fix(ui): 等值线 vtkSplineFilter 样条平滑(去DP简化,贴近原版圆滑曲线) + 标注沿线周期重复+降阈值(小等值线也标注)

src/app/panels/chart/ContourPlotItem.cpp

@@ -18,7 +18,8 @@ namespace {
 constexpr int kFillUpsample = 4;        // 填充图像每网格格细分 K（双线性插值平滑带边界）
 constexpr int kMaxFillDim = 2400;       // 填充图像单边像素上限（防极端网格爆内存）
 constexpr int kLabelFontPx = 10;        // 等值线标注字号
-constexpr int kLabelMinSegPx = 60;      // 太短的等值线不标注（像素长度阈值，draw 期判定）
+constexpr double kLabelMinLenPx = 24.0;   // 整条线像素长度小于此不标注（极短碎线）
+constexpr double kLabelSpacingPx = 220.0; // 沿线每隔此像素重复一个标注（对齐原版密度）
 constexpr double kRad2Deg = 57.29577951308232;  // 180/π（避免依赖 M_PI）
 }  // namespace
 
@@ -202,25 +203,43 @@ void ContourPlotItem::draw(QPainter* painter, const QwtScaleMap& xMap, const Qwt
             f.setPixelSize(kLabelFontPx);
             painter->setFont(f);
             painter->setPen(QColor(0, 0, 0));
+            const QFontMetricsF fm(f);
             for (const auto& ln : lines_) {
                 if (ln.pts.size() < 2 || std::isnan(ln.level)) continue;
-                // 取折线中段两点定位置/朝向。
-                const std::size_t mid = ln.pts.size() / 2;
-                const QPointF a = mapPt(ln.pts[mid - 1]);
-                const QPointF b = mapPt(ln.pts[mid]);
-                // 整条线像素长度太短不标注（避免密集杂乱）。
-                const QPointF s = mapPt(ln.pts.front());
-                const QPointF e = mapPt(ln.pts.back());
-                if (std::hypot(e.x() - s.x(), e.y() - s.y()) < kLabelMinSegPx) continue;
-                double ang = std::atan2(b.y() - a.y(), b.x() - a.x()) * kRad2Deg;
-                if (ang > 90.0) ang -= 180.0;  // 保持文字大体正向（不上下颠倒）
-                if (ang < -90.0) ang += 180.0;
+                // 映射到像素 + 累计像素弧长。
+                std::vector<QPointF> px;
+                px.reserve(ln.pts.size());
+                for (const auto& p : ln.pts) px.push_back(mapPt(p));
+                double total = 0.0;
+                for (std::size_t i = 1; i < px.size(); ++i)
+                    total += std::hypot(px[i].x() - px[i - 1].x(), px[i].y() - px[i - 1].y());
+                if (total < kLabelMinLenPx) continue;  // 极短碎线不标注
                 const QString txt = QString::number(ln.level, 'g', 4);
-                painter->save();
-                painter->translate((a.x() + b.x()) * 0.5, (a.y() + b.y()) * 0.5);
-                painter->rotate(ang);
-                painter->drawText(QPointF(-12, -2), txt);
-                painter->restore();
+                const double halfW = fm.horizontalAdvance(txt) * 0.5;
+                // 沿线每隔 kLabelSpacingPx 放一个标注；首个在半间距处（短线即中点附近）。
+                double nextAt = std::min(kLabelSpacingPx * 0.5, total * 0.5);
+                double acc = 0.0;
+                for (std::size_t i = 1; i < px.size() && nextAt <= total; ++i) {
+                    const double seg =
+                        std::hypot(px[i].x() - px[i - 1].x(), px[i].y() - px[i - 1].y());
+                    while (nextAt <= acc + seg && nextAt <= total) {
+                        const double t = seg > 1e-6 ? (nextAt - acc) / seg : 0.0;
+                        const QPointF pos(px[i - 1].x() + (px[i].x() - px[i - 1].x()) * t,
+                                          px[i - 1].y() + (px[i].y() - px[i - 1].y()) * t);
+                        double ang =
+                            std::atan2(px[i].y() - px[i - 1].y(), px[i].x() - px[i - 1].x()) *
+                            kRad2Deg;
+                        if (ang > 90.0) ang -= 180.0;  // 文字大体正向
+                        if (ang < -90.0) ang += 180.0;
+                        painter->save();
+                        painter->translate(pos);
+                        painter->rotate(ang);
+                        painter->drawText(QPointF(-halfW, -2), txt);
+                        painter->restore();
+                        nextAt += kLabelSpacingPx;
+                    }
+                    acc += seg;
+                }
             }
             painter->restore();
         }

src/render/ContourBands.cpp

@@ -11,6 +11,7 @@
 #include <vtkPointData.h>
 #include <vtkPoints.h>
 #include <vtkPolyData.h>
+#include <vtkSplineFilter.h>
 #include <vtkStripper.h>
 #include <vtkUnstructuredGrid.h>
 
@@ -161,8 +162,15 @@ ContourBandsResult buildContourBands(const Grid& g, const ColorScale& cs, const
             vtkNew<vtkStripper> stripper;
             stripper->SetInputData(edges);
             stripper->JoinContiguousSegmentsOn();
-            stripper->Update();
-            vtkPolyData* joined = stripper->GetOutput();
+            // 样条平滑：把折线拟合成平滑曲线并按弧长重采样（对齐原版圆滑等值线）。
+            // 重采样间距取数据 x 跨度的 ~1/300，足够平滑且点数可控。
+            const double xspan = g.x.empty() ? 1.0 : (g.x.back() - g.x.front());
+            vtkNew<vtkSplineFilter> spline;
+            spline->SetInputConnection(stripper->GetOutputPort());
+            spline->SetSubdivideToLength();
+            spline->SetLength(xspan > 0 ? xspan / 300.0 : 1.0);
+            spline->Update();
+            vtkPolyData* joined = spline->GetOutput();
             joined->BuildCells();
             const vtkIdType nLines = joined->GetNumberOfCells();
             for (vtkIdType c = 0; c < nLines; ++c) {
@@ -173,7 +181,7 @@ ContourBandsResult buildContourBands(const Grid& g, const ColorScale& cs, const
                     double xyz[3]; cp->GetPoint(p, xyz);
                     cl.pts.push_back(Vec2{xyz[0], xyz[1]});
                 }
-                simplifyInPlace(cl.pts, opt.simplifyTol);
+                // 不再 DP 简化：样条已平滑且点数受重采样间距控制；简化会重新折线化。
                 if (cl.pts.size() >= 2) out.lines.push_back(std::move(cl));
             }
         }