Fix logic in wxTextWrapper::Wrap()

The existing code behaved completely wrongly whenever a word longer than
the maximal width was present as it just gave up and didn't wrap
anything at all after it -- when it should have just let this word
overflow but still wrap the rest.

Fix this and add a unit test checking that this works correctly now
(several of the tests would have failed before).

See #23339, #25100.

(cherry picked from commit 5972730200)

docs/changes.txt

@@ -272,6 +272,7 @@ All (GUI):
 - Improve wxPropGrid checkboxes in high DPI (Alex Shvartzkop, #24650, #24651).
 - Don't break AUI layout if Update() called when window is iconized (#24930).
 - Improve wxInfoBar appearance (#24838, #24902, #25048).
+- Fix multiple bugs in wxStaticText::Wrap() (#23339).
 - Fix WX_GL_COMPAT_PROFILE spelling (#24964).
 
 wxGTK:

src/common/stattextcmn.cpp

@@ -142,19 +142,27 @@ void wxTextWrapper::Wrap(wxWindow *win, const wxString& text, int widthMax)
             }
 
             // Find the last word to chop off.
-            const size_t lastSpace = line.rfind(' ', posEnd);
-            if ( lastSpace == wxString::npos )
+            size_t posSpace = line.rfind(' ', posEnd);
+            if ( posSpace == wxString::npos )
             {
-                // No spaces, so can't wrap.
-                DoOutputLine(line);
-                break;
+                // No spaces, so can't wrap, output until the end of the word
+                // which is defined here as just a sequence of non-space chars.
+                //
+                // TODO: Implement real Unicode word break algorithm.
+                posSpace = line.find(' ', posEnd);
+                if ( posSpace == wxString::npos )
+                {
+                    // No more spaces at all, output the rest of the line.
+                    DoOutputLine(line);
+                    break;
+                }
             }
 
             // Output the part that fits.
-            DoOutputLine(line.substr(0, lastSpace));
+            DoOutputLine(line.substr(0, posSpace));
 
             // And redo the layout with the rest.
-            line = line.substr(lastSpace + 1);
+            line = line.substr(posSpace + 1);
         }
     }
 }

tests/Makefile.in

@@ -265,6 +265,7 @@ TEST_GUI_OBJECTS =  \
 	test_gui_garbage.o \
 	test_gui_safearrayconverttest.o \
 	test_gui_settings.o \
+	test_gui_textwrap.o \
 	test_gui_socket.o \
 	test_gui_tlw.o \
 	test_gui_dataview.o \
@@ -1175,6 +1176,9 @@ test_gui_safearrayconverttest.o: $(srcdir)/misc/safearrayconverttest.cpp $(TEST_
 test_gui_settings.o: $(srcdir)/misc/settings.cpp $(TEST_GUI_ODEP)
 	$(CXXC) -c -o $@ $(TEST_GUI_CXXFLAGS) $(srcdir)/misc/settings.cpp
 
+test_gui_textwrap.o: $(srcdir)/misc/textwrap.cpp $(TEST_GUI_ODEP)
+	$(CXXC) -c -o $@ $(TEST_GUI_CXXFLAGS) $(srcdir)/misc/textwrap.cpp
+
 test_gui_socket.o: $(srcdir)/net/socket.cpp $(TEST_GUI_ODEP)
 	$(CXXC) -c -o $@ $(TEST_GUI_CXXFLAGS) $(srcdir)/net/socket.cpp
 

tests/makefile.gcc

@@ -239,6 +239,7 @@ TEST_GUI_OBJECTS =  \
 	$(OBJS)\test_gui_garbage.o \
 	$(OBJS)\test_gui_safearrayconverttest.o \
 	$(OBJS)\test_gui_settings.o \
+	$(OBJS)\test_gui_textwrap.o \
 	$(OBJS)\test_gui_socket.o \
 	$(OBJS)\test_gui_tlw.o \
 	$(OBJS)\test_gui_dataview.o \
@@ -1134,6 +1135,9 @@ $(OBJS)\test_gui_safearrayconverttest.o: ./misc/safearrayconverttest.cpp
 $(OBJS)\test_gui_settings.o: ./misc/settings.cpp
 	$(CXX) -c -o $@ $(TEST_GUI_CXXFLAGS) $(CPPDEPS) $<
 
