tdf#127316 ooxml/ww8export: DFLT_ESC_*_AUTO - use better formulas

See tdf#99602 and tdf#120412 for many fixes related to escapement.
The poor formulas for AUTO style came to light in 6.3.0.1
with 6.4 commit 32262b0a537207832d7d126d8427d8949b9e821d

Looking at sw/source/core/txtnode/swfont.cxx, we can see in
CalcEsc() that for superscript the DFLT_ESC_SUPER_AUTO
is calculated as the difference between the two ascents.
Because the superscript is smaller, it has a smaller ascent,
so to reach the same ascent line as the original, we can
raise its baseline by fontAscent(fA) - superscriptAscent(ssA).
Since the ascent is approximately 80% of the total fontheight(fH),
we can calculate the Esc number (percentage * 100) as:
EscHeight = fA - ssA  (formula in CalcEsc)
ssA = nProp/100 * fA  (superscript ascent/height reduced by nProp)
.8 = fA/fHeight       (improvement would be to query font.GetAscent)
Esc% = EscHeight / fHeight

Esc% = (fA - nProp/100*fA) / fHeight
Esc% = (1 - nProp/100)*fA/fHeight
Esc = (100 - nProp) * 0.8

DFLT_ESC_SUB_AUTO subscript is similar with the descent(fD)
being the remainding 20% of the fontHeight.
EscHeight = fD - ssD (formula in CalcEsc)
ssD = nProp/100 * fD (by definition of the function of nProp)
.2 = fD/fHeight      (an approximation - each font will be different)

Esc% = (fD - nProp/100*fD) / fHeight
Esc% = (1 - nProp/100)*fD/fHeight
Esc = (100 - nProp) * 0.2 (in the negative direction)

For RTF, I can see no reason for the ++nProp except
to try and avoid nProp == 0. It is only .01% after all...

Change-Id: Ia7b9f8784572193dd05cb80afa56c90540c3e676
Reviewed-on: https://gerrit.libreoffice.org/80306
Tested-by: Jenkins
Reviewed-by: Justin Luth <justin_luth@sil.org>
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>

2 files changed, 17 insertions, 4 deletions

diff --git a/sw/qa/extras/ww8export/data/tdf127316_autoEscapement2.odt b/sw/qa/extras/ww8export/data/tdf127316_autoEscapement2.odt
new file mode 100644
index 000000000000..d98fae0ad4d6
--- /dev/null
+++ b/sw/qa/extras/ww8export/data/tdf127316_autoEscapement2.odt
diff --git a/sw/qa/extras/ww8export/ww8export3.cxx b/sw/qa/extras/ww8export/ww8export3.cxx
index 014274e98bbf..d4a65e685f4a 100644
--- a/sw/qa/extras/ww8export/ww8export3.cxx
+++ b/sw/qa/extras/ww8export/ww8export3.cxx
@@ -177,11 +177,24 @@ DECLARE_WW8EXPORT_TEST(testTdf127316_autoEscapement, "tdf127316_autoEscapement.o
 {
     uno::Reference<text::XTextRange> xPara = getParagraph(2);
     CPPUNIT_ASSERT_DOUBLES_EQUAL( 0.f, getProperty<float>(getRun(xPara, 1, "Normal text "), "CharEscapement"), 0);
-    // Automatic escapement SHOULD BE limited by the font bottom line(?)
-    // and so the calculations ought to be different. There is room for a lot of export improvement here.
     // Negative escapements (subscripts) were decreasing by 1% every round-trip due to bad manual rounding.
-    // The actual number of 50% isn't so important here, but test that it is stable across multiple round-trips.
-    CPPUNIT_ASSERT_DOUBLES_EQUAL_MESSAGE("Did you fix or break me?", -50.f, getProperty<float>(getRun(xPara, 2), "CharEscapement"), 1);
+    // This should be roughly .2*35% of the ORIGINAL (non-reduced) size. However, during export the
+    // proportional height has to be changed into direct formatting, which then changes the relative percent.
+    // In this case, a 24pt font, proportional at 65% becomes roughly a 16pt font.
+    // Thus an escapement of 7% (1.68pt) becomes roughly 10.5% for the 16pt font.
+    CPPUNIT_ASSERT_DOUBLES_EQUAL_MESSAGE("Subscript", -10.f, getProperty<float>(getRun(xPara, 2), "CharEscapement"), 1);
+}
+
+DECLARE_WW8EXPORT_TEST(testTdf127316_autoEscapement2, "tdf127316_autoEscapement2.odt")
+{
+    uno::Reference<text::XTextRange> xPara = getParagraph(1);
+    CPPUNIT_ASSERT_DOUBLES_EQUAL( 0.f, getProperty<float>(getRun(xPara, 1, "Base1"), "CharEscapement"), 0);
+    // Font is 80% of 40pt or 32pt, original escapement is 6.4pt, so round-trip escapement is 20%.
+    CPPUNIT_ASSERT_DOUBLES_EQUAL(20.f, getProperty<float>(getRun(xPara, 2,"AutoSuperscript"), "CharEscapement"), 1);
+    xPara.set( getParagraph(3) );
+    CPPUNIT_ASSERT_DOUBLES_EQUAL( 0.f, getProperty<float>(getRun(xPara, 1, "Base3"), "CharEscapement"), 0);
+    // font is 20% of 40pt or 8pt, original escapement is 25.6pt, so round-trip escapement is 320%.
+    CPPUNIT_ASSERT_DOUBLES_EQUAL(320.f, getProperty<float>(getRun(xPara, 2,"AutoSuperscript"), "CharEscapement"), 3);
 }
 
 DECLARE_WW8EXPORT_TEST(testTdf120412_proportionalEscapement, "tdf120412_proportionalEscapement.odt")