From bd4e71203152cdb31ecb939c6113e9db78d1d767 Mon Sep 17 00:00:00 2001
From: xyc <jc_xiong@hotmail.com>
Date: 星期一, 05 十月 2026 11:57:04 +0800
Subject: [PATCH] docs: fix handoff todo section reference

---
 traffic-audit-server/src/main/java/com/trafficaudit/holiday/service/HolidayTrendChartService.java |  230 +++++++++++++++++++++++++++++++++++++++++++++++----------
 1 files changed, 188 insertions(+), 42 deletions(-)

diff --git a/traffic-audit-server/src/main/java/com/trafficaudit/holiday/service/HolidayTrendChartService.java b/traffic-audit-server/src/main/java/com/trafficaudit/holiday/service/HolidayTrendChartService.java
index 8d359c4..4343f08 100644
--- a/traffic-audit-server/src/main/java/com/trafficaudit/holiday/service/HolidayTrendChartService.java
+++ b/traffic-audit-server/src/main/java/com/trafficaudit/holiday/service/HolidayTrendChartService.java
@@ -74,7 +74,8 @@
     private static final Color MUTED_TEXT_COLOR = new Color(102, 102, 102);
     private static final double UNIT_LABEL_BAND = 58.0;
     private static final double RIGHT_LABEL_BAND = 74.0;
-    private static final double ITEM_LABEL_GAP = 12.0;
+    private static final double ITEM_LABEL_GAP = 10.0;
+    private static final float HALO_OUTLINE_WIDTH = 4.0f;
     private static final Color ITEM_LABEL_COLOR = new Color(55, 55, 55);
     private static final Color[] SERIES_COLORS = {
             new Color(192, 80, 77),
@@ -841,7 +842,6 @@
         graphics.setFont(ITEM_LABEL_FONT);
         FontMetrics metrics = graphics.getFontMetrics();
         List<Rectangle2D> placedLabels = new ArrayList<>();
-        List<Rectangle2D> markers = new ArrayList<>();
         if (unitLabel != null && !unitLabel.isEmpty()) {
             placedLabels.add(new Rectangle2D.Double(0.0, 0.0,
                     dataArea.getMinX() + 100.0, dataArea.getMinY() + 30.0));
@@ -849,13 +849,6 @@
         int itemCount = 0;
         for (int seriesIndex = 0; seriesIndex < dataset.getSeriesCount(); seriesIndex++) {
             itemCount = Math.max(itemCount, dataset.getItemCount(seriesIndex));
-            for (int itemIndex = 0; itemIndex < dataset.getItemCount(seriesIndex); itemIndex++) {
-                Point2D point = itemPoint(plot, dataset, seriesIndex, itemIndex, dataArea);
-                if (point != null) {
-                    markers.add(new Rectangle2D.Double(point.getX() - 9.0,
-                            point.getY() - 9.0, 18.0, 18.0));
-                }
-            }
         }
 