+$(OBJS)\test_gui_textwrap.o: ./misc/textwrap.cpp
+	$(CXX) -c -o $@ $(TEST_GUI_CXXFLAGS) $(CPPDEPS) $<
+
 $(OBJS)\test_gui_socket.o: ./net/socket.cpp
 	$(CXX) -c -o $@ $(TEST_GUI_CXXFLAGS) $(CPPDEPS) $<
 

tests/makefile.vc

@@ -255,6 +255,7 @@ TEST_GUI_OBJECTS =  \
 	$(OBJS)\test_gui_garbage.obj \
 	$(OBJS)\test_gui_safearrayconverttest.obj \
 	$(OBJS)\test_gui_settings.obj \
+	$(OBJS)\test_gui_textwrap.obj \
 	$(OBJS)\test_gui_socket.obj \
 	$(OBJS)\test_gui_tlw.obj \
 	$(OBJS)\test_gui_dataview.obj \
@@ -1432,6 +1433,9 @@ $(OBJS)\test_gui_safearrayconverttest.obj: .\misc\safearrayconverttest.cpp
 $(OBJS)\test_gui_settings.obj: .\misc\settings.cpp
 	$(CXX) /c /nologo /TP /Fo$@ $(TEST_GUI_CXXFLAGS) .\misc\settings.cpp
 
+$(OBJS)\test_gui_textwrap.obj: .\misc\textwrap.cpp
+	$(CXX) /c /nologo /TP /Fo$@ $(TEST_GUI_CXXFLAGS) .\misc\textwrap.cpp
+
 $(OBJS)\test_gui_socket.obj: .\net\socket.cpp
 	$(CXX) /c /nologo /TP /Fo$@ $(TEST_GUI_CXXFLAGS) .\net\socket.cpp
 

