ar.com.hjg.pngj
Class FileHelper

java.lang.Object
  extended by ar.com.hjg.pngj.FileHelper

public class FileHelper
extends java.lang.Object

A few static utility methods related with PngReader/PngWriter that read/writes to files.

This is not essential to the PNGJ library, and the writer will not work in sandboxed environments (eg. Google App Engine)


Constructor Summary
FileHelper()
           
 
Method Summary
static PngReader createPngReader(java.io.File file)
           
static PngWriter createPngWriter(java.io.File file, ImageInfo imgInfo, boolean allowOverwrite)
          WARNING: This will throw exception if run in a sandboxed environment (as Google App Engine) that does not permit to use Java class java.io.FileOutputStream.
static java.io.InputStream openFileForReading(java.io.File file)
           
static java.io.OutputStream openFileForWriting(java.io.File file, boolean allowOverwrite)
          WARNING: This method will throw exception if run in a sandboxed environment (as Google App Engine) that does not permit to use Java class java.io.FileOutputStream We use reflection to be sure that this just throw run time exception in that case, but that the class is loadable
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

FileHelper

public FileHelper()
Method Detail

createPngReader

public static PngReader createPngReader(java.io.File file)

createPngWriter

public static PngWriter createPngWriter(java.io.File file,
                                        ImageInfo imgInfo,
                                        boolean allowOverwrite)
WARNING: This will throw exception if run in a sandboxed environment (as Google App Engine) that does not permit to use Java class java.io.FileOutputStream. You can always use the PngWriter constructor with an arbitrary OutputStream

Parameters:
file - File to be writen
imgInfo - Target image basic info
allowOverwrite - if true, file will be overwriten if it already exists.
Returns:
a new PngWriter - see constructor doc

openFileForReading

public static java.io.InputStream openFileForReading(java.io.File file)

openFileForWriting

public static java.io.OutputStream openFileForWriting(java.io.File file,
                                                      boolean allowOverwrite)
WARNING: This method will throw exception if run in a sandboxed environment (as Google App Engine) that does not permit to use Java class java.io.FileOutputStream We use reflection to be sure that this just throw run time exception in that case, but that the class is loadable

Parameters:
file -
allowOverwrite -
Returns:
outputStream (should be of type FileOutputStream)