CoordinateTransform

public final class CoordinateTransform

This class represents the transform from one OutputTransform to another.

This class can be used to map the coordinates of one OutputTransform to another, given that they are associated with the same ViewPort. OutputTransform can represent the output of a UseCase or PreviewView. For example, mapping the coordinates of detected objects from ImageAnalysis output to the drawing location in PreviewView. 

// imageProxy the output of an ImageAnalysis.
OutputTransform source = ImageProxyTransformFactory().getOutputTransform(imageProxy);
OutputTransform target = previewView.getOutputTransform();

// Build the transform from ImageAnalysis to PreviewView
CoordinateTransform coordinateTransform = new CoordinateTransform(source, target);

// Detect face in ImageProxy and transform the coordinates to PreviewView.
// The value of faceBox can be used to highlight the face in PreviewView.
RectF faceBox = detectFaceInImageProxy(imageProxy);
coordinateTransform.mapRect(faceBox);

Summary

Public constructors

Creates the transform between the source and the target.

Public methods
void

Apply this transform to the PointF, and write the transformed points back into the array
void
mapPoints(@NonNull float[] points)

Apply this transform to the array of 2D points, and write the transformed points back into the array
void

Apply this transform to the rectangle, and write the transformed rectangle back into it.
void
transform(@NonNull Matrix outMatrix)

Copies the current transform to the specified Matrix.

Public constructors

CoordinateTransform

Added in 1.1.0
public CoordinateTransform(
    @NonNull OutputTransform source,
    @NonNull OutputTransform target
)

Creates the transform between the source and the target.

The source and the target must be associated with the same ViewPort.

Parameters
@NonNull OutputTransform source

the source
@NonNull OutputTransform target

the target
See also
UseCaseGroup
ViewPort

Public methods

mapPoint

Added in 1.1.0
public void mapPoint(@NonNull PointF point)

Apply this transform to the PointF, and write the transformed points back into the array

Parameters
@NonNull PointF point

The point to transform.

mapPoints

Added in 1.1.0
public void mapPoints(@NonNull float[] points)

Apply this transform to the array of 2D points, and write the transformed points back into the array

Parameters
@NonNull float[] points

The array [x0, y0, x1, y1, ...] of points to transform.
See also
mapPoints

mapRect

Added in 1.1.0
public void mapRect(@NonNull RectF rect)

Apply this transform to the rectangle, and write the transformed rectangle back into it. This is accomplished by transforming the 4 corners of rect, and then setting it to the bounds of those points.

Parameters
@NonNull RectF rect

The rectangle to transform.

transform

Added in 1.1.0
public void transform(@NonNull Matrix outMatrix)

Copies the current transform to the specified Matrix.

Parameters
@NonNull Matrix outMatrix

a android.graphics.Matrix in which to copy the current transform.