# Conversion

In iink SDK terminology, “conversion” refers to the replacement of some handwritten content by a clean, typeset equivalent.

## Conversion vs. recognition

Conversion is an explicit action you can trigger to replace ink content with a typeset equivalent. It is different from the recognition process it relies on, which runs in background and interprets any input, making it interactive.

You can convert any content block by calling the convert:targetState:error: method of your editor object.

## Target state

When calling convert:targetState:error:, you are expected to provide the target state you want to reach:

• DigitalPublish - Typeset content, adapted for publication (small font size, and fitted graphics in the case of a Text Document),
• DigitalEdit - Typeset content, suitable for edition (font size that is large enough for editing, expanded graphics).
You can convert back and forth between the DigitalPublish and DigitalEdit states.

## Computing font metrics

To convert your text content, iink SDK needs to have information about the font you use, which itself depends on your styling options. To do so, it requires you to attach to your editor an object conforming to the IINKIFontMetricsProvider protocol using setFontMetricsProvider:.

As implementing a font metrics provider is a rather touchy task, MyScript provides you via the iink SDK example repository with a reference implementation.

If you rely on the reference implementation, registering an editor with the editor view automatically attaches a font metrics provider to your editor.

## Application to the example

You can add a button to the example calculator to trigger the conversion. As previously explained, associating the editor view with the editor automatically attaches a font metrics provider.

As a math part is composed of a single block (hosting the math content), you can select it using the rootBlock property of the editor. If pressing the “solve” button of the UI calls a solve: method of the Calculator object, an implementation can be:

- (IBAction)solve:(id)sender
{
[self.editor convert:self.editor.rootBlock
targetState:IINKConversionStateDigitalEdit
error:nil];
}
As you are dealing with math content and did not deactivate the solver, converting the math will trigger solving, if the required conditions are in place.

Here is an example of what it could look like:

The next step of the guide will take you through the ability to import or export content.