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(Unicode C) PDF Signature with Background Image (Seal/Stamp/etc.)See more PDF Signatures ExamplesDemonstrates how to sign a PDF with an appearance that includes a background image, such as a seal, stamp, etc. Note: This example requires Chilkat v9.5.0.85 or greater.
#include <C_CkPdfW.h> #include <C_CkJsonObjectW.h> #include <C_CkBinDataW.h> #include <C_CkCertW.h> void ChilkatSample(void) { HCkPdfW pdf; BOOL success; HCkJsonObjectW json; HCkBinDataW jpgData; HCkCertW cert; // This example requires the Chilkat API to have been previously unlocked. // See Global Unlock Sample for sample code. pdf = CkPdfW_Create(); // Load a PDF to be signed. // The "hello.pdf" is available at https://chilkatsoft.com/hello.pdf success = CkPdfW_LoadFile(pdf,L"qa_data/pdf/hello.pdf"); if (success == FALSE) { wprintf(L"%s\n",CkPdfW_lastErrorText(pdf)); CkPdfW_Dispose(pdf); return; } // Options for signing are specified in JSON. json = CkJsonObjectW_Create(); // In most cases, the signingCertificateV2 and signingTime attributes are required. CkJsonObjectW_UpdateInt(json,L"signingCertificateV2",1); CkJsonObjectW_UpdateInt(json,L"signingTime",1); // Put the signature on page 1, top left CkJsonObjectW_UpdateInt(json,L"page",1); CkJsonObjectW_UpdateString(json,L"appearance.y",L"top"); CkJsonObjectW_UpdateString(json,L"appearance.x",L"left"); // Use a font scale of 10.0 CkJsonObjectW_UpdateString(json,L"appearance.fontScale",L"10.0"); // In this example, the appearance of the digital signature will contain three lines: // 1) The signing certificate's common name // 2) The current date/time // 3) Some arbitrary text. // The keyword "cert_cn" is replaced with the Certificate's Subject Common Name. // The keyword "current_dt" is replaced with the current date/time. // Any number of appearance text lines can be added. CkJsonObjectW_UpdateString(json,L"appearance.text[0]",L"Digitally signed by: cert_cn"); CkJsonObjectW_UpdateString(json,L"appearance.text[1]",L"current_dt"); CkJsonObjectW_UpdateString(json,L"appearance.text[2]",L"The crazy brown fox jumps over the lazy dog."); // Load a JPG image to be shown with 30% opacity in the background. // (the image must be in the JPG format) // The sample university.jpb is available at https://example-code.com/images/university.jpg jpgData = CkBinDataW_Create(); success = CkBinDataW_LoadFile(jpgData,L"qa_data/jpg/university.jpg"); if (success == FALSE) { wprintf(L"Failed to load the JPG image.\n"); CkPdfW_Dispose(pdf); CkJsonObjectW_Dispose(json); CkBinDataW_Dispose(jpgData); return; } success = CkPdfW_SetSignatureJpeg(pdf,jpgData); if (success == FALSE) { wprintf(L"%s\n",CkPdfW_lastErrorText(pdf)); CkPdfW_Dispose(pdf); CkJsonObjectW_Dispose(json); CkBinDataW_Dispose(jpgData); return; } // Specify that we want to display the JPG image in the center with 30% opacity. CkJsonObjectW_UpdateString(json,L"appearance.image",L"custom-jpg"); CkJsonObjectW_UpdateString(json,L"appearance.imagePlacement",L"center"); CkJsonObjectW_UpdateString(json,L"appearance.imageOpacity",L"30"); // Load the signing certificate. (Use your own certificate.) cert = CkCertW_Create(); success = CkCertW_LoadPfxFile(cert,L"qa_data/pfx/myPdfSigningCert.pfx",L"secret"); if (success == FALSE) { wprintf(L"%s\n",CkCertW_lastErrorText(cert)); CkPdfW_Dispose(pdf); CkJsonObjectW_Dispose(json); CkBinDataW_Dispose(jpgData); CkCertW_Dispose(cert); return; } // Tell the pdf object to use the certificate for signing. success = CkPdfW_SetSigningCert(pdf,cert); if (success == FALSE) { wprintf(L"%s\n",CkPdfW_lastErrorText(pdf)); CkPdfW_Dispose(pdf); CkJsonObjectW_Dispose(json); CkBinDataW_Dispose(jpgData); CkCertW_Dispose(cert); return; } success = CkPdfW_SignPdf(pdf,json,L"qa_output/hello_signed.pdf"); if (success == FALSE) { wprintf(L"%s\n",CkPdfW_lastErrorText(pdf)); CkPdfW_Dispose(pdf); CkJsonObjectW_Dispose(json); CkBinDataW_Dispose(jpgData); CkCertW_Dispose(cert); return; } wprintf(L"The PDF has been successfully cryptographically signed.\n"); // The appearance of the signature appears in Adobe Acrobat as shown below. // The JPG is automatically scaled to the size of the signature based on the signature's font scale // and number of text lines. CkPdfW_Dispose(pdf); CkJsonObjectW_Dispose(json); CkBinDataW_Dispose(jpgData); CkCertW_Dispose(cert); } |
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