Develop Reference

Android ImageView scale bitmap to the width and crop the height

I have a fixed size ImageView. I want to achieve this :
Scale the Bitmap always to the width, if the Bitmap is wider or smaller than Imageview width.
Crop the height if taller than ImageView height else scale it to the height.
I want something like this answer, but the other way around (FitXCropY). I have tried changing this answer with no success.
Thank you.

Based on this answer ImageView to scale to fixed height, but crop excess width
public class FitXCropYImageView extends ImageView {
boolean done = false;
#SuppressWarnings("UnusedDeclaration")
public FitXCropYImageView(Context context) {
super(context);
setScaleType(ScaleType.MATRIX);
}
#SuppressWarnings("UnusedDeclaration")
public FitYCropXImageView(Context context, AttributeSet attrs) {
super(context, attrs);
setScaleType(ScaleType.MATRIX);
}
#SuppressWarnings("UnusedDeclaration")
public FitXCropYImageView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
setScaleType(ScaleType.MATRIX);
}
private final RectF drawableRect = new RectF(0, 0, 0,0);
private final RectF viewRect = new RectF(0, 0, 0,0);
private final Matrix m = new Matrix();
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
if (done) {
return;//Already fixed drawable scale
}
final Drawable d = getDrawable();
if (d == null) {
return;//No drawable to correct for
}
int viewHeight = getMeasuredHeight();
int viewWidth = getMeasuredWidth();
int drawableWidth = d.getIntrinsicWidth();
int drawableHeight = d.getIntrinsicHeight();
drawableRect.set(0, 0, drawableWidth, drawableHeight);//Represents the original image
//Compute the left and right bounds for the scaled image
float viewHalfHeight = viewHeight / 2;
float scale = (float) viewWidth / (float) drawableWidth;
float scaledHeight = drawableHeight * scale;
float scaledHalfHeight = scaledHeight / 2;
viewRect.set(0, viewHalfHeight-scaledHalfHeight,viewWidth, viewHalfHeight+scaledHalfHeight);
m.setRectToRect(drawableRect, viewRect, Matrix.ScaleToFit.CENTER /* This constant doesn't matter? */);
setImageMatrix(m);
done = true;
requestLayout();
}
}

Try like this,
Add inside Oncreate
viewImage = (ImageView) findViewById(R.id.pictureImageview123);
viewImage.setScaleType(ScaleType.FIT_XY);

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);
}
}

Android: How to expand rectangular image with same ratio to fit the screen

I have the following rectangular image to be set in my application.
Now I am trying to expand the image with same ratio on both sides until it fits to the screen.But I cant get the expected image.
So far my code is :
<ImageView
android:id="#+id/imgid"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:src="#drawable/shayneward"
android:scaleType="fitXY"/>
It dont care that the image gets cut off, but it should expand on both sides with same ratio until it fits to the screen.

Change android:scaleType="fitXY" to android:scaleType="centerCrop" to get the behavior that you want.
The different scaling options are documented under ImageView.ScaleType.

Try using this:
android:scaleType="centerCrop"
From the Android documentation, center crop does the following:
Scale the image uniformly (maintain the image's aspect ratio) so that
both dimensions (width and height) of the image will be equal to or
larger than the corresponding dimension of the view (minus padding).
See documentation for ImageView.ScaleType here.

if the image is too small could be a problem because it is not scaled to fit screen dimensions.
I use this class to solve this issue:
public class FixedCenterCrop extends ImageView {
public FixedCenterCrop(Context context) {
super(context);
setScaleType(ScaleType.MATRIX);
}
public FixedCenterCrop(Context context, AttributeSet attrs) {
super(context, attrs);
setScaleType(ScaleType.MATRIX);
}
public FixedCenterCrop(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
setScaleType(ScaleType.MATRIX);
}
#Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
recomputeImgMatrix();
}
#Override
protected boolean setFrame(int l, int t, int r, int b) {
recomputeImgMatrix();
return super.setFrame(l, t, r, b);
}
private void recomputeImgMatrix() {
final Matrix matrix = getImageMatrix();
float scale;
final int viewWidth = getWidth() - getPaddingLeft() - getPaddingRight();
final int viewHeight = getHeight() - getPaddingTop() - getPaddingBottom();
final int drawableWidth = getDrawable().getIntrinsicWidth();
final int drawableHeight = getDrawable().getIntrinsicHeight();
if (drawableWidth * viewHeight > drawableHeight * viewWidth) {
scale = (float) viewHeight / (float) drawableHeight;
} else {
scale = (float) viewWidth / (float) drawableWidth;
}
matrix.setScale(scale, scale);
matrix.postTranslate((viewWidth - drawableWidth * scale) / 2, (viewHeight - drawableHeight*scale)/2);
setImageMatrix(matrix);
}
}

