Clean up tinted ImageView subclasses

chrome/android/java/src/org/chromium/chrome/browser/widget/ImageViewTinter.java

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.chrome.browser.widget;
+
+import android.content.res.ColorStateList;
+import android.content.res.TypedArray;
+import android.graphics.Canvas;
+import android.graphics.PorterDuff;
+import android.support.annotation.Nullable;
+import android.util.AttributeSet;
+import android.widget.ImageView;
+
+import org.chromium.chrome.R;
+
+/**
+ * Utility for tinting an ImageView and its Drawable.
+ *
+ * Example usage in XML:
+ * <ImageViewTinterInstanceOwner
+ *     xmlns:android="http://schemas.android.com/apk/res/android"
+ *     xmlns:chrome="http://schemas.android.com/apk/res-auto"
+ *     chrome:chrometint="@color/light_active_color" />
+ *
+ * The default style used by the Application will likely cause your Drawable to be automatically
+ * tinted.  To prevent this, set the value of chrome:chrometint to "@null".
+ */
+public class ImageViewTinter {
+    /** Classes that own an ImageViewTinter must implement these functions. */
+    public static interface ImageViewTinterOwner {
+        /** See {@link ImageViewTinter#drawableStateChanged}. */
+        void drawableStateChanged();
+
+        /** See {@link ImageViewTinter#setTint}. */
+        void setTint(ColorStateList tintList);
+
+        /** See {@link ImageView#onDraw}. */
+        void onDraw(Canvas canvas);
+    }
+
+    private ImageView mImageView;
+    private ColorStateList mTintList;
+
+    /**
+     * Constructor.  Should be called with the AttributeSet and style of the ImageView so that XML
+     * attributes for it can be parsed.
+     * @param view     ImageView being tinted.
+     * @param attrs    AttributeSet that is pulled in from an XML layout.  May be null.
+     * @param defStyle Style that is pulled in from an XML layout.
+     */
+    public ImageViewTinter(ImageViewTinterOwner view, @Nullable AttributeSet attrs, int defStyle) {
+        assert view instanceof ImageView;
+        mImageView = (ImageView) view;
+
+        // Parse out the attributes from the XML.
+        if (attrs != null) {
+            TypedArray a = mImageView.getContext().obtainStyledAttributes(
+                    attrs, R.styleable.TintedImage, defStyle, 0);
+            setTint(a.getColorStateList(R.styleable.TintedImage_chrometint));
+            a.recycle();
+        }
+    }
+
+    /**
+     * Sets the tint color for the given ImageView for all states.
+     * @param tintList The set of colors to use.
+     */
+    public void setTint(ColorStateList tintList) {
+        if (mTintList == tintList) return;
+        mTintList = tintList;
+        updateTintColor();
+    }
+
+    /** Call when the state of the Drawable has changed. */
+    public void drawableStateChanged() {
+        updateTintColor();
+    }
+
+    private void updateTintColor() {
+        if (mImageView.getDrawable() == null) {
+            return;
+        } else if (mTintList == null) {
+            mImageView.clearColorFilter();
+            return;
+        }
+
+        int tintColor = mTintList.getColorForState(mImageView.getDrawableState(), 0);
+        mImageView.setColorFilter(tintColor, PorterDuff.Mode.SRC_IN);
+    }
+}