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Merged
shps951023 merged 1 commit into from
Sep 8, 2026
Merged

Improve XLSX clustered column chart visual parity #156

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22 changes: 21 additions & 1 deletion src/MiniPdf/ExcelReader.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -4214,13 +4214,20 @@ private static List<ExcelChartInfo> ReadSheetCharts(ZipArchive archive, string w
XElement? overlayChartTypeEl = null;
var overlayChartType = "";
var overlaySeries = new List<ExcelChartSeries>();
var legendPosition = "";
var chartStyle = 0;
int? gapWidthPercent = null;

if (chartEntry != null)
{
using var cStream = chartEntry.Open();
var cDoc = XDocument.Load(cStream);
var cns = XNamespace.Get("http://schemas.openxmlformats.org/drawingml/2006/chart");

int.TryParse(cDoc.Root?.Element(cns + "style")?.Attribute("val")?.Value, out chartStyle);
var legend = cDoc.Descendants(cns + "legend").FirstOrDefault();
legendPosition = legend?.Element(cns + "legendPos")?.Attribute("val")?.Value ?? "";

// Extract chart title from <c:chart><c:title><c:tx><c:rich><a:r><a:t>
var titleEl = cDoc.Descendants(cns + "title").FirstOrDefault();
if (titleEl != null)
Expand Down Expand Up @@ -4261,6 +4268,10 @@ private static List<ExcelChartInfo> ReadSheetCharts(ZipArchive archive, string w
chartType = groupingVal.Contains("percent", StringComparison.OrdinalIgnoreCase)
? "percentStacked_" + chartType
: "stacked_" + chartType;

if (int.TryParse(chartTypeEl.Element(cns + "gapWidth")?.Attribute("val")?.Value,
out var parsedGapWidth))
gapWidthPercent = Math.Max(0, parsedGapWidth);
}

// Extract axis titles
Expand Down Expand Up @@ -4456,7 +4467,10 @@ private static List<ExcelChartInfo> ReadSheetCharts(ZipArchive archive, string w
showDataLabelVal, dataLabelFmtCode, valAxisFmtCode, isTwoCellAnchor)
{
OverlaySeries = overlaySeries,
OverlayChartType = overlayChartType
OverlayChartType = overlayChartType,
LegendPosition = legendPosition,
ChartStyle = chartStyle,
GapWidthPercent = gapWidthPercent
};
charts.Add(chartInfo);
}
Expand Down Expand Up @@ -4716,6 +4730,12 @@ internal sealed record ExcelChartInfo(
public List<ExcelChartSeries> OverlaySeries { get; init; } = new();
/// <summary>Chart type for overlay series (e.g., "lineChart" when primary is "barChart").</summary>
public string OverlayChartType { get; init; } = "";
/// <summary>Legend position from chart XML (r, l, t, b, tr); empty when hidden.</summary>
public string LegendPosition { get; init; } = "";
/// <summary>Built-in chart style identifier; zero when unspecified.</summary>
public int ChartStyle { get; init; }
/// <summary>Gap between bar clusters as a percentage of one bar width.</summary>
public int? GapWidthPercent { get; init; }
};

/// <summary>
Expand Down
63 changes: 49 additions & 14 deletions src/MiniPdf/ExcelToPdfConverter.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2765,15 +2765,26 @@ float RenderPrintTitleRows()
private static void RenderChart(PdfPage page, ExcelChartInfo chart,
float x, float top, float width, float height, float baseFontSize)
{
var chartFitsPage = x >= 0 && x + width <= page.Width;
var useStyle10Layout = chart.ChartStyle == 10 && chartFitsPage;
var titleFontSize = baseFontSize + 2;
var labelFontSize = baseFontSize - 1;
var axisFontSize = baseFontSize - 2;
var padding = 8f;
var chartColor = chart.ChartTextColor;
var chartFont = chart.ChartFontName;

if (useStyle10Layout)
{
var borderColor = new PdfColor(0.82f, 0.82f, 0.82f);
page.AddLine(x, top, x + width, top, borderColor, 0.5f);
page.AddLine(x + width, top, x + width, top - height, borderColor, 0.5f);
page.AddLine(x + width, top - height, x, top - height, borderColor, 0.5f);
page.AddLine(x, top - height, x, top, borderColor, 0.5f);
}

// Draw chart title (clipped to chart width)
var titleY = top;
var titleY = top - (useStyle10Layout ? 12f : 0f);
if (!string.IsNullOrEmpty(chart.Title))
{
var titleAvailWidth = width - padding * 2; // use nearly full chart width
Expand All @@ -2782,15 +2793,19 @@ private static void RenderChart(PdfPage page, ExcelChartInfo chart,
// Center the title horizontally
var titleTextWidth = (float)MeasureHelveticaWidth(clippedTitle, titleFontSize);
var titleX = x + (width - titleTextWidth) / 2f;
page.AddText(clippedTitle, titleX, titleY - titleFontSize, titleFontSize, chartColor, preferredFontName: chartFont);
page.AddText(clippedTitle, titleX, titleY - titleFontSize, titleFontSize, chartColor, bold: useStyle10Layout, preferredFontName: chartFont);
titleY -= titleFontSize * 2.2f;
}

