How can I create signature widget appearance from PDF content stream?

[Shirley Gong]

Question:

We have a custom appearance in vector form and we want to use it as a custom appearance for a Signature Widget. 

How do we apply the appearance for any given page rotation?

Answer:

Approach 1:

This will generate appearance in vector form:

// Adds a custom appearance to a specified Signature Widget by using RubberStamp to adjust the appearance rotation.

//

// doc - PDFDoc containing the signature widget to add custom appearance

// page - page containing the signature widget

// widget - Signature Widget to add custom appearance

// appData - custom appearance

// bbox - user specified bounding box for the appearance

static void AddAppearanceToWidget(PDFDoc doc, Page page, Widget widget, byte[] appData, Rect bbox)

{

    Obj appObj = doc.CreateIndirectStream(appData);

    appObj.PutRect("BBox", bbox.x1, bbox.y1, bbox.x2, bbox.y2);

    RubberStamp tempAnnot = RubberStamp.Create(doc, new Rect(0,0,bbox.Width(), bbox.Height()));

    tempAnnot.SetAppearance(appObj);

    int rotation = Page.RotationToDegree(page.GetRotation());

    if(rotation != 0)

    {

        tempAnnot.RotateAppearance(rotation);

    }

    widget.SetAppearance(appObj);

    appObj.PutName("Subtype", "Form");

    appObj.PutName("Type", "XObject");

    appObj.putDict("Resources");

}

Approach 2:

This will generate appearance in image form:

// Adds a custom appearance to a specified Signature Widget by using PDFDraw.

// R.raw.appearance is the file containing the PDF content stream

// mAnnot is the signature widget of interest

// mAnnotPageNum is page number where the signature widget is on

void addSignatureStampToWidget() {

        PDFDraw pdfDraw = null;

        InputStream is = null;

        PDFDoc tempDoc = null;

        try {

            String sigTempFilePath = mPdfViewCtrl.getContext().getFilesDir().getAbsolutePath() + "/" + SIGNATURE_TEMP_FILE;

            is = mPdfViewCtrl.getContext().getResources().openRawResource(R.raw.appearance);

            byte[] appearance = IOUtils.toByteArray(is);

            tempDoc = new PDFDoc();

            Obj contents = tempDoc.createIndirectStream(appearance);

            Page appPage = tempDoc.pageCreate();

            appPage.getSDFObj().put("Contents", contents);

            Rect bbox = appPage.getVisibleContentBox();

            appPage.setCropBox(bbox);

            Rect cropBox = appPage.getCropBox();

            int width = (int) cropBox.getWidth();

            int height = (int) cropBox.getHeight();

            pdfDraw = new PDFDraw();

            pdfDraw.setPageTransparent(true);

            pdfDraw.setImageSize(width, height, true);

            pdfDraw.export(appPage, sigTempFilePath, "jpeg");

            // Set the appearance of the signature

            SignatureWidget signatureWidget = new SignatureWidget(mAnnot);

            Image img = Image.create(mPdfViewCtrl.getDoc(), sigTempFilePath);

            signatureWidget.createSignatureAppearance(img);

            File sigTempFile = new File(sigTempFilePath);

            if (sigTempFile.exists()) {

                //noinspection ResultOfMethodCallIgnored

                sigTempFile.delete();

            }

            mPdfViewCtrl.update(mAnnot, mAnnotPageNum);

        } catch (Exception e) {

            e.printStackTrace();

        } finally {

            if (pdfDraw != null) {

                try {

                    pdfDraw.destroy();

                } catch (PDFNetException ignored) {

                }

            }

            Utils.closeQuietly(is);

            Utils.closeQuietly(tempDoc);

        }

}