fix(docx): give a centred or right-aligned line that fills its box Word's room

CHANGELOG.md

@@ -8,6 +8,16 @@ follow semantic versioning; release dates are ISO 8601.
 
 ### Public API
 
+- **A centred or right-aligned line that fills its box keeps to one line in Word.** Word sets
+  a size in half points, so a 6.8pt line is set at 7pt, 2.9% wider, and no longer fits a box it
+  fills. A flush-left paragraph was already given that much more measure; a centred or
+  right-aligned one of one line now is too, at both edges or at its left, so the line stays
+  where the page sets it. In a table cell the left edge gives no more than its indent, since
+  Word draws no text past a cell's left edge, and a line short of that moves by the rest.
+  `VioletGrid`'s "INFORMATION ARCHITECTURE" broke onto two lines in its skill tile, and the
+  tile's text stood 7.5pt low under it. Lines more than 2pt off in Word fall from 2 to none
+  across the corpus. In LibreOffice, which still sets `VioletGrid` on two pages, its median
+  falls from 5.2pt to 0.4pt.
 - **A table or a row keeps its own margins in DOCX.** Its left margin is now written into its
   indent (`w:tblInd`), as a paragraph's is: it was dropped everywhere, and `PaymentsInvoice`'s
   bank details stood 36.7pt left of the page's in Word. A table indented in a cell takes that

docs/recipes/docx-export.md

@@ -309,9 +309,15 @@ of several lines stays a point short of that, unless a line needs the room, so a
 broke off by a fraction of a point is not pulled back up. A paragraph of one line is never
 narrowed, and has room for a line three hundredths wider than its own: Word sets a face other
 than the page's, or emboldens one whose file does not say it is bold, a little wider, and a
-line of one broken in Word is a line more. A centred or right-aligned paragraph keeps
-the page's measure, as moving its other edge would move its lines. A list's items, a line pair's
-line, text over the flow and a header's or footer's line keep the page's measure too.
+line of one broken in Word is a line more. A centred or right-aligned paragraph of one line
+whose line, as Word sets it and three hundredths wider, does not fit its box is given that
+room: at both edges, half each, or at its left edge, so the line stays where the page sets
+it. In a table cell, where Word draws no text past the cell's left edge, the left indent
+gives no more than it has, and the right edge gives the rest, the line moving by that much.
+Any other centred or right-aligned paragraph keeps the page's measure: in one of several
+lines a wider measure takes another word onto a line, and a short line's box already has
+room for it. A list's items, a line pair's line, text over the flow and a header's or
+footer's line keep the page's measure too.
 
 ## Named styles, so the document can be restyled
 

qa/src/test/resources/docx-fidelity/libreoffice-linux-lines.tsv

@@ -1727,8 +1727,9 @@ cv-violet_grid	0:b96067918254	-0.26	uxresearch
 cv-violet_grid	0:9058674fd905	-0.21	userinterviews,surveys,
 cv-violet_grid	0:0cdd38014d79	-0.22	personas,journeymaps,
 cv-violet_grid	0:61e4ba28d469	-0.22	competitiveanalysis
-cv-violet_grid	0:db5c6756c4b6	7.59	sitemaps,userflows,card
-cv-violet_grid	0:6c7ad1834a60	7.58	sorting,contentstrategy
+cv-violet_grid	0:3de6be58cb9f	-0.26	informationarchitecture
+cv-violet_grid	0:db5c6756c4b6	-0.21	sitemaps,userflows,card
+cv-violet_grid	0:6c7ad1834a60	-0.22	sorting,contentstrategy
 cv-violet_grid	0:187737d59250	-0.26	wireframing
 cv-violet_grid	0:2286e5aa328a	-0.21	lowtohigh-fidelity
 cv-violet_grid	0:5c4b21cb1af8	-0.26	prototyping

