An axis legend source regarding the range as ordinary numbers and producing

string legends for them.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@30526 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/apps/debuganalyzer/gui/chart/DefaultChartAxisLegendSource.cpp

@@ -0,0 +1,96 @@
+/*
+ * Copyright 2009, Ingo Weinhold, ingo_weinhold@gmx.de.
+ * Distributed under the terms of the MIT License.
+ */
+
+#include "chart/DefaultChartAxisLegendSource.h"
+
+#include <math.h>
+#include <stdio.h>
+
+#include "chart/ChartDataRange.h"
+#include "chart/StringChartLegend.h"
+
+
+int32
+DefaultChartAxisLegendSource::GetAxisLegends(const ChartDataRange& range,
+	ChartLegend** legends, double* values, int32 maxLegends)
+{
+// TODO: Also support scientific notation! Otherwise the numbers can get really
+// long.
+	double start = range.min;
+	double end = range.max;
+	double rangeSpan = end - start;
+
+	if (rangeSpan >= maxLegends / 2) {
+		// We only need to consider the integer part.
+
+		// find an interval so that we get maxLegends / 2 to maxLegends legends
+		double baseInterval = 1;
+		double relativeFactor = 1;
+		while (rangeSpan / baseInterval / relativeFactor >= maxLegends) {
+			if (relativeFactor == 1) {
+				relativeFactor = 2;
+			} else if (relativeFactor == 2) {
+				relativeFactor = 5;
+			} else if (relativeFactor == 5) {
+				baseInterval *= 10;
+				relativeFactor = 1;
+			}
+		}
+
+		// generate the legends
+		int32 count = 0;
+		double interval = baseInterval * relativeFactor;
+		double value = ceil(start / interval) * interval;
+		for (; value <= end; value += interval) {
+			char buffer[128];
+			snprintf(buffer, sizeof(buffer), "%.0f", value);
+			StringChartLegend* legend
+				= new(std::nothrow) StringChartLegend(buffer, 1);
+			if (legend == NULL)
+				return count;
+	
+			legends[count] = legend;
+			values[count++] = value;
+		}
+
+		return count;
+	}
+
+	// The range is so small that we need a fraction interval.
+
+	// First find out how many places after the decimal point we need.
+	int positions = 0;
+	double factor = 1;
+	while (rangeSpan * factor < maxLegends / 2) {
+		factor *= 10;
+		positions++;
+	}
+
+	double relativeFactor = 1;
+	if (rangeSpan * factor / relativeFactor >= maxLegends) {
+		relativeFactor = 2;
+		if (rangeSpan * factor / relativeFactor >= maxLegends)
+			relativeFactor = 5;
+	}
+
+	// generate the legends
+	int32 count = 0;
+	double interval = relativeFactor / factor;
+	double shiftedValue = ceil(start / interval);
+	for (; shiftedValue * interval <= end; shiftedValue++) {
+		double value = shiftedValue * interval;
+		char buffer[128];
+		snprintf(buffer, sizeof(buffer), "%.*f", positions, value);
+		StringChartLegend* legend
+			= new(std::nothrow) StringChartLegend(buffer, 1);
+		if (legend == NULL)
+			return count;
+
+		legends[count] = legend;
+		values[count++] = value;
+	}
+
+	return count;
+}

src/apps/debuganalyzer/gui/chart/DefaultChartAxisLegendSource.h

@@ -0,0 +1,19 @@
+/*
+ * Copyright 2009, Ingo Weinhold, ingo_weinhold@gmx.de.
+ * Distributed under the terms of the MIT License.
+ */
+#ifndef DEFAULT_CHART_AXIS_LEGEND_SOURCE_H
+#define DEFAULT_CHART_AXIS_LEGEND_SOURCE_H
+
+#include "chart/ChartAxisLegendSource.h"
+
+
+class DefaultChartAxisLegendSource : public ChartAxisLegendSource {
+public:
+	virtual	int32				GetAxisLegends(const ChartDataRange& range,
+									ChartLegend** legends, double* values,
+									int32 maxLegends);
+};
+
+
+#endif	// DEFAULT_CHART_AXIS_LEGEND_SOURCE_H

src/apps/debuganalyzer/gui/chart/Jamfile

@@ -14,6 +14,7 @@ MergeObject DebugAnalyzer_gui_chart.o
 	ChartDataSource.cpp
 	ChartLegend.cpp
 	ChartRenderer.cpp
+	DefaultChartAxisLegendSource.cpp
 	LegendChartAxis.cpp
 	LineChartRenderer.cpp
 	StringChartLegend.cpp