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package flamegraph
import (
"bufio"
"fmt"
"hash"
"hash/fnv"
"io"
"strings"
"sync"
)
var svgEscaper = strings.NewReplacer(
"&", "&",
"<", "<",
">", ">",
`"`, """,
"'", "'",
)
var fnv32aPool = sync.Pool{
New: func() any {
return fnv.New32a()
},
}
// SVGConfig controls the layout and styling of generated flamegraph SVGs.
//
// Width is the virtual canvas width in pixels, FrameHeight is the height of each
// stack frame row, FontSize is the base font size, and MinWidthPx controls the
// minimum rendered width for a frame (smaller frames are skipped to avoid noise).
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,
}
}
// DefaultSVGConfig returns the default SVG configuration values.
func DefaultSVGConfig() SVGConfig {
return defaultSVGConfig()
}
// WriteSVG renders a flamegraph trie into an interactive SVG document.
//
// The output is a self-contained SVG that includes embedded CSS and JavaScript
// for zoom, search, and highlighting, and is designed to be served directly to
// a browser (for example via ServeSVG) without any external assets.
func WriteSVG(w io.Writer, t *trie, cfg SVGConfig) error {
cfg = sanitizeSVGConfig(cfg)
canvasHeight := canvasHeightFor(cfg, t)
bw := bufio.NewWriter(w)
if err := writeSVGHeader(bw, cfg, canvasHeight); err != nil {
return err
}
for _, frame := range BuildFrameLayout(t, cfg) {
if err := writeFrame(bw, frame.Name, frame.Title, frame.Fill,
frame.X, frame.Y, frame.Width, frame.Height, frame.Depth, cfg.FontSize); 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="100%%" height="%d" viewBox="0 0 %d %d" preserveAspectRatio="xMinYMin meet">`+"\n",
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="fgUndoZoom()">Undo Zoom</text><text x="280" y="42" onclick="fgResetZoom()">Reset Zoom</text><text id="fg-info" x="390" y="42"></text></g>`+"\n")
return err
}
func writeSVGFooter(bw *bufio.Writer) error {
_, err := fmt.Fprintln(bw, "</svg>")
return err
}
func writeFrame(bw *bufio.Writer, name, title, fill string, x, y, w, h float64, depth, fontSize int) error {
textStyle := ""
labelStyle := ""
if w <= float64(fontSize*2) {
labelStyle = ` style="display:none"`
}
if labelStyle != "" {
textStyle = labelStyle
}
_, err := fmt.Fprintf(bw, `<g class="frame" data-name="%s" data-x="%.3f" data-w="%.3f" data-depth="%d" data-base-fill="%s">
<title>%s</title><rect x="%.3f" y="%.3f" width="%.3f" height="%.3f" fill="%s"/>
<text x="%.3f" y="%.3f"%s>%s</text>
</g>
`,
svgEscape(name), x, w, depth, fill,
svgEscape(title), x, y, w, h, fill,
x+3, y+float64(fontSize), textStyle, svgEscape(name))
return err
}
func frameColor(name string) string {
hasher := fnv32aPool.Get().(hash.Hash32)
hasher.Reset()
_, _ = io.WriteString(hasher, name)
h := hasher.Sum32()
fnv32aPool.Put(hasher)
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; }
.title, .controls text, .frame text { user-select: none; -webkit-user-select: none; }
`, cfg.FontSize+2, cfg.FontSize, cfg.FontSize-1)
}
func svgEscape(s string) string {
return svgEscaper.Replace(s)
}
|
