Integrating Visualforce and Google Charts

1swfobject.registerObject("clippy.codeblock-0", "9");
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16
17/* This class contains the encoding algorithm for use with the 
18   Google chartAPI. */
19   
20public class GoogleDataEncoding { 
21    // Exceptions to handle any erroneous data
22    public class EncodingException extends Exception {}
23    public class UnsupportedEncodingTypeException 
24           extends Exception {}  
25
26    /* The encoding map which takes an integer key and returns the 
27       respective encoding value as defined by Google. 
28       This map is initialized in init() */
29      private Map<Integer, String> encodingMap { get; set; }
30    
31   /* The maximum encoding value supported for the given encoding 
32      type. This value is set during init() */
33    private Integer encodingMax { get; set; }
34    
35    /* The minimum encoding value supported for the given encoding 
36       type. This value is set during init() */
37    private Integer encodingMin { get; set; }
38    
39    /* The encoding type according to Google's API. Only SIMPLE 
40       is implemented. */
41    public enum EncodingType { TEXT, SIMPLE, EXTENDED }
42    
43    /* The minimum value to use in the generation of an encoding 
44       value. */
45    public Integer min { get; private set; }
46    
47    /* The maximum value to use in the generation of an encoding 
48       value. */
49    public Integer max { get; private set; }
50    
51    // The encoding type according to the API defined by Google
52    public EncodingType eType { get; private set; }       
53    
54    // Corresponds to the data set provided by the page 
55    public String dataSet { get; set; }
56    
57    // Corresponds to the type of graph selected on the page 
58    public String graph { get; set; }
59    
60    // The URL that renders the Google Chart
61    public String chartURL { get; set; }  
62
63    // Indicates whether the chart should be displayed 
64    public Boolean displayChart { get; set; }
65    
66    public GoogleDataEncoding() {
67        min = 0;
68        max = 61;
69        eType = EncodingType.SIMPLE;
70        displayChart = false;
71        init();
72    } 
73    
74    public PageReference create() {
75        String[] dataSetList = dataSet.split(',', 0);
76        String mappedValue = 'chd=s:';
77        
78        chartURL = 'http://chart.apis.google.com/chart?chs=600x300'
79         + '&amp;chtt=Time+vs|Distance&amp;chxt=x,y,x,y' 
80         + '&amp;chxr=0,0,10,1|1,0,65,5'
81         + '&amp;chxl=2:|Seconds|3:|Meters';
82        
83        if (graph.compareTo('barChart') == 0)
84        {
85            chartURL += '&amp;cht=bvs';
86        }
87        else if (graph.compareTo('lineChart') == 0)
88        {
89            chartURL += '&amp;cht=ls';
90        }
91        else
92        {
93            throw new EncodingException('An unsupported chart type' 
94                + 'was selected: ' + graph + ' does not exist.');
95        }
96        
97        for(String dataPoint : dataSetList)
98        {
99            mappedValue += 
100               getEncode(Integer.valueOf(dataPoint.trim()));
101        }
102        
103        chartURL += '&amp;' + mappedValue;
104        displayChart = true;
105        return null;
106    }
107
108    
109    /* This method returns the encoding type parameter value that 
110       matches the specified encoding type. */
111   public static String getEncodingDescriptor(EncodingType t) {
112        if(t == EncodingType.TEXT) return 't';
113        else if(t == EncodingType.SIMPLE) return 's';
114        else if(t == EncodingType.EXTENDED) return 'e';
115        else return '';
116    }  
117    
118    /* This method takes a given number within the declared 
119       range of the encoding class and encodes it according to the 
120       encoding type. If the value provided fall outside of the 
121       declared range, an EncodingException is thrown. */
122    public String getEncode(Integer d) {    
123        if(d > max || d < min) {
124            throw new EncodingException('Value provided ' + d 
125                + ' was outside the declared min/max range (' 
126                + min + '/' + max + ')');         
127        } 
128        else {
129            return encodingMap.get(d);
130        }
131    }  
132    
133    /* This method initializes the encoding map which is then 
134       stored for expected repetitious use to minimize statement 
135       invocation. */
136    private void init() {
137        if(eType == EncodingType.SIMPLE) {
138            encodingMax = 61;
139            encodingMin = 0;
140            encodingMap = new Map<Integer, String>();
141            encodingMap.put(0,'A');
142            encodingMap.put(1,'B');
143            encodingMap.put(2,'C');
144            encodingMap.put(3,'D');
145            encodingMap.put(4,'E');
146            encodingMap.put(5,'F');
147            encodingMap.put(6,'G');
148            encodingMap.put(7,'H');
149            encodingMap.put(8,'I');
150            encodingMap.put(9,'J');
151            encodingMap.put(10,'K');
152            encodingMap.put(11,'L');
153            encodingMap.put(12,'M');
154            encodingMap.put(13,'N');
155            encodingMap.put(14,'O');
156            encodingMap.put(15,'P');
157            encodingMap.put(16,'Q');
158            encodingMap.put(17,'R');
159            encodingMap.put(18,'S');
160            encodingMap.put(19,'T');
161            encodingMap.put(20,'U');
162            encodingMap.put(21,'V');
163            encodingMap.put(22,'W');
164            encodingMap.put(23,'X');
165            encodingMap.put(24,'Y');
166            encodingMap.put(25,'Z');
167            encodingMap.put(26,'a');
168            encodingMap.put(27,'b');
169            encodingMap.put(28,'c');
170            encodingMap.put(29,'d');
171            encodingMap.put(30,'e');
172            encodingMap.put(31,'f');
173            encodingMap.put(32,'g');
174            encodingMap.put(33,'h');
175            encodingMap.put(34,'i');
176            encodingMap.put(35,'j');
177            encodingMap.put(36,'k');
178            encodingMap.put(37,'l');
179            encodingMap.put(38,'m');
180            encodingMap.put(39,'n');
181            encodingMap.put(40,'o');
182            encodingMap.put(41,'p');
183            encodingMap.put(42,'q');
184            encodingMap.put(43,'r');
185            encodingMap.put(44,'s');
186            encodingMap.put(45,'t');
187            encodingMap.put(46,'u');
188            encodingMap.put(47,'v');
189            encodingMap.put(48,'w');
190            encodingMap.put(49,'x');
191            encodingMap.put(50,'y');
192            encodingMap.put(51,'z');
193            encodingMap.put(52,'0');
194            encodingMap.put(53,'1');
195            encodingMap.put(54,'2');
196            encodingMap.put(55,'3');
197            encodingMap.put(56,'4');
198            encodingMap.put(57,'5');
199            encodingMap.put(58,'6');
200            encodingMap.put(59,'7');
201            encodingMap.put(60,'8');
202            encodingMap.put(61,'9');
203        }
204    } 
205}