com.bumptech.glide.load.resource.bitmap

Class Downsampler

java.lang.Object

com.bumptech.glide.load.resource.bitmap.Downsampler

public final class Downsampler
extends Object

Downsamples, decodes, and rotates images according to their exif orientation.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	Downsampler.DecodeCallbacks Callbacks for key points during decodes.

Field Summary

Fields

Modifier and Type	Field and Description
static Option<Boolean>	ALLOW_HARDWARE_CONFIG Indicates that it's safe or unsafe to decode Bitmaps with Bitmap.Config#HARDWARE.
static Option<DecodeFormat>	DECODE_FORMAT Indicates the DecodeFormat that will be used in conjunction with the image format to determine the Bitmap.Config to provide to BitmapFactory.Options.inPreferredConfig when decoding the image.
static Option<DownsampleStrategy>	DOWNSAMPLE_STRATEGY Indicates the 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.
static Option<Boolean>	FIX_BITMAP_SIZE_TO_REQUESTED_DIMENSIONS Ensure that the size of the bitmap is fixed to the requested width and height of the resource from the caller.

Constructor Summary

Constructors

Constructor and Description
Downsampler(List<ImageHeaderParser> parsers, DisplayMetrics displayMetrics, BitmapPool bitmapPool, ArrayPool byteArrayPool)

Method Summary

Modifier and Type	Method and Description
Resource<Bitmap>	decode(InputStream is, int outWidth, int outHeight, Options options) Returns a Bitmap decoded from the given InputStream that is rotated to match any EXIF data present in the stream and that is downsampled according to the given dimensions and any provided DownsampleStrategy option.
Resource<Bitmap>	decode(InputStream is, int requestedWidth, int requestedHeight, Options options, Downsampler.DecodeCallbacks callbacks) Returns a Bitmap decoded from the given InputStream that is rotated to match any EXIF data present in the stream and that is downsampled according to the given dimensions and any provided DownsampleStrategy option.
boolean	handles(ByteBuffer byteBuffer)
boolean	handles(InputStream is)

Methods inherited from class java.lang.Object

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

Field Detail

DECODE_FORMAT

public static final Option<DecodeFormat> DECODE_FORMAT

Indicates the DecodeFormat that will be used in conjunction with the image format to determine the Bitmap.Config to provide to BitmapFactory.Options.inPreferredConfig when decoding the image.

DOWNSAMPLE_STRATEGY

public static final Option<DownsampleStrategy> DOWNSAMPLE_STRATEGY

Indicates the 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.

FIX_BITMAP_SIZE_TO_REQUESTED_DIMENSIONS

public static final Option<Boolean> FIX_BITMAP_SIZE_TO_REQUESTED_DIMENSIONS

Ensure that the size of the bitmap is fixed to the requested width and height of the resource from the caller. The final resource dimensions may differ from the requested width and height, and thus setting this to true may result in the bitmap size differing from the resource dimensions. This can be used as a performance optimization for KitKat and above by fixing the size of the bitmap for a collection of requested resources so that the bitmap pool will not need to allocate new bitmaps for images of different sizes.

ALLOW_HARDWARE_CONFIG

public static final Option<Boolean> ALLOW_HARDWARE_CONFIG

Indicates that it's safe or unsafe to decode Bitmaps with Bitmap.Config#HARDWARE.

Callers should almost never set this value to true manually. Glide will already do so when Glide believes it's safe to do (when no transformations are applied). Instead, callers can set this value to false to prevent Glide from decoding hardware bitmaps if Glide is unable to detect that hardware bitmaps are unsafe. For example, you should set this to false if you plan to draw it to a software Canvas or if you plan to inspect the Bitmaps pixels with Bitmap.getPixel(int, int) or Bitmap.getPixels(int[], int, int, int, int, int, int).

Callers can disable hardware Bitmaps for all loads using GlideBuilder.setDefaultRequestOptions(RequestOptions).

This option is ignored unless we're on Android O+.

Constructor Detail

Downsampler

public Downsampler(List<ImageHeaderParser> parsers,
                   DisplayMetrics displayMetrics,
                   BitmapPool bitmapPool,
                   ArrayPool byteArrayPool)

Method Detail

handles

public boolean handles(InputStream is)

handles

public boolean handles(ByteBuffer byteBuffer)

decode

public Resource<Bitmap> decode(InputStream is,
                               int outWidth,
                               int outHeight,
                               Options options)
                        throws IOException

Returns a Bitmap decoded from the given InputStream that is rotated to match any EXIF data present in the stream and that is downsampled according to the given dimensions and any provided DownsampleStrategy option.

Throws:

IOException

See Also:

decode(InputStream, int, int, Options, DecodeCallbacks)

decode

public Resource<Bitmap> decode(InputStream is,
                               int requestedWidth,
                               int requestedHeight,
                               Options options,
                               Downsampler.DecodeCallbacks callbacks)
                        throws IOException

Returns a Bitmap decoded from the given InputStream that is rotated to match any EXIF data present in the stream and that is downsampled according to the given dimensions and any provided DownsampleStrategy option.

If a Bitmap is present in the BitmapPool whose dimensions exactly match those of the image for the given InputStream is available, the operation is much less expensive in terms of memory.

The provided InputStream must return true from InputStream.markSupported() and is expected to support a reasonably large mark limit to accommodate reading large image headers (~5MB).

Parameters:

is - An InputStream to the data for the image.

requestedWidth - The width the final image should be close to.

requestedHeight - The height the final image should be close to.

options - A set of options that may contain one or more supported options that influence how a Bitmap will be decoded from the given stream.

callbacks - A set of callbacks allowing callers to optionally respond to various significant events during the decode process.

Returns:

A new bitmap containing the image from the given InputStream, or recycle if recycle is not null.

Throws:

IOException