feat: add annotation tool settings menus

internal/application/annotation.go

@@ -22,11 +22,12 @@ import (
 // Annotation describes a user-drawn mark relative to the selected screenshot.
 // Coordinates are logical pixels in the same coordinate system as the overlay.
 type Annotation struct {
-	Tool     string  `json:"tool"`
-	Color    string  `json:"color"`
-	Points   []Point `json:"points"`
-	Text     string  `json:"text,omitempty"`
-	FontSize float64 `json:"fontSize,omitempty"`
+	Tool        string  `json:"tool"`
+	Color       string  `json:"color"`
+	Points      []Point `json:"points"`
+	Text        string  `json:"text,omitempty"`
+	StrokeWidth float64 `json:"strokeWidth,omitempty"`
+	FontSize    float64 `json:"fontSize,omitempty"`
 }
 
 type Point struct {
@@ -66,7 +67,11 @@ func ApplyAnnotationsWithScale(pngBytes []byte, annotations []Annotation, scaleX
 		if err != nil {
 			c = color.RGBA{R: 59, G: 130, B: 246, A: 255}
 		}
-		width := int(math.Max(2, math.Round(3*strokeScale)))
+		strokeWidth := ann.StrokeWidth
+		if strokeWidth <= 0 {
+			strokeWidth = 3
+		}
+		width := int(math.Max(1, math.Round(strokeWidth*strokeScale)))
 		switch ann.Tool {
 		case "pen":
 			drawPolyline(dst, ann.Points, scaleX, scaleY, width, c)

internal/application/annotation_test.go

@@ -140,3 +140,34 @@ func TestApplyAnnotationsWithScaleDrawsTextAtDevicePosition(t *testing.T) {
 		t.Fatalf("expected text to be drawn near scaled x=100, min red x=%d", minX)
 	}
 }
+
+func TestApplyAnnotationsUsesStrokeWidth(t *testing.T) {
+	src := image.NewRGBA(image.Rect(0, 0, 80, 80))
+	draw.Draw(src, src.Bounds(), &image.Uniform{C: color.White}, image.Point{}, draw.Src)
+
+	var buf bytes.Buffer
+	if err := png.Encode(&buf, src); err != nil {
+		t.Fatalf("encode source: %v", err)
+	}
+
+	out, err := ApplyAnnotations(buf.Bytes(), []Annotation{
+		{
+			Tool:        "rect",
+			Color:       "#ef4444",
+			Points:      []Point{{X: 20, Y: 20}, {X: 60, Y: 60}},
+			StrokeWidth: 8,
+		},
+	}, 1)
+	if err != nil {
+		t.Fatalf("apply annotations: %v", err)
+	}
+
+	img, err := png.Decode(bytes.NewReader(out))
+	if err != nil {
+		t.Fatalf("decode output: %v", err)
+	}
+	got := color.RGBAModel.Convert(img.At(20, 24)).(color.RGBA)
+	if got.R < 180 || got.G > 180 || got.B > 180 {
+		t.Fatalf("expected thick rectangle stroke to cover y=24, got %#v", got)
+	}
+}