1 files changed, 78 insertions, 0 deletions
diff --git a/internal/flamegraph/layout.go b/internal/flamegraph/layout.go
new file mode 100644
index 0000000..c319800
--- /dev/null
+++ b/internal/flamegraph/layout.go
@@ -0,0 +1,78 @@
+package flamegraph
+
+import "fmt"
+
+// FrameLayout captures renderer-agnostic flamegraph geometry for a single frame.
+//
+// The layout is reusable by non-SVG renderers (for example SDL or WASM UIs) so
+// they can render the same hierarchy without depending on SVG internals.
+type FrameLayout struct {
+	Name    string
+	Title   string
+	Fill    string
+	X       float64
+	Y       float64
+	Width   float64
+	Height  float64
+	Depth   int
+	Total   uint64
+	Percent float64
+}
+
+func sanitizeSVGConfig(cfg SVGConfig) SVGConfig {
+	if cfg.Width <= 0 || cfg.FrameHeight <= 0 || cfg.FontSize <= 0 || cfg.MinWidthPx <= 0 {
+		return defaultSVGConfig()
+	}
+	if cfg.Title == "" {
+		cfg.Title = defaultSVGConfig().Title
+	}
+	return cfg
+}
+
+func canvasHeightFor(cfg SVGConfig, t *trie) int {
+	return cfg.FrameHeight*(t.maxDepth+1) + 80
+}
+
+// BuildFrameLayout builds renderer-agnostic frame coordinates from a flamegraph trie.
+func BuildFrameLayout(t *trie, cfg SVGConfig) []FrameLayout {
+	if t == nil || t.root == nil || t.root.total == 0 {
+		return nil
+	}
+	cfg = sanitizeSVGConfig(cfg)
+	canvasHeight := canvasHeightFor(cfg, t)
+	out := make([]FrameLayout, 0, len(t.root.children))
+	collectFrameLayout(&out, t.root, t.root.total, cfg, 0, 0, canvasHeight, true)
+	return out
+}
+
+func collectFrameLayout(out *[]FrameLayout, node *trieNode, rootTotal uint64,
+	cfg SVGConfig, x float64, depth int, canvasHeight int, isRoot bool) {
+
+	if !isRoot {
+		w := float64(cfg.Width) * (float64(node.total) / float64(rootTotal))
+		if w < cfg.MinWidthPx {
+			return
+		}
+		y := float64(canvasHeight - (depth+1)*cfg.FrameHeight)
+		pct := 100 * float64(node.total) / float64(rootTotal)
+		*out = append(*out, FrameLayout{
+			Name:    node.name,
+			Title:   fmt.Sprintf("%s (%d, %.2f%%)", node.name, node.total, pct),
+			Fill:    frameColor(node.name),
+			X:       x,
+			Y:       y,
+			Width:   w,
+			Height:  float64(cfg.FrameHeight - 1),
+			Depth:   depth,
+			Total:   node.total,
+			Percent: pct,
+		})
+	}
+
+	cursor := x
+	for _, child := range node.children {
+		cw := float64(cfg.Width) * (float64(child.total) / float64(rootTotal))
+		collectFrameLayout(out, child, rootTotal, cfg, cursor, depth+1, canvasHeight, false)
+		cursor += cw
+	}
+}