Upstream oodles of Chrome for Android code into Chromium.

chrome/android/java_staging/src/org/chromium/chrome/browser/ntp/MostVisitedLayout.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.Canvas;
+import android.graphics.drawable.Drawable;
+import android.util.AttributeSet;
+import android.view.View;
+import android.widget.FrameLayout;
+
+import com.google.android.apps.chrome.R;
+
+import org.chromium.base.ApiCompatibilityUtils;
+
+/**
+ * A layout that arranges most visited items in a grid. All items must be the same size.
+ */
+public class MostVisitedLayout extends FrameLayout {
+
+    private int mHorizontalSpacing;
+    private int mVerticalSpacing;
+    private int mTwoColumnMinWidth;
+    private int mThreeColumnMinWidth;
+
+    /**
+     * The ideal width of a child. The children may need be stretched or shrunk a bit to fill the
+     * available width.
+     */
+    private int mDefaultChildWidth;
+
+    private Drawable mEmptyTileDrawable;
+    private int mNumEmptyTiles;
+    private int mEmptyTileTop;
+    private int mFirstEmptyTileLeft;
+
+    /**
+     * @param context The view context in which this item will be shown.
+     * @param attrs The attributes of the XML tag that is inflating the view.
+     */
+    public MostVisitedLayout(Context context, AttributeSet attrs) {
+        super(context, attrs);
+        setWillNotDraw(false);
+
+        Resources res = getResources();
+        mHorizontalSpacing = res.getDimensionPixelOffset(R.dimen.most_visited_spacing);
+        mVerticalSpacing = mHorizontalSpacing;
+        mDefaultChildWidth = res.getDimensionPixelSize(R.dimen.most_visited_tile_width);
+        mTwoColumnMinWidth = res.getDimensionPixelOffset(R.dimen.most_visited_two_column_min_width);
+        mThreeColumnMinWidth = res.getDimensionPixelOffset(
+                R.dimen.most_visited_three_column_min_width);
+    }
+
+    @Override
+    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
+        // Determine the number of columns in the grid.
+        final int totalWidth = MeasureSpec.getSize(widthMeasureSpec);
+        int childWidth = mDefaultChildWidth;
+        int childWidthWithSpacing = childWidth + mHorizontalSpacing;
+
+        int numColumns;
+        if (totalWidth + mHorizontalSpacing >= 3 * childWidthWithSpacing) {
+            numColumns = 3;
+        } else if (totalWidth < mTwoColumnMinWidth) {
+            numColumns = 1;
+        } else {
+            numColumns = totalWidth < mThreeColumnMinWidth ? 2 : 3;
+
+            // Resize the tiles to make them fill the entire available width.
+            childWidthWithSpacing = Math.max(mHorizontalSpacing,
+                    (totalWidth + mHorizontalSpacing) / numColumns);
+            childWidth = childWidthWithSpacing - mHorizontalSpacing;
+        }
+
+        int childCount = getChildCount();
+        int childHeight = 0;
+        if (childCount > 0) {
+            // Measure the children.
+            int childWidthSpec = MeasureSpec.makeMeasureSpec(childWidth, MeasureSpec.EXACTLY);
+            int childHeightSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
+            for (int i = 0; i < childCount; i++) {
+                getChildAt(i).measure(childWidthSpec, childHeightSpec);
+            }
+            childHeight = getChildAt(0).getMeasuredHeight();
+        }
+
+        // Arrange the children in a grid.
+        int childStart = 0;
+        int childTop = 0;
+        int column = 0;
+        boolean isRtl = ApiCompatibilityUtils.isLayoutRtl(this);
+        for (int i = 0; i < childCount; i++) {
+            View child = getChildAt(i);
+            MarginLayoutParams layoutParams = (MarginLayoutParams) child.getLayoutParams();
+            layoutParams.setMargins(isRtl ? 0 : childStart, childTop,
+                    isRtl ? childStart : 0, 0);
+            child.setLayoutParams(layoutParams);
+            column++;
+            if (column == numColumns) {
+                column = 0;
+                childStart = 0;
+                childTop += childHeight + mVerticalSpacing;
+            } else {
+                childStart += childWidthWithSpacing;
+            }
+        }
+
+        // Fill the rest of the current row with empty tiles.
+        if (column != 0) {
+            mNumEmptyTiles = numColumns - column;
+            mEmptyTileTop = childTop + getPaddingTop();
+            mFirstEmptyTileLeft = isRtl ? 0 : childStart;
+        } else {
+            mNumEmptyTiles = 0;
+        }
+
+        int numRows = (childCount + mNumEmptyTiles) / numColumns;
+        int totalHeight = getPaddingTop() + getPaddingBottom() + numRows * childHeight
+                + (numRows - 1) * mVerticalSpacing;
+
+        int gridWidth = numColumns * childWidthWithSpacing - mHorizontalSpacing;
+        setMeasuredDimension(gridWidth, resolveSize(totalHeight, heightMeasureSpec));
+    }
+
+    @Override
+    protected void onDraw(Canvas canvas) {
+        super.onDraw(canvas);
+        if (mNumEmptyTiles == 0 || getChildCount() == 0) return;
+
+        // Draw empty tiles.
+        if (mEmptyTileDrawable == null) {
+            mEmptyTileDrawable = ApiCompatibilityUtils.getDrawable(
+                    getResources(), R.drawable.most_visited_item_empty);
+        }
+        int tileLeft = mFirstEmptyTileLeft;
+        int tileWidth = getChildAt(0).getMeasuredWidth();
+        int tileHeight = getChildAt(0).getMeasuredHeight();
+        for (int i = 0; i < mNumEmptyTiles; i++) {
+            mEmptyTileDrawable.setBounds(
+                    tileLeft,
+                    mEmptyTileTop,
+                    tileLeft + tileWidth,
+                    mEmptyTileTop + tileHeight);
+            mEmptyTileDrawable.draw(canvas);
+            tileLeft += tileWidth + mHorizontalSpacing;
+        }
+    }
+}