PDF patterns and shadings in C++

//---------------------------------------------------------------------------------------
// Copyright (c) 2001-2023 by Apryse Software Inc. All Rights Reserved.
// Consult legal.txt regarding legal and license information.
//---------------------------------------------------------------------------------------

#include <PDF/PDFNet.h>
#include <PDF/PDFDoc.h>
#include <PDF/Image.h>
#include <PDF/ElementBuilder.h>
#include <PDF/ElementWriter.h>
#include <PDF/ElementReader.h>

#include <iostream>
#include "../../LicenseKey/CPP/LicenseKey.h"

using namespace std;
using namespace pdftron;
using namespace SDF;
using namespace PDF;

const string input_path =  "../../TestFiles/";

Obj CreateTilingPattern(PDFDoc& doc) 
{
	ElementWriter writer;	
	ElementBuilder eb;

	// Create a new pattern content stream - a heart. ------------
	writer.Begin(doc);
	eb.PathBegin();
	eb.MoveTo(0, 0);
	eb.CurveTo(500, 500, 125, 625, 0, 500);
	eb.CurveTo(-125, 625, -500, 500, 0, 0);
	Element heart = eb.PathEnd();
	heart.SetPathFill(true); 
	
	// Set heart color to red.
	heart.GetGState().SetFillColorSpace(ColorSpace::CreateDeviceRGB()); 
	heart.GetGState().SetFillColor(ColorPt(1, 0, 0)); 
	writer.WriteElement(heart);

	Obj pattern_dict = writer.End();

	// Initialize pattern dictionary. For details on what each parameter represents please 
	// refer to Table 4.22 (Section '4.6.2 Tiling Patterns') in PDF Reference Manual.
	pattern_dict.PutName("Type", "Pattern");
	pattern_dict.PutNumber("PatternType", 1);

	// TilingType - Constant spacing.
	pattern_dict.PutNumber("TilingType",1); 

	// This is a Type1 pattern - A colored tiling pattern.
	pattern_dict.PutNumber("PaintType", 1);

	// Set bounding box
	pattern_dict.PutRect("BBox", -253, 0, 253, 545);

	// Create and set the matrix
	Common::Matrix2D pattern_mtx(0.04,0,0,0.04,0,0);
	pattern_dict.PutMatrix("Matrix", pattern_mtx);

	// Set the desired horizontal and vertical spacing between pattern cells, 
	// measured in the pattern coordinate system.
	pattern_dict.PutNumber("XStep", 1000);
	pattern_dict.PutNumber("YStep", 1000);
	
	return pattern_dict; // finished creating the Pattern resource
}

Obj CreateImageTilingPattern(PDFDoc& doc) 
{
	ElementWriter writer;	
	ElementBuilder eb;

	// Create a new pattern content stream - a single bitmap object ----------
	writer.Begin(doc);
	Image image = Image::Create(doc, (input_path + "dice.jpg").c_str());
	Element img_element = eb.CreateImage(image, 0, 0, image.GetImageWidth(), image.GetImageHeight());
	writer.WritePlacedElement(img_element);
	Obj pattern_dict = writer.End();

	// Initialize pattern dictionary. For details on what each parameter represents please 
	// refer to Table 4.22 (Section '4.6.2 Tiling Patterns') in PDF Reference Manual.
	pattern_dict.PutName("Type", "Pattern");
	pattern_dict.PutNumber("PatternType",1);

	// TilingType - Constant spacing.
	pattern_dict.PutNumber("TilingType", 1); 

	// This is a Type1 pattern - A colored tiling pattern.
	pattern_dict.PutNumber("PaintType", 1);

	// Set bounding box
	pattern_dict.PutRect("BBox", -253, 0, 253, 545);

	// Create and set the matrix
	Common::Matrix2D pattern_mtx(0.3,0,0,0.3,0,0);
	pattern_dict.PutMatrix("Matrix", pattern_mtx);

	// Set the desired horizontal and vertical spacing between pattern cells, 
	// measured in the pattern coordinate system.
	pattern_dict.PutNumber("XStep", 300);
	pattern_dict.PutNumber("YStep", 300);
	
	return pattern_dict; // finished creating the Pattern resource
}

Obj CreateAxialShading(PDFDoc& doc) 
{
	// Create a new Shading object ------------
	Obj pattern_dict = doc.CreateIndirectDict();

