User:Incnis Mrsi/PDF-PNG.js

// Fixes for some deficiencies of [[mw:Extension:PdfHandler]]

var jpgE = /jpg$/;
var JP_E_G = /JPE?G/;

function PdfToPNG() {
	var images = document.getElementsByTagName( "img" );
	var replaced = 0; // counter
    for (var i = 0, n = images.length; i < n; i++) {
    	var src = images[i].getAttribute('src');
    	if ( src.match(/\/page.*\.jpg$/) // MediaWiki PDF → JPEG conversion
    	) { 
    		images[i].setAttribute('src', src.replace(jpgE, 'png') );
    		replaced++;
    	}
    }
    if (replaced) {
    	// The following code is relevent to File: pages only
		var resolutioninfo = document.getElementsByClassName( "mw-filepage-resolutioninfo" );
		if (
		     resolutioninfo.length
	//	  && resolutioninfo[0].innerHTML.match(JP_E_G) -- made redundant by later checks
		) {
			var childr = resolutioninfo[0].children;
			if ( (childr.length > 1) && (childr[1].tagName == 'SPAN') ) {
				// We have (in resolutioninfo[0]) the mw-filepage-resolutioninfo thing arranged as we expected:
    			var JPGtext = resolutioninfo[0].firstChild;
    			if ( JPGtext.textContent.match(JP_E_G) ) {
	    			var newRes = childr[1].cloneNode(true); // the future list of PNG thumb links in other resolutions
					// add the *current* resolution to the list of .jpg links
    				childr[1].insertBefore(childr[0].cloneNode(true), childr[1].lastNode);
    				// now change .jpg to .png in the first (the current image) link...
    				if (childr[0].tagName == 'A') {
	        			childr[0].setAttribute('href',
	        				childr[0].getAttribute('href').replace(jpgE, 'png')
    	    			);
    				};
    				// ... and edit the respective text
    				var tn = document.createTextNode( JPGtext.textContent.replace(JP_E_G, 'PNG') );
    				resolutioninfo[0].insertBefore(tn, JPGtext);
	    			JPGtext.remove();
	    			// The old other-resolutions now points to JPEGs, whereas on the page we already have PNG
    				var otherres = childr[1].firstChild;
    				tn = document.createTextNode(' JPEG: ');
    				childr[1].insertBefore(tn, otherres);
    				otherres.remove();
    				// And now make replacements in newRes
	    			var ress = newRes.children;
	    			for (var j = 0, n = ress.length; j < n; j++) {
    		    		if (ress[j].tagName == 'A') {
        					ress[j].setAttribute('href',
        	    				ress[j].getAttribute('href').replace(jpgE, 'png')
		        			);
        				}
	    			};
	    			resolutioninfo[0].insertBefore(newRes, childr[1]);
    			} // match(JP_E_G)
			} // childr[1].tagName == 'SPAN'
			else {
    			// childr.length may be 0 on cross-wiki (not local) File:⋯.pdf pages
    			if (childr.length) {
    				alert('Error at PDF-PNG.js: the mw-filepage-resolutioninfo thing is present and has ' +
		        		childr.length + ' child elements, but can’t locate “other resolutions” links among them.');
    			}
			}
		} // resolutioninfo.length
    } // replaced
}; // function PdfToPNG()

// At the end, add hooks:
$( document ).load( PdfToPNG );
mw.hook( 'wikipage.content' ).add( PdfToPNG );