p);
Display d = getWindowManager().getDefaultDisplay();
#SuppressWarnings("deprecation")
int x = d.getWidth();
#SuppressWarnings("deprecation")
int y = d.getHeight();
ImageView imgView = (ImageView) findViewById(R.id.imgViewEdit_Pic);
Bitmap scaledBmap = Bitmap.createScaledBitmap(bmap, y, x, true);
Matrix matrix = new Matrix();
matrix.postRotate(90, 180, 270);
Bitmap rotatedBmap = Bitmap.createBitmap(scaledBmap,0,0,scaledBmap.getWidth(),scaledBmap.getHeight(),matrix,true);
imgView.setImageBitmap(rotatedBmap);
}
});

this piece of code may help you and it is self explanatory...
public class TestActivity extends Activity {
private int rotation;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState != null) {
rotation = savedInstanceState.getInt("ANGLE");
}
final ImageView imageView = (ImageView) findViewById(R.id.imageView);
final Button button = (Button) findViewById(R.id.iv_icon);
DisplayMetrics metrics = getResources().getDisplayMetrics();
final int width = metrics.widthPixels;
final int height = metrics.heightPixels;
final Bitmap imageBitmap = BitmapFactory.decodeResource(
getResources(), R.drawable.image1);
final Bitmap scaledBitmap = Bitmap.createScaledBitmap(imageBitmap, width, height, true);
imageView.setImageBitmap(getRotatedBitmap(scaledBitmap));
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
rotation += 90;
rotation %= 360;
Bitmap bitmap = getRotatedBitmap(scaledBitmap);
imageView.setImageBitmap(bitmap);
}
});
}
private Bitmap getRotatedBitmap(Bitmap bitmap) {
if (rotation % 360 == 0) {
return bitmap;
}
Matrix matrix = new Matrix();
matrix.postRotate(rotation, bitmap.getWidth() / 2,
bitmap.getHeight() / 2);
return Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(),
bitmap.getHeight() / 2, matrix, true);
}
#Override
protected void onSaveInstanceState(Bundle outState) {
outState.putInt("ANGLE", rotation);
super.onSaveInstanceState(outState);
}
}

yourimage.setRotation(yourimage.getRotation() + 90);

In manifest file, lock your screen orientation like this:
android:screenOrientation="portrait"
or
android:screenOrientation="landscape"

Updating a Layout class

My problem is, that I have a Layout class called by an Inflater and I want to run a method from this class to update a picture every few seconds.
I wanted to do this with handlers and the run() method, but my problem is, the picture only updates itself when I am interacting with the screen (clicking my only button).
Do you know what I did wrong?
Here is my GameLayout class:
package de.undeadleech.frogjump;
public class GameLayout extends View implements Runnable
{
private Sprite sprite;
private Bitmap bmp;
private Handler handler = new Handler();
public GameLayout(Context context)
{
super(context);
bmp = BitmapFactory.decodeResource(getResources(), R.drawable.froschanimation);
sprite = new Sprite(bmp, 0, 0, 400, 100, 5, 4);
handler.postDelayed(this, 0);
}
#Override
protected void onDraw(Canvas canvas)
{
sprite.draw(canvas);
}
public void update(long currentTimeMillis)
{
sprite.update(currentTimeMillis);
}
#Override
public void run()
{
sprite.update(System.currentTimeMillis());
handler.postDelayed(this, 0);
}
}
EDIT:
Here is my Sprite class because you wanted to see it:
package de.undeadleech.frogjump;
public class Sprite
{
//private static final String TAG = Sprite.class.getSimpleName();
private Bitmap bitmap; // the animation sequence
private Rect sourceRect; // the rectangle to be drawn from the animation bitmap
private int frameNr; // number of frames in animation
private int currentFrame; // the current frame
private long frameTicker; // the time of the last frame update
private int framePeriod; // milliseconds between each frame (1000/fps)
private int spriteWidth; // the width of the sprite to calculate the cut out rectangle
private int spriteHeight; // the height of the sprite
private int x; // the X coordinate of the object (top left of the image)
private int y; // the Y coordinate of the object (top left of the image)
public Sprite(Bitmap bitmap, int x, int y, int width, int height, int fps, int frameCount)
{
this.bitmap = bitmap;
this.x = x;
this.y = y;
currentFrame = 0;
frameNr = frameCount;
spriteWidth = bitmap.getWidth() / frameCount;
spriteHeight = bitmap.getHeight();
sourceRect = new Rect( 0, 0, spriteWidth, spriteHeight);
framePeriod = 1000 / fps;
frameTicker = 0l;
}
public void update(long gameTime)
{
if (gameTime > frameTicker + framePeriod)
{
frameTicker = gameTime;
// increment the frame
currentFrame++;
if (currentFrame >= frameNr)
{
currentFrame = 0;
}
}
// define the rectangle to cut out sprite
this.sourceRect.left = currentFrame * spriteWidth;
this.sourceRect.right = this.sourceRect.left + spriteWidth;
}
public void draw(Canvas canvas)
{
// where to draw the sprite
Rect destRect = new Rect( x, y, x + spriteWidth, y + spriteHeight);
canvas.drawBitmap(bitmap, sourceRect, destRect, null);
}
}

Instead of posting Runnable you should call invalidate() when you need to redraw your layout. Also you should update state of your Sprite in onDraw method as well.

How to rotate the image without changing its size?

