Upstream oodles of Chrome for Android code into Chromium.

chrome/android/java_staging/src/org/chromium/chrome/browser/ntp/MostVisitedThumbnail.java

+// Copyright 2015 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.ntp;
+
+import android.content.Context;
+import android.content.res.Resources;
+import android.graphics.Bitmap;
+import android.graphics.Color;
+import android.graphics.Matrix;
+import android.util.AttributeSet;
+import android.widget.ImageView;
+
+import com.google.android.apps.chrome.R;
+
+/**
+ * Displays a thumbnail for a most visited item on the NTP.
+ */
+public class MostVisitedThumbnail extends ImageView {
+
+    private final int mDesiredWidth;
+    private final int mDesiredHeight;
+    private Bitmap mThumbnail;
+    private Matrix mImageMatrix;
+
+    /**
+     * Constructor for inflating from XML.
+     */
+    public MostVisitedThumbnail(Context context, AttributeSet attrs) {
+        super(context, attrs);
+        Resources res = getResources();
+        mDesiredWidth = res.getDimensionPixelSize(R.dimen.most_visited_thumbnail_width);
+        mDesiredHeight = res.getDimensionPixelSize(R.dimen.most_visited_thumbnail_height);
+    }
+
+    /**
+     * Updates the thumbnail and trigger a redraw with the new thumbnail.
+     */
+    void setThumbnail(Bitmap thumbnail) {
+        mThumbnail = thumbnail;
+        if (thumbnail != null) {
+            setImageBitmap(thumbnail);
+            setScaleType(ImageView.ScaleType.MATRIX);
+            updateThumbnailMatrix();
+        } else {
+            setBackgroundColor(Color.WHITE);
+            setImageResource(R.drawable.most_visited_thumbnail_placeholder);
+            setScaleType(ImageView.ScaleType.CENTER);
+        }
+    }
+
+    /**
+     * Updates the matrix used to scale the thumbnail when drawing it. This needs to be called
+     * whenever the thumbnail changes or this view's size changes.
+     *
+     * This matrix ensures that the thumbnail is anchored at the top left corner of this view and
+     * is scaled as small as possible while still covering the entire view. Surprisingly, there's
+     * no way to get this behavior using the other ImageView.ScaleTypes.
+     */
+    private void updateThumbnailMatrix() {
+        if (mThumbnail == null) return;
+
+        if (mImageMatrix == null) mImageMatrix = new Matrix();
+        float widthScale = (float) getMeasuredWidth() / mThumbnail.getWidth();
+        float heightScale = (float) getMeasuredHeight() / mThumbnail.getHeight();
+        float scale = Math.max(widthScale, heightScale);
+        mImageMatrix.setScale(scale, scale);
+        setImageMatrix(mImageMatrix);
+    }
+
+    @Override
+    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
+        super.onSizeChanged(w, h, oldw, oldh);
+        updateThumbnailMatrix();
+    }
+
+    /**
+     * Maintains this view's aspect ratio, even when its width is constrained. We can't just use
+     * android:adjustViewBounds, since that won't work when the source drawable isn't set or when
+     * it's the "missing thumbnail" gray circle, which has a different aspect ratio than thumbnails.
+     */
+    @Override
+    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
+        int width = resolveSize(mDesiredWidth, widthMeasureSpec);
+        int height;
+        if (width == mDesiredWidth) {
+            height = mDesiredHeight;
+        } else {
+            // The width is fixed. Find the height that keeps the proper aspect ratio.
+            height = Math.round((float) mDesiredHeight / mDesiredWidth * width);
+            height = resolveSize(height, heightMeasureSpec);
+        }
+        super.onMeasure(MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY),
+                MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY));
+    }
+}