WIP charts2 parts

chart_export.go

@@ -0,0 +1,49 @@
+package mujica
+
+import (
+	"bytes"
+	"image/png"
+	"log/slog"
+
+	"github.com/egoist/mygo/ui"
+)
+
+// ChartExportOptions configure a ChartExport.
+type ChartExportOptions struct {
+	// Width and Height are the image size in DIPs; required.
+	Width, Height int
+	// Scale is device pixels per DIP; 0 means 2.
+	Scale float32
+}
+
+// ChartExport renders chart off screen in this window's theme and returns PNG bytes; it writes no file.
+func ChartExport(c *ui.Context, chart func(c *ui.Context), opts ChartExportOptions) ([]byte, error) {
+	if chart == nil || opts.Width <= 0 || opts.Height <= 0 || opts.Scale < 0 {
+		panic("mujica: ChartExport needs a chart, a positive size and Scale ≥ 0")
+	}
+	scale := opts.Scale
+	if scale == 0 {
+		scale = 2
+	}
+	w := current(c)
+	settings := Settings{Mode: Light, Density: w.density, Locale: w.locale, Messages: w.messages}
+	if w.tokens.Dark {
+		settings.Mode = Dark
+	}
+	tokens := w.tokens
+	img := ui.Render(func(c *ui.Context) {
+		if settings.Mode == Dark {
+			settings.Dark = &tokens
+		} else {
+			settings.Light = &tokens
+		}
+		Use(c, settings)
+		ui.Column(c).Fill().Background(tokens.Surface).Padding(Density(c).Unit() * 4).Children(func() { chart(c) })
+	}, opts.Width, opts.Height, scale)
+	var buf bytes.Buffer
+	if err := png.Encode(&buf, img); err != nil {
+		return nil, err
+	}
+	slog.Debug("mujica: chart_export png", "bytes", buf.Len(), "width", opts.Width, "height", opts.Height)
+	return buf.Bytes(), nil
+}