// Plot area bounds
var plotLeft = x + padding + 40f; // leave room for Y-axis labels
var plotRight = x + width - padding - 10f;
var showRightLegend = chart.LegendPosition is "r" or "tr"
&& chart.Series.Any(series => !string.IsNullOrEmpty(series.Name))
&& chartFitsPage;
Comment on lines +2801 to +2803
var legendWidth = showRightLegend ? Math.Min(32f, width * 0.1f) : 0f;
var plotLeft = x + padding + (useStyle10Layout ? 47f : 40f);
var plotRight = x + width - padding - 10f - legendWidth;
var plotTop = titleY - padding;
var plotBottom = top - height + padding + 30f; // leave room for X-axis labels
var plotBottom = top - height + padding + (useStyle10Layout ? 37f : 30f);
var plotWidth = plotRight - plotLeft;
var plotHeight = plotTop - plotBottom;

Expand Down Expand Up @@ -2866,6 +2881,20 @@ private static void RenderChart(PdfPage page, ExcelChartInfo chart,
{
page.AddText(chart.CategoryAxisTitle, plotLeft + plotWidth * 0.35f, plotBottom - 22f, axisFontSize, chartColor, preferredFontName: chartFont);
}

if (showRightLegend)
{
var legendX = plotRight + 10f;
var legendY = plotBottom + plotHeight * 0.5f;
for (var index = 0; index < chart.Series.Count; index++)
{
var seriesName = chart.Series[index].Name;
if (string.IsNullOrEmpty(seriesName)) continue;
var entryY = legendY - index * (labelFontSize + 6f);
page.AddRectangle(legendX, entryY, 7f, 7f, ChartColors[index % ChartColors.Length]);
page.AddText(seriesName, legendX + 11f, entryY - 1f, labelFontSize, chartColor, preferredFontName: chartFont);
}
}
}

/// <summary>Renders a bar/column chart.</summary>
Expand Down Expand Up @@ -2917,11 +2946,11 @@ private static void RenderBarChart(PdfPage page, ExcelChartInfo chart,
dataMax = allValues.Max();
var rawMin = allValues.Min();
// Zero-base the axis for typical positive data, but when values are
// tightly clustered far above zero (e.g. stock prices around 150),
// LibreOffice's auto-scale keeps the range close to the data instead
// of compressing it against a distant zero baseline.
dataMin = rawMin > 0 && (dataMax - rawMin) < rawMin * 0.5
? rawMin
// tightly clustered far above zero, LibreOffice expands the lower
// bound by half the data range before rounding to a nice interval.
var dataRange = dataMax - rawMin;
dataMin = rawMin > 0 && rawMin / dataMax > 5.0 / 6.0
? rawMin - dataRange / 2.0
: Math.Min(0, rawMin);
}

Expand All @@ -2934,8 +2963,11 @@ private static void RenderBarChart(PdfPage page, ExcelChartInfo chart,

var numSeries = series.Count;
var groupWidth = plotWidth / numCats;
var barWidth = isStacked ? groupWidth * 0.7f : groupWidth * 0.7f / numSeries;
var groupPadding = groupWidth * 0.15f;
var barsPerGroup = isStacked ? 1 : numSeries;
var barWidth = chart.GapWidthPercent.HasValue
? groupWidth / (barsPerGroup + chart.GapWidthPercent.Value / 100f)
: groupWidth * 0.7f / barsPerGroup;
var groupPadding = (groupWidth - barWidth * barsPerGroup) / 2f;

// Y-axis baseline: where value=0 sits, clamped into the visible axis
// range. When the axis is auto-scaled away from zero (data clustered
Expand Down Expand Up @@ -3120,8 +3152,11 @@ private static void RenderHorizontalBarChart(PdfPage page, ExcelChartInfo chart,
if (range <= 0) range = 1;

var groupHeight = plotHeight / numCats;
var barHeight = isStacked ? groupHeight * 0.7f : groupHeight * 0.7f / numSeries;
var groupPadding = groupHeight * 0.15f;
var barsPerGroup = isStacked ? 1 : numSeries;
var barHeight = chart.GapWidthPercent.HasValue
? groupHeight / (barsPerGroup + chart.GapWidthPercent.Value / 100f)
: groupHeight * 0.7f / barsPerGroup;
var groupPadding = (groupHeight - barHeight * barsPerGroup) / 2f;

var baselineX = plotLeft + (float)((0 - niceMin) / range) * plotWidth;

Expand Down
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