qa/src/test/resources/docx-fidelity/libreoffice-linux.tsv

@@ -25,7 +25,7 @@ cv-slate_orange	1	1	87	86	3.27	3.87	86
 cv-teal_pulse	1	1	57	57	0.22	0.64	0
 cv-terracotta_rail	1	1	102	102	0.44	0.94	0
 cv-timeline_minimal	2	2	89	86	0.45	0.50	0
-cv-violet_grid	1	2	80	76	5.21	21.41	39
+cv-violet_grid	1	2	80	77	0.36	21.41	37
 invoice-classic	1	1	56	56	0.12	0.30	0
 invoice-classic_long	2	2	166	166	0.20	0.27	0
 invoice-consulting	1	1	92	92	0.67	0.96	0

qa/src/test/resources/docx-fidelity/libreoffice-windows-lines.tsv

@@ -1633,8 +1633,9 @@ cv-violet_grid	0:b96067918254	-0.26	uxresearch
 cv-violet_grid	0:9058674fd905	-0.21	userinterviews,surveys,
 cv-violet_grid	0:0cdd38014d79	-0.22	personas,journeymaps,
 cv-violet_grid	0:61e4ba28d469	-0.22	competitiveanalysis
-cv-violet_grid	0:db5c6756c4b6	7.59	sitemaps,userflows,card
-cv-violet_grid	0:6c7ad1834a60	7.58	sorting,contentstrategy
+cv-violet_grid	0:3de6be58cb9f	-0.26	informationarchitecture
+cv-violet_grid	0:db5c6756c4b6	-0.21	sitemaps,userflows,card
+cv-violet_grid	0:6c7ad1834a60	-0.22	sorting,contentstrategy
 cv-violet_grid	0:187737d59250	-0.26	wireframing
 cv-violet_grid	0:2286e5aa328a	-0.21	lowtohigh-fidelity
 cv-violet_grid	0:5c4b21cb1af8	-0.26	prototyping

qa/src/test/resources/docx-fidelity/libreoffice-windows.tsv

@@ -25,7 +25,7 @@ cv-slate_orange	1	1	87	86	3.27	3.87	86
 cv-teal_pulse	1	1	57	57	0.22	0.64	0
 cv-terracotta_rail	1	1	102	102	0.44	0.94	0
 cv-timeline_minimal	2	2	89	86	0.45	0.50	0
-cv-violet_grid	1	2	80	76	5.21	21.41	39
+cv-violet_grid	1	2	80	77	0.36	21.41	37
 invoice-classic	1	1	56	56	0.17	0.32	0
 invoice-classic_long	2	2	166	166	0.22	0.27	0
 invoice-consulting	1	1	92	92	0.67	1.01	0

qa/src/test/resources/docx-fidelity/word-windows-lines.tsv

@@ -1726,8 +1726,9 @@ cv-violet_grid	0:b96067918254	-0.23	uxresearch
 cv-violet_grid	0:9058674fd905	-0.28	userinterviews,surveys,
 cv-violet_grid	0:0cdd38014d79	-0.36	personas,journeymaps,
 cv-violet_grid	0:61e4ba28d469	-0.28	competitiveanalysis
-cv-violet_grid	0:db5c6756c4b6	7.52	sitemaps,userflows,card
-cv-violet_grid	0:6c7ad1834a60	7.47	sorting,contentstrategy
+cv-violet_grid	0:3de6be58cb9f	-0.23	informationarchitecture
+cv-violet_grid	0:db5c6756c4b6	-0.28	sitemaps,userflows,card
+cv-violet_grid	0:6c7ad1834a60	-0.36	sorting,contentstrategy
 cv-violet_grid	0:187737d59250	-0.23	wireframing
 cv-violet_grid	0:2286e5aa328a	-0.28	lowtohigh-fidelity
 cv-violet_grid	0:5c4b21cb1af8	-0.23	prototyping

qa/src/test/resources/docx-fidelity/word-windows.tsv

@@ -25,7 +25,7 @@ cv-slate_orange	1	1	87	85	0.53	1.18	0
 cv-teal_pulse	1	1	57	57	0.11	0.38	0
 cv-terracotta_rail	1	1	102	102	0.42	0.87	0
 cv-timeline_minimal	2	2	89	86	0.36	0.48	0
-cv-violet_grid	1	1	80	77	0.22	1.09	2
+cv-violet_grid	1	1	80	78	0.23	0.37	0
 invoice-classic	1	1	56	56	0.22	0.36	0
 invoice-classic_long	2	2	166	166	0.27	0.34	0
 invoice-consulting	1	1	92	92	0.70	1.02	0

render-docx/src/main/java/com/demcha/compose/document/backend/semantic/docx/DocxSemanticBackend.java

