Android page control like iPhone page control

Question

I would like to put something back to this VERY helpful site, so this is not really a question, but rather my solution to this issue. I would also add that this solution was gleaned form support from this site and many others, so it represents the combined efforts of many other developers. To them I say thank you!

The QUESTION is "How can you recreate the horizontal scrollView aspects of iPhone apps and the associated page control in the Android environment?"

This arose because I wanted to display the steps in recipe, the associated method fro each step and the necessary ingredients in a single scroll view. I also wanted a page control to display to the user where they were in the steps and allow them to move to any specific step

This part of my app displays the steps in a recipe. Each step appears on a page and has three components. A step identifier(ie. STEP 1, STEP 2), a method and a ingredients required for the step.

Below the recipe section we display a page control that show which page is active and can be used to navigate to specific pages. You will notice that the page control has image buttons and the two images are simple circles, one for the non selected page (page.png) and one for the selected page (page_selected.png)

When the activity is created the steps for the selected recipe are retrieved from the data and the scroller section created by adding a view for each step in the recipe. When you swipe the scroller the view snaps to the next or previous page and the pager display is updated to indicate which page you are on

First 3 xml layouts (res/layout)

recipe.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content" >

 <!--Scroller section-->

   <HorizontalScrollView
       android:id="@+id/scroll_view"
        android:layout_width="match_parent"
        android:layout_height="320dp"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginTop="100dp" >

            <LinearLayout
                android:id="@+id/methodScrollView"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:orientation="horizontal" >
            </LinearLayout>

    </HorizontalScrollView>

<!-- pager section --> 

    <LinearLayout
        android:id="@+id/pager"
        android:layout_width="match_parent"
        android:layout_height="20dp"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true"
        android:layout_marginLeft="20dp"
        android:layout_marginRight="20dp"
        android:layout_marginTop="430dp"
        android:gravity="center"
        android:orientation="horizontal" >

    </LinearLayout>

</RelativeLayout>

recipesscroll.xml (the view that will be added to the scroller section for each recipe step. Note that the scroller section has a onTouchlistner in recipeViewController.java to handle page scrolling)

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/recipeScroll"
    android:layout_width="320dp"
    android:layout_height="320dp"
    android:gravity="center_vertical" >

   <TextView
    android:id="@+id/method"
    style="@style/scrollMethod"
    android:layout_width="wrap_content"
    android:layout_height="200dp"
    android:layout_alignParentTop="true"
    android:text="Method" />

   <TextView
    android:id="@+id/ingredients"
    style="@style/scrollIngredients"
    android:layout_width="wrap_content"
    android:layout_height="120dp"
    android:layout_alignParentTop="true"
    android:text="Ingredients" />

   <TextView
    android:id="@+id/methodStep"
    style="@style/scrollStep"
    android:layout_width="wrap_content"
    android:layout_height="20dp"
    android:layout_alignParentTop="true"
    android:text="Step" />

</RelativeLayout>

recipiespager.xml ( the view that will be added to the pager section for each recipe step. Note that each of these will have a onClick event in recipeViewController.java that will scroll to the specific page selected in the pager control)

<?xml version="1.0" encoding="utf-8"?>
<Button xmlns:android="http://schemas.android.com/apk/res/android"
            style="@style/pageButton"
            android:layout_marginLeft="10dp"
            android:layout_width="16dp"
            android:layout_height="16dp"
            android:onClick="selectPage">

</Button>

This is all brought together in recipeViewController.java

//my package name change this to yours
package com.infactdata.spinAdinner;

import java.util.ArrayList;

//DataModel is the model for my data change this to yours or ignore 
because it is just away of holding the data that will populate the views
import com.infactdata.plist.DataModel;

import android.content.res.Resources;
import android.graphics.Typeface;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.View.OnTouchListener;
import android.widget.Button;
import android.widget.HorizontalScrollView;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
import android.widget.TableLayout;
import android.widget.TableRow;
import android.widget.TextView;

public class RecipeViewController extends RootViewController {
    private DataModel currentData;
    HorizontalScrollView h_scroll;
    int numberOfPages = 0;
    int thePage;
    int otherPage;

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

        //first of the xml files
        setContentView(R.layout.recipe);

        //reference to my global variables
        GlobalClass global = (GlobalClass)getApplicationContext();

        //because I wanted a particular type face
        Typeface face=Typeface.createFromAsset(getAssets(), "fonts/trebucit.ttf");

        //VERY IMPORTANT because we need to use this to add the content to the scroll
        and pager sections   
        LayoutInflater inflater = getLayoutInflater();

        //current data held a dataModel
        currentData = global.getCurrent();  

        currentName.setText(currentData.getName());

        String imageFile = currentData.getImage();
        Resources r = getResources();

        int res = r.getIdentifier(imageFile, "drawable", "com.infactdata.spinAdinner");
        image.setImageResource(res);

        //recources that change the pager indicators to different images
        thePage = r.getIdentifier("page_selected", "drawable","com.infactdata.spinAdinner");
        otherPage = r.getIdentifier("page", "drawable", "com.infactdata.spinAdinner");

        //Get the method(ArrayList) out of the currentData(DataModel). This is the array of 
        data that will fill the added view with different content (ie. the specific
        instructions for the recipe step. This could be your own data array.   

