Android example source code file (InternalSelectionScroll.java)

This example Android source code file (InternalSelectionScroll.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

activity, android, app, application, internalselectionscroll, internalselectionview, linearlayout, os, override, scrollview, ui, view, widget

The InternalSelectionScroll.java Android example source code

/*
 * Copyright (C) 2007 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.example.android.apis.view;

import android.app.Activity;
import android.os.Bundle;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.ScrollView;

/**
 * Demonstrates how a well behaved view with internal selection
 * ({@link InternalSelectionView}) can cause its parent {@link android.widget.ScrollView}
 * to scroll to keep the internally interesting rectangle on the screen.
 *
 * {@link InternalSelectionView} achieves this by calling {@link android.view.View#requestRectangleOnScreen}
 * each time its internal selection changes.
 *
 * {@link android.widget.ScrollView}, in turn, implements {@link android.view.View#requestRectangleOnScreen}
 * thereby acheiving the result.  Note that {@link android.widget.ListView} also implements the
 * method, so views that call {@link android.view.View#requestRectangleOnScreen} that are embedded
 * within either {@link android.widget.ScrollView}s or {@link android.widget.ListView}s can
 * expect to keep their internal interesting rectangle visible.
 */
public class InternalSelectionScroll extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        ScrollView sv = new ScrollView(this);
        ViewGroup.LayoutParams svLp = new ScrollView.LayoutParams(
                ViewGroup.LayoutParams.MATCH_PARENT,
                ViewGroup.LayoutParams.WRAP_CONTENT);

        LinearLayout ll = new LinearLayout(this);
        ll.setLayoutParams(svLp);
        sv.addView(ll);

        InternalSelectionView isv = new InternalSelectionView(this, 10);
        int screenHeight = getWindowManager().getDefaultDisplay().getHeight();
        LinearLayout.LayoutParams llLp = new LinearLayout.LayoutParams(
                ViewGroup.LayoutParams.MATCH_PARENT,
                2 * screenHeight);  // 2x screen height to ensure scrolling
        isv.setLayoutParams(llLp);
        ll.addView(isv);
        
        setContentView(sv);
    }
}