Scroll of the slow, heavy Gridview,

Question

I’m trying to create an app that is a kind of gallery. Search the photos on mobile and shows the user.

The app is already working, but it turns out that the gridview scroll is slow.

I don’t know what else to do to try to improve performance. I am using Lrucache to store the images, the images are loaded asynchronously.

I put all the codes I think are pertinent.

Gridadapter

package abcde.xyz;

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.support.v4.util.LruCache;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;

import java.util.ArrayList;

/**
 * Created by Lucas on 25/03/2017.
 */

public class GridImagesAdapter extends ArrayAdapter {


    private Context context;
    private int layoutResourceId;
    private ArrayList data = new ArrayList();
    public static LruCache<Integer, Bitmap> mMemoryCache;

    public GridImagesAdapter(Context context, int layoutResourceId, ArrayList<Integer> data) {
        super(context, layoutResourceId, data);
        this.layoutResourceId = layoutResourceId;
        this.context = context;
        this.data = data;


        final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);

        final int cacheSize = maxMemory / 4;
        if(mMemoryCache == null){
            mMemoryCache = new LruCache<Integer, Bitmap>(cacheSize) {
                @Override
                protected int sizeOf(Integer key, Bitmap bitmap) {
                    return bitmap.getByteCount() / 1024;
                }
            };
        }
        mMemoryCache.evictAll();

    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View row = convertView;

        if (row == null) {
            LayoutInflater inflater = ((Activity) context).getLayoutInflater();
            row = inflater.inflate(layoutResourceId, parent, false);

            ImageView image = (ImageView)row.findViewById(R.id.image);
            final Integer item = (Integer)data.get(position);


            image.setImageBitmap(null);
            ImageGridHandler handler = new ImageGridHandler(context, image);
            handler.execute(item);
        }

        return row;
    }
}

Imagegridhandler

package abcde.xyz;

import android.content.Context;
import android.graphics.Bitmap;
import android.os.AsyncTask;
import android.provider.MediaStore;
import android.util.Log;
import android.widget.ImageView;

import java.lang.ref.WeakReference;

/**
 * Created by Lucas on 29/03/2017.
 */

public class ImageGridHandler extends AsyncTask<Integer, Void, Bitmap> {
    private final WeakReference<ImageView> imageViewReference;
    private Context context;
    public ImageGridHandler(Context context, ImageView img){
        imageViewReference = new WeakReference<ImageView>(img);
        this.context = context;
    }

    @Override
    protected Bitmap doInBackground(Integer... params) {

        return loadBitmap(params[0]);

    }

    @Override
    protected void onPostExecute(Bitmap result) {
        final ImageView imageView = imageViewReference.get();

        if(imageView != null) {
            //imageView.setScaleType(ImageView.ScaleType.CENTER);
            imageView.setImageBitmap(result);
        }
    }


    public void addBitmapToMemoryCache(Integer key, Bitmap bitmap) {
        if (getBitmapFromMemCache(key) == null) {
            GridImagesAdapter.mMemoryCache.put(key, bitmap);
        }
    }

    public Bitmap getBitmapFromMemCache(Integer key) {
        return GridImagesAdapter.mMemoryCache.get(key);
    }

    public Bitmap loadBitmap(Integer resId) {


        Bitmap bitmap = getBitmapFromMemCache(resId);
        if (bitmap == null) {

           Log.d("ImageGridHandler", "Loading: " + resId);
            if(resId != null) {
                bitmap = MediaStore.Images.Thumbnails.getThumbnail(
                        context.getContentResolver(), resId,
                        MediaStore.Images.Thumbnails.MICRO_KIND,
                        null);
                if(bitmap != null) {
                    addBitmapToMemoryCache(resId, bitmap);
                }
            }

            Log.d("GRIDADAPTER", "ImageLoaded");
        }

        return bitmap;
    }


}

Layouts

content_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="umdev.images24.MainActivity"
    tools:showIn="@layout/activity_main">
    <android.support.v4.widget.SwipeRefreshLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/swipeRefresh"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        tools:layout_editor_absoluteY="8dp"
        tools:layout_editor_absoluteX="8dp">

     <GridView
         android:id="@+id/gridView"
         android:layout_width="fill_parent"
         android:layout_height="wrap_content"
         android:layout_margin="0dp"
         android:drawSelectorOnTop="true"
         android:gravity="center"
         android:columnWidth="100dp"
         android:numColumns="auto_fit"
         android:stretchMode="columnWidth"
         android:verticalSpacing="0dp"
         android:focusable="true"
         android:clickable="true"
         android:fastScrollEnabled="true"/>

    </android.support.v4.widget.SwipeRefreshLayout>
</android.support.constraint.ConstraintLayout>

grid_item_layout.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:padding="2dp"
    android:background="#fff">

    <ImageView
        android:id="@+id/image"
        android:layout_width="120dp"
        android:layout_height="120dp" />

</LinearLayout>

Answer 1

The android has few features to display the images (which are usually heavy). To solve this problem, you should use an image processing library (to save you the trouble). An example is the Glide. The library manages all image caching/processing/download automatically.

When linking the image in imageView through your methods

 image.setImageBitmap(null);
 ImageGridHandler handler = new ImageGridHandler(context, image);
 handler.execute(item); , 

you must use

Glide.with(meuContexto).load(minhaImagem).into(image);

where the variable "myImage" can be a url, a Resource or a bitmap.

Answer 2

The problem was loading a larger image than Imageview. In this case Imageview had to make a change the size of the image always.

Load a Scaled Down Version into Memory

https://developer.android.com/topic/performance/graphics/load-bitmap.html