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Display Images in an Image Viewer - Android Java

This tutorial shows how to load, display, and save images using the LEADTOOLS SDK in an Android Java application.

Overview
Summary	This tutorial covers how to display images in an Image Viewer in an Android application.
Completion Time	30 minutes
Android Studio Project	Download tutorial project (4 MB)
Platform	Android (Java)
IDE	Android Studio
Development License	Download LEADTOOLS
Try it in another language	C#: .NET 6+ (WinForms), WPF, .NET Framework (WinForms) Apple: macOS App Java: Android HTML5: HTML5 JavaScript, HTML5 React JS

Required Knowledge

Get familiar with the basic steps of creating a project by reviewing the Add References and Set a License tutorial, before working on the Display Images in an Image Viewer - Android Java tutorial.

Create the Project and Add the LEADTOOLS References

Start with a copy of the project created in the Add References and Set a License tutorial. If you do not have that project, follow the steps in that tutorial to create it.

The references needed depend upon the purpose of the project. This project requires the following .JAR and .SO files:

The .JAR files can be found at: <INSTALL_DIR>\Bin\Java

Leadtools.jar
Leadtools.codecs.jar
Leadtools.controls.android.jar
Leadtools.caching.jar
Leadtools.converters.android.jar

The .SO files can be found at: <INSTALL_DIR>\Bin\Android

libleadtools.so
libleadtools.codecs.so
libleadtools.codecs.bmp.so
libleadtools.codecs.cmp.so
libleadtools.codecs.fax.so
libleadtools.codecs.png.so
libleadtools.codecs.tif.so

For a complete list of which DLL files are required for your application, refer to Files to be Included With Your Application.

Set the License File

The License unlocks the features needed for the project. It must be set before any toolkit function is called. For details, including tutorials for different platforms, refer to Setting a Runtime License.

There are two types of runtime licenses:

Evaluation license, obtained at the time the evaluation toolkit is downloaded. It allows the toolkit to be evaluated.
Deployment license. If a Deployment license file and developer key are required, refer to Obtaining a License.

Note

Adding LEADTOOLS local references and setting a license are covered in more detail in the Add References and Set a License tutorial.

Set the Application Layout

In the Project Explorer window, open the activity_main.xml file found in the app/src/main/res/layout directory. Replace the current code with the XML below.

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:orientation="vertical" 
    android:weightSum="1.0" 
    android:background="@android:color/black"> 
 
    <Button 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:text="Select Image From Gallery" 
        android:onClick="onSelectImage"/> 
 
    <leadtools.controls.RasterImageViewer 
        android:id="@+id/rasterimageviewer" 
        android:layout_width="match_parent" 
        android:layout_height="0dp" 
        android:layout_weight=".96" 
        android:background="@android:color/white"/> 
 
    <Button 
        android:id="@+id/button" 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:text="Save image" 
        android:onClick="onSaveImage"/> 
</LinearLayout>

Add the Load, Display, and Save Code

Navigate to MainActivity.java and add the following import statements before the MainActivity class.

Java

import android.content.Context; 
import android.content.Intent; 
import android.net.Uri; 
import android.view.View; 
import leadtools.LeadStreamFactory; 
import leadtools.RasterImage; 
import leadtools.RasterImageFormat; 
import leadtools.ILeadStream; 
import leadtools.codecs.RasterCodecs; 
import leadtools.controls.RasterImageViewer; 
import leadtools.controls.ImageViewerPanZoomInteractiveMode; 
import java.io.File;

Add the following member variables.

Java

private static final int IMAGE_GALLERY = 0x0001; 
private RasterImageViewer mViewer; 
private RasterCodecs codecs; 
private Intent intent;

Update the onCreate() function as shown below.

Java

 @Override 
    protected void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState); 
        setContentView(R.layout.activity_main); 
         
        // Load LEADTOOLS native libraries 
        try{ 
            Platform.setLibPath(sharedLibsPath); 
            Platform.loadLibrary(LTLibrary.LEADTOOLS); 
            Platform.loadLibrary(LTLibrary.CODECS); 
        } 
        catch(Exception ex) { 
            Log.d(TAG,"Failed to load LEADTOOLS Native libraries" ); 
        } 
         
        mViewer = (RasterImageViewer)findViewById(R.id.rasterimageviewer); 
        mViewer.setTouchInteractiveMode(new ImageViewerPanZoomInteractiveMode()); 
        codecs = new RasterCodecs(); 
        intent = new Intent(); 
 
    }

Add the following functions to enable loading, displaying, and saving an image.

Java

public void onSelectImage(View v) 
    { 
        intent.setType("image/*"); 
        intent.setAction(Intent.ACTION_GET_CONTENT); 
        startActivityForResult(Intent.createChooser(intent, "Select Picture"), IMAGE_GALLERY); 
    } 
    public void onSaveImage(View v ) 
    { 
        RasterImage image = mViewer.getImage(); 
        File file = new File(this.getFilesDir(), "input.png"); 
        String path = file.getAbsolutePath(); 
 
        if(image != null) 
        { 
            codecs.save(image, LeadStreamFactory.create(path), RasterImageFormat.PNG, 0); 
            Toast.makeText(this, path, Toast.LENGTH_LONG).show(); 
        } 
        else 
        { 
            Toast.makeText(this, "No Image is loaded", Toast.LENGTH_LONG).show(); 
        } 
    } 
 
    @Override 
    protected void onActivityResult(int requestCode, int resultCode, Intent data) 
    { 
        if(resultCode == RESULT_OK)  
        { 
            if(requestCode == IMAGE_GALLERY)  
            { 
                Uri imageUri = data.getData(); 
                try 
                { 
                    ILeadStream stream = LeadStreamFactory.create(getContentResolver().openInputStream(imageUri),true); 
                    RasterImage image = codecs.load(stream); 
                    mViewer.setImage(image); 
                } 
                catch(Exception ex) 
                { 
                    Toast.makeText(this, ex.getMessage(), Toast.LENGTH_LONG).show(); 
                } 
            } 
        } 
    }

Run the application

Press Shift + F10 to run the application.

On the device, press SELECT IMAGE FROM GALLERY to load and display an image.
Press the SAVE IMAGE button to save the image.

Wrap-up

This tutorial showed how to load, display, and save images. In addition, it showed how to use the RasterImageViewer and RasterCodecs classes.

Display Images in an Image Viewer - Android Java

Required Knowledge

Create the Project and Add the LEADTOOLS References

Set the License File

Set the Application Layout

Add the Load, Display, and Save Code

Run the application

Wrap-up

See Also