         for (int itemIndex = 0; itemIndex < itemCount; itemIndex++) {
@@ -876,35 +869,95 @@
                     return Double.compare(first.getPoint().getY(), second.getPoint().getY());
                 }
             });
-            double previousBottom = Double.NEGATIVE_INFINITY;
+            List<List<LineLabelCandidate>> candidateSets = new ArrayList<>();
             for (DayLabel label : labels) {
-                int width = metrics.stringWidth(label.getText());
-                int height = metrics.getHeight();
-                double x = label.getPoint().getX() - width / 2.0;
-                double top = Math.max(label.getPoint().getY() - ITEM_LABEL_GAP - height,
-                        previousBottom + 3.0);
-                Rectangle2D chosen = null;
-                double bestPenalty = Double.MAX_VALUE;
-                for (int step = 0; step <= 4; step++) {
-                    Rectangle2D candidate = boundToDataArea(new Rectangle2D.Double(
-                            x, top + step * (height + 4.0), width, height), dataArea);
-                    if (candidate == null) continue;
-                    double penalty = overlapArea(candidate, placedLabels) * 1000.0
-                            + overlapArea(candidate, markers);
-                    if (penalty < bestPenalty) {
-                        bestPenalty = penalty;
-                        chosen = candidate;
-                    }
-                    if (penalty <= 0.0) break;
+                List<LineLabelCandidate> candidates = lineLabelCandidates(
+                        label, metrics, dataArea);
+                if (candidates.isEmpty()) {
+                    candidateSets.clear();
+                    break;
                 }
-                if (chosen == null) continue;
+                candidateSets.add(candidates);
+            }
+            if (candidateSets.isEmpty()) continue;
+
+            // Dynamic programming keeps each label near its own point while preserving
+            // the same top-to-bottom order as the data points for that date.
+            List<int[]> backPointers = new ArrayList<>();
+            List<LineLabelCandidate> firstCandidates = candidateSets.get(0);
+            double[] previousCosts = new double[firstCandidates.size()];
+            for (int i = 0; i < firstCandidates.size(); i++) {
+                previousCosts[i] = lineLabelCost(firstCandidates.get(i), labels.get(0),
+                        labels, placedLabels);
+            }
+
+            for (int labelIndex = 1; labelIndex < candidateSets.size(); labelIndex++) {
+                List<LineLabelCandidate> previousCandidates = candidateSets.get(labelIndex - 1);
+                List<LineLabelCandidate> currentCandidates = candidateSets.get(labelIndex);
+                double[] currentCosts = new double[currentCandidates.size()];
+                Arrays.fill(currentCosts, Double.MAX_VALUE);
+                int[] back = new int[currentCandidates.size()];
+                Arrays.fill(back, -1);
+                for (int currentIndex = 0; currentIndex < currentCandidates.size(); currentIndex++) {
+                    LineLabelCandidate current = currentCandidates.get(currentIndex);
+                    double currentCost = lineLabelCost(current, labels.get(labelIndex),
+                            labels, placedLabels);
+                    for (int previousIndex = 0; previousIndex < previousCandidates.size(); previousIndex++) {
+                        if (previousCosts[previousIndex] == Double.MAX_VALUE) continue;
+                        LineLabelCandidate previous = previousCandidates.get(previousIndex);
+                        if (previous.getRectangle().getCenterY()
+                                > current.getRectangle().getCenterY() + 0.1) {
+                            continue;
+                        }
+                        double overlapPenalty = overlapArea(previous.getRectangle(),
+                                Collections.singletonList(current.getRectangle())) * 1000000.0;
+                        double cost = previousCosts[previousIndex] + currentCost + overlapPenalty;
+                        if (cost < currentCosts[currentIndex]) {
+                            currentCosts[currentIndex] = cost;
+                            back[currentIndex] = previousIndex;
+                        }
+                    }
+                }
+                previousCosts = currentCosts;
+                backPointers.add(back);
+            }
+
+            int bestLastIndex = -1;
+            double bestCost = Double.MAX_VALUE;
+            for (int i = 0; i < previousCosts.length; i++) {
+                if (previousCosts[i] < bestCost) {
+                    bestCost = previousCosts[i];
+                    bestLastIndex = i;
+                }
+            }
+            if (bestLastIndex < 0) continue;
+
+            int[] chosenIndexes = new int[candidateSets.size()];
+            chosenIndexes[chosenIndexes.length - 1] = bestLastIndex;
+            for (int labelIndex = chosenIndexes.length - 2; labelIndex >= 0; labelIndex--) {
+                int nextIndex = chosenIndexes[labelIndex + 1];
+                chosenIndexes[labelIndex] = backPointers.get(labelIndex)[nextIndex];
+            }
+            for (int labelIndex = 0; labelIndex < chosenIndexes.length; labelIndex++) {
+                DayLabel label = labels.get(labelIndex);
+                Rectangle2D chosen = candidateSets.get(labelIndex)
+                        .get(chosenIndexes[labelIndex]).getRectangle();
                 drawLabelWithHalo(graphics, label.getText(), chosen, metrics,
                         seriesColor(label.getSeriesIndex()));
-                placedLabels.add(new Rectangle2D.Double(chosen.getX() - 5.0, chosen.getY() - 5.0,
-                        chosen.getWidth() + 10.0, chosen.getHeight() + 10.0));
-                previousBottom = chosen.getMaxY();
+                placedLabels.add(new Rectangle2D.Double(chosen.getX() - 4.0, chosen.getY() - 4.0,
+                        chosen.getWidth() + 8.0, chosen.getHeight() + 8.0));
             }
         }
+    }
+
+    private static class LineLabelCandidate {
+        private final Rectangle2D rectangle;
+
+        private LineLabelCandidate(Rectangle2D rectangle) {
+            this.rectangle = rectangle;
+        }
+
+        private Rectangle2D getRectangle() { return rectangle; }
     }
 
