= PDF.js

:Notice: Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at. http://www.apache.org/licenses/LICENSE-2.0 . Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR  CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

The PDF.js module integrates with the xref:vw:ROOT:about.adoc[Wicket Viewer], rendering a `Blob` property containing a PDF using the link:https://mozilla.github.io/pdf.js/[PDF.js] library.


== Setup

=== Dependency Management

In your application's top level `pom.xml`, add a dependency for this module's own bill of materials (BOM):

[source,xml,subs="attributes+"]
.pom.xml
----
<dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.apache.causeway.extensions</groupId>
            <artifactId>causeway-extensions-pdfjs</artifactId>
            <scope>import</scope>
            <type>pom</type>
            <version>{page-causewayreleaseversion}</version>
        </dependency>
    </dependencies>
</dependencyManagement>
----

=== Dependencies / Imports

In those modules where there are domain objects with xref:refguide:applib:index/value/Blob.adoc[Blob] properties containing PDF data, add a dependency/import to the applib module:

* add this dependency:
+
[source,xml,subs="attributes+"]
.pom.xml
----
<dependencies>
    <dependency>
        <groupId>org.apache.causeway.extensions</groupId>
        <artifactId>causeway-extensions-pdfjs-applib</artifactId>
    </dependency>
</dependencies>
----

* and `@Import` this module:
+
[source,java]
.MyModule.java
----
@Configuration
@Import({
    CausewayModuleExtPdfjsApplib.class,
    // ...
})
public class MyModule { ... }
----

In addition, in the webapp module of your application, add the following dependency:

[source,xml]
.pom.xml
----
<dependency>
    <groupId>org.apache.causeway.extensions</groupId>
    <artifactId>causeway-extensions-pdfjs-wicket-ui</artifactId>
</dependency>
----

And in your application's xref:userguide::modules.adoc#appmanifest[App Manifest], import the extension's implementation module:

[source,java]
.AppManifest.java
----
@Configuration
@Import({
        CausewayModuleExtPdfjsWicketUi.class,
        ...
})
public class AppManifest {
}
----


== Usage

To use the extension, annotate an xref:refguide:applib:index/value/Blob.adoc[Blob] property with the xref:refguide:extensions:index/pdfjs/applib/annotations/PdfJsViewer.adoc[@PdfJsViewer] annotation.

For example:

[source,java]
----
@PdfJsViewer            // <.>
@Property()
@PropertyLayout(fieldSetId = "content", sequence = "1")
public Blob getAttachment() { ... }
----

<.> indicates that the `Blob` returns a set of bytes that correspond to a PDF, and so should be rendered as such.
+
NOTE: The `Blob` is expected also to have a mime type of `application/pdf`.

Optionally, you can also provide an implementation of the xref:refguide:extensions:index/pdfjs/applib/spi/PdfJsViewerAdvisor.adoc[] SPI, which advises on the size of the viewer (and has callbacks to keep track of which page of the PDF is being viewed).
The framework provides a fallback implementation that sets the height to 800px, and scaled to 75% normal size.


