Merge branch 'html-page-break-inside'

Add support for style="page-break-inside:avoid" to wxHTML.

See https://github.com/wxWidgets/wxWidgets/pull/837

docs/changes.txt

@@ -106,6 +106,7 @@ All (GUI):
 - Add wxHtmlEasyPrinting::SetPromptMode() (pavel-t).
 - Fix possible infinite loop in wxHtmlWindow layout (trivia21).
 - Add "hint" property support to XRC for wxComboBox and wxSearchCtrl.
+- Add support for style="page-break-inside:avoid" to <div> in wxHTML.
 
 wxGTK:
 

samples/html/printing/test.htm

@@ -55,6 +55,8 @@ is split into base and GUI libraries.
 
 <P>
 
+<!-- Avoid page breaks inside individual version change logs -->
+<div style="page-break-inside:avoid">
 <H2>Release 2.1.11 (final)</H2>
 
 <ul>
@@ -71,18 +73,22 @@ combined base/GUI library for GUI applications only.
 <li>Rewritten timer.cpp, possible wxChrono class.
 <li>Bug tracking system in place.
 </ul>
+</div>
 
 <P>
 
+<div style="page-break-inside:avoid">
 <H4>Release 2.1.12</H4>
 
 <ul>
 <li>Release date: January 9th, 2000
 <li>Miscellaneous fixes and small enhancements.
 </ul>
+</div>
 
 <P>
 
+<div style="page-break-inside:avoid">
 <H4>Release 2.1.13</H4>
 
 <ul>
@@ -90,6 +96,7 @@ combined base/GUI library for GUI applications only.
 <li>Miscellaneous fixes and small enhancements.
 <li>wxDateTime class in beta.
 </ul>
+</div>
 
 <P>
 
@@ -102,6 +109,7 @@ combined base/GUI library for GUI applications only.
 
 <P>
 
+<div style="page-break-inside:avoid">
 <H2>Release 2.2.x (final)</H2>
 
 <ul>
@@ -109,15 +117,18 @@ combined base/GUI library for GUI applications only.
 <li>Unicode compilation working in wxGTK and wxMSW.
 <li>wxDateTime class.
 </ul>
+</div>
 
 <P>
 
+<div style="page-break-inside:avoid">
 <H2>Release 2.3.x (final)</H2>
 
 <ul>
 <li>Release date: unknown
 <li>WinCE port available.
 </ul>
+</div>
 
 <P>
 

src/html/m_layout.cpp

@@ -187,6 +187,35 @@ TAG_HANDLER_BEGIN(DIV, "DIV")
                 m_WParser->OpenContainer();
                 return false;
             }
+            else if(style.IsSameAs(wxT("PAGE-BREAK-INSIDE:AVOID"), false))
+            {
+                // As usual, reuse the current container if it's empty.
+                wxHtmlContainerCell *c = m_WParser->GetContainer();
+                if (c->GetFirstChild() != NULL)
+                {
+                    // If not, open a new one.
+                    m_WParser->CloseContainer();
+                    c = m_WParser->OpenContainer();
+                }
+
+                // Force this container to live entirely on the same page.
+                c->SetCanLiveOnPagebreak(false);
+
+                // Use a nested container so that nested tags that close and
+                // reopen a container again close this one, but still remain
+                // inside the outer "unbreakable" container.
+                m_WParser->OpenContainer();
+
+                ParseInner(tag);
+
+                // Close both the inner and the outer containers and reopen the
+                // new current one.
+                m_WParser->CloseContainer();
+                m_WParser->CloseContainer();
+                m_WParser->OpenContainer();
+
+                return true;
+            }
             else
             {
                 // Treat other STYLE parameters here when they're supported.

tests/html/htmprint.cpp

@@ -59,6 +59,17 @@ TEST_CASE("wxHtmlPrintout::Pagination", "[html][print]")
     // the DPI-dependent factor, but it doesn't seem to be worth doing it).
     pr.SetMargins(0, 0, 0, 0, 0);
 
