Package com.journeyapps.barcodescanner.camera

Class PreviewScalingStrategy

java.lang.Object

com.journeyapps.barcodescanner.camera.PreviewScalingStrategy

Direct Known Subclasses:

CenterCropStrategy, FitCenterStrategy, FitXYStrategy, LegacyPreviewScalingStrategy

public abstract class PreviewScalingStrategy
extends Object

Constructor Summary

Constructors

Constructor	Description
PreviewScalingStrategy()

Method Summary

Modifier and Type	Method	Description
List<Size>	getBestPreviewOrder(List<Size> sizes, Size desired)	Sort previews based on their suitability.
Size	getBestPreviewSize(List<Size> sizes, Size desired)	Choose the best preview size, based on our viewfinder size.
protected float	getScore(Size size, Size desired)	Get a score for our size.
abstract Rect	scalePreview(Size previewSize, Size viewfinderSize)	Scale and position the preview relative to the viewfinder.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PreviewScalingStrategy

public PreviewScalingStrategy()

Method Detail

getBestPreviewSize

public Size getBestPreviewSize(List<Size> sizes,
                               Size desired)

Choose the best preview size, based on our viewfinder size. The default implementation lets subclasses calculate a score for each size, the picks the one with the best score. The sizes list may be reordered by this call.

Parameters:

sizes - supported preview sizes, containing at least one size. Sizes are in natural camera orientation.

desired - The desired viewfinder size, in the same orientation

Returns:

the best preview size, never null

getBestPreviewOrder

public List<Size> getBestPreviewOrder(List<Size> sizes,
                                      Size desired)

Sort previews based on their suitability. In most cases, getBestPreviewSize(List, Size) should be used instead. The sizes list may be reordered by this call.

Parameters:

sizes - supported preview sizes, containing at least one size. Sizes are in natural camera orientation.

desired - The desired viewfinder size, in the same orientation

Returns:

an ordered list, best preview first

getScore

protected float getScore(Size size,
                         Size desired)

Get a score for our size. 1.0 is perfect (exact match). 0.0 means we can't use it at all. Subclasses should override this.

Parameters:

size - the camera preview size (that can be scaled)

desired - the viewfinder size

Returns:

the score

scalePreview

public abstract Rect scalePreview(Size previewSize,
                                  Size viewfinderSize)

Scale and position the preview relative to the viewfinder.

Parameters:

previewSize - the size of the preview (camera), in current display orientation

viewfinderSize - the size of the viewfinder (display), in current display orientation

Returns:

a rect placing the preview, relative to the viewfinder