fix: Smarter tick placement (#21)

* Move more tick handling into the axes * Smarter tic spacing * Ensure plots are updated when axes are updated * Much better linear tick points * Better log axes * Fix c++ formatting * Fix QML formatting
disorderedmaterials · Jun 5, 2024 · df618aa · df618aa
1 parent 1a5e73f
commit df618aa
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Showing 10 changed files with 154 additions and 42 deletions.
diff --git a/src/AxisModel.qml b/src/AxisModel.qml
@@ -28,9 +28,8 @@ Node {
         model: axis.tickLabels
 
         delegate: Node {
-            position: axis.direction ? Qt.vector3d(-root.scl.x + 2 * tickX * root.scl.x / (rep.count - 1), -root.scl.y - 210, 0) : Qt.vector3d(-root.scl.x - 30, -root.scl.y - 180 + 2 * tickY * root.scl.y / (rep.count - 1), 0)
+            position: axis.direction ? Qt.vector3d(-root.scl.x + tickX * root.scl.x, -root.scl.y - 210, 0) : Qt.vector3d(-root.scl.x - 30, -root.scl.y - 180 + tickY * root.scl.y, 0)
 
-            /* position: axis.direction ? Qt.vector3d(-root.scl.x + 2 * index * root.scl.x / (rep.count - 1), -root.scl.y - 210, 0) : Qt.vector3d(-root.scl.x - 30.0, -root.scl.y - 180 + 2 * index * root.scl.y / (rep.count - 1), 0) */
             Item {
                 anchors.centerIn: parent
                 height: 400

diff --git a/src/LineModel.qml b/src/LineModel.qml
@@ -29,4 +29,19 @@ Model {
             baseColor: root.color
         }
     ]
+
+    Connections {
+        function onDataChanged() {
+            plotLine.dataChanged();
+        }
+
+        target: xAxis
+    }
+    Connections {
+        function onDataChanged() {
+            plotLine.dataChanged();
+        }
+
+        target: yAxis
+    }
 }
diff --git a/src/ScatterModel.qml b/src/ScatterModel.qml
@@ -29,4 +29,19 @@ Model {
             baseColor: root.color
         }
     ]
+
+    Connections {
+        function onDataChanged() {
+            plotLine.dataChanged();
+        }
+
+        target: xAxis
+    }
+    Connections {
+        function onDataChanged() {
+            plotLine.dataChanged();
+        }
+
+        target: yAxis
+    }
 }
diff --git a/src/axis.cpp b/src/axis.cpp
@@ -1,9 +1,10 @@
 #include "axis.h"
 #include <algorithm>
 
+#include <cmath>
 #include <iostream>
 
-Axis::Axis() : direction_(false), minimum_(-1), maximum_(1), thickness_(0.001), tickLabels_(*this)
+Axis::Axis() : minimum_(-1), maximum_(1), direction_(false), thickness_(0.001), tickLabels_(*this)
 {
     updateData();
     connect(this, &Axis::dataChanged, this, &Axis::updateData);
@@ -15,14 +16,42 @@ bool Axis::direction() const { return direction_; }
 double Axis::minimum() const { return minimum_; }
 double Axis::maximum() const { return maximum_; }
 
-int Axis::tickCount() const { return tickLabels_.tickCount(); }
+int Axis::tickCount() const { return tics_.size(); }
 
-void Axis::setTickCount(const int count) { tickLabels_.setTickCount(count); }
+void Axis::updateTicks_()
+{
+
+    auto full_diff = maximum_ - minimum_;
+    auto diff = pow(10.0, floor(log(full_diff) / log(10.0)));
+    while (full_diff / diff < 4)
+    {
+        diff /= 2;
+    }
+    while (full_diff / diff > 9)
+    {
+        diff *= 2;
+    }
+    tics_.clear();
+
+    auto current = floor(minimum_ / diff) * diff;
+
+    while (current < minimum_)
+        current += diff;
+
+    while (current <= maximum_)
+    {
+        tics_.emplace_back(current);
+        current += diff;
+    }
+}
 
 void Axis::updateData()
 {
     clear();
 
