Fix #4848: Ensure Complete Content Descriptions for Custom HTML Tags in CustomHtmlContentHandler #5614
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
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@@ -25,9 +25,17 @@ class CustomHtmlContentHandler private constructor( | |
| private var originalContentHandler: ContentHandler? = null | ||
| private var currentTrackedTag: TrackedTag? = null | ||
| private val currentTrackedCustomTags = ArrayDeque<TrackedCustomTag>() | ||
| private val contentDescriptionBuilder = StringBuilder() | ||
| private val tagContentDescriptions = mutableMapOf<Int, String>() | ||
| private var isInListItem = false | ||
| private var pendingNewline = false | ||
| private val blockTags = setOf("p", "ol", "ul", "li", "oppia-ul", "oppia-ol", "oppia-li", "div") | ||
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| override fun endElement(uri: String?, localName: String?, qName: String?) { | ||
| originalContentHandler?.endElement(uri, localName, qName) | ||
| if (localName in blockTags) { | ||
| isInListItem = false | ||
| } | ||
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There was a problem hiding this comment. This could have been: val tagName = qName ?: localName // Fallback to localName if qName is null
if (tagName in blockTags) {
isInListItem = false
}qName (qualified name) is generally more reliable unless your parser enforces namespaces. |
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| currentTrackedTag = null | ||
| } | ||
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@@ -45,6 +53,11 @@ class CustomHtmlContentHandler private constructor( | |
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| override fun characters(ch: CharArray?, start: Int, length: Int) { | ||
| originalContentHandler?.characters(ch, start, length) | ||
| if (pendingNewline) { | ||
| contentDescriptionBuilder.append('\n') | ||
| pendingNewline = false | ||
| } | ||
| ch?.let { contentDescriptionBuilder.append(String(it, start, length)) } | ||
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There was a problem hiding this comment.
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| } | ||
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| override fun endDocument() { | ||
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@@ -56,6 +69,10 @@ class CustomHtmlContentHandler private constructor( | |
| // Defer custom tag management to the tag handler so that Android's element parsing takes | ||
| // precedence. | ||
| currentTrackedTag = TrackedTag(checkNotNull(localName), checkNotNull(atts)) | ||
| if (localName in blockTags) { | ||
| pendingNewline = true | ||
| isInListItem = true | ||
| } | ||
| originalContentHandler?.startElement(uri, localName, qName, atts) | ||
| } | ||
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@@ -110,6 +127,14 @@ class CustomHtmlContentHandler private constructor( | |
| "Expected tracked tag $currentTrackedTag to match custom tag: $tag" | ||
| } | ||
| val (_, attributes, openTagIndex) = currentTrackedCustomTag | ||
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| val handler = customTagHandlers.getValue(tag) | ||
| if (handler is ContentDescriptionProvider) { | ||
| val contentDesc = handler.getContentDescription(attributes) | ||
| if (contentDesc != null) { | ||
| tagContentDescriptions[openTagIndex] = contentDesc | ||
| } | ||
| } | ||
| customTagHandlers.getValue(tag).handleClosingTag(output, indentation = 0, tag) | ||
| customTagHandlers.getValue(tag) | ||
| .handleTag(attributes, openTagIndex, output.length, output, imageRetriever) | ||
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@@ -123,7 +148,26 @@ class CustomHtmlContentHandler private constructor( | |
| val attributes: Attributes, | ||
| val openTagIndex: Int | ||
| ) | ||
| /** | ||
| * Returns the complete content description for the processed HTML, including descriptions | ||
| * from all custom tags. | ||
| */ | ||
| private fun getContentDescription(): String { | ||
| val rawDesc = buildString { | ||
| var lastIndex = 0 | ||
| tagContentDescriptions.entries.sortedBy { it.key }.forEach { (index, description) -> | ||
| if (index > lastIndex) { | ||
| append(contentDescriptionBuilder.substring(lastIndex, index)) | ||
| } | ||
| append(description) | ||
| lastIndex = index | ||
| } | ||
| if (lastIndex < contentDescriptionBuilder.length) { | ||
| append(contentDescriptionBuilder.substring(lastIndex)) | ||
| } | ||
| } | ||
| return rawDesc.replace(Regex("\n+"), "\n").trim() | ||
| } | ||
| /** Handler interface for a custom tag and its attributes. */ | ||
| interface CustomTagHandler { | ||
| /** | ||
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@@ -166,6 +210,15 @@ class CustomHtmlContentHandler private constructor( | |
| fun handleClosingTag(output: Editable, indentation: Int, tag: String) {} | ||
| } | ||
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| /** Handler Interface for tag handlers that provide content descriptions. */ | ||
| interface ContentDescriptionProvider { | ||
| /** | ||
| * Returns a content description string for this tag based on its attributes, | ||
| * or null if no description is available. | ||
| */ | ||
| fun getContentDescription(attributes: Attributes): String? | ||
| } | ||
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| /** | ||
| * Retriever of images for custom tag handlers. The built-in Android analog for this class is | ||
| * Html's ImageGetter. | ||
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@@ -196,6 +249,24 @@ class CustomHtmlContentHandler private constructor( | |
| } | ||
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| companion object { | ||
| /** | ||
| * Returns the content description for the HTML content, processing all custom tags that implement | ||
| * [ContentDescriptionProvider]. | ||
| */ | ||
| fun <T> getContentDescription( | ||
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There was a problem hiding this comment. I noticed that while this function was created, it was not used as required by the issue description. The only present usage is in According to #4848, we should ensure descriptions are generated for answers, link cases, including anchors, or any case when text can appear between tags. This means this new function should be used with |
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| html: String, | ||
| imageRetriever: T?, | ||
| customTagHandlers: Map<String, CustomTagHandler> | ||
| ): String where T : Html.ImageGetter, T : ImageRetriever { | ||
| val handler = CustomHtmlContentHandler(customTagHandlers, imageRetriever) | ||
| HtmlCompat.fromHtml( | ||
| "<init-custom-handler/>$html", | ||
| HtmlCompat.FROM_HTML_MODE_LEGACY, | ||
| imageRetriever, | ||
| handler | ||
| ) | ||
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There was a problem hiding this comment. This code appears unused, what does it do? There was a problem hiding this comment. The code is not unused, It triggers the HTML parsing process, allowing This approach leverages Android’s built-in HTML parsing system, ensuring compatibility with the framework’s expectations, and allows the reuse of the same parsing logic for both content description and display purposes. I'll add comments explaining this and the
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| return handler.getContentDescription() | ||
| } | ||
| /** | ||
| * Returns a new [Spannable] with HTML parsed from [html] using the specified [imageRetriever] | ||
| * for handling image retrieval, and map of tags to [CustomTagHandler]s for handling custom | ||
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I'm not sure what pending new line here means, maybe a rename or adding a comment might clear things up. I had a bit of trouble understanding how it is used in
override fun charactersbelow.There was a problem hiding this comment.
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It acts as a flag that indicates whether a newline character should be inserted before the next text content. It's used when dealing with block-level HTML elements