Android Fullscreen Image Slider with Swipe and Pinch Zoom Gestures
Creating new project
1. Create new project in Eclipse IDE from File ⇒ New ⇒ Android Application Project and fill all the required details. I kept my package name as info.nishal.imageslider and main activity name as GridViewActivity.java
App Constant Class
I am creating a app constant class file to store static variables which will be used across application. In this way you don’t have modify much code if you want to change app configuration.
2. In order to maintaining good project structure I am creating a separate package for storing this kind of helper classes. Right click on src ⇒ New ⇒ Package and name it as your_package_name.helper.
(So my helper package becomes info.nishal.imageslider.helper)
3. Under helper package create a new class named AppConstant.java and paste the following code. In the following I declared required constant variables
NUM_OF_COLUMNS – Number of columns to be displayed in Grid view
PHOTO_ALBUM – Name of the photo album directory in the sd card. Make sure that you have some images inside this directory before you start the project.
FILE_EXTN – Image file extensions to be supported
AppConstant.java
package info.nishal.imageslider.helper;
import java.util.Arrays;
import java.util.List;
public class AppConstant {
// Number of columns of Grid View
public static final int NUM_OF_COLUMNS = 3;
// Gridview image padding
public static final int GRID_PADDING = 8; // in dp
// SD card image directory
public static final String PHOTO_ALBUM = "nishal";
// supported file formats
public static final List<String> FILE_EXTN = Arrays.asList("jpg", "jpeg",
"png");
}
Helper Utils ClasS
4. I am creating another class to define reusable functions across applications. Create another class under helper package named Utils.java
Following are major functions defined in Utils class
getFilePaths() – This function will return all image paths of a directory
IsSupportedFile() – This will check for supported file extensions
Utils.java
package info.nishal.imageslider.helper;
import java.io.File;
import java.util.ArrayList;
import java.util.Locale;
import android.app.AlertDialog;
import android.content.Context;
import android.graphics.Point;
import android.view.Display;
import android.view.WindowManager;
import android.widget.Toast;
public class Utils {
private Context _context;
// constructor
public Utils(Context context) {
this._context = context;
}
// Reading file paths from SDCard
public ArrayList<String> getFilePaths() {
ArrayList<String> filePaths = new ArrayList<String>();
File directory = new File(
android.os.Environment.getExternalStorageDirectory()
+ File.separator + AppConstant.PHOTO_ALBUM);
// check for directory
if (directory.isDirectory()) {
// getting list of file paths
File[] listFiles = directory.listFiles();
// Check for count
if (listFiles.length > 0) {
// loop through all files
for (int i = 0; i < listFiles.length; i++) {
// get file path
String filePath = listFiles[i].getAbsolutePath();
// check for supported file extension
if (IsSupportedFile(filePath)) {
// Add image path to array list
filePaths.add(filePath);
}
}
} else {
// image directory is empty
Toast.makeText(
_context,
AppConstant.PHOTO_ALBUM
+ " is empty. Please load some images in it !",
Toast.LENGTH_LONG).show();
}
} else {
AlertDialog.Builder alert = new AlertDialog.Builder(_context);
alert.setTitle("Error!");
alert.setMessage(AppConstant.PHOTO_ALBUM
+ " directory path is not valid! Please set the image directory name AppConstant.java class");
alert.setPositiveButton("OK", null);
alert.show();
}
return filePaths;
}
// Check supported file extensions
private boolean IsSupportedFile(String filePath) {
String ext = filePath.substring((filePath.lastIndexOf(".") + 1),
filePath.length());
if (AppConstant.FILE_EXTN
.contains(ext.toLowerCase(Locale.getDefault())))
return true;
else
return false;
}
/*
* getting screen width
*/
public int getScreenWidth() {
int columnWidth;
WindowManager wm = (WindowManager) _context
.getSystemService(Context.WINDOW_SERVICE);
Display display = wm.getDefaultDisplay();
final Point point = new Point();
try {
display.getSize(point);
} catch (java.lang.NoSuchMethodError ignore) { // Older device
point.x = display.getWidth();
point.y = display.getHeight();
}
columnWidth = point.x;
return columnWidth;
}
}
Displaying thumbnail images in Grid View
Until now we are done with some utility functions which required further. So let’s start first view of the application which is displaying images in grid view.
