Calendar Painting Pipeline

Overview

Calendar rendering is decomposed across 11 partial files plus a 9-file LayoutTheme subsystem. The architecture uses a centralized dispatcher method Paint() that chooses between a new style-based painter system (_usePainterSystem) and a legacy renderer fallback (DrawWithLegacyRenderer). At design time in Visual Studio, the calendar renders a simplified preview instead.

Paint Dispatcher

// Centralized entry point called from DrawContent and Draw:
private void Paint(Graphics g, Rectangle bounds)
{
    if (IsDesignModeSafe)
        DrawDesignTimePreview(g, bounds);       // VS designer placeholder
    else if (_usePainterSystem && _stylePainter != null)
        DrawWithPainter(g, contentRect);        // New style-based system
    else
        DrawWithLegacyRenderer(g, contentRect);  // Legacy fallback
}

// Entry points from BaseControl framework:
protected override void DrawContent(Graphics g)
    => Paint(g, DrawingRect);

public override void Draw(Graphics graphics, Rectangle rectangle)
    => Paint(graphics, rectangle);

View Renderers

View Rendering Details

Month View

Renders a 7x5 or 7x6 grid of day cells. Each cell contains: day number (top-left), event blocks (colored by category), "+N more" indicator for overflow. Events that span multiple days are rendered across consecutive cells. The current cell's category colors come from LayoutTheme.MonthCells.cs.

Week / Day View

Time slots are rendered at 30 or 60 minute intervals depending on DensityMode. The current time line (red) is drawn when the view contains today. Event blocks are positioned absolutely within the time grid, with their top offset proportional to start time and height proportional to duration. Events that overlap share column width equally.

List View

Events displayed chronologically in a single scrollable list. Each row: date header (group separator), time column (left), event title (center), location and category badge (right). Multi-day events span multiple entries with a "continues" indicator.

Design-Time Preview

Controlled by BeepCalendar.Painting.DesignTime.cs. When IsDesignModeSafe returns true (hosted in Visual Studio designer):

• Renders a simplified month grid for the current month
• 2-3 sample events spanning multiple days with sample titles
• Today cell highlighted with accent color
• No interaction support — static preview only
• Uses placeholder data, no real event model required

Sidebar Calendar

When ShowSidebar is true, BeepCalendar.Painting.Sidebar.cs renders a compact mini-calendar in a narrow sidebar panel (~200px):

• One month displayed at a time with abbreviated day-of-week headers (S M T W T F S)
• Navigation arrows (</>) to scroll months forward/backward
• Dot indicator beneath days that have one or more events
• Today date highlighted with a colored circle
• Clicking a date in the sidebar navigates the main view to that date

LayoutTheme Subsystem (9 Files)

Visual Updates

3 files manage rendering performance via scoped invalidation:

• VisualUpdates.Flush.cs — Full redraw of the entire calendar surface via Invalidate()
• VisualUpdates.Scope.cs — Partial invalidation: only redraws the area containing a changed event for better performance during drag operations
• VisualUpdates.Strategy.cs — Dirty-rect tracking optimization: maintains a union of dirty rectangles to avoid redundant repaints

Code Examples

// Switch view modes
cal.ViewMode = CalendarViewMode.Month;    // 7-column grid
cal.ViewMode = CalendarViewMode.Week;     // 7-day + hourly slots
cal.ViewMode = CalendarViewMode.Day;      // Single day
cal.ViewMode = CalendarViewMode.Agenda;   // Event list

// Density modes
cal.DensityMode = CalendarDensityMode.Compact;     // Smaller fonts, tight
cal.DensityMode = CalendarDensityMode.Comfortable; // Larger fonts, spaced

// Sidebar
cal.ShowSidebar = true;  // Compact mini-calendar panel