Master

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s Thesis 2006 

FACHHOCHSCHULE

HOCHSCHULE F

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STUTTGART

TECHNIK

The implementation 

        STUTTGART UNIVERSITY OF APPLIED 

SCIENCES 

3.7  Raster image viewer development 

As  described  before,  PNG  is  the  mostly  image  format  used  in  mobile  device 

application. In J2ME, the 

Graphics

 class provides a method for drawing images, static 

image  and  non static  image.  Static  image  can  not  be  modified  after  been  created; 

non static image is drawn by the J2ME drawing function. Because the limited process 

speed and memory, the PNG map should be created in form of static image. The static 

image can be created based on the binary PNG format. 

Image img=Image.createImage(byte[], int offset, int length); 

Listing 23:

 Create static image though binary PNG format. 

At first the PNG image data is read though the data stream from WMS, and then puts 

the data into one byte buffer. At last the Viewer reads those data from the byte buffer 

and paints the image on the screen according to the data.   

   55,66, 47, 103, 85,105,106, 30,

13,17, 68, 11,88,43,45,13,69,21, 11

, 106,62,4,6, 25,112,62, 4, 28,115,1

21, 67, 128,127, 50,107, 109,78,8,7

, 88,14,108, 74,27, 26,41, 14, 32, 8

3,123, 4, 38, 41,30,112, 21,43,45,1

3,69,21, 82, 63,45,42,73,103, 126, 

19, 102,7        

Fig. 25: 

Read image data as byte array 

Similar to SVGT Viewer, the PNG Viewer was developed with such  functions, Pan, 

Zoom, Orig View, and Help. See Figure 26. 

49