5. Create a new layout file under res ⇒ layout folder named activity_grid_view.xml and paste the following code
activity_grid_view.xml
<?xml version="1.0" encoding="utf-8"?>
<GridView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/grid_view"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:numColumns="auto_fit"
android:gravity="center"
android:stretchMode="columnWidth"
android:background="#000000">
</GridView>
GridView Adapter
I am creating a custom grid adapter class for the grid view. In this way you can create a reusable view for the grid view blocks. As this class is not an activity class I prefer to keep it in another package.
6. Create another package named adapter under src folder. I created another package namedinfo.nishal.imageslider.adapter
7. Under adapter package create a class file named GridViewImageAdapter.java and extend it from BaseAdapter This adapter class simply returns image view to gridview.
GridViewImageAdapter.java
package info.nishal.imageslider.adapter;
import info.nishal.imageslider.FullScreenViewActivity;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
public class GridViewImageAdapter extends BaseAdapter {
private Activity _activity;
private ArrayList<String> _filePaths = new ArrayList<String>();
private int imageWidth;
public GridViewImageAdapter(Activity activity, ArrayList<String> filePaths,
int imageWidth) {
this._activity = activity;
this._filePaths = filePaths;
this.imageWidth = imageWidth;
}
@Override
public int getCount() {
return this._filePaths.size();
}
@Override
public Object getItem(int position) {
return this._filePaths.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView;
if (convertView == null) {
imageView = new ImageView(_activity);
} else {
imageView = (ImageView) convertView;
}
// get screen dimensions
Bitmap image = decodeFile(_filePaths.get(position), imageWidth,
imageWidth);
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
imageView.setLayoutParams(new GridView.LayoutParams(imageWidth,
imageWidth));
imageView.setImageBitmap(image);
// image view click listener
imageView.setOnClickListener(new OnImageClickListener(position));
return imageView;
}
class OnImageClickListener implements OnClickListener {
int _postion;
// constructor
public OnImageClickListener(int position) {
this._postion = position;
}
@Override
public void onClick(View v) {
// on selecting grid view image
// launch full screen activity
Intent i = new Intent(_activity, FullScreenViewActivity.class);
i.putExtra("position", _postion);
_activity.startActivity(i);
}
}
/*
* Resizing image size
*/
public static Bitmap decodeFile(String filePath, int WIDTH, int HIGHT) {
try {
File f = new File(filePath);
BitmapFactory.Options o = new BitmapFactory.Options();
o.inJustDecodeBounds = true;
BitmapFactory.decodeStream(new FileInputStream(f), null, o);
final int REQUIRED_WIDTH = WIDTH;
final int REQUIRED_HIGHT = HIGHT;
int scale = 1;
while (o.outWidth / scale / 2 >= REQUIRED_WIDTH
&& o.outHeight / scale / 2 >= REQUIRED_HIGHT)
scale *= 2;
BitmapFactory.Options o2 = new BitmapFactory.Options();
o2.inSampleSize = scale;
return BitmapFactory.decodeStream(new FileInputStream(f), null, o2);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
return null;
}
8. Finally open the activity class for grid view. In my case my grid view activity name is GridViewActivity.java.
InitilizeGridLayout() – This will initialize the grid view layout by setting necessary attributes like padding, number of columns, spacing between grid images etc.,
GridViewActivity.java
package info.nishal.slider;
import info.nishal.imageslider.adapter.GridViewImageAdapter;
import info.nishal.imageslider.helper.AppConstant;
import info.nishal.imageslider.helper.Utils;
import java.util.ArrayList;
import android.app.Activity;
import android.content.res.Resources;
import android.os.Bundle;
import android.util.TypedValue;
import android.widget.GridView;
public class GridViewActivity extends Activity {
private Utils utils;
private ArrayList<String> imagePaths = new ArrayList<String>();
private GridViewImageAdapter adapter;
private GridView gridView;
private int columnWidth;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_grid_view);
gridView = (GridView) findViewById(R.id.grid_view);
utils = new Utils(this);
// Initilizing Grid View
InitilizeGridLayout();
// loading all image paths from SD card
imagePaths = utils.getFilePaths();
// Gridview adapter
adapter = new GridViewImageAdapter(GridViewActivity.this, imagePaths,
columnWidth);
// setting grid view adapter
gridView.setAdapter(adapter);
}
private void InitilizeGridLayout() {
Resources r = getResources();
float padding = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,
AppConstant.GRID_PADDING, r.getDisplayMetrics());
columnWidth = (int) ((utils.getScreenWidth() - ((AppConstant.NUM_OF_COLUMNS + 1) * padding)) / AppConstant.NUM_OF_COLUMNS);
gridView.setNumColumns(AppConstant.NUM_OF_COLUMNS);
gridView.setColumnWidth(columnWidth);
gridView.setStretchMode(GridView.NO_STRETCH);
gridView.setPadding((int) padding, (int) padding, (int) padding,
(int) padding);
gridView.setHorizontalSpacing((int) padding);
gridView.setVerticalSpacing((int) padding);
}
}
Now run your project and test it once. You should see a grid view displaying the images from the sd card. Following is the screenshot of my grid view
Creating Fullscreen Image Slider
Second task in this tutorial is to build a fullscreen image slider for the images displayed in the grid view. This also involves swiping gesture to navigate through the album.