     private static class DayLabel {
@@ -937,10 +990,99 @@
         return new Point2D.Double(x, y);
     }
 
-    private void addLabelCandidate(List<Rectangle2D> result, double x, double y,
-                                   int width, int height, double dx, double dy) {
-        result.add(new Rectangle2D.Double(x + dx - width / 2.0,
-                y + dy - height / 2.0, width, height));
+    private List<LineLabelCandidate> lineLabelCandidates(DayLabel label, FontMetrics metrics,
+                                                         Rectangle2D dataArea) {
+        List<LineLabelCandidate> result = new ArrayList<>();
+        int width = metrics.stringWidth(label.getText());
+        int height = metrics.getHeight();
+        double x = label.getPoint().getX();
+        double y = label.getPoint().getY();
+        double horizontalOffset = ITEM_LABEL_GAP + width / 2.0;
+        double farHorizontalOffset = horizontalOffset + 18.0;
+        double verticalOffset = ITEM_LABEL_GAP + height / 2.0;
+        double farVerticalOffset = verticalOffset + height + 6.0;
+        addLabelCandidate(result, x, y, width, height, 0.0, -verticalOffset, dataArea);
+        addLabelCandidate(result, x, y, width, height, 0.0, verticalOffset, dataArea);
+        addLabelCandidate(result, x, y, width, height, horizontalOffset, 0.0, dataArea);
+        addLabelCandidate(result, x, y, width, height, -horizontalOffset, 0.0, dataArea);
+        addLabelCandidate(result, x, y, width, height, farHorizontalOffset, 0.0, dataArea);
+        addLabelCandidate(result, x, y, width, height, -farHorizontalOffset, 0.0, dataArea);
+        addLabelCandidate(result, x, y, width, height,
+                horizontalOffset, -verticalOffset, dataArea);
+        addLabelCandidate(result, x, y, width, height,
+                horizontalOffset, verticalOffset, dataArea);
+        addLabelCandidate(result, x, y, width, height,
+                -horizontalOffset, -verticalOffset, dataArea);
+        addLabelCandidate(result, x, y, width, height,
+                -horizontalOffset, verticalOffset, dataArea);
+        addLabelCandidate(result, x, y, width, height,
+                farHorizontalOffset, -verticalOffset, dataArea);
+        addLabelCandidate(result, x, y, width, height,
+                farHorizontalOffset, verticalOffset, dataArea);
+        addLabelCandidate(result, x, y, width, height,
+                -farHorizontalOffset, -verticalOffset, dataArea);
+        addLabelCandidate(result, x, y, width, height,
+                -farHorizontalOffset, verticalOffset, dataArea);
+        addLabelCandidate(result, x, y, width, height, 0.0, -farVerticalOffset, dataArea);
+        addLabelCandidate(result, x, y, width, height, 0.0, farVerticalOffset, dataArea);
+        addLabelCandidate(result, x, y, width, height,
+                horizontalOffset, -farVerticalOffset, dataArea);
+        addLabelCandidate(result, x, y, width, height,
+                horizontalOffset, farVerticalOffset, dataArea);
+        addLabelCandidate(result, x, y, width, height,
+                -horizontalOffset, -farVerticalOffset, dataArea);
+        addLabelCandidate(result, x, y, width, height,
+                -horizontalOffset, farVerticalOffset, dataArea);
+        addLabelCandidate(result, x, y, width, height,
+                farHorizontalOffset, -farVerticalOffset, dataArea);
+        addLabelCandidate(result, x, y, width, height,
+                farHorizontalOffset, farVerticalOffset, dataArea);
+        addLabelCandidate(result, x, y, width, height,
+                -farHorizontalOffset, -farVerticalOffset, dataArea);
+        addLabelCandidate(result, x, y, width, height,
+                -farHorizontalOffset, farVerticalOffset, dataArea);
+        return result;
+    }
+
+    private void addLabelCandidate(List<LineLabelCandidate> result, double x, double y,
+                                   int width, int height, double dx, double dy,
+                                   Rectangle2D dataArea) {
+        Rectangle2D candidate = boundToDataArea(new Rectangle2D.Double(
+                x + dx - width / 2.0, y + dy - height / 2.0, width, height), dataArea);
+        if (candidate == null) return;
+        for (LineLabelCandidate existing : result) {
+            if (Math.abs(existing.getRectangle().getX() - candidate.getX()) < 0.5
+                    && Math.abs(existing.getRectangle().getY() - candidate.getY()) < 0.5) {
+                return;
+            }
+        }
+        result.add(new LineLabelCandidate(candidate));
+    }
+
+    private double lineLabelCost(LineLabelCandidate candidate, DayLabel label,
+                                List<DayLabel> sameDayLabels,
+                                List<Rectangle2D> placedLabels) {
+        Rectangle2D rectangle = candidate.getRectangle();
+        double dx = rectangle.getCenterX() - label.getPoint().getX();
+        double dy = rectangle.getCenterY() - label.getPoint().getY();
+        double ownDistance = Math.sqrt(dx * dx + dy * dy);
+        double cost = ownDistance * 10.0 + overlapArea(rectangle, placedLabels) * 10000.0;
+        Rectangle2D ownMarker = new Rectangle2D.Double(label.getPoint().getX() - 9.0,
+                label.getPoint().getY() - 9.0, 18.0, 18.0);
+        if (rectangle.intersects(ownMarker)) cost += 3000.0;
+        for (DayLabel other : sameDayLabels) {
+            if (other == label) continue;
+            double otherDx = rectangle.getCenterX() - other.getPoint().getX();
+            double otherDy = rectangle.getCenterY() - other.getPoint().getY();
+            double otherDistance = Math.sqrt(otherDx * otherDx + otherDy * otherDy);
+            if (otherDistance < ownDistance - 1.0) {
+                cost += (ownDistance - otherDistance) * 5000.0;
+            }
+            Rectangle2D otherMarker = new Rectangle2D.Double(other.getPoint().getX() - 9.0,
+                    other.getPoint().getY() - 9.0, 18.0, 18.0);
+            if (rectangle.intersects(otherMarker)) cost += 2000.0;
+        }
+        return cost;
     }
 