tests/misc/textwrap.cpp

@@ -0,0 +1,148 @@
+///////////////////////////////////////////////////////////////////////////////
+// Name:        tests/misc/textwrap.cpp
+// Purpose:     wxTextWrapper unit test
+// Author:      Vadim Zeitlin
+// Created:     2025-01-19
+// Copyright:   (c) 2025 Vadim Zeitlin
+///////////////////////////////////////////////////////////////////////////////
+
+// ----------------------------------------------------------------------------
+// headers
+// ----------------------------------------------------------------------------
+
+#include "testprec.h"
+
+#ifndef WX_PRECOMP
+    #include "wx/app.h"
+#endif // !PCH
+
+#include "wx/textwrapper.h"
+
+// ----------------------------------------------------------------------------
+// wrapper implementation for testing
+// ----------------------------------------------------------------------------
+
+namespace
+{
+
+class HardBreakWrapper : public wxTextWrapper
+{
+public:
+    HardBreakWrapper() = default;
+
+    // Return the window used for wrapping: for now, use the main frame because
+    // it doesn't really matter which one we use.
+    wxWindow* GetWindow() const
+    {
+        return wxTheApp->GetTopWindow();
+    }
+
+    // Helper function returning the width of the given text.
+    int GetExtent(const wxString& text) const
+    {
+        return GetWindow()->GetTextExtent(text).x;
+    }
+
+    // Wrap and return the number of lines in the wrapped text.
+    size_t Do(const wxString& text, int width)
+    {
+        Wrap(GetWindow(), text, width);
+
+        return m_lines.size();
+    }
+
+    const wxString& GetLine(size_t n) const
+    {
+        REQUIRE( n < m_lines.size() );
+
+        return m_lines[n];
+    }
+
+    wxString GetResult() const { return wxJoin(m_lines, '\n'); }
+
+protected:
+    void OnOutputLine(const wxString& line) override { m_lines.push_back(line); }
+
+private:
+    wxArrayString m_lines;
+};
+
+} // anonymous namespace
+
+// ----------------------------------------------------------------------------
+// the tests
+// ----------------------------------------------------------------------------
+
+TEST_CASE("wxTextWrapper::Wrap", "[text]")
+{
+    // Note that this text shouldn't contain line breaks.
+    const wxString text =
+        "Lorem ipsum dolor sit amet, consectetur adipiscing elit, "
+        "sed do eiusmod tempor incididunt ut labore et dolore magna aliqua."
+        ;
+
+    HardBreakWrapper w;
+
+    // Check that not wrapping the text works.
+    SECTION("None")
+    {
+        REQUIRE( w.Do(text, -1) == 1 );
+        CHECK( w.GetLine(0) == text );
+    }
+
+    SECTION("Wide")
+    {
+        REQUIRE( w.Do(text, 200*w.GetExtent("x")) == 1 );
+        CHECK( w.GetLine(0) == text );
+    }
+
+    // Check that wrapping the text using reasonable width works.
+    SECTION("Normal")
+    {
+        const auto n = w.Do(text, 40*w.GetExtent("x"));
+        INFO("Wrapped text:\n" << w.GetResult() << "\n");
+        CHECK( n >= 3 );
+    }
+
+    SECTION("Narrow")
+    {
+        const auto n = w.Do(text, 20*w.GetExtent("x"));
+        INFO("Wrapped text:\n" << w.GetResult() << "\n");
+        CHECK( n >= 7 );
+    }
+
+    // Make the window too narrow to fit the word "consectetur" and check that
+    // the text is still wrapped reasonableness well.
+    SECTION("Thin")
+    {
+        const auto n = w.Do(text, w.GetExtent("Lorum"));
+        INFO("Wrapped text:\n" << w.GetResult() << "\n");
+        CHECK( n > 10 );
+        CHECK( w.GetLine(0) == "Lorem" );
+
+        // There should be just one line with the word "consectetur", longer
+        // than the wrap width.
+        bool found = false;
+        for ( size_t i = 1; i < n; ++i )
+        {
+            if ( w.GetLine(i) == "consectetur" )
+            {
+                found = true;
+                break;
+            }
+        }
+
+        CHECK( found );
+    }
+
+    // Make the window too narrow to fit even a single character so that
+    // wrapped text has one word per line.
+    SECTION("Narrowest")
+    {
+        const auto n = w.Do(text, 1);
+        INFO("Wrapped text:\n" << w.GetResult() << "\n");
+        REQUIRE( n == static_cast<size_t>(text.Freq(' ')) + 1 );
+        CHECK( w.GetLine(0) == "Lorem" );
+        CHECK( w.GetLine(5) == "consectetur" );
+    }
+}

tests/test.bkl

@@ -269,6 +269,7 @@
             misc/garbage.cpp
             misc/safearrayconverttest.cpp
             misc/settings.cpp
+            misc/textwrap.cpp
             <!--
                 This one is intentionally duplicated here (it is also part of
                 non-GUI test) as sockets behave differently in console and GUI

tests/test_gui.vcxproj

@@ -568,6 +568,7 @@
     <ClCompile Include="misc\safearrayconverttest.cpp" />
     <ClCompile Include="misc\selstoretest.cpp" />
     <ClCompile Include="misc\settings.cpp" />
+    <ClCompile Include="misc\textwrap.cpp" />
     <ClCompile Include="net\socket.cpp" />
     <ClCompile Include="persistence\tlw.cpp" />
     <ClCompile Include="persistence\dataview.cpp" />

tests/test_gui.vcxproj.filters

@@ -257,6 +257,9 @@
     <ClCompile Include="controls\textentrytest.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="misc\textwrap.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
     <ClCompile Include="controls\togglebuttontest.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>