Extract method about text to the design system module.

libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/text/AnnotatedStrings.kt

@@ -0,0 +1,84 @@
+/*
+ * Copyright (c) 2023 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.libraries.designsystem.text
+
+import android.graphics.Typeface
+import android.text.SpannableString
+import android.text.style.ForegroundColorSpan
+import android.text.style.StyleSpan
+import android.text.style.UnderlineSpan
+import androidx.annotation.StringRes
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.AnnotatedString
+import androidx.compose.ui.text.SpanStyle
+import androidx.compose.ui.text.buildAnnotatedString
+import androidx.compose.ui.text.font.FontStyle
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.style.TextDecoration
+import io.element.android.libraries.designsystem.LinkColor
+
+fun String.toAnnotatedString(): AnnotatedString = buildAnnotatedString {
+    append(this@toAnnotatedString)
+    val spannable = SpannableString(this@toAnnotatedString)
+    spannable.getSpans(0, spannable.length, Any::class.java).forEach { span ->
+        val start = spannable.getSpanStart(span)
+        val end = spannable.getSpanEnd(span)
+        when (span) {
+            is StyleSpan -> when (span.style) {
+                Typeface.BOLD -> addStyle(SpanStyle(fontWeight = FontWeight.Bold), start, end)
+                Typeface.ITALIC -> addStyle(SpanStyle(fontStyle = FontStyle.Italic), start, end)
+                Typeface.BOLD_ITALIC -> addStyle(SpanStyle(fontWeight = FontWeight.Bold, fontStyle = FontStyle.Italic), start, end)
+            }
+            is UnderlineSpan -> addStyle(SpanStyle(textDecoration = TextDecoration.Underline), start, end)
+            is ForegroundColorSpan -> addStyle(SpanStyle(color = Color(span.foregroundColor)), start, end)
+        }
+    }
+}
+
+/**
+ * Convert a string to an [AnnotatedString] with styles applied.
+ *
+ * @param fullTextRes the string resource to use as the full text. Must contain a single %s
+ * @param coloredTextRes the string resource to use as the colored part of the string
+ * @param color the color to apply to the string
+ * @param underline whether to underline the string
+ * @param bold whether to bold the string
+ */
+@Composable
+fun buildAnnotatedStringWithStyledPart(
+    @StringRes fullTextRes: Int,
+    @StringRes coloredTextRes: Int,
+    color: Color = LinkColor,
+    underline: Boolean = true,
+    bold: Boolean = false,
+) = buildAnnotatedString {
+    val coloredPart = stringResource(coloredTextRes)
+    val fullText = stringResource(fullTextRes, coloredPart)
+    val startIndex = fullText.indexOf(coloredPart)
+    append(fullText)
+    addStyle(
+        style = SpanStyle(
+            color = color,
+            textDecoration = if (underline) TextDecoration.Underline else null,
+            fontWeight = if (bold) FontWeight.Bold else null,
+        ),
+        start = startIndex,
+        end = startIndex + coloredPart.length,
+    )
+}