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Scanned Paper Form Sample

Scanned Paper Form Sample

Description of the scanned paper form sample for the Tablet PC.

In this C# sample, a paper form has been scanned as a Portable Network Graphics (PNG) file and specified as the background image at run time for an InkPicture control. The sample uses a message box to display handwriting recognition results.

The sample includes an Extensible Markup Language (XML) file, Formdata.xml. The XML file contains the name of the PNG file. It also contains FieldInfo elements that define rectangular regions on the form where a user can enter ink. The information in the FieldInfo element is shown in the following example:

    <FieldInfo>
        <Name>first name</Name>
        <Left>88</Left>
        <Top>65</Top>
        <Right>332</Right>
        <Bottom>94</Bottom>
    </FieldInfo>

The Left, Top, Right, and Bottom elements are definitions of pixel coordinates for each field.

The sample initializes a new DataSet Leave Site with the data contained in Formdata.xml:

    formData = new DataSet("FormData");
    formData.ReadXml("formdata.xml"); 

The form image specified in Formdata.xml is loaded as the background of the InkPicture control:

    inkPicture1.BackgroundImage =
        System.Drawing.Image.FromFile(
        (string) formData.Tables["FormData"].Rows[0]["Image"]);

Ink collection is then enabled for the InkPicture control:

    inkPicture1.InkEnabled = true;

Menu Event Handlers

The application includes click event handlers for all of the menus displayed along the top of the form.

Recognize Menu Item

The Recognize menu click event handler disables ink collection for the control and checks for a handwriting recognizer. If no recognizer is installed, a dialog box is displayed. A user must then click the Ink or Pen menu option to re-enable the control for ink input.

If a recognizer is installed, the Recognize function retrieves the XML data that specifies pixel coordinates for each form field. The coordinates are converted to ink space coordinates, and a rectangle is defined for each form field. After rectangles are defined, the function finds the strokes that intersect and lie within each rectangle. Finally, it performs recognition on the ink and displays the results in a message box.

Ink Menu Item

The Ink menu click event handler enables the InkPicture control.

Pen Menu Item

The Pen menu click event handler performs the following tasks:

  • Disables ink collection for the InkPicture control (which is necessary before changing the EditingMode property).
  • Sets the EditingMode property to collect ink.
  • Re-enables ink collection for the InkPicture control and toggles the Pen, Select, and Eraser menus to indicate the active mode.

Edit Menu Item

The Edit menu click event handler is similar to the Pen menu event handler. It performs the following tasks:

  • Disables ink collection.
  • Sets the EditingMode property to Select, which enables the user to perform ink selection.
  • Re-enables ink collection and toggles the Pen, Edit, and Eraser menus to indicate the active mode.

Eraser Menu Item

The Eraser menu click event handler sets the InkPicture control EditingMode to Delete, which enables a user to erase ink. It also toggles the Pen, Edit, and Eraser menu items.

Clear Menu Item

The Clear menu click event handler deletes the current Strokes collection for the InkPicture control, thereby erasing all of the ink on the form.

Closing the Form

In the Windows Form Designer generated code, the InkPicture control is added to the form's component list when the form is initialized. When the form closes, the InkPicture control is disposed, as well as the other components of the form, by the form's Dispose Leave Site method.

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