📰 Adjust the card display depending on the screen width.

chrome/android/java/src/org/chromium/chrome/browser/ntp/UiConfig.java

Index: chrome/android/java/src/org/chromium/chrome/browser/ntp/UiConfig.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/ntp/UiConfig.java b/chrome/android/java/src/org/chromium/chrome/browser/ntp/UiConfig.java
new file mode 100644
index 0000000000000000000000000000000000000000..1f2916c71c1add24918db29a7947ef66378a373b
--- /dev/null
+++ b/chrome/android/java/src/org/chromium/chrome/browser/ntp/UiConfig.java
@@ -0,0 +1,130 @@
+// Copyright 2016 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.support.annotation.IntDef;
+import android.view.View;
+
+import org.chromium.base.Log;
+import org.chromium.ui.widget.Toast;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Exposes general configuration info about the NTP UI.
+ */
+public class UiConfig {
+    /** The different supported UI setups. Listeners can register to be notified of changes.*/
+    @Retention(RetentionPolicy.SOURCE)
+    @IntDef({DISPLAY_STYLE_UNDEFINED, DISPLAY_STYLE_NARROW, DISPLAY_STYLE_REGULAR,
+            DISPLAY_STYLE_WIDE})
+    public @interface DisplayStyle {}
+    public static final int DISPLAY_STYLE_UNDEFINED = -1;
+    public static final int DISPLAY_STYLE_NARROW = 0;
+    public static final int DISPLAY_STYLE_REGULAR = 1;
+    public static final int DISPLAY_STYLE_WIDE = 2;
+
+    private static final int REGULAR_CARD_MIN_WIDTH_DP = 360;
+    private static final int WIDE_CARD_MIN_WIDTH_DP = 600;
+
+    private static final String TAG = "Ntp";
+    private static final boolean DEBUG = false;
+
+    @DisplayStyle
+    private int mCurrentDisplayStyle = DISPLAY_STYLE_UNDEFINED;
+
+    private final List<DisplayStyleObserver> mListeners = new ArrayList<>();
+    private final Context mContext;
+    private final ViewObserver mViewObserver = new ViewObserver();
+
+    /**
+     * Observes the relevant changes to the reference view, to let UiConfig know when it should
+     * update the display style and notify the listeners.
+     */
+    private class ViewObserver
+            implements View.OnLayoutChangeListener, View.OnAttachStateChangeListener {
+        @Override
+        public void onViewAttachedToWindow(View v) {
+            updateDisplayStyle();
+        }
+
+        @Override
+        public void onViewDetachedFromWindow(View v) {}
+
+        @Override
+        public void onLayoutChange(View v, int left, int top, int right, int bottom, int oldLeft,
+                int oldTop, int oldRight, int oldBottom) {
+            int oldWidth = oldRight - oldLeft;
+            int newWidth = right - left;
+
+            if (oldWidth == newWidth) return;
+            Log.d(TAG, "The viewport size changed: %d -> %d", oldWidth, newWidth);
+            updateDisplayStyle();
+        }
+    }
+
+    /**
+     * @param referenceView the View we observe to deduce the configuration from.
+     */
+    public UiConfig(View referenceView) {
+        mContext = referenceView.getContext();
+
+        referenceView.addOnLayoutChangeListener(mViewObserver);
+        referenceView.addOnAttachStateChangeListener(mViewObserver);
+
+        updateDisplayStyle();
+    }
+
+    public void addListener(DisplayStyleObserver listener) {

[Bernhard Bauer, 2016/07/19 14:46:53]

Nit: It's an observer.

[dgn, 2016/07/19 23:33:56]

Done.

+        mListeners.add(listener);
+    }
+
+    public void removeListener(DisplayStyleObserver listener) {
+        mListeners.remove(listener);
+    }
+
+    @DisplayStyle
+    public int getDisplayStyle() {
+        return mCurrentDisplayStyle;
+    }
+
+    /**
+     * Refresh the display style, notify listeners of changes.
+     */
+    public void updateDisplayStyle() {
+        int widthDp = mContext.getResources().getConfiguration().screenWidthDp;
+
+        String debugString;
+
+        @DisplayStyle
+        int newDisplayStyle;
+        if (widthDp < REGULAR_CARD_MIN_WIDTH_DP) {
+            newDisplayStyle = DISPLAY_STYLE_NARROW;
+            if (DEBUG) debugString = String.format("DISPLAY_STYLE_NARROW (w=%ddp)", widthDp);
+        } else if (widthDp >= WIDE_CARD_MIN_WIDTH_DP) {
+            newDisplayStyle = DISPLAY_STYLE_WIDE;
+            if (DEBUG) debugString = String.format("DISPLAY_STYLE_WIDE (w=%ddp)", widthDp);
+        } else {
+            newDisplayStyle = DISPLAY_STYLE_REGULAR;
+            if (DEBUG) debugString = String.format("DISPLAY_STYLE_REGULAR (w=%ddp)", widthDp);
+        }
+
+        if (newDisplayStyle == mCurrentDisplayStyle) return;
+
+        if (DEBUG) {
+            Log.d(TAG, debugString);
+            Toast.makeText(mContext, debugString, Toast.LENGTH_SHORT).show();
+        }
+
+        mCurrentDisplayStyle = newDisplayStyle;
+        for (DisplayStyleObserver listener : mListeners) {
+            listener.onDisplayStyleChanged(newDisplayStyle);
+        }
+    }
+}