Add a MaterialAttributes#resolveAttribute method that doesn't throw, a

MaterialColors#getColor method that allows for a default value, and a MaterialResources#getColorStateList that accepts a TintTypedArray

PiperOrigin-RevId: 219170329

Author: dsn5ft

lib/java/com/google/android/material/color/MaterialColors.java

@@ -24,6 +24,7 @@
 import android.support.annotation.RestrictTo;
 import com.google.android.material.resources.MaterialAttributes;
 import android.support.v4.graphics.ColorUtils;
+import android.util.TypedValue;
 import android.view.View;
 
 /**
@@ -40,10 +41,31 @@ public class MaterialColors {
   public static final float ALPHA_LOW = 0.32F;
   public static final float ALPHA_DISABLED_LOW = 0.12F;
 
+  /**
+   * Returns the color int for the provided theme color attribute, or throws an {@link
+   * IllegalArgumentException} if the attribute is not set in the current theme.
+   */
+  @ColorInt
   public static int getColor(View view, @AttrRes int colorAttributeResId) {
     return MaterialAttributes.resolveAttributeOrThrow(view, colorAttributeResId).data;
   }
 
+  /**
+   * Returns the color int for the provided theme color attribute, or the default value if the
+   * attribute is not set in the current theme.
+   */
+  @ColorInt
+  public static int getColor(
+      View view, @AttrRes int colorAttributeResId, @ColorInt int defaultValue) {
+    TypedValue typedValue =
+        MaterialAttributes.resolveAttribute(view.getContext(), colorAttributeResId);
+    if (typedValue != null) {
+      return typedValue.data;
+    } else {
+      return defaultValue;
+    }
+  }
+
   /**
    * Convenience method that calculates {@link MaterialColors#layer(View, int, int, float)} without
    * an {@code overlayAlpha} value by passing in {@code 1f} for the alpha value.

lib/java/com/google/android/material/resources/MaterialAttributes.java

@@ -19,6 +19,7 @@
 
 import android.content.Context;
 import android.support.annotation.AttrRes;
+import android.support.annotation.Nullable;
 import android.support.annotation.RestrictTo;
 import android.util.TypedValue;
 import android.view.View;
@@ -33,9 +34,9 @@ public class MaterialAttributes {
 
   public static TypedValue resolveAttributeOrThrow(
       View componentView, @AttrRes int attributeResId) {
-    TypedValue typedValue = new TypedValue();
     Context context = componentView.getContext();
-    if (!context.getTheme().resolveAttribute(attributeResId, typedValue, true)) {
+    TypedValue typedValue = resolveAttribute(context, attributeResId);
+    if (typedValue == null) {
       String errorMessage =
           "The %1$s view requires a value for the %2$s attribute to be set in your app theme. "
               + "You can either set the attribute in your theme or "
@@ -48,4 +49,13 @@ public static TypedValue resolveAttributeOrThrow(
     }
     return typedValue;
   }
+
+  @Nullable
+  public static TypedValue resolveAttribute(Context context, @AttrRes int attributeResId) {
+    TypedValue typedValue = new TypedValue();
+    if (context.getTheme().resolveAttribute(attributeResId, typedValue, true)) {
+      return typedValue;
+    }
+    return null;
+  }
 }

lib/java/com/google/android/material/resources/MaterialResources.java

@@ -28,6 +28,7 @@
 import android.support.annotation.RestrictTo;
 import android.support.annotation.StyleableRes;
 import android.support.v7.content.res.AppCompatResources;
+import android.support.v7.widget.TintTypedArray;
 
 /** Utility methods to resolve resources for components. */
 @RestrictTo(LIBRARY_GROUP)
@@ -36,8 +37,8 @@ public class MaterialResources {
   private MaterialResources() {}
 
   /**
-   * Returns the {@link ColorStateList} from the given attributes. The resource can include
-   * themeable attributes, regardless of API level.
+   * Returns the {@link ColorStateList} from the given {@link TypedArray} attributes. The resource
+   * can include themeable attributes, regardless of API level.
    */
   @Nullable
   public static ColorStateList getColorStateList(
@@ -64,6 +65,35 @@ public static ColorStateList getColorStateList(
     return attributes.getColorStateList(index);
   }
 
+  /**
+   * Returns the {@link ColorStateList} from the given {@link TintTypedArray} attributes. The
+   * resource can include themeable attributes, regardless of API level.
+   */
+  @Nullable
+  public static ColorStateList getColorStateList(
+      Context context, TintTypedArray attributes, @StyleableRes int index) {
+    if (attributes.hasValue(index)) {
+      int resourceId = attributes.getResourceId(index, 0);
+      if (resourceId != 0) {
+        ColorStateList value = AppCompatResources.getColorStateList(context, resourceId);
+        if (value != null) {
+          return value;
+        }
+      }
+    }
+
+    // Reading a single color with getColorStateList() on API 15 and below doesn't always correctly
+    // read the value. Instead we'll first try to read the color directly here.
+    if (VERSION.SDK_INT <= VERSION_CODES.ICE_CREAM_SANDWICH_MR1) {
+      int color = attributes.getColor(index, -1);
+      if (color != -1) {
+        return ColorStateList.valueOf(color);
+      }
+    }
+
+    return attributes.getColorStateList(index);
+  }
+
   /**
    * Returns the drawable object from the given attributes.
    *