flamegraph: add native svg renderer and embedded js

1 files changed, 154 insertions, 0 deletions

diff --git a/internal/flamegraph/svgwriter.go b/internal/flamegraph/svgwriter.go
new file mode 100644
index 0000000..26e203e
--- /dev/null
+++ b/internal/flamegraph/svgwriter.go
@@ -0,0 +1,154 @@
+package flamegraph
+
+import (
+	"bufio"
+	"fmt"
+	"hash/fnv"
+	"io"
+	"strings"
+)
+
+type SVGConfig struct {
+	Title       string
+	Width       int
+	FrameHeight int
+	FontSize    int
+	MinWidthPx  float64
+}
+
+func defaultSVGConfig() SVGConfig {
+	return SVGConfig{
+		Title:       "I/O Flame Graph",
+		Width:       1200,
+		FrameHeight: 16,
+		FontSize:    12,
+		MinWidthPx:  1.0,
+	}
+}
+
+func WriteSVG(w io.Writer, t *trie, cfg SVGConfig) error {
+	if cfg.Width <= 0 || cfg.FrameHeight <= 0 || cfg.FontSize <= 0 || cfg.MinWidthPx <= 0 {
+		cfg = defaultSVGConfig()
+	}
+	if cfg.Title == "" {
+		cfg.Title = defaultSVGConfig().Title
+	}
+
+	canvasHeight := cfg.FrameHeight*(t.maxDepth+1) + 80
+	bw := bufio.NewWriter(w)
+	if err := writeSVGHeader(bw, cfg, canvasHeight); err != nil {
+		return err
+	}
+	if t.root.total > 0 {
+		if err := renderFrames(bw, t.root, t.root.total, cfg, 0, 0, canvasHeight, true); err != nil {
+			return err
+		}
+	}
+	if err := writeSVGFooter(bw); err != nil {
+		return err
+	}
+	return bw.Flush()
+}
+
+func writeSVGHeader(bw *bufio.Writer, cfg SVGConfig, height int) error {
+	_, err := fmt.Fprintf(bw, `<svg xmlns="http://www.w3.org/2000/svg" width="%d" height="%d" viewBox="0 0 %d %d">`+"\n",
+		cfg.Width, height, cfg.Width, height)
+	if err != nil {
+		return err
+	}
+	_, err = fmt.Fprintf(bw, "<style><![CDATA[%s]]></style>\n", flamegraphCSS(cfg))
+	if err != nil {
+		return err
+	}
+	_, err = fmt.Fprintf(bw, "<script><![CDATA[%s]]></script>\n", flamegraphJS)
+	if err != nil {
+		return err
+	}
+	_, err = fmt.Fprintf(bw, `<text class="title" x="10" y="22">%s</text>`+"\n", svgEscape(cfg.Title))
+	if err != nil {
+		return err
+	}
+	_, err = fmt.Fprintf(bw, `<g class="controls"><text x="10" y="42" onclick="fgSearch()">Search</text><text x="80" y="42" onclick="fgResetSearch()">Reset Search</text><text x="190" y="42" onclick="fgResetZoom()">Reset Zoom</text><text id="fg-info" x="320" y="42"></text></g>`+"\n")
+	return err
+}
+
+func writeSVGFooter(bw *bufio.Writer) error {
+	_, err := fmt.Fprintln(bw, "</svg>")
+	return err
+}
+
+func renderFrames(bw *bufio.Writer, node *trieNode, rootTotal uint64, cfg SVGConfig, x float64, depth int, canvasHeight int, isRoot bool) error {
+	if !isRoot {
+		w := float64(cfg.Width) * (float64(node.total) / float64(rootTotal))
+		if w < cfg.MinWidthPx {
+			return nil
+		}
+		y := float64(canvasHeight - (depth+1)*cfg.FrameHeight)
+		fill := frameColor(node.name)
+		pct := 100 * float64(node.total) / float64(rootTotal)
+		title := fmt.Sprintf("%s (%d, %.2f%%)", node.name, node.total, pct)
+		if err := writeFrame(bw, node.name, title, fill, x, y, w, float64(cfg.FrameHeight-1), depth, cfg.FontSize); err != nil {
+			return err
+		}
+	}
+
+	cursor := x
+	for _, child := range node.children {
+		cw := float64(cfg.Width) * (float64(child.total) / float64(rootTotal))
+		if err := renderFrames(bw, child, rootTotal, cfg, cursor, depth+1, canvasHeight, false); err != nil {
+			return err
+		}
+		cursor += cw
+	}
+	return nil
+}
+
+func writeFrame(bw *bufio.Writer, name, title, fill string, x, y, w, h float64, depth, fontSize int) error {
+	_, err := fmt.Fprintf(bw, `<g class="frame" data-name="%s" data-x="%.3f" data-w="%.3f" data-depth="%d" data-base-fill="%s">`+"\n",
+		svgEscape(name), x, w, depth, fill)
+	if err != nil {
+		return err
+	}
+	if _, err = fmt.Fprintf(bw, `<title>%s</title><rect x="%.3f" y="%.3f" width="%.3f" height="%.3f" fill="%s"/>`+"\n",
+		svgEscape(title), x, y, w, h, fill); err != nil {
+		return err
+	}
+	if w > float64(fontSize*2) {
+		_, err = fmt.Fprintf(bw, `<text x="%.3f" y="%.3f">%s</text>`+"\n", x+3, y+float64(fontSize), svgEscape(name))
+		if err != nil {
+			return err
+		}
+	}
+	_, err = fmt.Fprintln(bw, "</g>")
+	return err
+}
+
+func frameColor(name string) string {
+	hasher := fnv.New32a()
+	_, _ = hasher.Write([]byte(name))
+	h := hasher.Sum32()
+	r := 200 + int(h%35)
+	g := 80 + int((h>>8)%120)
+	b := 40 + int((h>>16)%90)
+	return fmt.Sprintf("rgb(%d,%d,%d)", r, g, b)
+}
+
+func flamegraphCSS(cfg SVGConfig) string {
+	return fmt.Sprintf(`
+.title { font-size: %dpx; font-family: monospace; }
+.controls text { font-size: %dpx; font-family: monospace; cursor: pointer; fill: #444; }
+.frame text { font-size: %dpx; font-family: monospace; pointer-events: none; fill: #111; }
+.frame rect { stroke: rgba(0,0,0,0.18); stroke-width: 0.5; }
+`, cfg.FontSize+2, cfg.FontSize, cfg.FontSize-1)
+}
+
+func svgEscape(s string) string {
+	replacer := strings.NewReplacer(
+		"&", "&amp;",
+		"<", "&lt;",
+		">", "&gt;",
+		`"`, "&quot;",
+		"'", "&apos;",
+	)
+	return replacer.Replace(s)
+}