App grid preview for screen zoom

Change-Id: I718468dc03800d125eea1c57c8e5dfbc84aa3367

src/com/android/settings/display/AppGridView.java

@@ -0,0 +1,146 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.display;
+
+import com.android.settings.R;
+
+import android.content.Context;
+import android.content.Intent;
+import android.content.pm.PackageManager;
+import android.content.pm.ResolveInfo;
+import android.graphics.drawable.Drawable;
+import android.util.AttributeSet;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ArrayAdapter;
+import android.widget.GridView;
+import android.widget.ImageView;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+public class AppGridView extends GridView {
+    public AppGridView(Context context) {
+        this(context, null);
+    }
+
+    public AppGridView(Context context, AttributeSet attrs) {
+        this(context, attrs, 0);
+    }
+
+    public AppGridView(Context context, AttributeSet attrs, int defStyleAttr) {
+        this(context, attrs, defStyleAttr);
+    }
+
+    public AppGridView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleResId) {
+        super(context, attrs, defStyleAttr, defStyleResId);
+
+        setNumColumns(AUTO_FIT);
+
+        final int columnWidth = getResources().getDimensionPixelSize(
+                R.dimen.screen_zoom_preview_app_icon_width);
+        setColumnWidth(columnWidth);
+
+        setAdapter(new AppsAdapter(context, R.layout.screen_zoom_preview_app_icon,
+                android.R.id.text1, android.R.id.icon1));
+    }
+
+    /**
+     * Loads application labels and icons.
+     */
+    private static class AppsAdapter extends ArrayAdapter<ActivityEntry> {
+        private final PackageManager mPackageManager;
+        private final int mIconResId;
+
+        public AppsAdapter(Context context, int layout, int textResId, int iconResId) {
+            super(context, layout, textResId);
+
+            mIconResId = iconResId;
+            mPackageManager = context.getPackageManager();
+
+            loadAllApps();
+        }
+
+        @Override
+        public View getView(int position, View convertView, ViewGroup parent) {
+            final View view = super.getView(position, convertView, parent);
+            final ActivityEntry entry = getItem(position);
+            final ImageView iconView = (ImageView) view.findViewById(mIconResId);
+            final Drawable icon = entry.info.loadIcon(mPackageManager);
+            iconView.setImageDrawable(icon);
+            return view;
+        }
+
+        @Override
+        public boolean hasStableIds() {
+            return true;
+        }
+
+        @Override
+        public long getItemId(int position) {
+            return position;
+        }
+
+        @Override
+        public boolean isEnabled(int position) {
+            return false;
+        }
+
+        private void loadAllApps() {
+            final Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
+            mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);
+
+            final PackageManager pm = mPackageManager;
+            final ArrayList<ActivityEntry> results = new ArrayList<>();
+            final List<ResolveInfo> infos = pm.queryIntentActivities(mainIntent, 0);
+            for (ResolveInfo info : infos) {
+                final CharSequence label = info.loadLabel(pm);
+                if (label != null) {
+                    results.add(new ActivityEntry(info, label.toString()));
+                }
+            }
+
+            Collections.sort(results);
+
+            addAll(results);
+        }
+    }
+
+    /**
+     * Class used for caching the activity label and icon.
+     */
+    private static class ActivityEntry implements Comparable<ActivityEntry> {
+        public final ResolveInfo info;
+        public final String label;
+
+        public ActivityEntry(ResolveInfo info, String label) {
+            this.info = info;
+            this.label = label;
+        }
+
+        @Override
+        public int compareTo(ActivityEntry entry) {
+            return label.compareToIgnoreCase(entry.label);
+        }
+
+        @Override
+        public String toString() {
+            return label;
+        }
+    }
+}