Markwon

Configuration

WARNING

This is documentation for legacy versions. For the most current version click here.

MarkwonConfiguration class holds common Markwon functionality. These are configurable properties:

  • SyntaxHighlight
  • LinkSpan.Resolver
  • UrlProcessor
  • ImageSizeResolver
  • MarkwonHtmlParser

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Additionally MarkwonConfiguration holds:

  • MarkwonTheme
  • AsyncDrawableLoader
  • MarkwonHtmlRenderer
  • MarkwonSpansFactory

Please note that these values can be retrieved from MarkwonConfiguration instance, but their configuration must be done by a Plugin by overriding one of the methods:

  • Plugin#configureTheme
  • Plugin#configureImages
  • Plugin#configureHtmlRenderer
  • Plugin#configureSpansFactory

SyntaxHighlight

final Markwon markwon = Markwon.builder(this)
        .usePlugin(new AbstractMarkwonPlugin() {
            @Override
            public void configureConfiguration(@NonNull MarkwonConfiguration.Builder builder) {
                builder.syntaxHighlight(new SyntaxHighlightNoOp());
            }
        })
        .build();

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Use syntax-highlight to add syntax highlighting to your application

LinkSpan.Resolver

React to a link click event. By default LinkResolverDef is used, which tries to start an Activity given the link argument. If no Activity can handle link LinkResolverDef silently ignores click event

final Markwon markwon = Markwon.builder(this)
        .usePlugin(new AbstractMarkwonPlugin() {
            @Override
            public void configureConfiguration(@NonNull MarkwonConfiguration.Builder builder) {
                builder.linkResolver(new LinkSpan.Resolver() {
                    @Override
                    public void resolve(View view, @NonNull String link) {
                        // react to link click here
                    }
                });
            }
        })
        .build();

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Please note that Markwon will apply LinkMovementMethod to a resulting TextView if there is none registered. if you wish to register own instance of a MovementMethod apply it directly to a TextView or use MovementMethodPlugin

UrlProcessor

Process URLs in your markdown (for links and images). If not provided explicitly, default no-op implementation will be used, which does not modify URLs (keeping them as-is).

Markwon provides 2 implementations of UrlProcessor:

  • UrlProcessorRelativeToAbsolute
  • UrlProcessorAndroidAssets

UrlProcessorRelativeToAbsolute

UrlProcessorRelativeToAbsolute can be used to make relative URL absolute. For example if an image is defined like this: ![img](./art/image.JPG) and UrlProcessorRelativeToAbsolute is created with https://github.com/noties/Markwon/raw/master/ as the base: new UrlProcessorRelativeToAbsolute("https://github.com/noties/Markwon/raw/master/"), then final image will have https://github.com/noties/Markwon/raw/master/art/image.JPG as the destination.

UrlProcessorAndroidAssets

UrlProcessorAndroidAssets can be used to make processed links to point to Android assets folder. So an image: ![img](./art/image.JPG) will have file:///android_asset/art/image.JPG as the destination.

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Please note that UrlProcessorAndroidAssets will process only URLs that have no scheme information, so a ./art/image.png will become file:///android_asset/art/image.JPG whilst https://so.me/where.png will be kept as-is.

WARNING

In order to display an image from assets you still need to register ImagesPlugin#createWithAssets(Context) plugin in resulting Markwon instance. As UrlProcessorAndroidAssets only processes URLs and doesn't take any part in displaying an image.

ImageSizeResolver

ImageSizeResolver controls the size of an image to be displayed. Currently it handles only HTML images (specified via img tag).

final Markwon markwon = Markwon.builder(this)
        .usePlugin(new AbstractMarkwonPlugin() {
            @Override
            public void configureConfiguration(@NonNull MarkwonConfiguration.Builder builder) {
                builder.imageSizeResolver(new ImageSizeResolver() {
                    @NonNull
                    @Override
                    public Rect resolveImageSize(
                            @Nullable ImageSize imageSize,
                            @NonNull Rect imageBounds,
                            int canvasWidth,
                            float textSize) {
                        return null;
                    }
                });
            }
        })
        .build();

If not provided explicitly, default ImageSizeResolverDef implementation will be used. It handles 3 dimension units:

  • % (percent, relative to Canvas width)
  • em (relative to text size)
  • px (absolute size, every dimension that is not % or em is considered to be absolute)
<img width="100%">
<img width="2em" height="10px">
<img style="{width: 100%; height: 8em;}">

ImageSizeResolverDef keeps the ratio of original image if one of the dimensions is missing.

Height%

There is no support for % units for height dimension. This is due to the fact that height of an TextView in which markdown is displayed is non-stable and changes with time (for example when image is loaded and applied to a TextView it will increase TextView's height), so we will have no point-of-reference from which to calculate image height.

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ImageSizeResolverDef also takes care for an image to not exceed canvas width. If an image has greater width than a TextView Canvas, then image will be scaled-down to fit the canvas. Please note that this rule applies only if image has no absolute sizes (for example width is specified in pixels).

MarkwonHtmlParser

Specify which HTML parser to use. Default implementation is no-op.

WARNING

One must explicitly use HtmlPlugin in order to display HTML content in markdown. Without specified HTML parser no HTML content will be rendered.

Markwon.builder(context)
    .usePlugin(HtmlPlugin.create())

Please note that adding HtmlPlugin will take care of initializing parser, so after HtmlPlugin is used, no additional configuration steps are required.

Last Updated: 8/6/2019, 7:27:20 PM

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