+    updateTicks_();
+    tickLabels_.reset();
+
     int stride = 3 * sizeof(float);
 
     QByteArray vertexData(6 * stride, Qt::Initialization::Uninitialized);
@@ -92,7 +121,6 @@ std::vector<float> Axis::convert(QList<double> points) const
     return result;
 }
 
-double Axis::tick(int index, int count) const
-{
-    return minimum_ + (double)index / ((double)count - 1.0) * (maximum_ - minimum_);
-}
+double Axis::tick(int index) const { return tics_[index]; }
+
+double Axis::tickCoord(int index) const { return 2.0 * (tics_[index] - minimum_) / (maximum_ - minimum_); }
diff --git a/src/axis.h b/src/axis.h
@@ -13,7 +13,7 @@ class Axis : public QQuick3DGeometry
     Q_PROPERTY(double maximum MEMBER maximum_ NOTIFY dataChanged)
     Q_PROPERTY(bool direction MEMBER direction_ NOTIFY dataChanged)
     Q_PROPERTY(AxisTickLabels *tickLabels READ tickLabels NOTIFY dataChanged)
-    Q_PROPERTY(int tickCount READ tickCount WRITE setTickCount)
+    Q_PROPERTY(int tickCount READ tickCount NOTIFY dataChanged)
 
     public:
     Axis();
@@ -23,15 +23,20 @@ class Axis : public QQuick3DGeometry
     double minimum() const;
     double maximum() const;
     int tickCount() const;
-    void setTickCount(const int count);
-    virtual double tick(int index, int count) const;
+    double tick(int index) const;
+    virtual double tickCoord(int index) const;
 
     Q_SIGNALS:
     void dataChanged();
 
+    protected:
+    std::vector<double> tics_;
+    double minimum_, maximum_;
+
     private:
+    virtual void updateTicks_();
     void updateData();
     bool direction_;
-    double minimum_, maximum_, thickness_;
+    double thickness_;
     AxisTickLabels tickLabels_;
 };
diff --git a/src/axisTickLabels.cpp b/src/axisTickLabels.cpp
@@ -2,29 +2,20 @@
 #include "axis.h"
 #include <iostream>
 
-AxisTickLabels::AxisTickLabels(Axis &parent) : parent_(parent), N_(5) {}
+AxisTickLabels::AxisTickLabels(Axis &parent) : parent_(parent) {}
 
-int AxisTickLabels::tickCount() const { return N_; }
-
-void AxisTickLabels::setTickCount(const int count)
-{
-    beginResetModel();
-    N_ = count;
-    endResetModel();
-}
-
-int AxisTickLabels::rowCount([[maybe_unused]] const QModelIndex &parent) const { return N_; }
+int AxisTickLabels::rowCount([[maybe_unused]] const QModelIndex &parent) const { return parent_.tickCount(); }
 
 QVariant AxisTickLabels::data(const QModelIndex &index, int role) const
 {
     switch (role)
     {
         case Qt::UserRole:
-            return QString("%1").arg(parent_.tick(index.row(), N_));
+            return QString("%1").arg(parent_.tick(index.row()));
         case (Qt::UserRole + 1):
-            return parent_.direction() ? index.row() : 0;
+            return parent_.direction() ? parent_.tickCoord(index.row()) : 0;
         case (Qt::UserRole + 2):
-            return parent_.direction() ? 0 : index.row();
+            return parent_.direction() ? 0 : parent_.tickCoord(index.row());
         default:
             return index.row();
     }
@@ -38,3 +29,9 @@ QHash<int, QByteArray> AxisTickLabels::roleNames() const
     roles[Qt::UserRole + 2] = "tickY";
     return roles;
 }
+
+void AxisTickLabels::reset()
+{
+    beginResetModel();
+    endResetModel();
+}
diff --git a/src/axisTickLabels.h b/src/axisTickLabels.h
@@ -16,8 +16,8 @@ class AxisTickLabels : public QAbstractListModel
     QHash<int, QByteArray> roleNames() const override;
     int tickCount() const;
     void setTickCount(const int count);
+    void reset();
 
