progress using my own graphics interface

internal/graphics/graphics.go

@@ -3,9 +3,83 @@ package graphics
 import (
 	"fmt"
 	"math/rand"
+	"image/color"
 	rl "github.com/gen2brain/raylib-go/raylib"
 )
 
+type Graphics struct {
+	layout Layout 
+	style Style
+}
+
+type Layout struct {
+	// total monitor bounds
+	Monitor Rect
+	// bounds of the application window
+	Window Rect
+	// bounds of the ui controls area
+	Controls Rect
+	// bounds of the region of the app window reserved for rendering the graphics buffer
+	Viewport Rect
+	// bounds of the off screen graphics buffer where rendering happens
+	Graphics Rect
+}
+
+type Color color.RGBA
+
+type HSBA struct {
+	H uint
+	S, B float32
+	A uint8
+}
+
+type Style struct {
+	StrokeColor Color
+	StrokeWeight float32
+	FillColor Color
+}
+
+type Rect rl.Rectangle
+
+/**
+ * scale the given rect down to the target rect
+ * maintaining the aspect ratio of the original rect
+ */
+func (r Rect) ToRL() *rl.Rectangle {
+	return &rl.Rectangle { X: r.X, Y: r.Y, Width: r.Width, Height: r.Height }
+}
+
+func (r Rect) ScaleTo(tgt Rect) Rect {
+
+	outputWidth := tgt.Width
+	outputHeight := tgt.Height
+
+	aspect := r.Width / r.Height
+	tgtAspect := outputWidth / outputHeight
+
+	if aspect < tgtAspect {
+		// source is relatively taller than the target
+		// so we set the output height to the target height
+		// and calculate the width based on source aspect and center
+		outputWidth = float32(outputHeight) * aspect
+	} else {
+		// source is relatively wider than the target
+		// so we set the output width to the target width
+		// and calculate the height based on source aspect and center
+		outputHeight = float32(outputWidth) / aspect
+	}
+
+	// output width and height are correct -- center within TargetBounds
+	x := tgt.X + tgt.Width / 2.0 - outputWidth / 2.0 
+	y := tgt.Y + tgt.Height / 2.0 - outputHeight / 2.0 
+
+	return Rect {
+		X: x, Y: y,
+		Width: outputWidth,
+		Height: outputHeight,
+	}
+}
+
 var (
 	FlourescentHues = []float32{
 		0,   // hot magenta-red