Upstream oodles of Chrome for Android code into Chromium.

chrome/android/java_staging/src/org/chromium/chrome/browser/ntp/NewTabPageLayout.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.util.AttributeSet;
+import android.view.View;
+
+import com.google.android.apps.chrome.R;
+
+import org.chromium.chrome.browser.widget.BoundedLinearLayout;
+
+/**
+ * Layout for the new tab page. This positions the page elements in the correct vertical positions.
+ * There are no separate phone and tablet UIs; this layout adapts based on the available space.
+ */
+public class NewTabPageLayout extends BoundedLinearLayout {
+
+    // Space permitting, the spacers will grow from 0dp to the heights given below. If there is
+    // additional space, it will be distributed evenly between the top and bottom spacers.
+    private static final float TOP_SPACER_HEIGHT_DP = 44f;
+    private static final float MIDDLE_SPACER_HEIGHT_DP = 24f;
+    private static final float BOTTOM_SPACER_HEIGHT_DP = 44f;
+    private static final float TOTAL_SPACER_HEIGHT_DP = TOP_SPACER_HEIGHT_DP
+            + MIDDLE_SPACER_HEIGHT_DP + BOTTOM_SPACER_HEIGHT_DP;
+
+    private final int mTopSpacerHeight;
+    private final int mMiddleSpacerHeight;
+    private final int mBottomSpacerHeight;
+    private final int mTotalSpacerHeight;
+
+    private int mParentScrollViewportHeight;
+
+    private View mTopSpacer;
+    private View mMiddleSpacer;
+    private View mBottomSpacer;
+    private View mScrollCompensationSpacer;
+
+    /**
+     * Constructor for inflating from XML.
+     */
+    public NewTabPageLayout(Context context, AttributeSet attrs) {
+        super(context, attrs);
+        float density = getResources().getDisplayMetrics().density;
+        mTopSpacerHeight = Math.round(density * TOP_SPACER_HEIGHT_DP);
+        mMiddleSpacerHeight = Math.round(density * MIDDLE_SPACER_HEIGHT_DP);
+        mBottomSpacerHeight = Math.round(density * BOTTOM_SPACER_HEIGHT_DP);
+        mTotalSpacerHeight = Math.round(density * TOTAL_SPACER_HEIGHT_DP);
+    }
+
+    @Override
+    protected void onFinishInflate() {
+        super.onFinishInflate();
+        mTopSpacer = findViewById(R.id.ntp_top_spacer);
+        mMiddleSpacer = findViewById(R.id.ntp_middle_spacer);
+        mBottomSpacer = findViewById(R.id.ntp_bottom_spacer);
+        mScrollCompensationSpacer = findViewById(R.id.ntp_scroll_spacer);
+    }
+
+    /**
+     * Specifies the height of the scroll viewport for the container view of this View.
+     *
+     * <p>
+     * As this is required in onMeasure, we can not rely on the parent having the proper
+     * size set yet and thus must be told explicitly of this size.
+     *
+     * @param height The height of the scroll viewport containing this view.
+     */
+    public void setParentScrollViewportHeight(int height) {
+        mParentScrollViewportHeight = height;
+    }
+
+    @Override
+    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
+        mScrollCompensationSpacer.getLayoutParams().height = 0;
+        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
+        distributeExtraSpace(mTopSpacer.getMeasuredHeight());
+
+        int minScrollAmountRequired = 0;
+        for (int i = 0; i < getChildCount(); i++) {
+            View child = getChildAt(i);
+
+            MarginLayoutParams layoutParams = (MarginLayoutParams) child.getLayoutParams();
+            if (child.getVisibility() != View.GONE) {
+                minScrollAmountRequired += layoutParams.topMargin;
+            }
+
+            if (child.getId() == R.id.most_visited_layout) break;
+            if (child.getId() == R.id.opt_out_promo) break;
+
+            if (child.getVisibility() != View.GONE) {
+                minScrollAmountRequired += child.getMeasuredHeight();
+                minScrollAmountRequired += layoutParams.bottomMargin;
+            }
+        }
+
+        int scrollVsHeightDiff = getMeasuredHeight() - mParentScrollViewportHeight;
+        if (getMeasuredHeight() > mParentScrollViewportHeight
+                && scrollVsHeightDiff < minScrollAmountRequired) {
+            mScrollCompensationSpacer.getLayoutParams().height =
+                    minScrollAmountRequired - scrollVsHeightDiff;
+            mScrollCompensationSpacer.setVisibility(View.INVISIBLE);
+
+            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
+            distributeExtraSpace(mTopSpacer.getMeasuredHeight());
+        } else {
+            mScrollCompensationSpacer.setVisibility(View.GONE);
+        }
+    }
+
+    /**
+     * Distribute extra vertical space between the three spacer views.
+     * @param extraHeight The amount of extra space, in pixels.
+     */
+    private void distributeExtraSpace(int extraHeight) {
+        int topSpacerHeight;
+        int middleSpacerHeight;
+        int bottomSpacerHeight;
+
+        if (extraHeight < mTotalSpacerHeight) {
+            topSpacerHeight = Math.round(extraHeight
+                    * (TOP_SPACER_HEIGHT_DP / TOTAL_SPACER_HEIGHT_DP));
+            extraHeight -= topSpacerHeight;
+            middleSpacerHeight = Math.round(extraHeight * (MIDDLE_SPACER_HEIGHT_DP
+                    / (MIDDLE_SPACER_HEIGHT_DP + BOTTOM_SPACER_HEIGHT_DP)));
+            extraHeight -= middleSpacerHeight;
+            bottomSpacerHeight = extraHeight;
+        } else {
+            topSpacerHeight = mTopSpacerHeight;
+            middleSpacerHeight = mMiddleSpacerHeight;
+            bottomSpacerHeight = mBottomSpacerHeight;
+            extraHeight -= mTotalSpacerHeight;
+
+            // Distribute remaining space evenly between the top and bottom spacers.
+            topSpacerHeight += (extraHeight + 1) / 2;
+            bottomSpacerHeight += extraHeight / 2;
+        }
+
+        int widthSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.EXACTLY);
+        mTopSpacer.measure(widthSpec,
+                MeasureSpec.makeMeasureSpec(topSpacerHeight, MeasureSpec.EXACTLY));
+        mMiddleSpacer.measure(widthSpec,
+                MeasureSpec.makeMeasureSpec(middleSpacerHeight, MeasureSpec.EXACTLY));
+        mBottomSpacer.measure(widthSpec,
+                MeasureSpec.makeMeasureSpec(bottomSpacerHeight, MeasureSpec.EXACTLY));
+    }
+}