Cache Typeface for later animation

The Paint#setFontvariationSettings always creates new Typeface instance
from scratch. To avoid unnecessary Typeface creation for the same weight
variant, cache the Typeface and use it later same animation.

Bug: 189867246
Test: atest TextAnimatorTest TextInterpolatorTest

Change-Id: I67ca72f2c54ca9caf4bcf562557ac4f24b44f01e

packages/SystemUI/src/com/android/keyguard/TextAnimator.kt

@@ -21,7 +21,9 @@ import android.animation.AnimatorListenerAdapter
 import android.animation.TimeInterpolator
 import android.animation.ValueAnimator
 import android.graphics.Canvas
+import android.graphics.Typeface
 import android.text.Layout
+import android.util.SparseArray
 
 private const val TAG_WGHT = "wght"
 private const val DEFAULT_ANIMATION_DURATION: Long = 300
@@ -72,6 +74,8 @@ class TextAnimator(
         })
     }
 
+    private val typefaceCache = SparseArray<Typeface?>()
+
     fun updateLayout(layout: Layout) {
         textInterpolator.layout = layout
     }
@@ -120,7 +124,12 @@ class TextAnimator(
             textInterpolator.targetPaint.textSize = textSize
         }
         if (weight >= 0) {
-            textInterpolator.targetPaint.fontVariationSettings = "'$TAG_WGHT' $weight"
+            // Paint#setFontVariationSettings creates Typeface instance from scratch. To reduce the
+            // memory impact, cache the typeface result.
+            textInterpolator.targetPaint.typeface = typefaceCache.getOrElse(weight) {
+                textInterpolator.targetPaint.fontVariationSettings = "'$TAG_WGHT' $weight"
+                textInterpolator.targetPaint.typeface
+            }
         }
         if (color != null) {
             textInterpolator.targetPaint.color = color
@@ -155,3 +164,12 @@ class TextAnimator(
         }
     }
 }
+
+private fun <V> SparseArray<V>.getOrElse(key: Int, defaultValue: () -> V): V {
+    var v = get(key)
+    if (v == null) {
+        v = defaultValue()
+        put(key, v)
+    }
+    return v
+}

packages/SystemUI/tests/src/com/android/keyguard/TextAnimatorTest.kt

@@ -18,12 +18,14 @@ package com.android.keyguard
 
 import android.animation.AnimatorListenerAdapter
 import android.animation.ValueAnimator
+import android.graphics.Typeface
 import android.testing.AndroidTestingRunner
 import android.text.Layout
 import android.text.StaticLayout
 import android.text.TextPaint
 import androidx.test.filters.SmallTest
 import com.android.systemui.SysuiTestCase
+import com.google.common.truth.Truth.assertThat
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.mockito.ArgumentCaptor
@@ -140,4 +142,41 @@ class TextAnimatorTest : SysuiTestCase() {
         verify(animationEndCallback).run()
         verify(valueAnimator).removeListener(eq(captor.value))
     }
+
+    @Test
+    fun testCacheTypeface() {
+        val layout = makeLayout("Hello, World", PAINT)
+        val valueAnimator = mock(ValueAnimator::class.java)
+        val textInterpolator = mock(TextInterpolator::class.java)
+        val paint = TextPaint().apply {
+            typeface = Typeface.createFromFile("/system/fonts/Roboto-Regular.ttf")
+        }
+        `when`(textInterpolator.targetPaint).thenReturn(paint)
+
+        val textAnimator = TextAnimator(layout, {}).apply {
+            this.textInterpolator = textInterpolator
+            this.animator = valueAnimator
+        }
+
+        textAnimator.setTextStyle(
+                weight = 400,
+                animate = true
+        )
+
+        val prevTypeface = paint.typeface
+
+        textAnimator.setTextStyle(
+                weight = 700,
+                animate = true
+        )
+
+        assertThat(paint.typeface).isNotSameInstanceAs(prevTypeface)
+
+        textAnimator.setTextStyle(
+                weight = 400,
+                animate = true
+        )
+
+        assertThat(paint.typeface).isSameInstanceAs(prevTypeface)
+    }
 }