Last article "Display photos from SD in android.widget.Gallery" load Gallery photos in UI thread. As I mentioned in some previous posts, it's not a good practice to perform long time operation in UI thread, specially when you load many large size photos.
The main code, AndroidGalleryActivity.java, is further modified to perform the re-size job in background thread. Before the photos re-sized, the Gallery show items as a default bitmap (android.R.drawable.ic_menu_gallery). After re-size, myPhotoBarAdapter.notifyDataSetChanged() is called (in UI thread) to update Gallery.
Because every photo have its own background thread to re-size, and independent to each others. So the update sequence is not in order.
Cheers Guys!!
The main code, AndroidGalleryActivity.java, is further modified to perform the re-size job in background thread. Before the photos re-sized, the Gallery show items as a default bitmap (android.R.drawable.ic_menu_gallery). After re-size, myPhotoBarAdapter.notifyDataSetChanged() is called (in UI thread) to update Gallery.
Because every photo have its own background thread to re-size, and independent to each others. So the update sequence is not in order.
package com.AndroidGallery;
import java.io.File;
import java.util.ArrayList;
import java.util.List;
import android.R.color;
import android.app.Activity;
import android.app.Dialog;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.view.Gravity;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.webkit.MimeTypeMap;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.Gallery;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
public class AndroidGalleryActivity extends Activity {
Gallery photoBar;
Button buttonOpenDialog;
Button buttonUp, buttonSelectFolder;
TextView jpgList;
String KEY_TEXTPSS = "TEXTPSS";
static final int CUSTOM_DIALOG_ID = 0;
ListView dialog_ListView;
File root;
File curFolder;
private ListfileList = new ArrayList ();
class PhotoItem{
String bitmapImageSrc;
Bitmap bitmapImage = null;
final static int itemWidth = 150;
final static int itemHeight = 150;
Handler handler;
public PhotoItem(String src){
bitmapImageSrc = src;
StratBackgroundProcess();
bitmapImage = BitmapFactory.decodeResource(getResources(), android.R.drawable.ic_menu_gallery);
}
public Bitmap getImage(){
return bitmapImage;
}
private void runResize(){
BitmapFactory.Options bmpFactoryOptions = new BitmapFactory.Options();
bmpFactoryOptions.inJustDecodeBounds = true;
Bitmap bitmap = BitmapFactory.decodeFile(bitmapImageSrc, bmpFactoryOptions);
int heightRatio = (int)Math.ceil(bmpFactoryOptions.outHeight/(float)itemHeight);
int widthRatio = (int)Math.ceil(bmpFactoryOptions.outWidth/(float)itemWidth);
if (heightRatio > 1 || widthRatio > 1)
{
if (heightRatio > widthRatio){
bmpFactoryOptions.inSampleSize = heightRatio;
} else {
bmpFactoryOptions.inSampleSize = widthRatio;
}
}
bmpFactoryOptions.inJustDecodeBounds = false;
bitmapImage = BitmapFactory.decodeFile(bitmapImageSrc, bmpFactoryOptions);
}
private void StratBackgroundProcess(){
Runnable runnable = new Runnable(){
@Override
public void run() {
runResize();
handler.post(new Runnable(){
@Override
public void run() {
myPhotoBarAdapter.notifyDataSetChanged();
}});
}
};
handler = new Handler();
new Thread(runnable).start();
}
}
PhotoBarAdapter myPhotoBarAdapter;
public class PhotoBarAdapter extends BaseAdapter {
Context context;
ArrayListarrayPhotoItem;
PhotoBarAdapter(Context c){
context = c;
arrayPhotoItem = new ArrayList();
}
public void clear(){
arrayPhotoItem.clear();
}
public void addPhotoItem(PhotoItem item){
arrayPhotoItem.add(item);
}
@Override
public int getCount() {
return arrayPhotoItem.size();
}
@Override
public Object getItem(int position) {
return arrayPhotoItem.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
