The text displayed by a shape is represented by the NTextBlock class an instance of which can be obtained from the TextBlock property of each shape. The currently displayed text is controlled by the Text property of the text block. The shape also has a shortcut Text property, which allows you to display a string inside any shape like this:

NShape shape;
// ...
shape.Text = "NOV Diagram Rocks";

The text block has its own coordinate system. This means that the text block content is transformed with a certain transformation prior to be displayed.

A common requirement is to move the text block of a shape below its geometry. To do that, after setting the text of the shape, you should call the MoveTextBlockBelowShape of the NShape class:

shape.Text = "My Shape";
shape.MoveTextBlockBelowShape();

The properties that control the text block transformation can be logically separated in three categories:

• Local Pin Point
  The local pin point is a point in the text block coordinate system, which defines the point from the text block that is mapped to the text block location in shape coordinates – the pin point.
  
  LocPinX, LocPinY – specify the X and Y location of the local pin point. The local pin point is in either text block “local” or “local relative” coordinates as indicated by the LocPinRelative property. The GetLocPinPoint and SetLocPinPoint methods help you get and set the local pin point in text block “local” coordinates (i.e. perform the relative to local scaling for you if needed).
  LocPinRelative – indicates whether the local pin point is in text block “local” or “local relative coordinates”.             
  
  Typically the LocPinX and LocPinY are set to 0.5 and the LocPinRelative property is set to true. This is equivalent to binding the local pin point to the center of the text block Width/Height box.
• Pin Point
  The pin point is a point in shape coordinates, that defines the position of the text block inside the shape. When the text block local pin point is projected with the text block  transform, it is projected in the pin point. That is why the modification of the pin point is associated with the text block translation.
  
  The Pin point is specified by the PinX and PinY properties. The GetPinPoint and SetPinPoint methods help you modify the pin point (both methods work in shape coordinates). The SetPinPoint method binds the PinX and PinY properties to a point relative to the owner shape Width and Height. In this way when the owner shape is resized, the text block will preserve its relative position.
  
• Rotation
  The Angle property defines the rotation of the text block relative to the pin point.
  The text block transformation is always orthogonal, meaning that any two perpendicular vectors from the text block local coordinates remain perpendicular when transformed to shape coordinates.
  The text block transformation is also never a scaling transformation. This means that the distance between any two points in local coordinates will remain the same when these points are transformed to shape coordinates.

In order to function properly the text block transformation needs to be initialized first. The InitXForm method helps you properly initialize the transformation and resize behavior of the text block. The method takes a single parameter from the ENTextBlockXForm enumeration. Following is a description of the available options: 

ShapeBox
Sets the ResizeMode property to ShapeSize (i.e. resizes the text block to the shape).
Binds the pin to the middle of the shape.
Sets the Angle to zero.

ShapeLineMiddle
Sets the ResizeMode property to TextSize (i.e. resizes the text block to the size of its text).
Binds the pin to the middle of the shape line (the line connecting the Begin and End points of the shape).
Binds the angle to the shape line angle.

GeometryContourMiddle
Sets the ResizeMode property to TextSize (i.e. resizes the text block to the size of its text).
Binds the pin to the middle of the geometry contour (outline).
Binds the angle to the shape geometry contour angle in the middle.

CustomPin
Sets the ResizeMode property to TextSize (i.e. resizes the text block to the size of its text).
Leaves the PinX and PinX to be specified by the user.
Sets the angle to zero.

All types of text block transform bind the local pin point to the text block center.

If the shape transform is not explicitly initialized, NOV Diagram will perform automatic transform initialization, when the text block element is requested for the first time. The transform initialization is different for 1D and 2D shapes:

In many cases it is required to keep the text displayed by the text block with upward orientation. When the text block KeepUpward property is set to true, NOV Diagram internally applies such a transform to the text, so that its  Up vector is always oriented towards the top of the screen. This greatly increases the readability of diagrams.

The text block Width and Height control size of the text block. The Width and Height of the text block can be automatically computed based on the ResizeMode property, that accepts values from the ENTextBlockResizeMode enumeration:

• None - the text block is not automatically resized. It is up to the developer to specify either a fixed text block size or write expressions that define the text block Width and Height.

• ShapeSize - the text block Width and Height are bound to the owner shape Width and Height (i.e. the text block is resized to the shape).

• TextSize - the text block Width and Height are bound to the text block DesiredWidth and DesiredHeight, that are automatically calculated to the measured size of the text block (i.e. the text block is sized to the natural size of its content).

Below is a reference of the properties that affect the appearance of the text block:

The text block also supports rich formatted text which means that it can display text with mixed font style, font size, appearance etc. In fact the text block content has the full functionality of the Nevron NOV Rich Text control except the support for sections. The following code snippet shows how to add rich formatted text to a text block:

NParagraph paragraph = new NParagraph();
NTextInline textInline1 = new NTextInline("This paragraph contains text inlines with altered ");
paragraph.Inlines.Add(textInline1);
NTextInline textInline2 = new NTextInline("Font Name, ");
textInline2.FontName = "Tahoma";
paragraph.Inlines.Add(textInline2);
NTextInline textInline3 = new NTextInline("Font Size, ");
textInline3.FontSize = 14;
paragraph.Inlines.Add(textInline3);
NTextInline textInline4 = new NTextInline("Font Style (Bold), ");
textInline4.FontStyle |= ENFontStyle.Bold;
paragraph.Inlines.Add(textInline4);
NTextInline textInline5 = new NTextInline("Font Style (Italic), ");
textInline5.FontStyle |= ENFontStyle.Italic;
paragraph.Inlines.Add(textInline5);
NTextInline textInline6 = new NTextInline("Font Style (Underline), ");
textInline6.FontStyle |= ENFontStyle.Underline;
paragraph.Inlines.Add(textInline6);
NTextInline textInline7 = new NTextInline("Font Style (StrikeTrough) ");
textInline7.FontStyle |= ENFontStyle.Strikethrough;
paragraph.Inlines.Add(textInline7);
NTextInline textInline8 = new NTextInline("and Font Style All.");
textInline8.FontStyle = ENFontStyle.Bold | ENFontStyle.Italic | ENFontStyle.Underline | ENFontStyle.Strikethrough;
paragraph.Inlines.Add(textInline8);
someShape.TextBlock.Content.Blocks.Clear();
someShape.TextBlock.Content.Blocks.Add(paragraph);

For a full list of the features supported by Nevron NOV Rich Text control please consult with the control documentation.