Scale text over image in custom imageview

I have written a custom imageview to show a credit card. To create the credit card I have a base image and I have setters to set the PAN, Card holder, expiry. This text needs to be drawn on top of the base card image. My problem is maintaining the position and size of the text so that it will always look correct no matter the changing size of the base image. The only thing I can rely on is the aspect ratio of the image being the same as a normal credit card.
My custom ImageView
public class CardView extends ImageView {
private String mPan = "4321 0123 4567 8910";
private String mExpiry = "01/16";
private String mCardholder = "MR JOHN SMITH";
private float mPanTextSize = 22;
private float mOtherTextSize = 14;
private Paint mPanPaint = new Paint();
private Paint mCardholderPaint = new Paint();
public CardView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initCardView();
}
public CardView(Context context, AttributeSet attrs) {
super(context, attrs);
initCardView();
}
public CardView(Context context) {
super(context);
initCardView();
}
private final void initCardView() {
mPanPaint.setColor(0xFFFFFFFF);
mPanPaint.setShadowLayer(1, 1, 1, 0xAA000000);
mPanPaint.setAntiAlias(true);
mPanPaint.setTextSize(mPanTextSize * getResources().getDisplayMetrics().scaledDensity);
mPanPaint.setTypeface(Typeface.MONOSPACE);
mCardholderPaint.setColor(0xFFFFFFFF);
mCardholderPaint.setShadowLayer(1, 1, 1, 0xAA000000);
mCardholderPaint.setAntiAlias(true);
mCardholderPaint.setTextSize(mOtherTextSize * getResources().getDisplayMetrics().scaledDensity);
mCardholderPaint.setTypeface(Typeface.MONOSPACE);
setPadding(0,0,0,0);
//setAdjustViewBounds(true);
setScaleType(ImageView.ScaleType.CENTER_INSIDE);
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
float panLength = mPanPaint.measureText(mPan);
float x = (getWidth() - panLength)/2;
float y = -mPanPaint.ascent() + (getHeight() * 0.46f);
canvas.drawText(mPan, x, y, mPanPaint);
x = (getWidth() - panLength)/1.5f;
y = y - mCardholderPaint.ascent();
canvas.drawText(mExpiry, x, y, mCardholderPaint);
y = y - mCardholderPaint.ascent();
canvas.drawText(mCardholder, x, y, mCardholderPaint);
//super.onDraw(canvas);
}
public void setPan(String pan) {
mPan = pan;
invalidate();
}
public String getPan() {
return mPan;
}
public void setExpiry(String expiry) {
mExpiry = expiry;
invalidate();
}
public String getExpiry() {
return mExpiry;
}
public void setCardholder(String cardholder) {
mCardholder = cardholder;
invalidate();
}
public String getCardholder() {
return mCardholder;
}
}
So sometimes this looks ok but as you get to 10 inch screens the text is way too small, right in the center of the image (imagine looking at a credit card but the number only takes up the space of the middle 8 digits), and as you get to small screens the text is too big, going right up to the image sides or past them.
Any solutions? Any explanation why?

You need to make the text sizes dependent on the size of your image.
try to experiment with different values for yourPanFactor and yourCardholderFactor until you get the desired result
#Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
if (changed) {
final int height = bottom-top;
mPanPaint.setTextSize(height*yourPanFactor);
mCardholderPaint.setTextSize(height*yourCardholderFactor);
}
}

