Markwon/docs/docs/image-loader.md

Images

By default Markwon doesn't handle images. Although AsyncDrawable.Loader is defined in main artifact, it does not provide implementation.

The interface is pretty simple:

public interface Loader {

    void load(@NonNull String destination, @NonNull AsyncDrawable drawable);

    void cancel(@NonNull String destination);
}

AsyncDrawableLoader

AsyncDrawableLoader from markwon-image-loader artifact can be used.

:::tip Install Learn how to add markwon-image-loader to your project :::

Default instance of AsyncDrawableLoader can be obtain like this:

AsyncDrawableLoader.create();

Scheme support

By default AsyncDrawableLoader handles these URL schemes:

• file (including reference to android_assets)
• data (wiki) for inline image references
• all other schemes are considered to be network related and will be tried to obtain from network

Data

data scheme handler supports both base64 encoded content and plain:

<img src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg==" alt="Red dot" />

<img src='data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" aria-hidden="true" x="0px" y="0px" viewBox="0 0 100 100" width="15" height="15" class="icon outbound"><path fill="currentColor" d="M18.8,85.1h56l0,0c2.2,0,4-1.8,4-4v-32h-8v28h-48v-48h28v-8h-32l0,0c-2.2,0-4,1.8-4,4v56C14.8,83.3,16.6,85.1,18.8,85.1z"></path> <polygon fill="currentColor" points="45.7,48.7 51.3,54.3 77.2,28.5 77.2,37.2 85.2,37.2 85.2,14.9 62.8,14.9 62.8,22.9 71.5,22.9"></polygon></svg>' >

:::warning Note Data uri works with native markdown images, but only in base64 mode:

![svg](data:image/svg+xml;base64,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)

:::

Configuration

If you wish to configure AsyncDrawableLoader #builder factory method can be used:

AsyncDrawableLoader.builder()
        .build();

OkHttp client

AsyncDrawableLoader.builder()
        .client(OkHttpClient)
        .build();

If not provided explicitly, default new OkHttpClient() will be used

Resources

android.content.res.Resources to be used when obtaining an image from Android assets folder and to create Bitmaps.

AsyncDrawableLoader.builder()
        .resources(Resources)
        .build();

If not provided explicitly, default Resources.getSystem() will be used.

:::warning Resources.getSystem() can have unexpected side-effects (plus loading from assets won't work). As a rule of thumb always provide AsyncDrawableLoader with your Application's Resources. To quote Android documentation for #getSystem method:

Return a global shared Resources object that provides access to only system resources (no application resources), and is not configured for the current screen (can not use dimension units, does not change based on orientation, etc).

:::

Executor service

ExecutorService to be used to download images in background thread

AsyncDrawableLoader.builder()
        .executorService(ExecutorService)
        .build();

If not provided explicitly, default okHttpClient.dispatcher().executorService() will be used

Error drawable

errorDrawable to be used when image loader encountered an error loading image

AsyncDrawableLoader.builder()
        .errorDrawable(Drawable)
        .build();

if not provided explicitly, default null value will be used.

Media decoder

MediaDecoder is a simple asbtraction that encapsulates handling of a specific image type.

AsyncDrawableLoader.builder()
        .mediaDecoders(MediaDecoder...)
        .mediaDecoders(List<MediaDecoder>)
        .build();

If not provided explicitly, default MediaDecoders will be used (SVG, GIF, plain) with provided Resources and gif-autoplay=true

markwon-image-loader comes with 3 MediaDecoder implementations:

• SvgMediaDecoder (based on androidsvg)
• GifMediaDecoder (based on android-gif-drawable)
• ImageMediaDecoder (handling all plain images)

:::tip Always add a generic MediaDecoder instance at the end of the list. Order does matter. For example:

AsyncDrawableLoader.builder()
        .mediaDecoders(
                SvgMediaDecoder.create(Resources),
                GifMediaDecoder.create(boolean),
                ImageMediaDecoder.create(Resources)
        )
.build();

:::

SvgMediaDecoder

SvgMediaDecoder.create(Resources)

GifMediaDecoder

GifMediaDecoder.create(boolean)

boolean argument stands for autoPlayGif

ImageMediaDecoder

ImageMediaDecoder.create(Resources)