Don't emit unused Helvetica (#820)

* Don't emit unused Helvetica

* Refactor(Apply the suggestion)

Co-authored-by: terurou <terurou@denkiyagi.jp>

src/api/PDFPage.ts

@@ -980,22 +980,19 @@ export default class PDFPage {
     assertOrUndefined(options.wordBreaks, 'options.wordBreaks', [Array]);
     assertIsOneOfOrUndefined(options.blendMode, 'options.blendMode', BlendMode);
 
-    const [originalFont] = this.getFont();
-    if (options.font) this.setFont(options.font);
-    const [font, fontKey] = this.getFont();
-
+    const { oldFont, newFont, newFontKey } = this.setOrEmbedFont(options.font);
     const fontSize = options.size || this.fontSize;
 
     const wordBreaks = options.wordBreaks || this.doc.defaultWordBreaks;
-    const textWidth = (t: string) => font.widthOfTextAtSize(t, fontSize);
+    const textWidth = (t: string) => newFont.widthOfTextAtSize(t, fontSize);
     const lines =
       options.maxWidth === undefined
         ? lineSplit(cleanText(text))
         : breakTextIntoLines(text, wordBreaks, options.maxWidth, textWidth);
 
     const encodedLines = new Array(lines.length) as PDFHexString[];
     for (let idx = 0, len = lines.length; idx < len; idx++) {
-      encodedLines[idx] = font.encodeText(lines[idx]);
+      encodedLines[idx] = newFont.encodeText(lines[idx]);
     }
 
     const graphicsStateKey = this.maybeEmbedGraphicsState({
@@ -1007,7 +1004,7 @@ export default class PDFPage {
     contentStream.push(
       ...drawLinesOfText(encodedLines, {
         color: options.color ?? this.fontColor,
-        font: fontKey,
+        font: newFontKey,
         size: fontSize,
         rotate: options.rotate ?? degrees(0),
         xSkew: options.xSkew ?? degrees(0),
@@ -1019,7 +1016,10 @@ export default class PDFPage {
       }),
     );
 
-    if (options.font) this.setFont(originalFont);
+    if (options.font) {
+      if (oldFont) this.setFont(oldFont);
+      else this.resetFont();
+    }
   }
 
   /**
@@ -1537,6 +1537,19 @@ export default class PDFPage {
     this.drawEllipse({ ...options, xScale: size, yScale: size });
   }
 
+  private setOrEmbedFont(font?: PDFFont) {
+    const oldFont = this.font;
+    const oldFontKey = this.fontKey;
+
+    if (font) this.setFont(font);
+    else this.getFont();
+
+    const newFont = this.font!;
+    const newFontKey = this.fontKey!;
+
+    return { oldFont, oldFontKey, newFont, newFontKey };
+  }
+
   private getFont(): [PDFFont, string] {
     if (!this.font || !this.fontKey) {
       const font = this.doc.embedStandardFont(StandardFonts.Helvetica);
@@ -1545,6 +1558,11 @@ export default class PDFPage {
     return [this.font!, this.fontKey!];
   }
 
+  private resetFont(): void {
+    this.font = undefined;
+    this.fontKey = undefined;
+  }
+
   private getContentStream(useExisting = true): PDFContentStream {
     if (useExisting && this.contentStream) return this.contentStream;
     this.contentStream = this.createContentStream();