I am developing an android app where I have to rotate a circular image around another circular image, but when I am running this the size of my circular image gets automatically changing continuously. So please help me how to solve this. Here is my code
public class JobSearch extends Activity implements OnTouchListener {
private ImageView dialer;
private float y=0;
public boolean onTouch(View v, MotionEvent event) {
double r=Math.atan2(event.getX()-dialer.getWidth()/2, dialer.getHeight()/2-event.getY());
int rotation=(int)Math.toDegrees(r);
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
break;
case MotionEvent.ACTION_MOVE:
//x=event.getX();
y=event.getY();
updateRotation(rotation);
break;
case MotionEvent.ACTION_UP:
break;
}//switch
return true;
}//onTouch
private void updateRotation(double rot){
float newRot=new Float(rot);
Bitmap bitmap=BitmapFactory.decodeResource(getResources(),R.drawable.round_button_big);
Matrix matrix=new Matrix();
matrix.postRotate(newRot);//,bitmap.getWidth()/2,bitmap.getHeight()/2);
Bitmap reDrawnBitmap=Bitmap.createBitmap(bitmap,0,0,bitmap.getWidth(),bitmap.getHeight(),matrix,true);
dialer.setImageBitmap(reDrawnBitmap);
if(newRot>=-5 && newRot<=5)
Toast.makeText(this,"12 O\'Clock",Toast.LENGTH_SHORT).show();
if(newRot>=85 && newRot<=95)
Toast.makeText(this,"3 O\'Clock",Toast.LENGTH_SHORT).show();
if(newRot>=175 || newRot<=-175)
Toast.makeText(this,"6 O\'Clock",Toast.LENGTH_SHORT).show();
if(newRot>=-95 && newRot<=-85)
Toast.makeText(this,"9 O\'Clock",Toast.LENGTH_SHORT).show();
}
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
dialer = (ImageView) findViewById(R.id.big_button);
dialer.setOnTouchListener(this);
}//onCreate
}

This this one; worked for me perfectly.
private Bitmap rotateBitmap(Bitmap bitmap, int rotationAngleDegree){
int w = bitmap.getWidth();
int h = bitmap.getHeight();
int newW=w, newH=h;
if (rotationAngleDegree==90 || rotationAngleDegree==270){
newW = h;
newH = w;
}
Bitmap rotatedBitmap = Bitmap.createBitmap(newW,newH, bitmap.getConfig());
Canvas canvas = new Canvas(rotatedBitmap);
Rect rect = new Rect(0,0,newW, newH);
Matrix matrix = new Matrix();
float px = rect.exactCenterX();
float py = rect.exactCenterY();
matrix.postTranslate(-bitmap.getWidth()/2, -bitmap.getHeight()/2);
matrix.postRotate(rotationAngleDegree);
matrix.postTranslate(px, py);
canvas.drawBitmap(bitmap, matrix, new Paint( Paint.ANTI_ALIAS_FLAG | Paint.DITHER_FLAG | Paint.FILTER_BITMAP_FLAG ));
matrix.reset();
return rotatedBitmap;
}

Try this code for Rotating Image -
public class bitmaptest extends Activity {
#Override
public void onCreate(Bundle icicle) {
super.onCreate(icicle);
LinearLayout linLayout = new LinearLayout(this);
// load the origial BitMap (500 x 500 px)
Bitmap bitmapOrg = BitmapFactory.decodeResource(getResources(),
R.drawable.android);
int width = bitmapOrg.width();
int height = bitmapOrg.height();
int newWidth = 200;
int newHeight = 200;
// calculate the scale - in this case = 0.4f
float scaleWidth = ((float) newWidth) / width;
float scaleHeight = ((float) newHeight) / height;
// createa matrix for the manipulation
Matrix matrix = new Matrix();
// resize the bit map
matrix.postScale(scaleWidth, scaleHeight);
// rotate the Bitmap
matrix.postRotate(45);
// recreate the new Bitmap
Bitmap resizedBitmap = Bitmap.createBitmap(bitmapOrg, 0, 0,
width, height, matrix, true);
// make a Drawable from Bitmap to allow to set the BitMap
// to the ImageView, ImageButton or what ever
BitmapDrawable bmd = new BitmapDrawable(resizedBitmap);
ImageView imageView = new ImageView(this);
// set the Drawable on the ImageView
imageView.setImageDrawable(bmd);
// center the Image
imageView.setScaleType(ScaleType.CENTER);
// add ImageView to the Layout
linLayout.addView(imageView,
new LinearLayout.LayoutParams(
LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT
)
);
// set LinearLayout as ContentView
setContentView(linLayout);
}
}
And, also see this Tutorial

This is my code to rotate image around itself and slowly reduce the speed
rotateAnimation1 = new RotateAnimation(0, 360,
Animation.RELATIVE_TO_SELF, 0.5f,
Animation.RELATIVE_TO_SELF, 0.5f);
rotateAnimation1.setInterpolator(new LinearInterpolator());
rotateAnimation1.setDuration(duration);
rotateAnimation1.setRepeatCount(0);
imgBottle.startAnimation(rotateAnimation1);
flagSpinAvailable = false;
rotateAnimation1.setAnimationListener(new AnimationListener() {
public void onAnimationStart(Animation anim) {
};
public void onAnimationRepeat(Animation anim) {
};
public void onAnimationEnd(Animation anim) {
duration = duration + 70;
startMoving();
};
});

this is the code of rotate the image
Bitmap bMap = BitmapFactory.decodeResource(getResources(),R.drawable.test);
Matrix mat = new Matrix();
mat.postRotate(90);
Bitmap bMapRotate = Bitmap.createBitmap(bMap, 0, 0,
bMap.getWidth(), bMap.getHeight(), mat, true);
BitmapDrawable bmd = new BitmapDrawable(bMapRotate);
image.setImageBitmap(bMapRotate);
image.setImageDrawable(bmd);