Agent skill
maui-graphics-drawing
Guidance for custom drawing with Microsoft.Maui.Graphics, GraphicsView, canvas drawing operations, shapes, paths, text rendering, image drawing, shadows, clipping, and canvas state management. USE FOR: "custom drawing", "GraphicsView", "canvas drawing", "draw shapes", "draw path", "draw text", "ICanvas", "IDrawable", "shadows", "clipping", "Microsoft.Maui.Graphics". DO NOT USE FOR: view animations (use maui-animations), gesture handling on drawn elements (use maui-gestures), or app icons (use maui-app-icons-splash).
Install this agent skill to your Project
npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/other/other/maui-graphics-drawing
SKILL.md
.NET MAUI Graphics Drawing
Use this skill when implementing custom drawing in .NET MAUI apps using Microsoft.Maui.Graphics and GraphicsView.
GraphicsView and IDrawable
GraphicsView is the canvas host control. Assign an IDrawable implementation to its Drawable property.
<GraphicsView Drawable="{StaticResource myDrawable}"
HeightRequest="300"
WidthRequest="300" />
public class MyDrawable : IDrawable
{
public void Draw(ICanvas canvas, RectF dirtyRect)
{
// All drawing happens here
}
}
ICanvasprovides all drawing methods.RectF dirtyRectis the area that needs redrawing.- Call
graphicsView.Invalidate()to trigger a redraw from outside the drawable.
Drawing Shapes
Lines
canvas.StrokeColor = Colors.Blue;
canvas.StrokeSize = 2;
canvas.DrawLine(10, 10, 200, 10);
Rectangles
canvas.StrokeColor = Colors.Black;
canvas.DrawRectangle(10, 10, 100, 50);
canvas.FillColor = Colors.LightBlue;
canvas.FillRectangle(10, 10, 100, 50);
canvas.DrawRoundedRectangle(10, 10, 100, 50, 12);
canvas.FillRoundedRectangle(10, 10, 100, 50, 12);
Ellipses
canvas.DrawEllipse(10, 10, 100, 80);
canvas.FillEllipse(10, 10, 100, 80);
Arcs
canvas.DrawArc(10, 10, 100, 100, 0, 180, clockwise: true, closed: false);
Paths with PathF
Use PathF for complex shapes built from segments.
var path = new PathF();
path.MoveTo(10, 10);
path.LineTo(100, 10);
path.LineTo(100, 100);
path.QuadTo(50, 150, 10, 100); // control point, end point
path.CubicTo(0, 80, 0, 40, 10, 10); // cp1, cp2, end
path.Close();
canvas.StrokeColor = Colors.Red;
canvas.DrawPath(path);
canvas.FillColor = Colors.Orange;
canvas.FillPath(path);
MoveTo(x, y)— move without drawing.LineTo(x, y)— straight line to point.QuadTo(cx, cy, x, y)— quadratic Bézier curve.CubicTo(c1x, c1y, c2x, c2y, x, y)— cubic Bézier curve.Close()— close the path back to the start.
Drawing Text
canvas.FontColor = Colors.Black;
canvas.FontSize = 18;
canvas.Font = Microsoft.Maui.Graphics.Font.Default;
// DrawString with bounding rect and alignment
canvas.DrawString("Hello", 10, 10, 200, 40,
HorizontalAlignment.Center,
VerticalAlignment.Center);
// DrawString at a point (no bounding box)
canvas.DrawString("World", 10, 60, HorizontalAlignment.Left);
- Set
FontColor,FontSize, andFontbefore callingDrawString. - Overloads accept either a point or a bounding rectangle with alignment.
Canvas State Properties
Set these properties before draw calls to control appearance.
Stroke
canvas.StrokeColor = Colors.Navy;
canvas.StrokeSize = 4;
canvas.StrokeDashPattern = new float[] { 6, 3 }; // dash, gap
canvas.StrokeLineCap = LineCap.Round; // Butt, Round, Square
canvas.StrokeLineJoin = LineJoin.Round; // Miter, Round, Bevel
canvas.FillColor = Colors.CornflowerBlue;
Shadows
canvas.SetShadow(
offset: new SizeF(5, 5),
blur: 4,
color: Colors.Gray);
canvas.FillRectangle(20, 20, 100, 60); // drawn with shadow
canvas.SetShadow(SizeF.Zero, 0, null); // remove shadow
Clipping
Restrict drawing to a region.
// Clip to rectangle
canvas.ClipRectangle(20, 20, 100, 100);
// Clip to arbitrary path
var clipPath = new PathF();
clipPath.AppendCircle(80, 80, 50);
canvas.ClipPath(clipPath);
// Subtract a region from the current clip
canvas.SubtractFromClip(40, 40, 30, 30);
Canvas State Management
Use SaveState / RestoreState to isolate drawing settings.
canvas.SaveState();
canvas.StrokeColor = Colors.Red;
canvas.StrokeSize = 6;
canvas.DrawRectangle(10, 10, 80, 80);
canvas.RestoreState();
// StrokeColor, StrokeSize, clip, shadow, etc. are restored
- Always pair
SaveStateandRestoreState. - Saves/restores: stroke, fill, font, shadow, clip, and transforms.
- Nest calls for layered state isolation.
Triggering Redraws
graphicsView.Invalidate();
Invalidate()queues a redraw; the framework callsIDrawable.Drawon the next frame.- Do not call
Drawdirectly; always useInvalidate(). - Avoid calling
Invalidate()in a tight loop; batch state changes before invalidating.
Quick Reference
| Method / Property | Purpose |
|---|---|
DrawLine |
Stroke a line between two points |
DrawRectangle / FillRectangle |
Stroke or fill a rectangle |
DrawRoundedRectangle / FillRoundedRectangle |
Rounded-corner rectangle |
DrawEllipse / FillEllipse |
Stroke or fill an ellipse |
DrawArc |
Stroke an arc segment |
DrawPath / FillPath |
Stroke or fill a PathF |
DrawString |
Render text with alignment |
SetShadow |
Apply drop shadow to subsequent draws |
ClipRectangle / ClipPath |
Restrict drawing region |
SubtractFromClip |
Remove area from clip |
SaveState / RestoreState |
Push/pop canvas state |
graphicsView.Invalidate() |
Request a redraw |
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