Take a look at my implementation. Support for both Camera APIs: camera and camera2. You can zoom by using double finger touch.
This is how I use the code on my Activities.
For camera API just:
private void setupZoomHandler(final Camera.Parameters parameters) {
if ( parameters.isZoomSupported() ) {
SimpleZoomHandlerBuilder.forView( mCameraPreview )
.setMaxZoom( parameters.getMaxZoom() )
.setZoomListener( new SimpleZoomHandler.IZoomHandlerListener() {
@Override
public void onZoomChanged(int newZoom) {
Camera.Parameters params = mCamera.getParameters();
params.setZoom( newZoom );
mCamera.setParameters( params );
}
} )
.build();
}
}
And for camera2 API just:
private void setupZoomHandler(CameraCharacteristics cameraCharacteristics) {
ActiveArrayZoomHandlerBuilder.forView( mTextureView )
.setActiveArraySize( cameraCharacteristics.get( CameraCharacteristics.SENSOR_INFO_ACTIVE_ARRAY_SIZE ) )
.setMaxZoom( cameraCharacteristics.get( CameraCharacteristics.SCALER_AVAILABLE_MAX_DIGITAL_ZOOM ) * 10 )
.setZoomListener( new ActiveArrayZoomHandler.IZoomHandlerListener() {
@Override
public void onZoomChanged(Rect zoom) {
mCaptureRequestBuilder.set( CaptureRequest.SCALER_CROP_REGION, zoom );
updatePreview();
}
} )
.build();
}
Here are the classes you need to zoom handling:
public abstract class AbstractZoomHandler implements View.OnTouchListener {
private static final int FINGER_SPACING_DELTA_FOR_ZOOM = 25;
private static final int FINGER_SPACING_ZOOM_INCREMENT = 5;
private static final float DEFAULT_ZOOM_HARDNESS = 0.4f;
private float lastFingerSpacingTime;
private float fingerSpacingBuffer;
protected int zoomLevel;
protected float zoomIncrement;
protected float maxZoom;
public AbstractZoomHandler(View touchableView) {
touchableView.setOnTouchListener( this );
this.lastFingerSpacingTime = 0;
this.fingerSpacingBuffer = 0;
this.zoomLevel = 1;
setZoomHardness( DEFAULT_ZOOM_HARDNESS );
}
public void setMaxZoom(float maxZoom) {
this.maxZoom = maxZoom;
}
public void setZoomHardness(float zoomHardness) {
this.zoomIncrement = Math.round( zoomHardness * FINGER_SPACING_ZOOM_INCREMENT );
}
@Override
public boolean onTouch(View v, MotionEvent event) {
if ( !isPrepared() ) {
return true;
}
if ( event.getAction() == MotionEvent.ACTION_UP ) {
fingerSpacingBuffer = 0;
return true;
}
if ( isTwoFingersTouchEvent( event ) ) {
int newZoomLevel = performTwoFingersZoom( event );
recalculateZoom( newZoomLevel );
}
return true;
}
private boolean isTwoFingersTouchEvent(MotionEvent event) {
return event.getPointerCount() == 2;
}
private int performTwoFingersZoom(MotionEvent event) {
int newZoomLevel = zoomLevel;
float currentFingerSpacingTime = getFingerSpacing( event );
fingerSpacingBuffer += currentFingerSpacingTime - lastFingerSpacingTime;
if ( fingerSpacingBuffer >= FINGER_SPACING_DELTA_FOR_ZOOM && maxZoom > zoomLevel ) {
newZoomLevel += zoomIncrement;
fingerSpacingBuffer = 0;
} else if ( fingerSpacingBuffer <= -FINGER_SPACING_DELTA_FOR_ZOOM && zoomLevel > 1 ) {
newZoomLevel -= zoomIncrement;
;
fingerSpacingBuffer = 0;
}
lastFingerSpacingTime = currentFingerSpacingTime;
return newZoomLevel;
}
private void recalculateZoom(int newZoomLevel) {
if ( newZoomLevel == zoomLevel ||
newZoomLevel < 0 ||
newZoomLevel > maxZoom) {
return;
}
zoomLevel = newZoomLevel;
notifyZoomChanged( zoomLevel );
}
private float getFingerSpacing(MotionEvent event) {
float x = event.getX( 0 ) - event.getX( 1 );
float y = event.getY( 0 ) - event.getY( 1 );
return (float) Math.sqrt( x * x + y * y );
}
