init

internal/renderer/renderer.go

@@ -0,0 +1,237 @@
+package renderer
+
+import (
+	"github.com/kevin/go-jdenticon/internal/engine"
+)
+
+// Renderer defines the interface for rendering identicons to various output formats.
+// It provides a set of drawing primitives that can be implemented by concrete renderers
+// such as SVG, PNG, or other custom formats.
+type Renderer interface {
+	// Drawing primitives
+	MoveTo(x, y float64)
+	LineTo(x, y float64)
+	CurveTo(x1, y1, x2, y2, x, y float64)
+	ClosePath()
+	
+	// Fill and stroke operations
+	Fill(color string)
+	Stroke(color string, width float64)
+	
+	// Shape management
+	BeginShape(color string)
+	EndShape()
+	
+	// Background and configuration
+	SetBackground(fillColor string, opacity float64)
+	
+	// High-level shape methods
+	AddPolygon(points []engine.Point)
+	AddCircle(topLeft engine.Point, size float64, invert bool)
+	AddRectangle(x, y, width, height float64)
+	AddTriangle(p1, p2, p3 engine.Point)
+	
+	// Utility methods
+	GetSize() int
+	Clear()
+}
+
+// BaseRenderer provides default implementations for common renderer functionality.
+// Concrete renderers can embed this struct and override specific methods as needed.
+type BaseRenderer struct {
+	iconSize     int
+	currentColor string
+	background   string
+	backgroundOp float64
+	
+	// Current path state for primitive operations
+	currentPath []PathCommand
+	pathStart   engine.Point
+	currentPos  engine.Point
+}
+
+// PathCommandType represents the type of path command
+type PathCommandType int
+
+const (
+	MoveToCommand PathCommandType = iota
+	LineToCommand
+	CurveToCommand
+	ClosePathCommand
+)
+
+// PathCommand represents a single drawing command in a path
+type PathCommand struct {
+	Type   PathCommandType
+	Points []engine.Point
+}
+
+// NewBaseRenderer creates a new base renderer with the specified icon size
+func NewBaseRenderer(iconSize int) *BaseRenderer {
+	return &BaseRenderer{
+		iconSize:    iconSize,
+		currentPath: make([]PathCommand, 0),
+	}
+}
+
+// MoveTo moves the current drawing position to the specified coordinates
+func (r *BaseRenderer) MoveTo(x, y float64) {
+	pos := engine.Point{X: x, Y: y}
+	r.currentPos = pos
+	r.pathStart = pos
+	r.currentPath = append(r.currentPath, PathCommand{
+		Type:   MoveToCommand,
+		Points: []engine.Point{pos},
+	})
+}
+
+// LineTo draws a line from the current position to the specified coordinates
+func (r *BaseRenderer) LineTo(x, y float64) {
+	pos := engine.Point{X: x, Y: y}
+	r.currentPos = pos
+	r.currentPath = append(r.currentPath, PathCommand{
+		Type:   LineToCommand,
+		Points: []engine.Point{pos},
+	})
+}
+
+// CurveTo draws a cubic Bézier curve from the current position to (x, y) using (x1, y1) and (x2, y2) as control points
+func (r *BaseRenderer) CurveTo(x1, y1, x2, y2, x, y float64) {
+	endPos := engine.Point{X: x, Y: y}
+	r.currentPos = endPos
+	r.currentPath = append(r.currentPath, PathCommand{
+		Type: CurveToCommand,
+		Points: []engine.Point{
+			{X: x1, Y: y1},
+			{X: x2, Y: y2},
+			endPos,
+		},
+	})
+}
+
+// ClosePath closes the current path by drawing a line back to the path start
+func (r *BaseRenderer) ClosePath() {
+	r.currentPos = r.pathStart
+	r.currentPath = append(r.currentPath, PathCommand{
+		Type:   ClosePathCommand,
+		Points: []engine.Point{},
+	})
+}
+
+// Fill fills the current path with the specified color
+func (r *BaseRenderer) Fill(color string) {
