From 05a5e683ffc873418efc3f6b22f01102558b3afc Mon Sep 17 00:00:00 2001
From: Chris Watson <cawatson1993@gmail.com>
Date: Wed, 20 Nov 2024 05:17:53 -0700
Subject: [PATCH] =?UTF-8?q?=E2=9C=A8=20feat:=20add=20gradient=20background?=
 =?UTF-8?q?=20support=20with=20multiple=20gradient=20types?=
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The commit adds support for various gradient backgrounds including linear,
radial, angular, diamond, spiral, square, and star patterns. Each gradient
can be customized with stops, angle, center position and intensity.
---
 cmd/goshot/main.go         | 85 ++++++++++++++++++++++++++++++++++++++
 pkg/background/gradient.go |  5 ++-
 2 files changed, 89 insertions(+), 1 deletion(-)

diff --git a/cmd/goshot/main.go b/cmd/goshot/main.go
index f4b3824..c60097a 100644
--- a/cmd/goshot/main.go
+++ b/cmd/goshot/main.go
@@ -41,6 +41,14 @@ var (
 	windowTitle        string
 	windowCornerRadius float64
 
+	// Gradient stuff
+	gradientType      string
+	gradientStops     []string
+	gradientAngle     float64
+	gradientCenterX   float64
+	gradientCenterY   float64
+	gradientIntensity float64
+
 	// Padding and layout
 	tabWidth     int
 	startLine    int
@@ -95,6 +103,14 @@ func init() {
 	renderCmd.Flags().StringVar(&windowTitle, "window-title", "", "Show window title")
 	renderCmd.Flags().Float64Var(&windowCornerRadius, "window-corner-radius", 10, "Corner radius of the window")
 
+	// Gradient flags
+	renderCmd.Flags().StringVar(&gradientType, "gradient-type", "linear", "Gradient type. Available types: linear, radial")
+	renderCmd.Flags().StringArrayVar(&gradientStops, "gradient-stop", []string{"#232323;0", "#383838;100"}, "Gradient stops. eg. '--gradient-stop '#ff0000;0' --gradient-stop '#00ff00;100'")
+	renderCmd.Flags().Float64Var(&gradientAngle, "gradient-angle", 90, "Gradient angle in degrees")
+	renderCmd.Flags().Float64Var(&gradientCenterX, "gradient-center-x", 0.5, "Center X of the gradient")
+	renderCmd.Flags().Float64Var(&gradientCenterY, "gradient-center-y", 0.5, "Center Y of the gradient")
+	renderCmd.Flags().Float64Var(&gradientIntensity, "gradient-intensity", 5, "Intensity modifier for special gradients")
+
 	// Padding and layout flags
 	renderCmd.Flags().IntVar(&tabWidth, "tab-width", 4, "Tab width")
 	renderCmd.Flags().IntVar(&startLine, "start-line", 1, "Line to start from")
@@ -260,6 +276,40 @@ func renderImage(cmd *cobra.Command, args []string) {
 			return
 		}
 		bg = background.NewImageBackground(backgroundImage).SetScaleMode(fit)
+	} else if gradientType != "" {
+		stops, err := parseGradientStops(gradientStops)
+		if err != nil {
+			fmt.Printf("invalid gradient stops: %v", err)
+			return
+		}
+
+		var gradient background.GradientType
+		switch gradientType {
+		case "linear":
+			gradient = background.LinearGradient
+		case "radial":
+			gradient = background.RadialGradient
+		case "angular":
+			gradient = background.AngularGradient
+		case "diamond":
+			gradient = background.DiamondGradient
+		case "spiral":
+			gradient = background.SpiralGradient
+		case "square":
+			gradient = background.SquareGradient
+		case "star":
+			gradient = background.StarGradient
+		default:
+			fmt.Printf("invalid gradient type: %s", gradientType)
+			return
+		}
+
+		bg = background.NewGradientBackground(gradient, stops...).
+			SetAngle(gradientAngle).
+			SetCenter(gradientCenterX, gradientCenterY).
+			SetIntensity(gradientIntensity).
+			SetCenter(gradientCenterX, gradientCenterY).
+			SetPaddingDetailed(padHoriz, padVert, padVert, padHoriz)
 	} else {
 		bg = background.NewColorBackground().
 			SetColor(bgColor).
@@ -418,3 +468,38 @@ func parseFonts(input string) (string, float64) {
 
 	return "", 14.0
 }
+
+// parseGradientStops takes in a string slice of gradient stops and returns
+// a slice of background.GradientStop.
+func parseGradientStops(input []string) ([]background.GradientStop, error) {
+	var result []background.GradientStop
+	for _, part := range input {
+		parts := strings.Split(part, ";")
+		if len(parts) != 2 {
+			return nil, fmt.Errorf("invalid gradient stop format: %s", part)
+		}
+
+		hexColor := strings.TrimSpace(parts[0])
+		positionStr := strings.TrimSpace(parts[1])
+
+		color, err := parseHexColor(hexColor)
+		if err != nil {
+			return nil, fmt.Errorf("invalid color in gradient stop: %s", err)
+		}
+
+		position, err := strconv.ParseFloat(positionStr, 64)
+		if err != nil {
+			return nil, fmt.Errorf("invalid position in gradient stop: %s", err)
+		}
+
+		if position < 0 || position > 100 {
+			return nil, fmt.Errorf("gradient stop position must be between 0 and 100: %f", position)
+		}
+
+		result = append(result, background.GradientStop{
+			Color:    color,
+			Position: position / 100, // Convert percentage to decimal
+		})
+	}
+	return result, nil
+}
diff --git a/pkg/background/gradient.go b/pkg/background/gradient.go
index 2104f66..b725284 100644
--- a/pkg/background/gradient.go
+++ b/pkg/background/gradient.go
@@ -188,7 +188,10 @@ func (bg GradientBackground) Render(content image.Image) image.Image {
 				// Calculate distance from center
 				dx := float64(x) - centerX
 				dy := float64(y) - centerY
-				pos = math.Sqrt(dx*dx+dy*dy) / (math.Sqrt(centerX*centerX + centerY*centerY))
+				// Calculate maximum possible distance from center to any corner
+				maxDist := math.Sqrt(math.Max(centerX*centerX, math.Pow(float64(width)-centerX, 2)) +
+					math.Max(centerY*centerY, math.Pow(float64(height)-centerY, 2)))
+				pos = math.Sqrt(dx*dx+dy*dy) / maxDist
 			case AngularGradient:
 				// Calculate angle from center
 				dx := float64(x) - centerX