public abstract void notifyZoomChanged(int zoom);
public abstract boolean isPrepared();
}
For Camera:
public class SimpleZoomHandler extends AbstractZoomHandler {
private IZoomHandlerListener zoomHandlerListener;
SimpleZoomHandler(View touchableView) {
super( touchableView );
}
public void setZoomHandlerListener(IZoomHandlerListener zoomHandlerListener) {
this.zoomHandlerListener = zoomHandlerListener;
}
@Override
public void notifyZoomChanged(int zoom) {
zoomHandlerListener.onZoomChanged( zoom );
}
@Override
public boolean isPrepared() {
return zoomHandlerListener != null;
}
public interface IZoomHandlerListener {
void onZoomChanged(int newZoom);
}
}
And for Camera2:
public class ActiveArrayZoomHandler extends AbstractZoomHandler {
private IZoomHandlerListener zoomHandlerListener;
private Rect activeArraySize;
ActiveArrayZoomHandler(View touchableView) {
super( touchableView );
}
public void setZoomHandlerListener(IZoomHandlerListener zoomHandlerListener) {
this.zoomHandlerListener = zoomHandlerListener;
}
public void setActiveArraySize(Rect activeArraySize) {
this.activeArraySize = activeArraySize;
}
@Override
public void notifyZoomChanged(int zoom) {
int minW = (int) (activeArraySize.width() / maxZoom);
int minH = (int) (activeArraySize.height() / maxZoom);
int difW = activeArraySize.width() - minW;
int difH = activeArraySize.height() - minH;
int cropW = difW / 100 * zoomLevel;
int cropH = difH / 100 * zoomLevel;
cropW -= cropW & 3;
cropH -= cropH & 3;
Rect zoomRect = new Rect( cropW, cropH, activeArraySize.width() - cropW, activeArraySize.height() - cropH );
zoomHandlerListener.onZoomChanged( zoomRect );
}
@Override
public boolean isPrepared() {
return zoomHandlerListener != null && activeArraySize != null;
}
public interface IZoomHandlerListener {
void onZoomChanged(Rect zoom);
}
}
And their respective Builder to make it fluent interface. For camera API:
public class SimpleZoomHandlerBuilder {
private SimpleZoomHandler simpleZoomHandler;
public static SimpleZoomHandlerBuilder forView(View touchableView) {
return new SimpleZoomHandlerBuilder( touchableView );
}
private SimpleZoomHandlerBuilder(View touchableView) {
simpleZoomHandler = new SimpleZoomHandler( touchableView );
}
public SimpleZoomHandlerBuilder setZoomListener(SimpleZoomHandler.IZoomHandlerListener listener) {
simpleZoomHandler.setZoomHandlerListener( listener );
return this;
}
public SimpleZoomHandlerBuilder setMaxZoom(float maxZoom) {
simpleZoomHandler.setMaxZoom( maxZoom );
return this;
}
public SimpleZoomHandler build() {
return simpleZoomHandler;
}
}
And for camera2 API:
public class ActiveArrayZoomHandlerBuilder {
private ActiveArrayZoomHandler activeArrayZoomHandler;
public static ActiveArrayZoomHandlerBuilder forView(View touchableView) {
return new ActiveArrayZoomHandlerBuilder( touchableView );
}
private ActiveArrayZoomHandlerBuilder(View touchableView) {
activeArrayZoomHandler = new ActiveArrayZoomHandler( touchableView );
}
public ActiveArrayZoomHandlerBuilder setZoomListener(ActiveArrayZoomHandler.IZoomHandlerListener listener) {
activeArrayZoomHandler.setZoomHandlerListener( listener );
return this;
}
public ActiveArrayZoomHandlerBuilder setMaxZoom(float maxZoom) {
activeArrayZoomHandler.setMaxZoom( maxZoom );
return this;
}
public ActiveArrayZoomHandlerBuilder setActiveArraySize(Rect activeArraySize) {
activeArrayZoomHandler.setActiveArraySize( activeArraySize );
return this;
}
public ActiveArrayZoomHandler build() {
return activeArrayZoomHandler;
}
}