	// Initialize pattern dictionary. For details on what each parameter represents 
	// please refer to Tables 4.30 and 4.26 in PDF Reference Manual
	pattern_dict.PutName("Type", "Pattern");
	pattern_dict.PutNumber("PatternType", 2); // 2 stands for shading
	
	Obj shadingDict = pattern_dict.PutDict("Shading");
	shadingDict.PutNumber("ShadingType",2);
	shadingDict.PutName("ColorSpace","DeviceCMYK");
	
	// pass the coordinates of the axial shading to the output
	Obj shadingCoords = shadingDict.PutArray("Coords");
	shadingCoords.PushBackNumber(0);
	shadingCoords.PushBackNumber(0);
	shadingCoords.PushBackNumber(612);
	shadingCoords.PushBackNumber(794);

	// pass the function to the axial shading
	Obj function = shadingDict.PutDict("Function");
	Obj C0 = function.PutArray("C0");
	C0.PushBackNumber(1);
	C0.PushBackNumber(0);
	C0.PushBackNumber(0);
	C0.PushBackNumber(0);

	Obj C1 = function.PutArray("C1");
	C1.PushBackNumber(0);
	C1.PushBackNumber(1);
	C1.PushBackNumber(0);
	C1.PushBackNumber(0);
	
	Obj domain = function.PutArray("Domain");
	domain.PushBackNumber(0);
	domain.PushBackNumber(1);

	function.PutNumber("FunctionType", 2);
	function.PutNumber("N", 1);


	return pattern_dict;
}


int main(int argc, char *argv[])
{
	PDFNet::Initialize(LicenseKey);

	// Relative path to the folder containing test files.
	string output_path = "../../TestFiles/Output/";

	try  
	{	 
		PDFDoc doc;
		ElementWriter writer;	
		ElementBuilder eb;

		// The following sample illustrates how to create and use tiling patterns
		Page page = doc.PageCreate();
		writer.Begin(page);

		Element element = eb.CreateTextBegin(Font::Create(doc, Font::e_times_bold), 1);
		writer.WriteElement(element);  // Begin the text block

		const char* data = "G";
		element = eb.CreateTextRun((UChar*)data, UInt32(strlen(data)));
		element.SetTextMatrix(720, 0, 0, 720, 20, 240);
		GState gs = element.GetGState();
		gs.SetTextRenderMode(GState::e_fill_stroke_text);
		gs.SetLineWidth(4);

		// Set the fill color space to the Pattern color space. 
		gs.SetFillColorSpace(ColorSpace::CreatePattern());
		gs.SetFillColor(CreateTilingPattern(doc));

		writer.WriteElement(element);
		writer.WriteElement(eb.CreateTextEnd()); // Finish the text block

		writer.End();	// Save the page
		doc.PagePushBack(page);
		//-----------------------------------------------

		/// The following sample illustrates how to create and use image tiling pattern
		page = doc.PageCreate();
		writer.Begin(page);

		eb.Reset();
		element = eb.CreateRect(0, 0, 612, 794);

		// Set the fill color space to the Pattern color space. 
		gs = element.GetGState();
		gs.SetFillColorSpace(ColorSpace::CreatePattern());
		gs.SetFillColor(CreateImageTilingPattern(doc));
		element.SetPathFill(true);		

		writer.WriteElement(element);

		writer.End();	// Save the page
		doc.PagePushBack(page);
		//-----------------------------------------------

		/// The following sample illustrates how to create and use PDF shadings
		page = doc.PageCreate();
		writer.Begin(page);

		eb.Reset();
		element = eb.CreateRect(0, 0, 612, 794);

		// Set the fill color space to the Pattern color space. 
		gs = element.GetGState();
		gs.SetFillColorSpace(ColorSpace::CreatePattern());
		gs.SetFillColor(CreateAxialShading(doc));
		element.SetPathFill(true);		

		writer.WriteElement(element);

		writer.End();	// save the page
		doc.PagePushBack(page);
		//-----------------------------------------------

		doc.Save((output_path + "patterns.pdf").c_str(), SDFDoc::e_remove_unused, 0);
		cout << "Done. Result saved in patterns.pdf..." << endl;
	}
	catch(Common::Exception& e)
	{
		cout << e << endl;
	}
	catch(...)
	{
		cout << "Unknown Exception" << endl;
	}

	PDFNet::Terminate();
}