Glide/com.bumptech.glide.load.resource.bitmap/DownsampleStrategy

DownsampleStrategy

Indicates the algorithm to use when downsampling images.

DownsampleStrategy does not provide any guarantees about output sizes. Behavior will differ depending on the com.bumptech.glide.load.ResourceDecoder using the strategy and the version of Android the code runs on. Use DownsampleStrategy as an optimization to improve memory efficiency only. If you need a particular size or shape output, use an either instead or in addition to a DownsampleStrategy.

Some differences between versions of Android and s are listed below, but the list is not comprehensive because DownsampleStrategy only controls its output scale value, not how that output value is used.

On some versions of Android, precise scaling is not possible. In those cases, the strategies can only pick between downsampling to between 1x the requested size and 2x the requested size and between 0.5x the requested size and 1x the requested size because only power of two downsampling is supported. To preserve the potential for a com.bumptech.glide.load.Transformation to scale precisely without a loss in quality, all but AT_MOST will prefer to downsample to between 1x and 2x the requested size.

Types

SampleSizeRounding

enum SampleSizeRounding

Indicates whether to prefer to prefer downsampling or scaling to prefer lower memory usage or higher quality.

Functions

getSampleSizeRounding

abstract fun getSampleSizeRounding( sourceWidth: Int, sourceHeight: Int, requestedWidth: Int, requestedHeight: Int): DownsampleStrategy.SampleSizeRounding

Returns a non-null SampleSizeRounding to use to resolve rounding errors and conflicts between scaling for the width and the height of the image.

getScaleFactor

abstract fun getScaleFactor( sourceWidth: Int, sourceHeight: Int, requestedWidth: Int, requestedHeight: Int): Float

Returns a float (0, +infinity) indicating a scale factor to apply to the source width and height when displayed in the requested width and height.

Properties

AT_LEAST

val AT_LEAST: DownsampleStrategy

Downsamples so the image's smallest dimension is between the given dimensions and 2x the given dimensions, with no size restrictions on the image's largest dimension.

AT_MOST

val AT_MOST: DownsampleStrategy

Downsamples so the image's largest dimension is between 1/2 the given dimensions and the given dimensions, with no restrictions on the image's smallest dimension.

CENTER_INSIDE

val CENTER_INSIDE: DownsampleStrategy

Identical to FIT_CENTER, but never upscales.

CENTER_OUTSIDE

val CENTER_OUTSIDE: DownsampleStrategy

Scales, maintaining the original aspect ratio, so that one of the image's dimensions is exactly equal to the requested size and the other dimension is greater than or equal to the requested size.

DEFAULT

val DEFAULT: DownsampleStrategy

Default strategy, currently CENTER_OUTSIDE.

FIT_CENTER

val FIT_CENTER: DownsampleStrategy

Scales, maintaining the original aspect ratio, so that one of the image's dimensions is exactly equal to the requested size and the other dimension is less than or equal to the requested size.

NONE

val NONE: DownsampleStrategy

Performs no downsampling or scaling.

OPTION

val OPTION: Option<DownsampleStrategy>

Indicates the com.bumptech.glide.load.resource.bitmap.DownsampleStrategy option that will be used to calculate the sample size to use to downsample an image given the original and target dimensions of the image.