Text: add a LayoutDirection enum.

To be used as a placeholder argument in the reworked renderer APIs. No
intention to deal with the complexities of this right now, just taking
it to not have to deprecate & replace the API when this feature actually
gets implemented.

src/Magnum/Text/Direction.cpp

@@ -47,4 +47,21 @@ Debug& operator<<(Debug& debug, const ShapeDirection value) {
     return debug << "(" << Debug::nospace << reinterpret_cast<void*>(UnsignedByte(value)) << Debug::nospace << ")";
 }
 
+Debug& operator<<(Debug& debug, const LayoutDirection value) {
+    debug << "Text::LayoutDirection" << Debug::nospace;
+
+    switch(value) {
+        /* LCOV_EXCL_START */
+        #define _c(v) case LayoutDirection::v: return debug << "::" #v;
+        _c(Unspecified)
+        _c(HorizontalTopToBottom)
+        _c(VerticalLeftToRight)
+        _c(VerticalRightToLeft)
+        #undef _c
+        /* LCOV_EXCL_STOP */
+    }
+
+    return debug << "(" << Debug::nospace << reinterpret_cast<void*>(UnsignedByte(value)) << Debug::nospace << ")";
+}
+
 }}

src/Magnum/Text/Direction.h

@@ -26,7 +26,7 @@
 */
 
 /** @file
- * @brief Enum @ref Magnum::Text::ShapeDirection
+ * @brief Enum @ref Magnum::Text::ShapeDirection, @ref Magnum::Text::LayoutDirection
  * @m_since_latest
  */
 
@@ -40,7 +40,8 @@ namespace Magnum { namespace Text {
 @brief Direction a text is shaped in
 @m_since_latest
 
-@see @ref AbstractShaper::setDirection(), @ref AbstractShaper::direction()
+@see @ref AbstractShaper::setDirection(), @ref AbstractShaper::direction(),
+    @ref LayoutDirection
 */
 enum class ShapeDirection: UnsignedByte {
     /**
@@ -85,6 +86,31 @@ enum class ShapeDirection: UnsignedByte {
 /** @debugoperatorenum{ShapeDirection} */
 MAGNUM_TEXT_EXPORT Debug& operator<<(Debug& debug, ShapeDirection value);
 
+/**
+@brief Direction a text is laid out in
+@m_since_latest
+
+@see @ref ShapeDirection
+*/
+enum class LayoutDirection: UnsignedByte {
+    Unspecified = 0,
+
+    /** Horizontal text with lines advancing from top to bottom */
+    HorizontalTopToBottom = 1,
+
+    /* There's no HorizontalBottomToTop, as apparently no scripts use that. Not
+       even the CSS writing-mode property has it, so why should I. */
+
+    /** Vertical text with lines advancing from left to right */
+    VerticalLeftToRight,
+
+    /** Vertical text with lines advancing from right to left */
+    VerticalRightToLeft
+};
+
+/** @debugoperatorenum{LayoutDirection} */
+MAGNUM_TEXT_EXPORT Debug& operator<<(Debug& debug, LayoutDirection value);
+
 }}
 
 #endif

src/Magnum/Text/Test/DirectionTest.cpp

@@ -35,10 +35,12 @@ struct DirectionTest: TestSuite::Tester {
     explicit DirectionTest();
 
     void debugShape();
+    void debugLayout();
 };
 
 DirectionTest::DirectionTest() {
-    addTests({&DirectionTest::debugShape});
+    addTests({&DirectionTest::debugShape,
+              &DirectionTest::debugLayout});
 }
 
 void DirectionTest::debugShape() {
@@ -47,6 +49,12 @@ void DirectionTest::debugShape() {
     CORRADE_COMPARE(out.str(), "Text::ShapeDirection::RightToLeft Text::ShapeDirection(0xab)\n");
 }
 
+void DirectionTest::debugLayout() {
+    std::ostringstream out;
+    Debug{&out} << LayoutDirection::VerticalRightToLeft << LayoutDirection(0xab);
+    CORRADE_COMPARE(out.str(), "Text::LayoutDirection::VerticalRightToLeft Text::LayoutDirection(0xab)\n");
+}
+
 }}}}
 
 CORRADE_TEST_MAIN(Magnum::Text::Test::DirectionTest)

src/Magnum/Text/Text.h

@@ -43,6 +43,7 @@ class AbstractShaper;
 
 enum class Alignment: UnsignedByte;
 enum class ShapeDirection: UnsignedByte;
+enum class LayoutDirection: UnsignedByte;
 
 class AbstractGlyphCache;