     private Rectangle2D boundToDataArea(Rectangle2D rectangle, Rectangle2D dataArea) {
@@ -979,14 +1121,18 @@
                                    FontMetrics metrics, Color color) {
         int x = (int) Math.round(rectangle.getX());
         int y = (int) Math.round(rectangle.getY() + metrics.getAscent());
+        // A stroked white outline keeps the digit legible even when a line runs
+        // underneath it, which lets labels stay right next to their own point.
+        java.awt.font.TextLayout layout = new java.awt.font.TextLayout(
+                text, graphics.getFont(), graphics.getFontRenderContext());
+        java.awt.Shape outline = layout.getOutline(
+                java.awt.geom.AffineTransform.getTranslateInstance(x, y));
         graphics.setColor(Color.WHITE);
-        for (int dx = -1; dx <= 1; dx++) {
-            for (int dy = -1; dy <= 1; dy++) {
-                if (dx != 0 || dy != 0) graphics.drawString(text, x + dx, y + dy);
-            }
-        }
+        graphics.setStroke(new BasicStroke(HALO_OUTLINE_WIDTH,
+                BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND));
+        graphics.draw(outline);
         graphics.setColor(color);
-        graphics.drawString(text, x, y);
+        graphics.fill(outline);
     }
 
     public static final List<String> DAY_LABELS = Arrays.asList(

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