Thứ Sáu, 20 tháng 7, 2012

Implement custom LinearLayout for Gallery-like HorizontalScrollView

0
19:56
Last exercise explain the basic to "implement Gallery-like HorizontalScrollView". In this post, we are going to implement our custom LinearLayout for Gallery-like HorizontalScrollView.

Custom LinearLayout for Gallery-like HorizontalScrollView


MyHorizontalLayout.java, our custom LinearLayout for Gallery-like HorizontalScrollView.
package com.example.androidhorizontalscrollviewgallery;
import java.util.ArrayList;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.util.AttributeSet;
import android.widget.ImageView;
import android.widget.LinearLayout;

public class MyHorizontalLayout extends LinearLayout {

Context myContext;
ArrayList<String> itemList = new ArrayList<String>();

public MyHorizontalLayout(Context context) {
super(context);
myContext = context;
}

public MyHorizontalLayout(Context context, AttributeSet attrs) {
super(context, attrs);
myContext = context;
}

public MyHorizontalLayout(Context context, AttributeSet attrs,
int defStyle) {
super(context, attrs, defStyle);
myContext = context;
}

void add(String path){
int newIdx = itemList.size();
itemList.add(path);
addView(getImageView(newIdx));
}

ImageView getImageView(int i){
Bitmap bm = null;
if (i < itemList.size()){
bm = decodeSampledBitmapFromUri(itemList.get(i), 220, 220);
}

ImageView imageView = new ImageView(myContext);
imageView.setLayoutParams(new LayoutParams(220, 220));
imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
imageView.setImageBitmap(bm);

return imageView;
}

public Bitmap decodeSampledBitmapFromUri(String path, int reqWidth, int reqHeight) {
Bitmap bm = null;

// First decode with inJustDecodeBounds=true to check dimensions
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(path, options);

// Calculate inSampleSize
options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);

// Decode bitmap with inSampleSize set
options.inJustDecodeBounds = false;
bm = BitmapFactory.decodeFile(path, options);

return bm;
}

public int calculateInSampleSize(

BitmapFactory.Options options, int reqWidth, int reqHeight) {
// Raw height and width of image
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;

if (height > reqHeight || width > reqWidth) {
if (width > height) {
inSampleSize = Math.round((float)height / (float)reqHeight);
} else {
inSampleSize = Math.round((float)width / (float)reqWidth);
}
}

return inSampleSize;
}

}


Modify layout to include MyHorizontalLayout.
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">

<HorizontalScrollView
android:layout_width="match_parent"
android:layout_height="wrap_content" >
<com.example.androidhorizontalscrollviewgallery.MyHorizontalLayout
android:id="@+id/mygallery"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="horizontal"
/>
</HorizontalScrollView>

</LinearLayout>


See how simple is the main code:
package com.example.androidhorizontalscrollviewgallery;

import java.io.File;

import android.os.Bundle;
import android.os.Environment;
import android.app.Activity;
import android.widget.Toast;

public class MainActivity extends Activity {

MyHorizontalLayout myHorizontalLayout;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

myHorizontalLayout = (MyHorizontalLayout)findViewById(R.id.mygallery);

String ExternalStorageDirectoryPath = Environment
.getExternalStorageDirectory()
.getAbsolutePath();

String targetPath = ExternalStorageDirectoryPath + "/test/";

Toast.makeText(getApplicationContext(), targetPath, Toast.LENGTH_LONG).show();
File targetDirector = new File(targetPath);

File[] files = targetDirector.listFiles();
for (File file : files){
myHorizontalLayout.add(file.getAbsolutePath());
}
}

}


Download the files.

Next:
- Vertical Gallery-like ScrollView

Related:
- GridView loading photos from SD Card


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