ByteScout PDF Suite – Javascript – Use alpha channel with graphics for pdf with pdf generator sdk for javascript

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ByteScout PDF Suite – Javascript – Use alpha channel with graphics for pdf with pdf generator sdk for javascript

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ByteScout-PDF-Suite-Javascript-Use-alpha-channel-with-graphics-for-pdf-with-pdf-generator-sdk-for-javascript.pdf

How to use alpha channel with graphics for pdf with pdf generator sdk for javascript in Javascript using ByteScout PDF Suite

Continuous learning is a crucial part of computer science and this tutorial shows how to use alpha channel with graphics for pdf with pdf generator sdk for javascript in Javascript

An easy to understand guide on how to use alpha channel with graphics for pdf with pdf generator sdk for javascript in Javascript with this source code sample. ByteScout PDF Suite is the bundle that provides six different SDK libraries to work with PDF from generating rich PDF reports to extracting data from PDF documents and converting them to HTML. This bundle includes PDF (Generator) SDK, PDF Renderer SDK, PDF Extractor SDK, PDF to HTML SDK, PDF Viewer SDK and PDF Generator SDK for Javascript. It can be applied to use alpha channel with graphics for pdf with pdf generator sdk for javascript using Javascript.

The SDK samples given below describe how to quickly make your application do use alpha channel with graphics for pdf with pdf generator sdk for javascript in Javascript with the help of ByteScout PDF Suite. Just copy and paste the code into your Javascript application’s code and follow the instructions. Further improvement of the code will make it more robust.

All these programming tutorials along with source code samples and ByteScout free trial version are available for download from our website.

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checkdatauri.js

      	// checks if we have datauri support in current browser
        // if we have support for datauri support then we can stream generated PDF right into the browser
        // otherwise we should use Downloadify script to allow user to save PDF file
	function CheckDataURISupport(){

	var result = true;
	var checkDataURISupportImage = new Image();

	checkDataURISupportImage.onload = checkDataURISupportImage.onerror = function(){
		if(this.width != 1 || this.height != 1){
			result = false;
		}
	}
	checkDataURISupportImage.src = "data:image/gif;base64,R0lGODlhAQABAAD/ACwAAAAAAQABAAACADs=";
	// check if we have datauri support in current browser - end

		return result;
	}

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createpdf.js

      // function that creates BytescoutPDF instance (defined in BytescoutPDF.js script which have to be included into the same page)
// then calls API methods and properties to create PDF document
// and returns created BytescoutPDF object instance
// this CreatePDF() function is called from Sample.html
// IsInternetExplorer8OrLower parameter indicates if we use IE8 or lower so we CAN'T use images (as it requires HTML5 Canvas available in IE9 or higher). Other browsers should be working fine

// IMPORTANT ABOUT IMAGES: 
// When using Firefox or IE, pdf generation may fail because images are not accessible when pdf generation works
// the solution for this issue is to preload images in main HTML document before running PDF generation
// to preload images, put them into hidden div block "pdfreportimages" - you can see it in the sample.html right after <body> opening tag


function CreatePDF(IsInternetExplorer8OrLower) {

    // create BytescoutPDF object instance
    var pdf = new BytescoutPDF();
    // set document properties: Title, subject, keywords, author name and creator name
    pdf.propertiesSet("Sample document title", "Sample subject", "keyword1, keyword 2, keyword3", "Document Author Name", "Document Creator Name");
    
    pdf.pageAdd();

	// draw transparent star
    
    pdf.graphicsSetColor("ffff00");
	pdf.graphicsSetAlpha(125);
	
	var rad=200;
	var cx=300; var cy=300;
	
	pdf.graphicsSetLineWidth(10);
	
	for (var an = 0.0; an < Math.PI; an += Math.PI / 20) 
	{
		var x = rad * Math.sin(an);
		var y = rad * Math.cos(an);
		pdf.graphicsDrawLine(cx + x, cy + y, cx - x, cy - y);
	}
	
    // return BytescoutPDF object instance
    return pdf;
}