To create swiping gesture functionality I am using PagerAdapter class provided by android.
9. Create an xml layout file for full screen activity. I created a file called activity_fullscreen_view.xml under res ⇒ layout folder. Add a android.support.v4.view.ViewPager element inside it.
activity_fullscreen_view.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<android.support.v4.view.ViewPager
android:id="@+id/pager"
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
</LinearLayout>
10. In fullscreen view instead of showing only fullview image you might want to show some other UI elments like text, buttons along with the image. So I created a separate layout for fullscreen view, so that you can customize the fullscreen view in this layout file.
As of now I am just adding a close button over the image. Create an xml layout file under res ⇒ layout folder named layout_fullscreen_image.xml and add the following code
layout_fullscreen_image.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<ImageView
android:id="@+id/imgDisplay"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:scaleType="fitCenter" />
<Button
android:id="@+id/btnClose"
android:layout_width="wrap_content"
android:layout_height="30dp"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:layout_marginRight="15dp"
android:layout_marginTop="15dp"
android:paddingTop="2dp"
android:paddingBottom="2dp"
android:background="@drawable/button_background"
android:textColor="#ffffff"
android:text="Close" />
</RelativeLayout>
Also create a file called button_background.xml under drawable folder. This is just for styling the button
button_background.xml
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle" >
<corners android:radius="3dp" />
<solid android:color="#000000" />
<stroke
android:width="2px"
android:color="#ffffff" />
</shape>
Fullscreen Image Viewer Adapter
Just like grid adapter, we are going to create another adapter for the full screen activity too. This is the data provider for the fullscreen image viewer.
11. Create another class under adapter package named FullScreenImageAdapter.java and extend it from PagerAdapter.
package info.nishal.imageslider.adapter;import info.nishal.imageslider.R;import java.util.ArrayList;import android.app.Activity;import android.content.Context;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.support.v4.view.PagerAdapter;import android.support.v4.view.ViewPager;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.Button;import android.widget.ImageView;import android.widget.RelativeLayout;public class FullScreenImageAdapter extends PagerAdapter { private Activity _activity; private ArrayList<String> _imagePaths; private LayoutInflater inflater; // constructor public FullScreenImageAdapter(Activity activity, ArrayList<String> imagePaths) { this._activity = activity; this._imagePaths = imagePaths; } @Override public int getCount() { return this._imagePaths.size(); } @Override public boolean isViewFromObject(View view, Object object) { return view == ((RelativeLayout) object); } @Override public Object instantiateItem(ViewGroup container, int position) { ImageView imgDisplay; Button btnClose; inflater = (LayoutInflater) _activity .getSystemService(Context.LAYOUT_INFLATER_SERVICE); View viewLayout = inflater.inflate(R.layout.layout_fullscreen_image, container, false); imgDisplay = (ImageView) viewLayout.findViewById(R.id.imgDisplay); btnClose = (Button) viewLayout.findViewById(R.id.btnClose); BitmapFactory.Options options = new BitmapFactory.Options(); options.inPreferredConfig = Bitmap.Config.ARGB_8888; Bitmap bitmap = BitmapFactory.decodeFile(_imagePaths.get(position), options); imgDisplay.setImageBitmap(bitmap); // close button click event btnClose.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { _activity.finish(); } }); ((ViewPager) container).addView(viewLayout); return viewLayout; } @Override public void destroyItem(ViewGroup container, int position, Object object) { ((ViewPager) container).removeView((RelativeLayout) object); }}Also make sure that you have added FullScreenViewActivity to AndroidManifest.xml file before testing your project. |
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