Windows Mobile 6.5 Signature Capture Controls

This article provides an overview of the digital signature capture mechanisms and controls embedded into enterprise field service applications running on Windows Mobile 6.5. During the era of rugged handheld terminals, developers relied on a combination of proprietary OEM developer kits, specialized commercial component suites, and custom-built .NET Compact Framework controls to capture, render, and compress customer signatures on resistive touchscreens.

Native and Custom .NET Compact Framework Controls

Because the standard .NET Compact Framework (versions 2.0 and 3.5) lacked a native, fully featured InkPicture or InkOverlay control like the desktop Tablet PC edition, field service software architects routinely engineered custom controls.

  • Custom GDI+ Drawing Canvases: Developers subclassed System.Windows.Forms.Control or UserControl and intercepted OnMouseDown, OnMouseMove, and OnMouseUp events (which mapped directly to stylus input).
  • Direct Graphics Rendering: Strokes were drawn directly into an off-screen bitmap buffer using System.Drawing.Graphics methods (primarily DrawLine) to eliminate flicker on constrained hardware, before refreshing the screen via OnPaint.
  • Export Utilities: Custom logic converted the in-memory drawing canvas into monochrome or 8-bit BMP, GIF, or JPEG formats, or serialized stroke coordinates as raw vector arrays for lightweight transmission over slow GPRS or 3G networks.

Commercial Third-Party Component Suites

Commercial software vendors frequently integrated pre-built user interface toolkits to reduce development time and ensure reliable rendering performance.

  • Resco MobileForms Toolkit: The Resco.Controls.Signature control was one of the most widely deployed components in mobile field service applications. It offered out-of-the-box support for resistive touchscreens, configurable stroke widths, background watermark lines (such as a "Sign Here" baseline), vector-to-raster conversion, and automatic compression into compact binary strings suitable for slow mobile sync engines.
  • Topaz SigPlus Mobile: Field service solutions utilizing dedicated signature peripherals or advanced electronic signature compliance embedded Topaz Systems’ SigPlus controls (available via ActiveX and .NET CF libraries). This control captured biometric data—including stroke sequence, speed, and point coordinates—rather than simply capturing a flat raster image.
  • ComponentOne Studio for Mobile Devices: Provided drawing and input capture elements tailored for enterprise PDAs, enabling signature capture directly into forms tied to local SQL Server Compact (SQL CE) databases.

Hardware OEM Developer Kits (EMDKs)

Industrial field service deployments ran on specialized rugged handhelds from manufacturers like Motorola/Symbol, Intermec, and Honeywell. Software providers routinely integrated hardware-level signature controls directly from these vendors.

  • Motorola / Symbol EMDK: Provided native Win32/C++ libraries and .NET CF wrappers that interacted directly with the digitizer driver. The kit included high-performance signature capture sample controls and APIs designed to capture stylus input at higher sampling rates than standard WinForms events could process.
  • Intermec Developer Toolkit (IDT): Intermec provided dedicated data collection controls that included signature capture modules. These controls allowed applications running on devices like the CN3 or CN50 to capture signatures with automated bounding-box trimming and hardware-accelerated image compression.
  • Honeywell Dolphin SDK: Included specific touch-panel signature capture dialogs and embedded controls that presented a modal or embedded signature box, returning the captured image directly as an encoded string or saving it to the persistent device storage.