Handle color selector in DeferredColor.resolve (#32)

* Improve attribute resolution error messages
* Add KDoc warnings about attribute color selectors

deferred-resources/src/androidTest/java/com/backbase/deferredresources/DeferredColorTest.kt

@@ -1,44 +1,73 @@
 package com.backbase.deferredresources
 
 import android.graphics.Color
+import androidx.test.filters.SdkSuppress
 import com.backbase.deferredresources.test.R
 import com.google.common.truth.Truth.assertThat
 import org.junit.Test
 
 class DeferredColorTest {
 
-    @Test fun constant_withIntValue_returnsSameValue() {
+    //region Constant
+    @Test fun constantResolve_withIntValue_returnsSameValue() {
         val deferred = DeferredColor.Constant(Color.MAGENTA)
         assertThat(deferred.resolve(context)).isEqualTo(Color.MAGENTA)
     }
 
-    @Test fun constant_withStringValue_returnsParsedValue() {
+    @Test fun constantResolve_withStringValue_returnsParsedValue() {
         val deferred = DeferredColor.Constant("#00FF00")
         assertThat(deferred.resolve(context)).isEqualTo(Color.GREEN)
     }
+    //endregion
 
-    @Test fun resource_resolvesWithContext() {
+    //region Resource
+    @Test fun resourceResolve_withStandardColor_resolvesColor() {
         val deferred = DeferredColor.Resource(R.color.blue)
         assertThat(deferred.resolve(context)).isEqualTo(Color.BLUE)
     }
 
-    @Test fun attribute_resolvesWithContext() {
+    @Test fun resourceResolve_withSelectorColor_resolvesDefaultColor() {
+        val deferred = DeferredColor.Resource(R.color.stateful_color_without_attr)
+        assertThat(deferred.resolve(AppCompatContext())).isEqualTo(Color.parseColor("#aaaaaa"))
+    }
+
+    @SdkSuppress(minSdkVersion = 23)
+    @Test fun resourceResolve_withSelectorColorWithAttribute_resolvesDefaultColor() {
+        val deferred = DeferredColor.Resource(R.color.stateful_color_with_attr)
+        assertThat(deferred.resolve(AppCompatContext())).isEqualTo(Color.parseColor("#987654"))
+    }
+    //endregion
+
+    //region Attribute
+    @Test fun attributeResolve_withStandardColor_resolvesColor() {
         val deferred = DeferredColor.Attribute(R.attr.colorPrimary)
-        assertThat(deferred.resolve(AppCompatContext())).isEqualTo(Color.parseColor("#212121"))
+        assertThat(deferred.resolve(AppCompatContext())).isEqualTo(Color.parseColor("#987654"))
+    }
+
+    @Test fun attributeResolve_withSelectorColor_resolvesDefaultColor() {
+        val deferred = DeferredColor.Attribute(R.attr.subtitleTextColor)
+        assertThat(deferred.resolve(AppCompatContext())).isEqualTo(Color.parseColor("#aaaaaa"))
+    }
+
+    @SdkSuppress(minSdkVersion = 23)
+    @Test fun attributeResolve_withSelectorColorWithAttributeDefault_resolvesDefaultColor() {
+        val deferred = DeferredColor.Attribute(R.attr.titleTextColor)
+        assertThat(deferred.resolve(AppCompatContext())).isEqualTo(Color.parseColor("#987654"))
     }
 
     @Test(expected = IllegalArgumentException::class)
-    fun attribute_withUnknownAttribute_throwsException() {
+    fun attributeResolve_withUnknownAttribute_throwsException() {
         val deferred = DeferredColor.Attribute(R.attr.colorPrimary)
 
         // Default-theme context does not have <colorPrimary> attribute:
         deferred.resolve(context)
     }
 
     @Test(expected = IllegalArgumentException::class)
-    fun attribute_withWrongAttributeType_throwsException() {
+    fun attributeResolve_withWrongAttributeType_throwsException() {
         val deferred = DeferredColor.Attribute(R.attr.isLightTheme)
 
         deferred.resolve(AppCompatContext())
     }
+    //endregion
 }

deferred-resources/src/androidTest/java/com/backbase/deferredresources/TestContext.kt

@@ -25,7 +25,7 @@ internal fun AppCompatContext(
     light: Boolean = false
 ): Context = ContextThemeWrapper(
     context,
-    if (light) R.style.Theme_AppCompat_Light else R.style.Theme_AppCompat
+    if (light) R.style.TestTheme_Light else R.style.TestTheme
 )
 
 //region Configuration

deferred-resources/src/androidTest/res/color/stateful_color_with_attr.xml

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+
+  <item android:color="#dbdbdb" android:state_enabled="false" />
+
+  <item android:color="@android:color/darker_gray" android:state_checked="true" />
+
+  <item android:color="?colorPrimary" />
+
+</selector>

deferred-resources/src/androidTest/res/color/stateful_color_without_attr.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8"?>
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+
+  <item android:color="#dbdbdb" android:state_enabled="false" />
+
+  <item android:color="@android:color/darker_gray" />
+
+</selector>

