Support code blocks (#4090)

before
<img
src="https://github.com/tuskyapp/Tusky/assets/10157047/452b959f-7f97-4d04-a464-0dcf0bf56f79"
width="380"/>

after
<img
src="https://github.com/tuskyapp/Tusky/assets/10157047/0fb5b41c-dda3-4d46-878e-689d6ae51b0a"
width="380"/>

app/src/main/java/com/keylesspalace/tusky/components/viewthread/edits/ViewEditsAdapter.kt

@@ -5,10 +5,7 @@ import android.graphics.Typeface.DEFAULT_BOLD
 import android.graphics.drawable.ColorDrawable
 import android.graphics.drawable.Drawable
 import android.text.Editable
-import android.text.Html
-import android.text.Spannable
 import android.text.SpannableStringBuilder
-import android.text.Spanned
 import android.text.TextPaint
 import android.text.style.CharacterStyle
 import android.util.TypedValue
@@ -29,6 +26,7 @@ import com.keylesspalace.tusky.entity.StatusEdit
 import com.keylesspalace.tusky.interfaces.LinkListener
 import com.keylesspalace.tusky.util.AbsoluteTimeFormatter
 import com.keylesspalace.tusky.util.BindingHolder
+import com.keylesspalace.tusky.util.TuskyTagHandler
 import com.keylesspalace.tusky.util.aspectRatios
 import com.keylesspalace.tusky.util.decodeBlurHash
 import com.keylesspalace.tusky.util.emojify
@@ -118,7 +116,7 @@ class ViewEditsAdapter(
 
         val emojifiedText = edit
             .content
-            .parseAsMastodonHtml(TuskyTagHandler(context))
+            .parseAsMastodonHtml(EditsTagHandler(context))
             .emojify(edit.emojis, binding.statusEditContent, animateEmojis)
 
         setClickableText(binding.statusEditContent, emojifiedText, emptyList(), emptyList(), listener)
@@ -224,7 +222,7 @@ class ViewEditsAdapter(
  * Handle XML tags created by [ViewEditsViewModel] and create custom spans to display inserted or
  * deleted text.
  */
-class TuskyTagHandler(val context: Context) : Html.TagHandler {
+class EditsTagHandler(val context: Context) : TuskyTagHandler() {
     /** Class to mark the start of a span of deleted text */
     class Del
 
@@ -255,34 +253,7 @@ class TuskyTagHandler(val context: Context) : Html.TagHandler {
                     )
                 }
             }
-        }
+            else -> super.handleTag(opening, tag, output, xmlReader)
-    }
-
-    /** @return the last span in [text] of type [kind], or null if that kind is not in text */
-    private fun <T> getLast(text: Spanned, kind: Class<T>): Any? {
-        val spans = text.getSpans(0, text.length, kind)
-        return spans?.get(spans.size - 1)
-    }
-
-    /**
-     * Mark the start of a span of [text] with [mark] so it can be discovered later by [end].
-     */
-    private fun start(text: SpannableStringBuilder, mark: Any) {
-        val len = text.length
-        text.setSpan(mark, len, len, Spannable.SPAN_MARK_MARK)
-    }
-
-    /**
-     * Set a [span] over the [text] most from the point recently marked with [mark] to the end
-     * of the text.
-     */
-    private fun <T> end(text: SpannableStringBuilder, mark: Class<T>, span: Any) {
-        val len = text.length
-        val obj = getLast(text, mark)
-        val where = text.getSpanStart(obj)
-        text.removeSpan(obj)
-        if (where != len) {
-            text.setSpan(span, where, len, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE)
         }
     }
 

app/src/main/java/com/keylesspalace/tusky/components/viewthread/edits/ViewEditsViewModel.kt

@@ -18,8 +18,8 @@ package com.keylesspalace.tusky.components.viewthread.edits
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import at.connyduck.calladapter.networkresult.getOrElse
-import com.keylesspalace.tusky.components.viewthread.edits.TuskyTagHandler.Companion.DELETED_TEXT_EL
+import com.keylesspalace.tusky.components.viewthread.edits.EditsTagHandler.Companion.DELETED_TEXT_EL
-import com.keylesspalace.tusky.components.viewthread.edits.TuskyTagHandler.Companion.INSERTED_TEXT_EL
+import com.keylesspalace.tusky.components.viewthread.edits.EditsTagHandler.Companion.INSERTED_TEXT_EL
 import com.keylesspalace.tusky.entity.StatusEdit
 import com.keylesspalace.tusky.network.MastodonApi
 import kotlinx.coroutines.Dispatchers

app/src/main/java/com/keylesspalace/tusky/util/StatusParsingHelper.kt

@@ -17,21 +17,78 @@
 
 package com.keylesspalace.tusky.util
 
+import android.text.Editable
 import android.text.Html.TagHandler
+import android.text.Spannable
+import android.text.SpannableStringBuilder
 import android.text.Spanned
+import android.text.style.TypefaceSpan
 import androidx.core.text.parseAsHtml
+import org.xml.sax.XMLReader
 
 /**
  * parse a String containing html from the Mastodon api to Spanned
  */
 @JvmOverloads
-fun String.parseAsMastodonHtml(tagHandler: TagHandler? = null): Spanned {
+fun String.parseAsMastodonHtml(tagHandler: TagHandler? = tuskyTagHandler): Spanned {
     return this.replace("<br> ", "<br>&nbsp;")
         .replace("<br /> ", "<br />&nbsp;")
         .replace("<br/> ", "<br/>&nbsp;")
+        .replace("\n", "<br/>")
         .replace("  ", "&nbsp;&nbsp;")
         .parseAsHtml(tagHandler = tagHandler)
         /* Html.fromHtml returns trailing whitespace if the html ends in a </p> tag, which
          * most status contents do, so it should be trimmed. */
         .trimTrailingWhitespace()
 }
+
+val tuskyTagHandler = TuskyTagHandler()
+
+open class TuskyTagHandler : TagHandler {
+
+    class Code
+
+    override fun handleTag(opening: Boolean, tag: String, output: Editable, xmlReader: XMLReader) {
+        when (tag) {
+            "code" -> {
+                if (opening) {
+                    start(output as SpannableStringBuilder, Code())
+                } else {
+                    end(
+                        output as SpannableStringBuilder,
+                        Code::class.java,
+                        TypefaceSpan("monospace")
+                    )
+                }
+            }
+        }
+    }
+
+    /** @return the last span in [text] of type [kind], or null if that kind is not in text */
+    protected fun <T> getLast(text: Spanned, kind: Class<T>): Any? {
+        val spans = text.getSpans(0, text.length, kind)
+        return spans?.get(spans.size - 1)
+    }
+
+    /**
+     * Mark the start of a span of [text] with [mark] so it can be discovered later by [end].
+     */
+    protected fun start(text: SpannableStringBuilder, mark: Any) {
+        val len = text.length
+        text.setSpan(mark, len, len, Spannable.SPAN_MARK_MARK)
+    }
+
+    /**
+     * Set a [span] over the [text] from the point recently marked with [mark] to the end
+     * of the text.
+     */
+    protected fun <T> end(text: SpannableStringBuilder, mark: Class<T>, span: Any) {
+        val len = text.length
+        val obj = getLast(text, mark)
+        val where = text.getSpanStart(obj)
+        text.removeSpan(obj)
+        if (where != len) {
+            text.setSpan(span, where, len, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE)
+        }
+    }
+}