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      1 /**
      2  * Copyright (C) 2013 Google Inc.
      3  * Licensed to The Android Open Source Project.
      4  *
      5  * Licensed under the Apache License, Version 2.0 (the "License");
      6  * you may not use this file except in compliance with the License.
      7  * You may obtain a copy of the License at
      8  *
      9  *      http://www.apache.org/licenses/LICENSE-2.0
     10  *
     11  * Unless required by applicable law or agreed to in writing, software
     12  * distributed under the License is distributed on an "AS IS" BASIS,
     13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     14  * See the License for the specific language governing permissions and
     15  * limitations under the License.
     16  */
     17 
     18 package com.android.mail.ui;
     19 
     20 import android.content.Context;
     21 import android.content.res.Resources;
     22 
     23 import java.io.IOException;
     24 import java.io.InputStreamReader;
     25 import java.util.Formatter;
     26 
     27 /**
     28  * Abstract class to support common functionality for both
     29  * {@link com.android.mail.ui.HtmlConversationTemplates} and
     30  * {@link com.android.mail.print.HtmlPrintTemplates}.
     31  *
     32  * Renders data into very simple string-substitution HTML templates.
     33  *
     34  * Templates should be UTF-8 encoded HTML with '%s' placeholders to be substituted upon render.
     35  * Plain-jane string substitution with '%s' is slightly faster than typed substitution.
     36  */
     37 public abstract class AbstractHtmlTemplates {
     38     // TODO: refine. too expensive to iterate over cursor and pre-calculate total. so either
     39     // estimate it, or defer assembly until the end when size is known (deferring increases
     40     // working set size vs. estimation but is exact).
     41     private static final int BUFFER_SIZE_CHARS = 64 * 1024;
     42 
     43     protected Context mContext;
     44     protected Formatter mFormatter;
     45     protected StringBuilder mBuilder;
     46     protected boolean mInProgress = false;
     47 
     48     public AbstractHtmlTemplates(Context context) {
     49         mContext = context;
     50     }
     51 
     52     public String emit() {
     53         final String out = mFormatter.toString();
     54         // release the builder memory ASAP
     55         mFormatter = null;
     56         mBuilder = null;
     57         return out;
     58     }
     59 
     60     public void reset() {
     61         mBuilder = new StringBuilder(BUFFER_SIZE_CHARS);
     62         mFormatter = new Formatter(mBuilder, null /* no localization */);
     63     }
     64 
     65     protected String readTemplate(int id) throws Resources.NotFoundException {
     66         final StringBuilder out = new StringBuilder();
     67         InputStreamReader in = null;
     68         try {
     69             try {
     70                 in = new InputStreamReader(
     71                         mContext.getResources().openRawResource(id), "UTF-8");
     72                 final char[] buf = new char[4096];
     73                 int chars;
     74 
     75                 while ((chars=in.read(buf)) > 0) {
     76                     out.append(buf, 0, chars);
     77                 }
     78 
     79                 return out.toString();
     80 
     81             } finally {
     82                 if (in != null) {
     83                     in.close();
     84                 }
     85             }
     86         } catch (IOException e) {
     87             throw new Resources.NotFoundException("Unable to open template id="
     88                     + Integer.toHexString(id) + " exception=" + e.getMessage());
     89         }
     90     }
     91 
     92     protected void append(String template, Object... args) {
     93         mFormatter.format(template, args);
     94     }
     95 }
     96