@@ -4707,25 +4707,93 @@ private boolean letTheLineStandOut(XWPFParagraph para, ParagraphNode node, doubl
      * The glyphs are left as Word sets them — a scale would stay on the text a reader types
      * next — and the right indent gives the line the same share more room, or takes it.</p>
      *
-     * <p>Only a paragraph set flush left: moving a centred or right-aligned line's other edge
-     * would move the line off where the page sets it. A list's items, a line pair, text over
-     * the flow and a header's or footer's line are written elsewhere and keep the page's
-     * measure.</p>
+     * <p>A paragraph set flush left has its measure moved at its right edge. A centred or
+     * right-aligned one is given room only for a line of its own that Word sets past its box
+     * or within three hundredths of it ({@link #ONE_LINE_FACE_SLACK}), at both edges, half each,
+     * or at its left, so the line stays where the page sets it — in a cell, where Word draws no
+     * text past the left edge, the right edge gives what the left indent cannot:
+     * {@code VioletGrid}'s 6.8pt "INFORMATION ARCHITECTURE", set at 7pt and centred in a tile
+     * it fills, broke onto two lines, and the tile's text stood 7.5pt low under it. A centred
+     * paragraph of several lines is left as it is — a wider measure there takes another word
+     * onto a line Word already breaks elsewhere than the page — and so is a short line, whose
+     * box has room for it: measured, {@code MerchantInvoice}'s centred amounts, their cells'
+     * indents taken past the cells' edges, stood 0.12pt off their place. A list's items, a line pair, text over the flow and
+     * a header's or footer's line are written elsewhere and keep the page's measure.</p>
      *
      * @param room the width the paragraph's text is written in, in points
      */
     private void measureAtWordsSize(XWPFParagraph para, ParagraphNode node, double room) {
-        if (node.align() == TextAlign.CENTER || node.align() == TextAlign.RIGHT || !Double.isFinite(room)) {
+        boolean flushLeft = node.align() != TextAlign.CENTER && node.align() != TextAlign.RIGHT;
+        if (!Double.isFinite(room) || !flushLeft && layout.lineCount(node) != 1) {
             return;
         }
-        double more = wordsMeasure(node, room) - room;
+        double more = (flushLeft ? wordsMeasure(node, room) : oneLinesMeasure(node, room)) - room;
         if (!Double.isFinite(more) || Math.abs(more) < 0.05) {
             return;
         }
         CTPPr properties = para.getCTP().isSetPPr() ? para.getCTP().getPPr() : para.getCTP().addNewPPr();
         CTInd indent = properties.isSetInd() ? properties.getInd() : properties.addNewInd();
-        long right = twipsOf(indent.isSetRight() ? indent.getRight() : null);
-        indent.setRight(BigInteger.valueOf(right - Math.round(more * POINT_TO_TWIP)));
+        long twips = Math.round(more * POINT_TO_TWIP);
+        // The edge the text does not lean on moves: a centred line's two, half each.
+        long fromTheLeft = node.align() == TextAlign.RIGHT ? twips
+                : node.align() == TextAlign.CENTER ? twips / 2
+                : 0;
+        long left = twipsOf(indent.isSetLeft() ? indent.getLeft() : null);
+        if (currentCell != null) {
+            // Word draws no text past a cell's left edge (see leftIndentTwips): what the left
+            // indent cannot give, the right one does, and the line moves by that much. A hanging
+            // first line already starts that much further left.
+            long hanging = twipsOf(indent.isSetHanging() ? indent.getHanging() : null);
+            fromTheLeft = Math.min(fromTheLeft, Math.max(0, left - hanging));
+        }
+        long fromTheRight = twips - fromTheLeft;
+        if (fromTheLeft != 0) {
+            indent.setLeft(BigInteger.valueOf(left - fromTheLeft));
+        }
+        if (fromTheRight != 0) {
+            long right = twipsOf(indent.isSetRight() ? indent.getRight() : null);
+            indent.setRight(BigInteger.valueOf(right - fromTheRight));
+        }
+    }
+
+    /**
+     * The measure a paragraph of one line needs in Word, in points: its box, or its line as wide
+     * as Word sets it and a few hundredths more ({@link #ONE_LINE_FACE_SLACK}), whichever is
+     * wider.
+     */
+    private double oneLinesMeasure(ParagraphNode node, double room) {
+        double set = 0;
+        for (com.demcha.compose.document.layout.payloads.ParagraphLine line : layout.lines(node)) {
+            // A line of pictures alone is set at their size, in Word as on the page.
+            boolean text = line.spans().stream().anyMatch(span -> span.width() > 0
+                    && span instanceof com.demcha.compose.document.layout.payloads.ParagraphTextSpan run
+                    && run.textStyle() != null && run.textStyle().size() > 0);
+            if (text) {
+                set = Math.max(set, widthAtWordsSize(line));
+            }
+        }
+        return Math.max(room, set * (1 + ONE_LINE_FACE_SLACK));
+    }
+
+    /**
+     * How wide Word sets a line the page laid out: its text grown or shrunk to Word's size, its
+     * tracking, pictures and shapes as the page has them.
+     */
+    private static double widthAtWordsSize(com.demcha.compose.document.layout.payloads.ParagraphLine line) {
+        double set = 0;
+        for (com.demcha.compose.document.layout.payloads.ParagraphSpan span : line.spans()) {
+            if (!(span.width() > 0)) {
+                continue;
+            }
+            if (span instanceof com.demcha.compose.document.layout.payloads.ParagraphTextSpan run
+                && run.textStyle() != null && run.textStyle().size() > 0) {
+                double tracking = run.textStyle().letterSpacing() * run.text().codePointCount(0, run.text().length());
+                set += (span.width() - tracking) * wordsSize(run.textStyle().size()) / run.textStyle().size() + tracking;
+            } else {
+                set += span.width();
+            }
+        }
+        return set;
     }
 
