Draw-Signature-using-GraphicsView-in-.NET-MAUI

This sample demonstrates how to capture a handwritten signature inside a .NET MAUI application using the cross-platform GraphicsView control. The GraphicsView provides a drawable canvas that can respond to touch and pointer input, making it ideal for implementing signature pads, sketching surfaces, annotation tools, and any other free-hand drawing scenarios on iOS, Android, macOS (via Mac Catalyst), and Windows.

Overview

The .NET MAUI GraphicsView is a versatile view that hosts an IDrawable and renders it through the Microsoft.Maui.Graphics APIs. By combining GraphicsView with touch and pointer events, you can build a fully functional signature pad without relying on platform-specific code. This example walks through the complete implementation: creating a custom drawable to store and render the signature strokes, wiring up touch/pointer events to translate finger or stylus movements into path data, and exposing commands to clear or export the captured signature.

Prerequisites

To run this sample, you need the following installed on your development machine:

• Visual Studio 2026 (18.0 or later) with the .NET Multi-platform App UI development workload.
• .NET 6.0 SDK (or a newer Long-Term Support release supported by .NET MAUI).
• A configured build target for Android, iOS, Mac Catalyst (macOS only), or Windows.
• For iOS/Mac Catalyst builds: Xcode 15 or later installed on the Mac.
• For Android builds: an Android SDK and an emulator or physical device.

Project Structure

The solution is organized into a single .NET MAUI project that contains:

• SignatureView.cs – The custom GraphicsView subclass that captures pointer events, accumulates the signature path, and triggers a redraw whenever a new stroke is recorded. It also exposes a Clear method to reset the canvas.
• MainPage.xaml and MainPage.xaml.cs – The page that hosts the SignatureView, along with a Clear button to erase the canvas and a sample label describing the gesture.
• App.xaml, App.xaml.cs, and AppShell.xaml – Standard .NET MAUI application bootstrap and navigation shell.
• MauiProgram.cs – The application entry point that configures fonts, services, and the MAUI builder pipeline.
• Platforms/ – Platform-specific resources and entry points for Android, iOS, Mac Catalyst, Tizen, and Windows.
• Resources/ – Fonts, images, splash screen, and shared styles used throughout the app.

How the Signature Capture Works

1. Custom IDrawable: A small drawable class keeps a list of polylines (one per stroke). When the framework calls its Draw method, it iterates through the stored paths and renders them using a Path builder, producing smooth, anti-aliased strokes.
2. Touch/pointer capture: The SignatureView listens for StartInteraction, MoveInteraction, and EndInteraction events. Each event receives a Point in the view's coordinate space, which is appended to the active stroke.
3. Invalidation: After every move event, the view calls Invalidate(), prompting the GraphicsView to redraw the canvas with the updated path data.
4. Clear operation: The Clear method empties the stored paths and invalidates the view, restoring a blank canvas ready for a new signature.

Running the Sample

1. Clone or download this repository to your local machine.
2. Open the 2DGraphicsDrawing.sln file in Visual Studio 2026.
3. Restore the NuGet packages by right-clicking the solution and selecting Restore NuGet Packages.
4. Select your desired target framework from the run configuration dropdown (for example, net6.0-android, net6.0-ios, or net6.0-windows10.0.19041.0).
5. Choose an emulator, simulator, or connected device, then press F5 (or click the run button) to build and deploy the application.
6. Draw on the canvas with your finger, stylus, or mouse to create a signature, then tap Clear to start over.

Key Concepts Illustrated

• Cross-platform drawing surface: Using GraphicsView as a single API for drawing across all .NET MAUI targets.
• Microsoft.Maui.Graphics primitives: Creating Path objects, applying stroke thickness, line caps, and joins, and rendering them through ICanvas.
• Pointer interaction handling: Converting user input into a series of points and persisting them as a drawable model.
• MVVM-friendly separation: Keeping drawing state inside a reusable view that can be embedded in any page or view model.

Extending the Sample

Once the basic signature pad is working, you can extend the project in several useful directions:

• Save the signature as an image: Render the drawable to a Microsoft.Maui.Graphics.Platform.PlatformImage and write it to disk or stream it to a backend service.
• Add export options: Provide buttons to save the signature as PNG or SVG, copy it to the clipboard, or share it via the system share sheet.
• Stroke customization: Expose properties for stroke color, thickness, and smoothing so users can personalize their signature.
• Undo/redo support: Maintain a history of strokes and add commands to step backwards or forwards through the captured paths.
• Validation: Enforce a minimum number of strokes or points before allowing a signature to be submitted.

Troubleshooting

• If the project fails to build, ensure the .NET MAUI workload is installed by running dotnet workload install maui from a terminal.
• On Windows, confirm that the Windows App SDK and required Visual Studio components are present.
• For Android emulator issues, verify that hardware acceleration is enabled and that the emulator image matches your project's target framework.
• If touch input is not registered, make sure the SignatureView is not wrapped inside a scrollable container that might intercept the gestures.

Blog Reference

For a detailed walkthrough of the concepts used in this sample, refer to the Syncfusion blog post:

How to Draw 2D Graphics in .NET MAUI’s GraphicsView

Related Resources

• .NET MAUI documentation
• Microsoft.Maui.Graphics overview
• Syncfusion .NET MAUI controls

License

This sample is provided as a learning resource alongside the Syncfusion blog post. Refer to the repository's license file for redistribution terms.