Vector export (SVG and PDF)

Bar, line, area, combo, pie, scatter and bubble charts export as native vector SVG and PDF: shapes are real paths and rectangles, labels are real text (selectable and searchable), and the result stays sharp at any zoom or print size. Custom charts without Chart::draw() embed a raster image.

Chart	SVG Vector	PDF Vector
Pie / doughnut	yes	yes
Bar (grouped, stacked, horizontal)	yes	yes
Line, Area, Combo	yes	yes
Scatter / bubble	yes	yes

Saving

ExportOptions svg;
svg.svg_backend = SvgBackend::Vector;
ChartExporter::save(chart, "chart.svg", svg);

ExportOptions pdf;
pdf.pdf_backend = PdfBackend::Vector;           // PDF needs INSIGHTDOCK_WITH_PODOFO
ChartExporter::save(chart, "chart.pdf", pdf);

OutputFormat::PdfVector selects the vector backend directly. Embedding a chart into an existing PoDoFo page or a PdfReportBuilder report works the same way — pass PdfBackend::Vector in the ExportOptions (see PDF reports).

Capabilities and strict output

ChartExporter::capabilities(chart) reports vector (Native, RasterOnly, or Unknown) and pdf_available without drawing, cloning or validating the chart. Built-in charts advertise VectorCapability::Native. Custom charts default to Unknown; they can override Chart::vector_capability() to declare support. PDF availability reflects the library build. These declarations do not guarantee valid input or successful export.

To require native output, set vector_fallback:

ExportOptions options;
options.format = OutputFormat::Svg;
options.svg_backend = SvgBackend::Vector;
options.vector_fallback = VectorFallback::Reject;
Chart const &view = chart;
auto encoded = ChartExporter::encode(view, options);
if (!encoded && encoded.error() == ChartError::VectorUnsupported) {
  // Choose another format or tell the caller that native drawing is unavailable.
}

save() and encode() check the actual draw() return value, so existing custom charts with Unknown capability can still succeed in strict mode. If drawing returns false, strict mode returns VectorUnsupported without rendering an image. A rejected save() leaves an existing file intact. AllowRaster remains the default; fallback applies the requested supersampling and its pixel limits, and requires clone() above 1x. Native output ignores supersampling. PdfUnsupported takes precedence over the fallback policy in builds without PDF support. The policy applies only when a native vector backend is selected.

The void ChartExporter::draw_pdf() and draw_pdf_vector() embedding APIs throw std::runtime_error on strict rejection and propagate rendering/PoDoFo exceptions. A custom draw() that writes before returning false may leave marks in the supplied PDF page; embedding does not roll back page contents. Standalone save()/encode() discard partial vector output. Direct podofo::draw_chart_vector() helpers retain their legacy raster fallback behavior.

What carries over

Everything the raster renderer draws is emitted as vector: per-series dash patterns and markers, translucent fills (PDF uses ExtGState opacity), rounded and bordered bars, data labels, reference lines and bands, the secondary axis, rotated axis titles, x_label_mode, and the legend. Pie chart exports share their geometry and label wrapping with PNG, including explicit slice colors, color alpha multiplied by fill_opacity, gaps, stroke settings, doughnut cutouts and in-slice labels. SVG geometry uses decimal points regardless of the C or C++ process locale.

How it differs from PNG

• Text is drawn with the viewer's font. Layout (margins, label skipping, legend position) is computed with the embedded font, so geometry is identical everywhere, but SVG text uses DejaVu Sans, Verdana, Arial, sans-serif and PDF text uses Helvetica unless you pass a PoDoFo font. Glyph widths can differ by a pixel or two from the PNG.
• PDF text is WinAnsi. Latin-1 and € are drawn; other characters appear as ? (the PDF encoder can't represent them without embedding a font). SVG text is Unicode.
• Strokes are not pixel-snapped. Thin lines look slightly lighter than the anti-aliased raster version.
• supersample does not apply: vector output has no resolution.

Writing your own chart type

Cartesian charts draw through DrawTarget (insightdock/draw_target.h), a small pixel-space interface implemented by RasterTarget (PNG/JPEG), SvgTarget and PdfTarget. A custom CartesianChart subclass that draws only through ctx.target in draw_series() and draw_overlay() gets vector output for free. See Concepts.

Pie also implements Chart::draw(). DrawTarget::fill_sector() has a default polygon implementation, so existing custom drawing targets can render pies without adding an override. Raster and SVG targets override it with native sector rendering. PDF uses the polygon approximation.

For existing PDF report integrations, podofo::draw_pie() / draw_pie_slices() and the draw_chart_vector() overload accepting explicit PieVectorOptions retain the PDF-specific report layout. The overload without PieVectorOptions, used by ChartExporter, preserves the chart layout across backends. Default PDF pie exports now include the chart title and background, and no longer switch to the separate report layout.