     /** How far inside the page's measure, grown or shrunk as Word sets it, Word's is held, in points. */
@@ -4771,22 +4839,15 @@ private double wordsMeasure(ParagraphNode node, double room) {
         for (com.demcha.compose.document.layout.payloads.ParagraphLine line : layout.lines(node)) {
             broken++;
             double asked = 0;
-            double set = 0;
             boolean text = false;
             for (com.demcha.compose.document.layout.payloads.ParagraphSpan span : line.spans()) {
-                if (!(span.width() > 0)) {
-                    continue;
-                }
-                asked += span.width();
-                if (span instanceof com.demcha.compose.document.layout.payloads.ParagraphTextSpan run
-                    && run.textStyle() != null && run.textStyle().size() > 0) {
-                    double tracking = run.textStyle().letterSpacing() * run.text().codePointCount(0, run.text().length());
-                    set += (span.width() - tracking) * wordsSize(run.textStyle().size()) / run.textStyle().size() + tracking;
-                    text = true;
-                } else {
-                    set += span.width();
+                if (span.width() > 0) {
+                    asked += span.width();
+                    text |= span instanceof com.demcha.compose.document.layout.payloads.ParagraphTextSpan run
+                            && run.textStyle() != null && run.textStyle().size() > 0;
                 }
             }
+            double set = widthAtWordsSize(line);
             if (text) {
                 share = Double.isNaN(share) ? set / asked : Math.max(share, set / asked);
                 fits = Math.max(fits, set);