I managed to make this work in this lines of code
if (imageView.getWidth() <= resource.getWidth()) {
ratio = (float) resource.getWidth() / (float) imageView.getWidth();
} else {
ratio = (float) imageView.getWidth() / (float) resource.getWidth();
}
Paint paint = new Paint();
paint.setColor(Color.WHITE);
paint.setTextSize(editText.getTextSize() * ratio);
Note that the editText has the default text size which is 14 sp.
I hope it help you. and correct me if am wrong

android Gallery with arbitrary aspect ratios

i wish to have an android gallery that will host images of varying aspect ratios. what i'd like is something like CENTER_CROP for the images in the gallery. however, when i set the image scale type to this, the images overrun the gallery image border.
of course, FIT_XY results in squished / flattened images. CENTER results in horizontal or vertical black space inside the gallery image border.
any ideas how to accomplish this? every example i can find uses FIT_XY with fixed size images. i suppose i could crop the images myself but i'd rather not.
#Override
public View getView(int position, View convertView, ViewGroup parent) {
ImageView iv = (ImageView) convertView;
if (iv == null) {
iv = new ImageView(context);
iv.setScaleType(ImageView.ScaleType.FIT_XY);
iv.setBackgroundResource(galleryItemBackground);
iv.setLayoutParams(new Gallery.LayoutParams(200, 200));
}
InputStream is;
try {
is = getInputStream(position);
} catch (IOException ioe) {
// TODO?
throw new RuntimeException(ioe);
}
Bitmap bm = BitmapFactory.decodeStream(is);
iv.setImageBitmap(bm);
/*
* if (bitmaps[position] != null) { bitmaps[position].recycle();
* bitmaps[position] = null; } bitmaps[position] = bm;
*/
return iv;
}

I had the same problem as you and looking at ScaleType documentation I found it could be done using ScaleType.MATRIX, for example:
int w = 1000;
int h = 1000;
Paint p = new Paint();
p.setShader(new LinearGradient(0, 0, w, h, Color.BLACK, Color.RED, Shader.TileMode.CLAMP));
Bitmap bmp = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
Canvas g = new Canvas(bmp);
g.drawRect(new Rect(0, 0, w, h), p);
ImageView i3 = new ImageView(context);
i3.setImageBitmap(bmp);
i3.setScaleType(ScaleType.MATRIX);
int viewWidth = 300;
int viewHeight = 300;
Matrix matrix = new Matrix();
matrix.postScale(bmp.getWidth() / viewWidth, bmp.getHeight() / viewHeight, bmp.getWidth() / 2, bmp.getHeight() / 2);
i3.setImageMatrix(matrix);
LayoutParams lp2 = new LayoutParams(viewWidth, viewHeight);
lp2.leftMargin = 100;
lp2.topMargin = 400;
lp2.gravity = 0;
this.addView(i3, lp2);
This solution complicates things a little bit too much though. If you want to scroll and zoom the ImageView you need to use matrix scaling as well. So I'd be interested in knowing any possible alternative.

For this kind of tasks I use this simple class. It fits height or width scaling the image properly (it depends on which is the smaller dimension) . After this operation it centers the image in the ImageView bounds.
public class FixedCenterCrop extends ImageView {
public FixedCenterCrop(Context context) {
super(context);
setScaleType(ScaleType.MATRIX);
}
public FixedCenterCrop(Context context, AttributeSet attrs) {
super(context, attrs);
setScaleType(ScaleType.MATRIX);
}
public FixedCenterCrop(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
setScaleType(ScaleType.MATRIX);
}
#Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
recomputeImgMatrix();
}
#Override
protected boolean setFrame(int l, int t, int r, int b) {
recomputeImgMatrix();
return super.setFrame(l, t, r, b);
}
private void recomputeImgMatrix() {
final Matrix matrix = getImageMatrix();
float scale;
final int viewWidth = getWidth() - getPaddingLeft() - getPaddingRight();
final int viewHeight = getHeight() - getPaddingTop() - getPaddingBottom();
final int drawableWidth = getDrawable().getIntrinsicWidth();
final int drawableHeight = getDrawable().getIntrinsicHeight();
if (drawableWidth * viewHeight > drawableHeight * viewWidth) {
scale = (float) viewHeight / (float) drawableHeight;
} else {
scale = (float) viewWidth / (float) drawableWidth;
}
matrix.setScale(scale, scale);
matrix.postTranslate((viewWidth - drawableWidth * scale) / 2, (viewHeight - drawableHeight*scale)/2);
setImageMatrix(matrix);
}
}

I ended up just trimming the bitmap to a square myself, as,
Bitmap bm = BitmapFactory.decodeStream(is);
// make it square
int w = bm.getWidth();
int h = bm.getHeight();
if (w > h) {
// trim width
bm = Bitmap.createBitmap(bm, (w - h) / 2, 0, h, h);
} else {
bm = Bitmap.createBitmap(bm, 0, (h - w) / 2, w, w);
}