2026-05-26 18:27:37 +02:00

67 lines
2.2 KiB
Go

package platepdf
import (
"bytes"
"encoding/base64"
"fmt"
"printer.backend/internal/model"
)
const renderDPI = 300
// BuildCompositeSVG assembles a plate-sized SVG by embedding each item as a PNG
// rendered by rsvg-convert (identical to the standalone item file).
func BuildCompositeSVG(plate model.Plate, spec model.ItemSpec, itemSVG []byte, preview model.LayoutPreview) ([]byte, error) {
slotSVGs := make([][]byte, len(preview.Positions))
for i := range preview.Positions {
slotSVGs[i] = itemSVG
}
return BuildCompositeSVGSlots(plate, spec, slotSVGs, preview)
}
// BuildCompositeSVGSlots places one rendered item PNG per layout position.
// len(slotSVGs) must equal len(preview.Positions).
func BuildCompositeSVGSlots(plate model.Plate, spec model.ItemSpec, slotSVGs [][]byte, preview model.LayoutPreview) ([]byte, error) {
if len(slotSVGs) != len(preview.Positions) {
return nil, fmt.Errorf("slot svg count %d does not match positions %d", len(slotSVGs), len(preview.Positions))
}
canvasW := preview.CanvasWidthMM
canvasH := preview.CanvasHeightMM
if canvasW <= 0 || canvasH <= 0 {
canvasW = spec.CanvasWidthMM()
canvasH = spec.CanvasHeightMM()
}
slotPNGs := make([]string, len(slotSVGs))
for i, svg := range slotSVGs {
itemPNG, err := svgToPNGViaRsvg(svg, renderDPI)
if err != nil {
return nil, fmt.Errorf("render item slot %d: %w", i, err)
}
slotPNGs[i] = base64.StdEncoding.EncodeToString(itemPNG)
}
var b bytes.Buffer
fmt.Fprintf(&b, `<?xml version="1.0" encoding="UTF-8"?>
<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 %.4f %.4f" width="%.4fmm" height="%.4fmm">
<rect width="%.4f" height="%.4f" fill="#ffffff"/>
<rect x="%.4f" y="%.4f" width="%.4f" height="%.4f" fill="none" stroke="#cccccc" stroke-width="0.2"/>
`,
plate.WidthMM, plate.HeightMM, plate.WidthMM, plate.HeightMM,
plate.WidthMM, plate.HeightMM,
preview.PrintableXMM, preview.PrintableYMM, preview.PrintableWMM, preview.PrintableHMM,
)
for i, pos := range preview.Positions {
fmt.Fprintf(&b,
`<image x="%.4f" y="%.4f" width="%.4f" height="%.4f" href="data:image/png;base64,%s"/>`,
pos.XMM, pos.YMM, canvasW, canvasH, slotPNGs[i],
)
}
b.WriteString("\n</svg>")
return b.Bytes(), nil
}