        ArrayList<String[]> method = new ArrayList<String[]>();
        method = currentData.getMethod(0);
        numberOfPages = method.size();

        //now to build the views by adding the content and then adding the text for that 
        content that reflects the instructions for the step in the recipe  

        for( int i = 0; i < method.size(); i++){

            String[] methodStep = method.get(i);

            //find the scroll view
            LinearLayout scroll = (LinearLayout) findViewById(R.id.methodScrollView);

            //find the recipe scroller. the second xml file 
            RelativeLayout step = (RelativeLayout)findViewById(R.id.recipeScroll);

            //add the recipe step (step) to the scrollview (scroll)
            step = (RelativeLayout)inflater.inflate(R.layout.recipescroll, scroll, false);

            //add the instructions for this step in the recipe
            TextView stage = (TextView)step.findViewById(R.id.methodStep);
            stage.setText(methodStep[0].toString());
            stage.setTypeface(face);

            TextView methodText = (TextView)step.findViewById(R.id.method);
            methodText.setText(methodStep[1].toString());
            methodText.setTypeface(face);

            TextView ingredients = (TextView)step.findViewById(R.id.ingredients);
            ingredients.setText(methodStep[2].toString());
            ingredients.setTypeface(face);

            //create method step and add to scroll
            scroll.addView(step);

            //pager setup is a duplicate of the above
            //find the pager
            LinearLayout pager = (LinearLayout) findViewById(R.id.pager);

           //find the pager button. the third xml file
           Button page = (Button)inflater.inflate(R.layout.recipespager, pager, false);

           //give each button it own ID. This will be used to test which button should  be highlighted and used to move to a specific page. This is because the ID is equal to the page number (0 based of course) 
           page.setId(i);

           //because this is a fresh construction we will be on page 0 so highlight that button   
          if (i == 0){
              page.setBackgroundResource(thePage);
           }

           //create page control and add to pager
           pager.addView(page);
       }

      //create the onTouch controls 

      h_scroll = (HorizontalScrollView) findViewById(R.id.scroll_view);
      h_scroll.setOnTouchListener(scrolling);

 }

 private OnTouchListener scrolling = new OnTouchListener(){
     public boolean onTouch(View v, MotionEvent event) {
         if (event.getAction() == MotionEvent.ACTION_UP || event.getAction() == 
         MotionEvent.ACTION_CANCEL ){
             int scrollX = h_scroll.getScrollX();
             int itemWidth = h_scroll.getMeasuredWidth();
             int activePage = ((scrollX + itemWidth / 2) / itemWidth);
             int scrollTo = activePage * itemWidth;
             h_scroll.smoothScrollTo(scrollTo, 0);


             //page control display the active page button
             Log.v("MyDebug","Active page = "+activePage);
             for(int i = 0; i < numberOfPages; i++){
                Button aPage = (Button) findViewById(i);
                if(i == activePage){
                    aPage.setBackgroundResource(thePage);
                }else{
                    aPage.setBackgroundResource(otherPage);
                }
             }

             return true;
         } else {
             return false;
         }
     }

 };


 //this is the onClick handler for the page buttons and moves the scroller to the page 
 associated with the button. That is through the button ID, which matches the page 
 number (0 based of course

 public void selectPage(View v) {
     int newPage = v.getId();
     int itemWidth = h_scroll.getMeasuredWidth();
     int scrollTo = newPage * itemWidth;
     h_scroll.smoothScrollTo(scrollTo, 0);

   //page control display
     Log.v("MyDebug","Active page = "+newPage);
     for(int i = 0; i < numberOfPages; i++){
        Button aPage = (Button) findViewById(i);
        if(i == newPage){
            aPage.setBackgroundResource(thePage);
        }else{
            aPage.setBackgroundResource(otherPage);
        }
     }
  }

  public void finishActivity(View v){
      //perform back action
      finish();
  }

  public void nextActivity(View v){
      //move to next activity
  }
}

Well that was my solution. I am certain that there are much clever programers than me out there so I am sure someone can improve this. Anyhow THANKS stackoverflow!!!!

Answer 1

I think the GreenDroid library will help achieve something similar to the iPhone's UIPageControl.

Have a look at their app in marketplace GDCatalog. Also you can extract the files you want and make the pagecontrol. I've used it in my app and it works fine. Needs a bit optimisation to make it smoother.

https://github.com/cyrilmottier/GreenDroid