+	// Default implementation - concrete renderers should override
+}
+
+// Stroke strokes the current path with the specified color and width
+func (r *BaseRenderer) Stroke(color string, width float64) {
+	// Default implementation - concrete renderers should override
+}
+
+// BeginShape starts a new shape with the specified color
+func (r *BaseRenderer) BeginShape(color string) {
+	r.currentColor = color
+	r.currentPath = make([]PathCommand, 0)
+}
+
+// EndShape ends the current shape
+func (r *BaseRenderer) EndShape() {
+	// Default implementation - concrete renderers should override
+}
+
+// SetBackground sets the background color and opacity
+func (r *BaseRenderer) SetBackground(fillColor string, opacity float64) {
+	r.background = fillColor
+	r.backgroundOp = opacity
+}
+
+// AddPolygon adds a polygon to the renderer using the current fill color
+func (r *BaseRenderer) AddPolygon(points []engine.Point) {
+	if len(points) == 0 {
+		return
+	}
+	
+	// Move to first point
+	r.MoveTo(points[0].X, points[0].Y)
+	
+	// Line to subsequent points
+	for i := 1; i < len(points); i++ {
+		r.LineTo(points[i].X, points[i].Y)
+	}
+	
+	// Close the path
+	r.ClosePath()
+	
+	// Fill with current color
+	r.Fill(r.currentColor)
+}
+
+// AddCircle adds a circle to the renderer using the current fill color
+func (r *BaseRenderer) AddCircle(topLeft engine.Point, size float64, invert bool) {
+	// Approximate circle using cubic Bézier curves
+	// Magic number for circle approximation with Bézier curves
+	const kappa = 0.5522847498307936 // 4/3 * (sqrt(2) - 1)
+	
+	radius := size / 2
+	centerX := topLeft.X + radius
+	centerY := topLeft.Y + radius
+	
+	cp := kappa * radius // Control point distance
+	
+	// Start at rightmost point
+	r.MoveTo(centerX+radius, centerY)
+	
+	// Four cubic curves to approximate circle
+	r.CurveTo(centerX+radius, centerY+cp, centerX+cp, centerY+radius, centerX, centerY+radius)
+	r.CurveTo(centerX-cp, centerY+radius, centerX-radius, centerY+cp, centerX-radius, centerY)
+	r.CurveTo(centerX-radius, centerY-cp, centerX-cp, centerY-radius, centerX, centerY-radius)
+	r.CurveTo(centerX+cp, centerY-radius, centerX+radius, centerY-cp, centerX+radius, centerY)
+	
+	r.ClosePath()
+	r.Fill(r.currentColor)
+}
+
+// AddRectangle adds a rectangle to the renderer
+func (r *BaseRenderer) AddRectangle(x, y, width, height float64) {
+	points := []engine.Point{
+		{X: x, Y: y},
+		{X: x + width, Y: y},
+		{X: x + width, Y: y + height},
+		{X: x, Y: y + height},
+	}
+	r.AddPolygon(points)
+}
+
+// AddTriangle adds a triangle to the renderer
+func (r *BaseRenderer) AddTriangle(p1, p2, p3 engine.Point) {
+	points := []engine.Point{p1, p2, p3}
+	r.AddPolygon(points)
+}
+
+// GetSize returns the icon size
+func (r *BaseRenderer) GetSize() int {
+	return r.iconSize
+}
+
+// Clear clears the renderer state
+func (r *BaseRenderer) Clear() {
+	r.currentPath = make([]PathCommand, 0)
+	r.currentColor = ""
+	r.background = ""
+	r.backgroundOp = 0
+}
+
+// GetCurrentPath returns the current path commands
+func (r *BaseRenderer) GetCurrentPath() []PathCommand {
+	return r.currentPath
+}
+
+// GetCurrentColor returns the current drawing color
+func (r *BaseRenderer) GetCurrentColor() string {
+	return r.currentColor
+}
+
+// GetBackground returns the background color and opacity
+func (r *BaseRenderer) GetBackground() (string, float64) {
+	return r.background, r.backgroundOp
+}