Another method to parse font features (#554)

* Another method to parse font features

Needed for Compose. I compare it with Android, and Android/Compose by documentation uses this format without quotes: ttps://www.w3.org/TR/css-fonts-3/#font-feature-settings-prop

* Fix CI

.github/workflows/ci.yml

@@ -93,8 +93,8 @@ jobs:
           sudo apt-get install ninja-build fontconfig libfontconfig1-dev libglu1-mesa-dev libxrandr-dev libdbus-1-dev zip xvfb -y
           sudo Xvfb :0 -screen 0 1280x720x24 &
           export DISPLAY=:0
-          ./gradlew --stacktrace --info -Pskiko.native.enabled=true :skiko:linuxX64Test :skiko:awtTest
-          ./gradlew --stacktrace --info :skiko:publishToMavenLocal
+          ./gradlew --stacktrace --info -Pskiko.native.enabled=true -Pkotlin.native.cacheKind.linuxX64=none :skiko:linuxX64Test :skiko:awtTest
+          ./gradlew --stacktrace --info -Pkotlin.native.cacheKind.linuxX64=none :skiko:publishToMavenLocal
           ./gradlew --stacktrace --info :SkiaAwtSample:installDist # check jvm sample works
           ./gradlew -Pskiko.android.enabled=true :skiko:publishSkikoJvmRuntimeAndroidX64PublicationToMavenLocal :skiko:publishSkikoJvmRuntimeAndroidArm64PublicationToMavenLocal :skiko:publishAndroidPublicationToMavenLocal
       - uses: actions/upload-artifact@v2

skiko/src/commonMain/kotlin/org/jetbrains/skia/FontFeature.kt

@@ -98,10 +98,46 @@ class FontFeature(val _tag: Int, val value: Int, val start: UInt, val end: UInt)
             return FontFeature(m.group(tagIx)!!, value, start, end)
         }
 
+        /**
+         * Parse font features, which are separated by spaces. For example:
+         *
+         * smcp=0 frac
+         *
+         * If a value omitted, treat it as "1"
+         *
+         * If [str] is invalid, throws IllegalArgumentException
+         */
         fun parse(str: String): Array<FontFeature> {
             return _splitPattern.split(str).map { s -> parseOne(s) }.toTypedArray()
         }
 
+        /**
+         * Parse font features separated by comma, in W3 style (as in CSS):
+         *
+         * smcp 0, frac
+         *
+         * If a value omitted, treat it as "1"
+         *
+         * See https://www.w3.org/TR/css-fonts-3/#font-feature-settings-prop
+         *
+         * If [str] in invalid format, FontFeature won't be in the result
+         */
+        fun parseW3(str: String): Array<FontFeature> =
+            str
+                .splitToSequence(",")
+                .mapNotNull {
+                    val parts = it.trim().split(" ")
+                    val name = parts[0]
+                    val value = when (val value = parts.getOrNull(1)) {
+                        "on", null -> 1
+                        "off" -> 0
+                        else -> value.toIntOrNull() ?: 1
+                    }
+                    if (name.length == 4) FontFeature(name, value) else null
+                }
+                .toList()
+                .toTypedArray()
+
         internal fun InteropScope.arrayOfFontFeaturesToInterop(fontFeatures: Array<FontFeature>?): InteropPointer {
             val ints = IntArray(4 * (fontFeatures?.size ?: 0))
 

skiko/src/commonTest/kotlin/org/jetbrains/skia/PatternMatcherTests.kt

@@ -83,6 +83,47 @@ class PatternMatcherTests {
         assertEquals(42, f4.value)
     }
 
+    @Test
+    fun fontFeatureCanBeParsedAsW3() = runTest {
+        FontFeature.parseW3("abcd").apply {
+            assertEquals(1, size)
+            assertEquals("abcd", get(0).tag)
+            assertEquals(1, get(0).value)
+        }
+
+        FontFeature.parseW3("abcd 0").apply {
+            assertEquals(1, size)
+            assertEquals("abcd", get(0).tag)
+            assertEquals(0, get(0).value)
+        }
+
+        FontFeature.parseW3("abcd 0, vfgb").apply {
+            assertEquals(2, size)
+            assertEquals("abcd", get(0).tag)
+            assertEquals(0, get(0).value)
+            assertEquals("vfgb", get(1).tag)
+            assertEquals(1, get(1).value)
+        }
+
+        FontFeature.parseW3("abcd 0, abc, vfgb").apply {
+            assertEquals(2, size)
+            assertEquals("abcd", get(0).tag)
+            assertEquals(0, get(0).value)
+            assertEquals("vfgb", get(1).tag)
+            assertEquals(1, get(1).value)
+        }
+
+        FontFeature.parseW3("abcd vfgb").apply {
+            assertEquals(1, size)
+            assertEquals("abcd", get(0).tag)
+            assertEquals(1, get(0).value)
+        }
+
+        FontFeature.parseW3("").apply {
+            assertEquals(0, size)
+        }
+    }
+
     @Test
     fun fontVariationCanBeParsed() = runTest {
         val f1 = FontVariation.parseOne("abcd=111")