Android Open Source - field-data-app Ui Util

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License

The source code is released under:

MIT License

Java Source Code

package nz.cri.gns.springs.util;
//from  w w w .jav  a2 s .  c  o m
import java.util.ArrayList;
import java.util.List;

import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.text.TextWatcher;
import android.text.format.Time;
import android.view.View;
import android.view.ViewGroup;
import android.view.View.OnFocusChangeListener;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.EditText;
import android.widget.Spinner;
import android.widget.SpinnerAdapter;

/**
 * User interface utility functions.
 * @author duncanw
 */
public class UiUtil {
    
  /**
   * Maximum milliseconds between user screen taps for them to be considered 
   * a double-tap.
   */
  public static final long DOUBLE_TAP_DELAY_MILLIS = 500l; 
  
  /**
   * Loads an image from file, minimising memory usage by targeting the
   * given dimensions.
   * @param imageFile path of image file to load
   * @param targetHeight image display height, in pixels
   * @param targetWidth image display width, in pixels.
   * @return the loaded image, as a Bitmap.
   */
  public static Bitmap loadImage(String imageFile, int targetWidth, int targetHeight) {
    
        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeFile(imageFile, options);
        options.inSampleSize = UiUtil.calculateInSampleSize(options, targetWidth, targetHeight);
        options.inJustDecodeBounds = false;
        return BitmapFactory.decodeFile(imageFile, options);            
  }
  
  /**
   * Loads an image from this app's resourced directory, minimising memory usage by targeting the
   * given dimensions.
   * @param resources the app's resources, e.g from myActivity.getResources()
   * @param imageId id of the image to load, e.g R.drawable.my_image
   * @param targetHeight image display height, in pixels
   * @param targetWidth image display width, in pixels.
   * @return the loaded image, as a Bitmap.
   */
  public static Bitmap loadImage(Resources resources, int imageId, int targetWidth, int targetHeight) {
    
        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeResource(resources, imageId, options);
        options.inSampleSize = UiUtil.calculateInSampleSize(options, targetWidth, targetHeight);
        options.inJustDecodeBounds = false;
        return BitmapFactory.decodeResource(resources, imageId, options);           
  }
  
  /**
   * Calculates the best BitmapFactory.Options.inSampleSize value for minimising memory
   * usage when loading an image.
   * @param options
   * @param reqWidth the image display width
   * @param reqHeight the image display height
   * @return a sensible BitmapFactory.Options.inSampleSize value.
   */
  public static 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) {
      final int heightRatio = Math.round((float) height
          / (float) reqHeight);
      final int widthRatio = Math.round((float) width / (float) reqWidth);

      inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
    }

    return inSampleSize;
  }
  
  /**
   * Displays a dialog box with the given title, message and an 'OK' button which
   * closes the dialog.
   * @param context
   * @param title
   * @param message
   */
  public static void showMessageDialog(Context context, String title, String message) {
    new AlertDialog.Builder(context)
      .setTitle(title)
      .setMessage(message)
      .setPositiveButton("OK", new DialogInterface.OnClickListener() {
          public void onClick(DialogInterface dialog, int which) { 
              dialog.dismiss();
          }
       })
       .show();    
  }
  
  /**
   * Used for filtering views by the UiUtil.getChildren() method below.
   * @author duncanw
   */
  public interface ViewFilter {
    
    /**
     * @param view the View found in the search.
     * @return true if the given view matches the search criteria, otherwise false.
     */
    boolean matches(View view);
  }
  
  /**
   * Performs a depth-first search for Views contained in the given view, and returns
   * all views that match the given filter. Can be used to perform operations on the child
   * views directly by putting the operation in the ViewFilter's matches() method
   * @param v the root view.
   * @param viewList views that match the filter are added to this list.
   * @param filter specifies the search criteria for the search.
   * @return the given list, populated with matching views.
   */
  public static List<View> getChildren(View v, List<View> viewList, ViewFilter filter) {

      if (v instanceof ViewGroup) {
        ViewGroup viewGroup = (ViewGroup) v;
        for (int i = 0; i < viewGroup.getChildCount(); i++) {
            getChildren(viewGroup.getChildAt(i), viewList, filter);
        }      
      }
      
      if (filter.matches(v)) {
        viewList.add(v);
      }
     return viewList;
  }  
  
  /**
   * Adds the given listeners to all text input fields contained in the given view.
   * @param onFocusChangeListener
   * @param textChangedListener
   * @param rootView
   */
    public static void addEditTextListener(final OnFocusChangeListener onFocusChangeListener, final TextWatcher textChangedListener, View rootView) {

      getChildren(rootView, new ArrayList<View>(), new ViewFilter() {
      
      @Override
      public boolean matches(View view) {
        if (view instanceof EditText) {
          ((EditText)view).setOnFocusChangeListener(onFocusChangeListener);
          if (textChangedListener != null) {
            ((EditText)view).addTextChangedListener(textChangedListener);
          }
        }
        
        return false;
      }
    });
    }
    
    /**
     * Adds the given listener to all checkboxes contained in the given view.
     * @param changeListener
     * @param rootView
     */
    public static void addCheckBoxListener(final CompoundButton.OnCheckedChangeListener changeListener, View rootView) {

      getChildren(rootView, new ArrayList<View>(), new ViewFilter() {
      
      @Override
      public boolean matches(View view) {
        if (view instanceof CheckBox) {
          ((CheckBox)view).setOnCheckedChangeListener(changeListener);
        }
        
        return false;
      }
    });
    }  
    
    /**
     * @param date milliseconds since 1 January 1970 UTC.
     * @return the given date in the tablet's local timezone, in the tablet's default date format.
     */
    public static String getDisplayDate(long date) {
        Time now = new Time(Time.getCurrentTimezone());
         now.set(date);
         return now.format("%c");
    }
    
    /**
     * Sets a spinner (drop-down/select box) selection to the given selection.
     * @param rootView view containing the specified spinner
     * @param spinnerId e.g R.id.district_spinner
     * @param selection value to set as the spinner's current selection.
     */
    public static void setSelectedValue(View rootView, int spinnerId, String selection) {
      if (selection != null) {
        Spinner spinner = (Spinner) rootView.findViewById(spinnerId);   
        SpinnerAdapter adapter = spinner.getAdapter();
          for (int i = 0; i < adapter.getCount(); i++) {
            String option = adapter.getItem(i).toString();
            if (selection.equals(option)) {
              spinner.setSelection(i);
              return;
            }
          }         
      }
    }
    
    /**
     * Reads a user-entered value as a Double.
     * @param rootView view containing the specified input field
     * @param inputId e.g R.id.conductivity_input
     * @return the value entered, or null if the value is empty
     */
    public static Double getNumericInput(View rootView, int inputId) {
      String value = ((EditText) rootView.findViewById(inputId)).getText().toString();
      if (!value.isEmpty()) {
        return Double.parseDouble(value);
      } else {
        return null;
      }
    }
}

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