     private:
     Axis &parent_;
-    int N_;
 };
diff --git a/src/logAxis.cpp b/src/logAxis.cpp
@@ -3,6 +3,7 @@
 
 #include <cmath>
 #include <iostream>
+#include <vector>
 
 LogAxis::LogAxis() : Axis() {}
 
@@ -19,10 +20,51 @@ std::vector<float> LogAxis::convert(QList<double> points) const
     return result;
 }
 
-double LogAxis::tick(int index, int count) const
+void LogAxis::updateTicks_()
 {
-    auto min = log(minimum());
-    auto max = log(maximum());
+    std::vector<double> subTicks;
+    tics_.clear();
+
+    int orders = ceil(log(maximum_ / minimum_) / log(10.0));
+
+    switch (orders)
+    {
+        case 0:
+        case 1:
+            subTicks = {1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0};
+            break;
+        case 2:
+            subTicks = {1.0, 2.0, 3.0, 5.0, 8.0};
+            break;
+        case 3:
+        case 4:
+            subTicks = {1.0, 2.0, 5.0};
+            break;
+        case 5:
+            subTicks = {1.0, 3.0};
+            break;
+        default:
+            subTicks = {1.0};
+    }
+
+    double current = pow(10.0, floor(log(minimum_) / log(10.0)));
+
+    while (current <= maximum_)
+    {
+        for (auto sub : subTicks)
+        {
+            if (sub * current >= minimum_ && sub * current <= maximum_)
+                tics_.emplace_back(sub * current);
+        }
+        current *= 10.0;
+    }
+}
+
+double LogAxis::tickCoord(int index) const
+{
+    double actual = log10(tics_[index]);
+    double min = log10(minimum_);
+    double max = log10(maximum_);
 
-    return exp(min + (double)index / ((double)count - 1.0) * (max - min));
+    return 2.0 * (actual - min) / (max - min);
 }
diff --git a/src/logAxis.h b/src/logAxis.h
@@ -13,7 +13,10 @@ class LogAxis : public Axis
     public:
     LogAxis();
     std::vector<float> convert(QList<double> values) const override;
-    double tick(int index, int count) const override;
+    double tickCoord(int index) const override;
+
+    private:
+    void updateTicks_() override;
 
     Q_SIGNALS:
     void dataChanged();

diff --git a/src/main.qml b/src/main.qml
@@ -50,10 +50,9 @@ ApplicationWindow {
                 id: xAxis
 
                 direction: true
-                maximum: 1.0
-                minimum: -1.0
+                maximum: yMax.value
+                minimum: yMin.value
                 thickness: 0.01
-                tickCount: ticCount.value
             }
         }
         AxisModel {
@@ -67,7 +66,6 @@ ApplicationWindow {
                 maximum: 1.0
                 minimum: 0.01
                 thickness: 0.01
-                tickCount: ticCount.value
             }
         }
     }
@@ -147,14 +145,24 @@ ApplicationWindow {
                 onMoved: renderButton.onClicked()
             }
             Label {
-                text: "Tic Count"
+                text: "Y Min"
             }
             SpinBox {
-                id: ticCount
+                id: yMin
 
-                from: 2
-                to: 10
-                value: 5
+                from: -30
+                to: yMax.value
+                value: -1
+            }
+            Label {
+                text: "Y Max"
+            }
+            SpinBox {
+                id: yMax
+
+                from: 0
+                to: 30
+                value: 1
             }
             ColorDialog {
                 id: colorDialog