sw HTML export: avoid pixel height when height is scale and width is relative

Commit b17180a84cb4561b8a7bbf9e2281c91fffd56f87 (write out image size in
html export for 'keep ratio' images, 2021-06-29) changed the sw HTML
export to write the layout size of images in case one dimension is "keep
ratio" and the other is some more concrete value.

This is useful in case that other dimension is a fixed value, because
"keep ratio" on the UI only means to keep the ratio as the size changes,
it does not mean that the ratio will be the original ratio of the
bitmap. However, it's problematic to write this layout size of the "keep
ratio" dimension when the other dimension is relative, as this will mean
the image's aspect ratio will change if the user resizes the browser
window.

Fix the problem by extending the way we write the "height" and "width"
of fly frames:

1) Write a percentage in case of relative sizes

2) Write an explicit "auto" (or just omit the attribute in XHTML mode)
   in case the size is "keep ratio" and the other dimension is a
   relative size

3) Write the layout size in other cases (fixed size or "keep ratio", but
   the other dimension is a fixed size)

Note that HTML itself has no concept of relative sizes where 100% is not
the parent's size (e.g. page, not paragraph) and also has no concept of
keeping an aspect ratio which is not the aspect ratio of the bitmap, so
those cases remain unchanged.

Change-Id: Ic5c7dc4d697160eff81e960a2f7d335fb78ab7c0
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/134482
Reviewed-by: Miklos Vajna <vmiklos@collabora.com>
Tested-by: Jenkins

2 files changed, 78 insertions, 6 deletions

diff --git a/sw/qa/extras/htmlexport/htmlexport.cxx b/sw/qa/extras/htmlexport/htmlexport.cxx
index 639b744b05da..a85715f6bebc 100644
--- a/sw/qa/extras/htmlexport/htmlexport.cxx
+++ b/sw/qa/extras/htmlexport/htmlexport.cxx
@@ -2290,6 +2290,40 @@ CPPUNIT_TEST_FIXTURE(SwHtmlDomExportTest, testTableBackground)
     assertXPathNoAttribute(pXmlDoc, "//reqif-xhtml:table[2]/reqif-xhtml:tr[1]", "bgcolor");
 }
 
+CPPUNIT_TEST_FIXTURE(HtmlExportTest, testImageKeepRatio)
+{
+    // Given a document with an image: width is relative, height is "keep ratio":
+    createSwDoc();
+    uno::Reference<lang::XMultiServiceFactory> xFactory(mxComponent, uno::UNO_QUERY);
+    uno::Reference<beans::XPropertySet> xTextGraphic(
+        xFactory->createInstance("com.sun.star.text.TextGraphicObject"), uno::UNO_QUERY);
+    xTextGraphic->setPropertyValue("AnchorType",
+                                   uno::Any(text::TextContentAnchorType_AS_CHARACTER));
+    xTextGraphic->setPropertyValue("RelativeWidth", uno::Any(static_cast<sal_Int16>(42)));
+    xTextGraphic->setPropertyValue("IsSyncHeightToWidth", uno::Any(true));
+    uno::Reference<text::XTextDocument> xTextDocument(mxComponent, uno::UNO_QUERY);
+    uno::Reference<text::XText> xBodyText = xTextDocument->getText();
+    uno::Reference<text::XTextCursor> xCursor(xBodyText->createTextCursor());
+    uno::Reference<text::XTextContent> xTextContent(xTextGraphic, uno::UNO_QUERY);
+    xBodyText->insertTextContent(xCursor, xTextContent, false);
+
+    // When exporting to HTML:
+    uno::Reference<frame::XStorable> xStorable(mxComponent, uno::UNO_QUERY);
+    uno::Sequence<beans::PropertyValue> aStoreProperties = {
+        comphelper::makePropertyValue("FilterName", OUString("HTML (StarWriter)")),
+    };
+    xStorable->storeToURL(maTempFile.GetURL(), aStoreProperties);
+
+    // Then make sure that the width is not a fixed size, that would break on resizing the browser
+    // window:
+    htmlDocUniquePtr pDoc = parseHtml(maTempFile);
+    // Without the accompanying fix in place, this test would have failed with:
+    // - Expected: auto
+    // - Actual  : 2
+    // i.e. a static (CSS pixel) height was written.
+    assertXPath(pDoc, "/html/body/p/img", "height", "auto");
+}
+
 CPPUNIT_PLUGIN_IMPLEMENT();
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
diff --git a/sw/source/filter/html/htmlflywriter.cxx b/sw/source/filter/html/htmlflywriter.cxx
index 2ad597aea80d..940b7c9d9a86 100644
--- a/sw/source/filter/html/htmlflywriter.cxx
+++ b/sw/source/filter/html/htmlflywriter.cxx
@@ -975,22 +975,60 @@ void SwHTMLWriter::writeFrameFormatOptions(HtmlWriter& aHtml, const SwFrameForma
             ((nPercentWidth && nPercentWidth!=255) || aPixelSz.Width()) )
         {
             OString sWidth;
-            if (nPercentWidth && nPercentWidth != 255)
-                sWidth = OString::number(static_cast<sal_Int32>(nPercentWidth)) + "%";
+            if (nPercentWidth)
+            {
+                if (nPercentWidth == 255)
+                {
+                    if (nPercentHeight)
+                    {
+                        sWidth = "auto";
+                    }
+                    else
+                    {
+                        sWidth = OString::number(static_cast<sal_Int32>(aPixelSz.Width()));
+                    }
+                }
+                else
+                {
+                    sWidth = OString::number(static_cast<sal_Int32>(nPercentWidth)) + "%";
+                }
+            }
             else
                 sWidth = OString::number(static_cast<sal_Int32>(aPixelSz.Width()));
-            aHtml.attribute(OOO_STRING_SVTOOLS_HTML_O_width, sWidth);
+            if (!mbXHTML || sWidth != "auto")
+            {
+                aHtml.attribute(OOO_STRING_SVTOOLS_HTML_O_width, sWidth);
+            }
         }
 
         if( (nFrameOptions & HtmlFrmOpts::Height) &&
             ((nPercentHeight && nPercentHeight!=255) || aPixelSz.Height()) )
         {
             OString sHeight;
-            if (nPercentHeight && nPercentHeight != 255)
-                sHeight = OString::number(static_cast<sal_Int32>(nPercentHeight)) + "%";
+            if (nPercentHeight)
+            {
+                if (nPercentHeight == 255)
+                {
+                    if (nPercentWidth)
+                    {
+                        sHeight = "auto";
+                    }
+                    else
+                    {
+                        sHeight = OString::number(static_cast<sal_Int32>(aPixelSz.Height()));
+                    }
+                }
+                else
+                {
+                    sHeight = OString::number(static_cast<sal_Int32>(nPercentHeight)) + "%";
+                }
+            }
             else
                 sHeight = OString::number(static_cast<sal_Int32>(aPixelSz.Height()));
-            aHtml.attribute(OOO_STRING_SVTOOLS_HTML_O_height, sHeight);
+            if (!mbXHTML || sHeight != "auto")
+            {
+                aHtml.attribute(OOO_STRING_SVTOOLS_HTML_O_height, sHeight);
+            }
         }
     }