Add custom generic font mapping until JetBrains/compose-multiplatform…

…-core#994 is (hopefully) merged

common/src/commonMain/kotlin/tk/zwander/commonCompose/util/FontMapper.kt

@@ -0,0 +1,78 @@
+package tk.zwander.commonCompose.util
+
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.platform.LocalFontFamilyResolver
+import androidx.compose.ui.text.ExperimentalTextApi
+import androidx.compose.ui.text.font.FontFamily
+import androidx.compose.ui.text.font.GenericFontFamily
+import korlibs.memory.Platform
+import tk.zwander.common.util.CrossPlatformBugsnag
+
+object FontMapper {
+    private val GenericFontFamiliesMapping: Map<String, List<String>> by lazy {
+        when  {
+            Platform.isLinux ->
+                mapOf(
+                    FontFamily.SansSerif.name to listOf("Noto Sans", "DejaVu Sans", "Arial"),
+                    FontFamily.Serif.name to listOf("Noto Serif", "DejaVu Serif", "Times New Roman"),
+                    FontFamily.Monospace.name to listOf("Noto Sans Mono", "DejaVu Sans Mono", "Consolas"),
+                    // better alternative?
+                    FontFamily.Cursive.name to listOf("Comic Sans MS"),
+                )
+            Platform.isWindows ->
+                mapOf(
+                    // Segoe UI is the Windows system font, so try it first.
+                    // See https://learn.microsoft.com/en-us/windows/win32/uxguide/vis-fonts
+                    FontFamily.SansSerif.name to listOf("Segoe UI", "Arial"),
+                    FontFamily.Serif.name to listOf("Times New Roman"),
+                    FontFamily.Monospace.name to listOf("Consolas"),
+                    FontFamily.Cursive.name to listOf("Comic Sans MS"),
+                )
+            Platform.isMac || Platform.isIos || Platform.isTvos || Platform.isWatchos ->
+                mapOf(
+                    // .AppleSystem* aliases is the only legal way to get default SF and NY fonts.
+                    FontFamily.SansSerif.name to listOf(".AppleSystemUIFont", "Helvetica Neue", "Helvetica"),
+                    FontFamily.Serif.name to listOf(".AppleSystemUIFontSerif", "Times", "Times New Roman"),
+                    FontFamily.Monospace.name to listOf(".AppleSystemUIFontMonospaced", "Menlo", "Courier"),
+                    // Safari "font-family: cursive" real font names from macOS and iOS.
+                    FontFamily.Cursive.name to listOf("Apple Chancery", "Snell Roundhand"),
+                )
+            Platform.isAndroid -> // https://m3.material.io/styles/typography/fonts
+                mapOf(
+                    FontFamily.SansSerif.name to listOf("Roboto", "Noto Sans"),
+                    FontFamily.Serif.name to listOf("Roboto Serif", "Noto Serif"),
+                    FontFamily.Monospace.name to listOf("Roboto Mono", "Noto Sans Mono"),
+                    FontFamily.Cursive.name to listOf("Comic Sans MS"),
+                )
+            else ->
+                mapOf(
+                    FontFamily.SansSerif.name to listOf("Arial"),
+                    FontFamily.Serif.name to listOf("Times New Roman"),
+                    FontFamily.Monospace.name to listOf("Consolas"),
+                    FontFamily.Cursive.name to listOf("Comic Sans MS"),
+                )
+        }
+    }
+
+    @OptIn(ExperimentalTextApi::class)
+    @Composable
+    fun mapGenericFontFamilyToSpecificFontFamily(family: FontFamily): FontFamily {
+        if (family !is GenericFontFamily) {
+            return family
+        }
+
+        val mapped = GenericFontFamiliesMapping[family.name] ?: return family
+        val resolver = LocalFontFamilyResolver.current
+
+        return mapped.firstNotNullOfOrNull { fontName ->
+            try {
+                FontFamily(fontName).also {
+                    resolver.resolve()
+                }
+            } catch (e: Throwable) {
+                CrossPlatformBugsnag.notify(Exception("Unable to load font $fontName.", e))
+                null
+            }
+        } ?: family
+    }
+}

common/src/commonMain/kotlin/tk/zwander/commonCompose/view/components/CustomMaterialTheme.kt

@@ -1,20 +1,22 @@
 package tk.zwander.commonCompose.view.components
 
 import androidx.compose.material3.ColorScheme
+import androidx.compose.material3.LocalTextStyle
 import androidx.compose.material3.MaterialTheme
-import androidx.compose.material3.SwitchColors
 import androidx.compose.material3.darkColorScheme
 import androidx.compose.material3.lightColorScheme
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.CompositionLocalProvider
 import androidx.compose.ui.graphics.Color
+import tk.zwander.commonCompose.util.FontMapper
 import tk.zwander.commonCompose.util.ThemeInfo
 import tk.zwander.commonCompose.util.getThemeInfo
 
 /**
  * A Material theme with custom colors and such.
  */
 @Composable
-fun CustomMaterialTheme(block: @Composable()() -> Unit) {
+fun CustomMaterialTheme(block: @Composable () -> Unit) {
     val themeInfo = getThemeInfo()
 
     val colorScheme = if (themeInfo.isDarkMode) {
@@ -26,7 +28,15 @@ fun CustomMaterialTheme(block: @Composable()() -> Unit) {
     MaterialTheme(
         colorScheme = colorScheme,
     ) {
-        block()
+        CompositionLocalProvider(
+            LocalTextStyle provides LocalTextStyle.current.copy(
+                fontFamily = LocalTextStyle.current.fontFamily?.let {
+                    FontMapper.mapGenericFontFamilyToSpecificFontFamily(it)
+                },
+            ),
+        ) {
+            block()
+        }
     }
 }