Text: fixed alignment.

The original code assumed that the text bounds lower left corner is
always at origin. It is now not the case with multi-line text. All tests
now pass again.

src/Text/Renderer.cpp

@@ -123,12 +123,11 @@ std::tuple<std::vector<Vertex>, Rectangle> renderVerticesInternal(AbstractFont&
         /** @todo What about top-down text? */
 
         /* Horizontally align the rendered line */
-        const Float renderedWidth = lineRectangle.width();
         Float alignmentOffsetX = 0.0f;
         if((UnsignedByte(alignment) & Implementation::AlignmentHorizontal) == Implementation::AlignmentCenter)
-            alignmentOffsetX = -renderedWidth*0.5f;
+            alignmentOffsetX = -lineRectangle.left()-lineRectangle.width()*0.5f;
         else if((UnsignedByte(alignment) & Implementation::AlignmentHorizontal) == Implementation::AlignmentRight)
-            alignmentOffsetX = -renderedWidth;
+            alignmentOffsetX = -lineRectangle.right();
 
         /* Integer alignment */
         if(UnsignedByte(alignment) & Implementation::AlignmentIntegral)
@@ -152,12 +151,11 @@ std::tuple<std::vector<Vertex>, Rectangle> renderVerticesInternal(AbstractFont&
             pos != std::string::npos);
 
     /* Vertically align the rendered text */
-    const Float renderedHeight = rectangle.height();
     Float alignmentOffsetY = 0.0f;
     if((UnsignedByte(alignment) & Implementation::AlignmentVertical) == Implementation::AlignmentMiddle)
-        alignmentOffsetY = -renderedHeight*0.5f;
+        alignmentOffsetY = -rectangle.bottom()-rectangle.height()*0.5f;
     else if((UnsignedByte(alignment) & Implementation::AlignmentVertical) == Implementation::AlignmentTop)
-        alignmentOffsetY = -renderedHeight;
+        alignmentOffsetY = -rectangle.top();
 
     /* Integer alignment */
     if(UnsignedByte(alignment) & Implementation::AlignmentIntegral)

src/Text/Test/RendererGLTest.cpp

@@ -94,8 +94,8 @@ void RendererGLTest::renderData() {
     CORRADE_COMPARE(textureCoordinates.size(), 12);
     CORRADE_COMPARE(indices.size(), 18);
 
-    /* Alignment offset */
+    /* Alignment offset. Y would be -0.25f if it wasn't integral */
-    const Vector2 offset{-5.0f, -1.0f};
+    const Vector2 offset{-5.0f, 0.0f};
 
     /* Bounds */
     CORRADE_COMPARE(bounds, Rectangle({0.0f, -0.5f}, {5.0f, 1.0f}).translated(offset));
@@ -173,7 +173,7 @@ void RendererGLTest::renderMesh() {
     MAGNUM_VERIFY_NO_ERROR();
 
     /* Alignment offset */
-    const Vector2 offset{-2.5f, -1.5f};
+    const Vector2 offset{-2.5f, -1.0f};
 
     /* Bounds */
     CORRADE_COMPARE(bounds, Rectangle({0.0f, -0.5f}, {5.0f, 1.0f}).translated(offset));