+    // Use font size in pixels to make it DPI-independent: if we just used a
+    // normal (say 12pt) font, it would have different height in pixels on 96
+    // and 200 DPI systems, meaning that the text at the end of this test would
+    // take different number of (fixed to 1000px height) pages.
+    //
+    // We could also make the page height proportional to the DPI, but this
+    // would be more complicated as we also wouldn't be able to use hardcoded
+    // height attribute values in the HTML snippets below then.
+    const wxFont fontFixedPixelSize(wxFontInfo(wxSize(10, 16)));
+    pr.SetStandardFonts(fontFixedPixelSize.GetPointSize(), "Helvetica");
+
     wxBitmap bmp(1000, 1000);
     wxMemoryDC dc(bmp);
     pr.SetUp(dc);
@@ -107,6 +118,75 @@ TEST_CASE("wxHtmlPrintout::Pagination", "[html][print]")
             "</div>"
        );
     CHECK( CountPages(pr) == 2 );
+
+    // Also test that forbidding page breaks inside a paragraph works: it
+    // should move it entirely to the next page, resulting in one extra page
+    // compared to the version without "page-break-inside: avoid".
+    static const char* const text =
+"Early in the morning on the fourteenth of the spring month of Nisan the<br>"
+"Procurator of Judea, Pontius Pilate, in a white cloak lined with blood red,<br>"
+"emerged with his shuffling cavalryman's walk into the arcade connecting the two<br>"
+"wings of the palace of Herod the Great.<br>"
+"<br>"
+"More than anything else in the world the Procurator hated the smell of attar of<br>"
+"roses.  The omens for the day were bad, as this scent had been haunting him<br>"
+"since dawn.<br>"
+"<br>"
+"It seemed to the Procurator that the very cypresses and palms in the garden<br>"
+"were exuding the smell of roses, that this damned stench of roses was even<br>"
+"mingling with the smell of leather tackle and sweat from his mounted bodyguard.<br>"
+"<br>"
+"A haze of smoke was drifting toward the arcade across the upper courtyard of<br>"
+"the garden, coming from the wing at the rear of the palace, the quarters of the<br>"
+"first cohort of the XII Legion; known as the \"Lightning,\" it had been<br>"
+"stationed in Jerusalem since the Procurator's arrival.  The same oily perfume<br>"
+"of roses was mixed with the acrid smoke that showed that the centuries' cooks<br>"
+"had started to prepare breakfast<br>"
+"<br>"
+"\"Oh, gods, what are you punishing me for?..  No, there's no doubt, I have it<br>"
+"again, this terrible incurable pain...  hemicrania, when half the head aches...<br>"
+"There's no cure for it, nothing helps...  I must try not to move my head...\"<br>"
+"<br>"
+"A chair had already been placed on the mosaic floor by the fountain; without a<br>"
+"glance around, the Procurator sat in it and stretched out his hand to one side.<br>"
+"His secretary deferentially laid a piece of parchment in his hand.  Unable to<br>"
+"restrain a grimace of agony, the Procurator gave a fleeting sideways look at<br>"
+"its contents, returned the parchment to his secretary and said painfully, \"The<br>"
+"accused comes from Galilee, does he?  Was the case sent to the tetrarch?\"<br>"
+"<br>"
+"\"Yes, Procurator,\" replied the secretary.  \"He declined to confirm the<br>"
+"finding of the court and passed the Sanhedrin's sentence of death to you for<br>"
+"confirmation.\"<br>"
+"<br>"
+"The Procurator's cheek twitched, and he said quietly, \"Bring in the accused.\"<br>"
+        ;
+
+    pr.SetHtmlText
+       (
+            wxString::Format
+            (
+                "<img width=\"100\" height=\"500\" src=\"dummy\"/>"
+                "<div>%s</div>"
+                "<br/>"
+                "<img width=\"100\" height=\"400\" src=\"dummy\"/>",
+                text
+            )
+       );
+    CHECK( CountPages(pr) == 2 );
+
+    pr.SetHtmlText
+       (
+            wxString::Format
+            (
+                "<img width=\"100\" height=\"500\" src=\"dummy\"/>"
+                "<div style=\"page-break-inside:avoid\">%s</div>"
+                "<br/>"
+                "<img width=\"100\" height=\"400\" src=\"dummy\"/>",
+                text
+            )
+       );
+    INFO("Using base font size " << fontFixedPixelSize.GetPointSize());
+    CHECK( CountPages(pr) == 3 );
 }
 
 #endif //wxUSE_HTML