deferred-resources/src/androidTest/res/values/test_theme.xml

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+  <style name="TestTheme" parent="Theme.AppCompat">
+    <item name="colorPrimary">#987654</item>
+    <item name="titleTextColor">@color/stateful_color_with_attr</item>
+    <item name="subtitleTextColor">@color/stateful_color_without_attr</item>
+  </style>
+
+  <style name="TestTheme.Light" parent="Theme.AppCompat.Light">
+    <item name="colorPrimary">#987654</item>
+    <item name="titleTextColor">@color/stateful_color_with_attr</item>
+    <item name="subtitleTextColor">@color/stateful_color_without_attr</item>
+  </style>
+</resources>

deferred-resources/src/main/java/com/backbase/deferredresources/DeferredColor.kt

@@ -1,6 +1,7 @@
 package com.backbase.deferredresources
 
 import android.content.Context
+import android.content.res.ColorStateList
 import android.graphics.Color
 import android.util.TypedValue
 import androidx.annotation.AttrRes
@@ -45,7 +46,12 @@ interface DeferredColor {
         @ColorRes private val resId: Int
     ) : DeferredColor {
         /**
-         * Resolve [resId] to a [ColorInt] with the given [context].
+         * Resolve [resId] to a [ColorInt] with the given [context]. If [resId] resolves to a color selector resource,
+         * resolves the default color of that selector.
+         *
+         * Warning: On API < 23, resolving a color selector with [context]'s theme is unsupported. Thus, a color
+         * selector with an attribute reference as its default color will not resolve to the correct color on API 22 and
+         * below. A color selector with a resource reference as its default color will resolve correctly.
          */
         @ColorInt override fun resolve(context: Context): Int = ContextCompat.getColor(context, resId)
     }
@@ -61,19 +67,39 @@ interface DeferredColor {
         private val reusedTypedValue = TypedValue()
 
         /**
-         * Resolve [resId] to a [ColorInt] with the given [context]'s theme.
+         * Resolve [resId] to a [ColorInt] with the given [context]'s theme. If [resId] would resolve a color selector,
+         * resolves to the default color of that selector.
+         *
+         * Warning: On API < 23, resolving a color selector with [context]'s theme is unsupported. Thus, a color
+         * selector with an attribute reference as its default color will not resolve to the correct color on API 22 and
+         * below. A color selector with a resource reference as its default color will resolve correctly.
          *
          * @throws IllegalArgumentException if [resId] cannot be resolved to a color.
          */
-        @ColorInt override fun resolve(context: Context): Int = context.resolveColorAttribute(resId)
-
-        @ColorInt private fun Context.resolveColorAttribute(@AttrRes resId: Int): Int =
-            resolveAttribute(
-                resId, "color", reusedTypedValue,
-                TypedValue.TYPE_INT_COLOR_RGB8, TypedValue.TYPE_INT_COLOR_ARGB8,
-                TypedValue.TYPE_INT_COLOR_RGB4, TypedValue.TYPE_INT_COLOR_ARGB4
-            ) {
+        @ColorInt override fun resolve(context: Context): Int = context.resolveColorAttribute {
+            if (type == TypedValue.TYPE_STRING)
+                context.resolveColorStateList().defaultColor
+            else
                 data
-            }
+        }
+
+        private inline fun <T> Context.resolveColorAttribute(
+            toTypeSafeResult: TypedValue.() -> T
+        ): T = resolveAttribute(
+            resId, "color", reusedTypedValue,
+            TypedValue.TYPE_INT_COLOR_RGB8, TypedValue.TYPE_INT_COLOR_ARGB8,
+            TypedValue.TYPE_INT_COLOR_RGB4, TypedValue.TYPE_INT_COLOR_ARGB4,
+            TypedValue.TYPE_STRING,
+            toTypeSafeResult = toTypeSafeResult
+        )
+
+        private fun Context.resolveColorStateList(): ColorStateList = resolveAttribute(
+            resId, "reference", reusedTypedValue,
+            TypedValue.TYPE_REFERENCE,
+            resolveRefs = false
+        ) {
+            val colorSelectorResId = data
+            ContextCompat.getColorStateList(this@resolveColorStateList, colorSelectorResId)!!
+        }
     }
 }

deferred-resources/src/main/java/com/backbase/deferredresources/internal/Context.kt

@@ -28,10 +28,11 @@ internal inline fun <T> Context.resolveAttribute(
     attributeTypeName: String,
     reusedTypedValue: TypedValue,
     vararg expectedTypes: Int,
+    resolveRefs: Boolean = true,
     toTypeSafeResult: TypedValue.() -> T
 ): T {
     try {
-        val isResolved = theme.resolveAttribute(resId, reusedTypedValue, true)
+        val isResolved = theme.resolveAttribute(resId, reusedTypedValue, resolveRefs)
         if (isResolved && expectedTypes.contains(reusedTypedValue.type))
             return reusedTypedValue.toTypeSafeResult()
         else
@@ -53,13 +54,13 @@ private fun Context.createErrorMessage(
 ) = try {
     val name = resources.getResourceEntryName(resId)
     val couldNotResolve = "Could not resolve attribute <$name>"
-    val withContext = "with <$this>"
+    val withContext = "with context <$this>"
     if (isResolved)
         "$couldNotResolve to a $attributeTypeName $withContext"
     else
         "$couldNotResolve $withContext"
 } catch (notFoundException: Resources.NotFoundException) {
-    "Attribute <$resId> could not be found with <$this>"
+    "Attribute <$resId> could not be found with context <$this>"
 }
 
 /**