ImageDecoder Class

Definition

[Android.Runtime.Register("android/graphics/ImageDecoder", ApiSince=28, DoNotGenerateAcw=true)]
public sealed class ImageDecoder : Java.Lang.Object, IDisposable, Java.Interop.IJavaPeerable, Java.Lang.IAutoCloseable

[<Android.Runtime.Register("android/graphics/ImageDecoder", ApiSince=28, DoNotGenerateAcw=true)>]
type ImageDecoder = class
    inherit Object
    interface IAutoCloseable
    interface IJavaObject
    interface IDisposable
    interface IJavaPeerable

Inheritance

Object

Object

ImageDecoder

Attributes

RegisterAttribute

Implements

IJavaObject IJavaPeerable IAutoCloseable IDisposable

Remarks

A class for converting encoded images (like PNG, JPEG, WEBP, GIF, or HEIF) into Drawable or Bitmap objects.

To use it, first create a Source Source using one of the createSource overloads. For example, to decode from a Uri, call #createSource(ContentResolver, Uri) and pass the result to #decodeDrawable(Source) or #decodeBitmap(Source):

File file = new File(...);
             ImageDecoder.Source source = ImageDecoder.createSource(file);
             Drawable drawable = ImageDecoder.decodeDrawable(source);

To change the default settings, pass the Source Source and an OnHeaderDecodedListener OnHeaderDecodedListener to #decodeDrawable(Source, OnHeaderDecodedListener) or #decodeBitmap(Source, OnHeaderDecodedListener). For example, to create a sampled image with half the width and height of the original image, call #setTargetSampleSize setTargetSampleSize(2) inside OnHeaderDecodedListener#onHeaderDecoded onHeaderDecoded:

OnHeaderDecodedListener listener = new OnHeaderDecodedListener() {
                 public void onHeaderDecoded(ImageDecoder decoder, ImageInfo info, Source source) {
                     decoder.setTargetSampleSize(2);
                 }
             };
             Drawable drawable = ImageDecoder.decodeDrawable(source, listener);

The ImageInfo ImageInfo contains information about the encoded image, like its width and height, and the Source Source can be used to match to a particular Source Source if a single OnHeaderDecodedListener OnHeaderDecodedListener is used with multiple Source Source objects.

The OnHeaderDecodedListener OnHeaderDecodedListener can also be implemented as a lambda:

Drawable drawable = ImageDecoder.decodeDrawable(source, (decoder, info, src) -> {
                 decoder.setTargetSampleSize(2);
             });

If the encoded image is an animated GIF or WEBP, #decodeDrawable decodeDrawable will return an AnimatedImageDrawable. To start its animation, call AnimatedImageDrawable#start AnimatedImageDrawable.start():

Drawable drawable = ImageDecoder.decodeDrawable(source);
             if (drawable instanceof AnimatedImageDrawable) {
                 ((AnimatedImageDrawable) drawable).start();
             }

By default, a Bitmap created by ImageDecoder (including one that is inside a Drawable) will be immutable (i.e. Bitmap#isMutable Bitmap.isMutable() returns false), and it will typically have ConfigBitmap.Config#HARDWARE. Although these properties can be changed with #setMutableRequired setMutableRequired(true) (which is only compatible with #decodeBitmap(Source) and #decodeBitmap(Source, OnHeaderDecodedListener)) and #setAllocator, it is also possible to apply custom effects regardless of the mutability of the final returned object by passing a PostProcessor to #setPostProcessor setPostProcessor. A PostProcessor can also be a lambda:

Drawable drawable = ImageDecoder.decodeDrawable(source, (decoder, info, src) -> {
                 decoder.setPostProcessor((canvas) -> {
                         // This will create rounded corners.
                         Path path = new Path();
                         path.setFillType(Path.FillType.INVERSE_EVEN_ODD);
                         int width = canvas.getWidth();
                         int height = canvas.getHeight();
                         path.addRoundRect(0, 0, width, height, 20, 20, Path.Direction.CW);
                         Paint paint = new Paint();
                         paint.setAntiAlias(true);
                         paint.setColor(Color.TRANSPARENT);
                         paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC));
                         canvas.drawPath(path, paint);
                         return PixelFormat.TRANSLUCENT;
                 });
             });

If the encoded image is incomplete or contains an error, or if an Exception occurs during decoding, a DecodeException DecodeException will be thrown. In some cases, the ImageDecoder may have decoded part of the image. In order to display the partial image, an OnPartialImageListener OnPartialImageListener must be passed to #setOnPartialImageListener setOnPartialImageListener. For example:

Drawable drawable = ImageDecoder.decodeDrawable(source, (decoder, info, src) -> {
                 decoder.setOnPartialImageListener((DecodeException e) -> {
                         // Returning true indicates to create a Drawable or Bitmap even
                         // if the whole image could not be decoded. Any remaining lines
                         // will be blank.
                         return true;
                 });
             });

Java documentation for android.graphics.ImageDecoder.

Portions of this page are modifications based on work created and shared by the Android Open Source Project and used according to terms described in the Creative Commons 2.5 Attribution License.