Package com.journeyapps.barcodescanner.camera

Class LegacyPreviewScalingStrategy

java.lang.Object

com.journeyapps.barcodescanner.camera.PreviewScalingStrategy

com.journeyapps.barcodescanner.camera.LegacyPreviewScalingStrategy

public class LegacyPreviewScalingStrategy
extends PreviewScalingStrategy

Constructor Summary

Constructors

Constructor	Description
LegacyPreviewScalingStrategy()

Method Summary

Modifier and Type	Method	Description
Size	getBestPreviewSize(List<Size> sizes, Size desired)	Choose the best preview size, based on our display size.
static Size	scale(Size from, Size to)	Scale from so that to.fitsIn(size).
Rect	scalePreview(Size previewSize, Size viewfinderSize)	Scale the preview to cover the viewfinder, then center it.

Methods inherited from class com.journeyapps.barcodescanner.camera.PreviewScalingStrategy

getBestPreviewOrder, getScore

Methods inherited from class java.lang.Object

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

Constructor Detail

LegacyPreviewScalingStrategy

public LegacyPreviewScalingStrategy()

Method Detail

getBestPreviewSize

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

Choose the best preview size, based on our display size. We prefer: 1. no scaling 2. least downscaling 3. least upscaling We do not care much about aspect ratio, since we just crop away extra pixels. We only choose the size to minimize scaling. In the future we may consider choosing the biggest possible preview size, to maximize the resolution we have for decoding. We need more testing to see whether or not that is feasible.

Overrides:

getBestPreviewSize in class PreviewScalingStrategy

Parameters:

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

desired - The desired display size, in the same orientation

Returns:

the best preview size, never null

scale

public static Size scale(Size from,
                         Size to)

Scale from so that to.fitsIn(size). Tries to scale by powers of two, or by 3/2. Aspect ratio is preserved. These scaling factors will theoretically result in fast scaling with minimal quality loss. TODO: confirm whether or not this is the case in practice.

Parameters:

from - the start size

to - the minimum desired size

Returns:

the scaled size

scalePreview

public Rect scalePreview(Size previewSize,
                         Size viewfinderSize)

Scale the preview to cover the viewfinder, then center it. Aspect ratio is preserved.

Specified by:

scalePreview in class PreviewScalingStrategy

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