PDF font render improvements (qzind#1108)

* PDF font rendering improvements
* Improvements to "ignoreTransparency" logic

Co-authored-by: Berenz <thebrettberenz@gmail.com>

js/qz-tray.js

@@ -1529,6 +1529,8 @@ var qz = (function() {
          *   @param {string} [data.options.pageRanges] Optional with <code>[pdf]</code> formats. Comma-separated list of page ranges to include.
          *   @param {boolean} [data.options.ignoreTransparency=false] Optional with <code>[pdf]</code> formats. Instructs transparent PDF elements to be ignored.
          *       Transparent PDF elements are known to degrade performance and quality when printing.
+         *   @param {boolean} [data.options.altFontRendering=false] Optional with <code>[pdf]</code> formats. Instructs PDF to be rendered using PDFBOX 1.8 techniques.
+         *       Drastically improves low-DPI PDF print quality on Windows.
          * @param {...*} [arguments] Additionally three more parameters can be specified:<p/>
          *     <code>{boolean} [resumeOnError=false]</code> Whether the chain should continue printing if it hits an error on one the the prints.<p/>
          *     <code>{string|Array<string>} [signature]</code> Pre-signed signature(s) of the JSON string for containing <code>call</code>, <code>params</code>, and <code>timestamp</code>.<p/>

sample.html

@@ -613,9 +613,13 @@ <h3>Pixel Printing</h3>
                                                 <input type="number" id="pPxlHeight" class="form-control pull-right" />
                                             </div>
                                             <div class="form-group form-inline">
-                                                <label for="pPxlTransparent">Ignore Transparency:</label>
+                                                <label for="pPxlTransparent">Ignore Transparency (PDF only):</label>
                                                 <input type="checkbox" id="pPxlTransparent" class="pull-right" />
                                             </div>
+                                            <div class="form-group form-inline">
+                                                <label for="pPxlAltFontRendering">Alternate Font Rendering  (PDF only):</label>
+                                                <input type="checkbox" id="pPxlAltFontRendering" class="pull-right" />
+                                            </div>
                                         </div>
                                     </div>
                                 </fieldset>
@@ -3231,7 +3235,8 @@ <h4 class="panel-title">Options</h4>
                 pageWidth: $("#pPxlWidth").val(),
                 pageHeight: $("#pPxlHeight").val(),
                 pageRanges: $("#pPxlRange").val(),
-                ignoreTransparency: $("#pPxlTransparent").prop('checked')
+                ignoreTransparency: $("#pPxlTransparent").prop('checked'),
+                altFontRendering: $("#pPxlAltFontRendering").prop('checked')
             };
         } else {
             return {

src/qz/printer/action/PrintPDF.java

@@ -36,7 +36,6 @@
 import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.List;
-import java.util.Locale;
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
 
@@ -51,6 +50,7 @@ public class PrintPDF extends PrintPixel implements PrintProcessor {
     private double docWidth = 0;
     private double docHeight = 0;
     private boolean ignoreTransparency = false;
+    private boolean altFontRendering = false;
 
 
     public PrintPDF() {
@@ -83,6 +83,7 @@ public void parseData(JSONArray printData, PrintOptions options) throws JSONExce
                 }
 
                 ignoreTransparency = dataOpt.optBoolean("ignoreTransparency", false);
+                altFontRendering = dataOpt.optBoolean("altFontRendering", false);
 
                 if (!dataOpt.isNull("pageRanges")) {
                     String[] ranges = dataOpt.optString("pageRanges", "").split(",");
@@ -252,7 +253,7 @@ public void print(PrintOutput output, PrintOptions options) throws PrinterExcept
                 }
             }
 
-            PDFWrapper wrapper = new PDFWrapper(doc, scale, false, ignoreTransparency,
+            PDFWrapper wrapper = new PDFWrapper(doc, scale, false, ignoreTransparency, altFontRendering,
                                                 (float)(useDensity * pxlOpts.getUnits().as1Inch()),
                                                 false, pxlOpts.getOrientation(), hints);
 
@@ -320,5 +321,6 @@ public void cleanup() {
         docWidth = 0;
         docHeight = 0;
         ignoreTransparency = false;
+        altFontRendering = false;
     }
 }

src/qz/printer/action/pdf/PDFWrapper.java

@@ -26,20 +26,14 @@ public class PDFWrapper implements Printable {
 
     private PDFPrintable printable;
 
-    public PDFWrapper(PDDocument document, Scaling scaling, boolean showPageBorder, boolean ignoreTransparency, float dpi, boolean center, PrintOptions.Orientation orientation, RenderingHints hints) {
+    public PDFWrapper(PDDocument document, Scaling scaling, boolean showPageBorder, boolean ignoreTransparency, boolean useAlternateFontRendering, float dpi, boolean center, PrintOptions.Orientation orientation, RenderingHints hints) {
         this.document = document;
         this.scaling = scaling;
         if (orientation != null) {
             this.orientation = orientation.getAsOrientRequested();
         }
 
-        PDFRenderer renderer;
-        if (ignoreTransparency) {
-            renderer = new OpaquePDFRenderer(document);
-        } else {
-            renderer = new PDFRenderer(document);
-        }
-
+        PDFRenderer renderer = new ParamPdfRenderer(document, useAlternateFontRendering, ignoreTransparency);
         printable = new PDFPrintable(document, scaling, showPageBorder, dpi, center, renderer);
         printable.setRenderingHints(hints);
     }

src/qz/printer/action/pdf/ParamPdfRenderer.java

@@ -0,0 +1,47 @@
+package qz.printer.action.pdf;
+
+import org.apache.pdfbox.pdmodel.PDDocument;
+import org.apache.pdfbox.rendering.PDFRenderer;
+import org.apache.pdfbox.rendering.PageDrawer;
+import org.apache.pdfbox.rendering.PageDrawerParameters;
+import qz.printer.rendering.OpaqueDrawObject;
+import qz.printer.rendering.OpaqueGraphicStateParameters;
+import qz.printer.rendering.PdfFontPageDrawer;
+
+import java.io.IOException;
+
+public class ParamPdfRenderer extends PDFRenderer {
+
+    private boolean useAlternateFontRendering;
+    private boolean ignoreTransparency;
+
+    public ParamPdfRenderer(PDDocument document, boolean useAlternateFontRendering, boolean ignoreTransparency) {
+        super(document);
+
+        this.useAlternateFontRendering = useAlternateFontRendering;
+        this.ignoreTransparency = ignoreTransparency;
+    }
+
+    @Override
+    protected PageDrawer createPageDrawer(PageDrawerParameters parameters) throws IOException {
+        if (useAlternateFontRendering) {
+            return new PdfFontPageDrawer(parameters, ignoreTransparency);
+        } else if(ignoreTransparency) {
+            return new OpaquePageDrawer(parameters);
+        }
+        // Fallback to default PageDrawer
+        return new PageDrawer(parameters);
+    }
+
+    // override drawer to make use of customized draw object
+    private static class OpaquePageDrawer extends PageDrawer {
+        public OpaquePageDrawer(PageDrawerParameters parameters) throws IOException {
+            super(parameters);
+
+            // Note:  These must match PdfFontPageDrawer's ignoreTransparency condition
+            addOperator(new OpaqueDrawObject());
+            addOperator(new OpaqueGraphicStateParameters());
+        }
+    }
+}
+