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Diffstat (limited to 'demos/java/gsjava/README.txt')
| -rw-r--r-- | demos/java/gsjava/README.txt | 72 |
1 files changed, 69 insertions, 3 deletions
diff --git a/demos/java/gsjava/README.txt b/demos/java/gsjava/README.txt index 70265efc4..5eb068cb9 100644 --- a/demos/java/gsjava/README.txt +++ b/demos/java/gsjava/README.txt @@ -1,6 +1,72 @@ -required libraries for this library: +Required libraries for this library: gpdldll64.dll gs_jni.dll -this project should be compiled as a JAR file and is -not runnable
\ No newline at end of file +Java Library: + +This library contains direct bindings to Ghostscript as +well as several utility methods to make using the +Ghostscript calls easier. + +The direct Ghostscript calls are found in +com.artifex.gsjava.GSAPI and are named in the same way +in which they are documented on https://www.ghostscript.com/doc/current/API.htm + +The com.artifex.gsjava.callbacks package contains +interfaces which store interfaces and abstract classes +used to implement Ghostscript callbacks in Java. These +can be passed to Ghostscript through the GSAPI class. + +The com.artifex.gsjava.util package contains several +classes to assist in passing parameters and handling +native values. The Reference<T> and ByteArrayReference are +the only classes which need to be used, however the others +are avaliable if needed. The Reference class acts as +a pointer parameter in a C function. An example use of this +is in gsapi_new_instance which takes a Reference<Long> as +a parameter. Calling the method would place the new +Ghoscript instance in the Reference<Long>'s value field. + +The com.artifex.gsjava.GSInstance is a +utility class. The GSInstance class stores an instance +of Ghostscript and a client handle. The methods in this +class are named the same in which they are documented without +the need to pass the "instance" parameter through. + +The com.artifex.gsjava.devices package contains several +classes representing Ghoscript devices. Using the classes +in this package is the greatest amount of separation from +using the raw Ghoscript calls and it requires no direct +calls through the GSAPI class. All device classes in this +package are extensions of Device which provides a way +of setting up a Ghoscript device and setting parameters. +Subclasses have utility methods to set individual parameters +through method calls instead of using a String and parameter +type to specify the parameter name and type, respectively. + +Example code segment to set up an instance of Ghoscript: + +import com.artifex.gsjava.*; +import com.artifex.gsjava.util.*; + +public static void main(String[] args) { + // Stores a reference to the Ghoscript instance + Reference<Long> instanceReference = new Reference<>(); + + // Creates a new Ghoscript instance with a NULL caller handle, + // placing the instance into instanceReference + int code = GSAPI.gsapi_new_instance(instanceReference, GSAPI.GS_NULL); + + if (code != GSAPI.GS_ERROR_OK) { + // An error has occured. + return; + } + + // Returns the value the instanceReference references. + // This value is equivalent to a void * and has the same + // size in bytes. + long instance = instanceReference.getValue(); + + // Deletes the Ghoscript instance + GSAPI.gsapi_delete_instance(instance); +} |