Stroke styles control the outline appearance of shapes and lines. Adjust stroke width, color, dash patterns, and line endings to create clear, professional diagrams.
Basic Stroke Properties
Stroke Color
The color of the shape's outline.
To change stroke color:
- Select a shape
- Open the Inspector panel
- Find the Stroke section
- Click the stroke color well
- Choose a color from the picker
Like fills, strokes can use solid colors or be linked to color schemes.
Stroke Width
Controls the thickness of the outline.
To adjust stroke width:
- In the Inspector's Stroke section
- Use the Width slider or input field
- Range typically from 0 (no stroke) to 20+ pixels
- Common values:
- 1-2px: Fine outlines, detailed diagrams
- 3-4px: Standard outlines, most diagrams
- 5-8px: Bold outlines, emphasis
- 10+px: Very bold, decorative or presentation use
No Stroke
Remove the stroke entirely:
- In the Stroke section
- Set width to 0 or click No Stroke
- The shape outline disappears
Useful for:
- Filled shapes without borders
- Seamless shape arrangements
- Minimalist diagram styles
Dash Patterns
Create dashed or dotted lines instead of solid strokes.
Predefined Patterns
Diagrammix3 includes common dash patterns:
- Solid - Continuous line (default)
- Dashed - Regular dashes with gaps
- Dotted - Small dots with gaps
- Dash-Dot - Alternating dashes and dots
- Long Dash - Longer dashes, wider gaps
To apply a dash pattern:
- Select a shape or connector
- In the Stroke section of the Inspector
- Click the Dash Pattern dropdown
- Choose a pattern
Custom Dash Patterns
For advanced control, create custom dash patterns:
- Select Custom from the dash pattern menu
- Enter dash and gap lengths (in pixels)
- Pattern format:
[dash, gap, dash, gap, ...] - Example:
[10, 5, 2, 5]creates long dash, gap, dot, gap pattern
Use Cases for Dash Patterns
- Dashed lines: Indicate optional or future elements, temporary connections, boundaries
- Dotted lines: Show hidden or internal relationships, guides, less important connections
- Dash-dot: UML dependencies, architectural boundaries, alternate flows
- Solid lines: Standard, primary connections and shapes
Line Caps
Control how line ends are rendered (primarily for open paths and connectors).
Cap Styles
Butt Cap
- Line ends exactly at the endpoint
- Square, abrupt termination
- Default for most diagrams
Round Cap
- Line ends with a semicircular cap
- Extends slightly beyond endpoint
- Softer, friendlier appearance
Square Cap
- Line ends with a square cap
- Extends slightly beyond endpoint (half the stroke width)
- Precise, architectural look
To change line caps:
- Select a connector or open path
- In the Stroke section
- Click the Line Cap dropdown
- Choose: Butt, Round, or Square
Line Joins
Control how corners are rendered where two path segments meet.
Join Styles
Miter Join
- Creates sharp, pointed corners
- Default for most shapes
- Best for: Rectangles, polygons, angular designs
Round Join
- Creates rounded corners where segments meet
- Softer appearance
- Best for: Organic shapes, friendly diagrams
Bevel Join
- Creates flattened corners
- Cuts off the sharp point
- Best for: Technical diagrams, when miter would be too sharp
To change line joins:
- Select a shape
- In the Stroke section
- Click the Line Join dropdown
- Choose: Miter, Round, or Bevel
Note: Line join is most visible at sharp angles with thick strokes.
Stroke Opacity
Make strokes semi-transparent:
- In the Stroke section
- Adjust the Opacity slider (0-100%)
- 0% = invisible stroke
- 100% = fully opaque
Independent stroke opacity allows:
- Subtle outlines on bold fills
- Ghosted shapes in background
- Layered diagrams with overlapping elements
Color Schemes and Strokes
Link strokes to color schemes:
- In the Stroke section
- Click the Scheme dropdown
- Choose a color role (Border, Accent, etc.)
- Stroke updates when color scheme changes
This ensures consistent stroke colors across your diagram.
Combining Stroke Properties
Professional Combinations
Technical Diagram:
- Width: 2px
- Color: Dark gray or black
- Pattern: Solid
- Cap: Butt
- Join: Miter
Presentation Diagram:
- Width: 4px
- Color: Brand color
- Pattern: Solid
- Cap: Round
- Join: Round
Wireframe/Sketch:
- Width: 3px
- Color: Medium gray
- Pattern: Dashed or dotted
- Cap: Round
- Join: Round
Emphasis Element:
- Width: 6-8px
- Color: Bright accent
- Pattern: Solid
- Cap: Round
- Join: Round
Stroke and Fill Interaction
Strokes render on top of fills, sitting half inside and half outside the shape boundary.
Important implications:
- Wide strokes obscure fill color near the edge
- Transparent fills with strokes create outline-only shapes
- No stroke makes fill extend to true boundary
- Stroke width affects overall shape size slightly
Tips
- Match stroke width to scale - Thinner strokes for detailed diagrams, thicker for presentations
- Use consistent stroke widths - Vary only for emphasis, not randomly
- Contrast with fill - Ensure stroke is visible against fill color
- Dash patterns for meaning - Use consistently (e.g., always dashed for "future state")
- Round caps for friendliness - Sharp caps for technical precision
- Test at final size - Strokes may look different at presentation size vs. editing size
Stroke Performance
- Solid strokes render fastest
- Complex dash patterns are slightly slower
- Very wide strokes (15px+) can impact performance on diagrams with 100+ shapes
- Line joins/caps have minimal performance impact
Accessibility
When choosing stroke styles:
- Ensure contrast - Stroke must be visible against both fill and background
- Don't rely on dash patterns alone - Combine with text labels or other cues
- Minimum 1px width - Thinner strokes may be invisible on some displays
- Test in grayscale - Ensure stroke contrast works without color
Related Topics
- Fill Styles - Shape interior appearance
- Inspector Panel - Detailed property control
- Color Schemes - Theme-based coloring
- Connectors - Connector-specific stroke settings
- Copy & Apply Styles - Transfer styling between shapes