LinearLayout viewLayout = new LinearLayout(context);
viewLayout.setLayoutParams(new Gallery.LayoutParams(200, 200));
viewLayout.setGravity(Gravity.CENTER);
viewLayout.setBackgroundColor(color.background_light);
ImageView imageView;
imageView = new ImageView(context);
imageView.setLayoutParams(new Gallery.LayoutParams(150, 150));
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
imageView.setImageBitmap(arrayPhotoItem.get(position).getImage());
//return imageView;
viewLayout.addView(imageView);
return viewLayout;
}
}
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
photoBar = (Gallery)findViewById(R.id.photobar);
myPhotoBarAdapter = new PhotoBarAdapter(this);
photoBar.setAdapter(myPhotoBarAdapter);
jpgList = (TextView)findViewById(R.id.jpglist);
buttonOpenDialog = (Button)findViewById(R.id.opendialog);
buttonOpenDialog.setOnClickListener(new Button.OnClickListener(){
@Override
public void onClick(View arg0) {
showDialog(CUSTOM_DIALOG_ID);
}});
root = new File(Environment
.getExternalStorageDirectory()
.getAbsolutePath());
curFolder = root;
//ListJpgInFolder(curFolder);
preparePhotoBarInFolder(curFolder);
}
@Override
protected Dialog onCreateDialog(int id) {
Dialog dialog = null;
switch(id) {
case CUSTOM_DIALOG_ID:
dialog = new Dialog(AndroidGalleryActivity.this);
dialog.setContentView(R.layout.dialoglayout);
dialog.setTitle("Select JPG");
dialog.setCancelable(true);
dialog.setCanceledOnTouchOutside(true);
buttonUp = (Button)dialog.findViewById(R.id.up);
buttonUp.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View v) {
ListDir(curFolder.getParentFile());
}});
buttonSelectFolder = (Button)dialog.findViewById(R.id.selectfolder);
buttonSelectFolder.setOnClickListener(new OnClickListener(){
@Override
public void onClick(View v) {
Toast.makeText(AndroidGalleryActivity.this,
curFolder + " selected",
Toast.LENGTH_LONG).show();
dismissDialog(CUSTOM_DIALOG_ID);
//ListJpgInFolder(curFolder);
preparePhotoBarInFolder(curFolder);
}});
//Prepare ListView in dialog
dialog_ListView = (ListView)dialog.findViewById(R.id.dialoglist);
dialog_ListView.setOnItemClickListener(new OnItemClickListener(){
@Override
public void onItemClick(AdapterView parent, View view,
int position, long id) {
File selected = new File(fileList.get(position));
if(selected.isDirectory()){
ListDir(selected);
}
}});
break;
}
return dialog;
}
@Override
protected void onPrepareDialog(int id, Dialog dialog, Bundle bundle) {
super.onPrepareDialog(id, dialog, bundle);
switch(id) {
case CUSTOM_DIALOG_ID:
ListDir(curFolder);
break;
}
}
void ListDir(File f){
if(f.equals(root)){
buttonUp.setEnabled(false);
}else{
buttonUp.setEnabled(true);
}
curFolder = f;
buttonSelectFolder.setText("Select Folder " + curFolder);
File[] files = f.listFiles();
fileList.clear();
for (File file : files){
if(file.isDirectory()){
fileList.add(file.getPath());
}else{
Uri selectedUri = Uri.fromFile(file);
String fileExtension
= MimeTypeMap.getFileExtensionFromUrl(selectedUri.toString());
if(fileExtension.equalsIgnoreCase("jpg")){
fileList.add(file.getName());
}
}
}
ArrayAdapterdirectoryList
= new ArrayAdapter(this,
android.R.layout.simple_list_item_1, fileList);
dialog_ListView.setAdapter(directoryList);
}
private void preparePhotoBarInFolder(File folder){
String jpgs = "JPG fiels in folder " + folder.getAbsolutePath() + "\n\n";
File[] files = folder.listFiles();
myPhotoBarAdapter.clear();
for (File file : files){
if(!file.isDirectory()){
Uri selectedUri = Uri.fromFile(file);
String fileExtension
= MimeTypeMap.getFileExtensionFromUrl(selectedUri.toString());
if(fileExtension.equalsIgnoreCase("jpg")){
jpgs += file.getAbsolutePath() + "\n";
PhotoItem pItem = new PhotoItem(file.getAbsolutePath());
myPhotoBarAdapter.addPhotoItem(pItem);
myPhotoBarAdapter.notifyDataSetChanged();
}
}
}
jpgList.setText(jpgs);
}
}
