Do not use Paint.setFontVariationSettings as basis for variant Typefaces

Post cache eviction, it was possible to generate the wrong typeface
for an animation if the typeface was edited but not the font variation
settings as Paint.setFontVariationSettings would not. If the typeface
must be changed, reinitialization of the cache is also required.

Bug: 279877970
Test: Manually checked variant typeface generation
Change-Id: I5f76c0aa3d8aca7c1096c34c09b5861b980fe0ff

packages/SystemUI/animation/src/com/android/systemui/animation/TextAnimator.kt

@@ -23,8 +23,8 @@ import android.animation.ValueAnimator
 import android.graphics.Canvas
 import android.graphics.Typeface
 import android.graphics.fonts.Font
+import android.graphics.fonts.FontVariationAxis
 import android.text.Layout
-import android.text.TextPaint
 import android.util.LruCache
 
 private const val DEFAULT_ANIMATION_DURATION: Long = 300
@@ -33,18 +33,39 @@ private const val TYPEFACE_CACHE_MAX_ENTRIES = 5
 typealias GlyphCallback = (TextAnimator.PositionedGlyph, Float) -> Unit
 
 interface TypefaceVariantCache {
-    fun getTypefaceForVariant(fvar: String, targetPaint: TextPaint): Typeface?
+    fun getTypefaceForVariant(fvar: String?): Typeface?
+
+    companion object {
+        fun createVariantTypeface(baseTypeface: Typeface, fVar: String?): Typeface {
+            if (fVar.isNullOrEmpty()) {
+                return baseTypeface
+            }
+
+            val axes = FontVariationAxis.fromFontVariationSettings(fVar).toMutableList()
+            axes.removeIf { !baseTypeface.isSupportedAxes(it.getOpenTypeTagValue()) }
+            if (axes.isEmpty()) {
+                return baseTypeface
+            }
+            return Typeface.createFromTypefaceWithVariation(baseTypeface, axes)
+        }
+    }
 }
 
-class TypefaceVariantCacheImpl() : TypefaceVariantCache {
+class TypefaceVariantCacheImpl(
+    var baseTypeface: Typeface,
+) : TypefaceVariantCache {
     private val cache = LruCache<String, Typeface>(TYPEFACE_CACHE_MAX_ENTRIES)
-    override fun getTypefaceForVariant(fvar: String, targetPaint: TextPaint): Typeface? {
+    override fun getTypefaceForVariant(fvar: String?): Typeface? {
+        if (fvar == null) {
+            return baseTypeface
+        }
         cache.get(fvar)?.let {
             return it
         }
 
-        targetPaint.fontVariationSettings = fvar
-        return targetPaint.typeface?.also { cache.put(fvar, it) }
+        return TypefaceVariantCache
+            .createVariantTypeface(baseTypeface, fvar)
+            .also { cache.put(fvar, it) }
     }
 }
 
@@ -78,7 +99,7 @@ class TextAnimator(
     layout: Layout,
     private val invalidateCallback: () -> Unit,
 ) {
-    var typefaceCache: TypefaceVariantCache = TypefaceVariantCacheImpl()
+    var typefaceCache: TypefaceVariantCache = TypefaceVariantCacheImpl(layout.paint.typeface)
         get() = field
         set(value) {
             field = value
@@ -244,8 +265,7 @@ class TextAnimator(
         }
 
         if (!fvar.isNullOrBlank()) {
-            textInterpolator.targetPaint.typeface =
-                typefaceCache.getTypefaceForVariant(fvar, textInterpolator.targetPaint)
+            textInterpolator.targetPaint.typeface = typefaceCache.getTypefaceForVariant(fvar)
         }
 
         if (color != null) {
@@ -339,4 +359,3 @@ class TextAnimator(
         )
     }
 }
-

packages/SystemUI/animation/src/com/android/systemui/animation/TextInterpolator.kt

@@ -38,6 +38,8 @@ class TextInterpolator(
      * Once you modified the style parameters, you have to call reshapeText to recalculate base text
      * layout.
      *
+     * Do not bypass the cache and update the typeface or font variation directly.
+     *
      * @return a paint object
      */
     val basePaint = TextPaint(layout.paint)
@@ -48,6 +50,8 @@ class TextInterpolator(
      * Once you modified the style parameters, you have to call reshapeText to recalculate target
      * text layout.
      *
+     * Do not bypass the cache and update the typeface or font variation directly.
+     *
      * @return a paint object
      */
     val targetPaint = TextPaint(layout.paint)
@@ -217,14 +221,8 @@ class TextInterpolator(
                 run.fontRuns.forEach { fontRun ->
                     fontRun.baseFont =
                         fontInterpolator.lerp(fontRun.baseFont, fontRun.targetFont, progress)
-                    val fvar = run {
-                        val tmpFontVariationsArray = mutableListOf<FontVariationAxis>()
-                        fontRun.baseFont.axes.forEach {
-                            tmpFontVariationsArray.add(FontVariationAxis(it.tag, it.styleValue))
-                        }
-                        FontVariationAxis.toFontVariationSettings(tmpFontVariationsArray)
-                    }
-                    basePaint.typeface = typefaceCache.getTypefaceForVariant(fvar, basePaint)
+                    val fvar = FontVariationAxis.toFontVariationSettings(fontRun.baseFont.axes)
+                    basePaint.typeface = typefaceCache.getTypefaceForVariant(fvar)
                 }
             }
         }

packages/SystemUI/tests/src/com/android/systemui/animation/TextAnimatorTest.kt

@@ -39,10 +39,6 @@ import org.mockito.Mockito.verify
 
 import kotlin.math.ceil
 
-private val PAINT = TextPaint().apply {
-    textSize = 32f
-}
-
 @RunWith(AndroidTestingRunner::class)
 @SmallTest
 class TextAnimatorTest : SysuiTestCase() {

packages/SystemUI/tests/src/com/android/systemui/animation/TextInterpolatorTest.kt

@@ -49,7 +49,7 @@ private val VF_FONT = Font.Builder(File("/system/fonts/Roboto-Regular.ttf")).bui
 private fun Font.toTypeface() =
         Typeface.CustomFallbackBuilder(FontFamily.Builder(this).build()).build()
 
-private val PAINT = TextPaint().apply {
+internal val PAINT = TextPaint().apply {
     typeface = Font.Builder(VF_FONT).setFontVariationSettings("'wght' 400").build().toTypeface()
     textSize = 32f
 }
@@ -79,7 +79,7 @@ class TextInterpolatorTest : SysuiTestCase() {
 
     @Before
     fun setup() {
-        typefaceCache = TypefaceVariantCacheImpl()
+        typefaceCache = TypefaceVariantCacheImpl(PAINT.typeface)
     }
 
     @Test