Coloured slider tracks with double-click reset, aligned filter titles; entries release focus before their owners go (12.14c)

src/UI/HueSaturationSheet+Spectrum.cpp

@@ -0,0 +1,141 @@
+#include "UI/HueSaturationSheet.h"
+#include <QLabel>
+#include <QMouseEvent>
+#include <QPainter>
+#include <QPainterPath>
+#include <QVBoxLayout>
+#include <algorithm>
+#include <cmath>
+
+// Swift's SpectrumEditor: the bars, their handles and the readout.
+namespace {
+// Swift's 72 hue slices, as they are or adjusted.
+class Spectrum : public QWidget {
+public:
+    Spectrum(std::function<HueSaturationSettings()> value, bool after, QWidget *parent) : QWidget(parent), m_value(std::move(value)), m_after(after)
+    {
+        setFixedHeight(16);
+    }
+
+protected:
+    void paintEvent(QPaintEvent *) override
+    {
+        constexpr int slices = 72;
+        QPainter painter(this);
+        painter.setRenderHint(QPainter::Antialiasing);
+        QPainterPath rounded;
+        rounded.addRoundedRect(QRectF(rect()), 3, 3);
+        painter.setClipPath(rounded);
+        const HueSaturationSettings settings = m_value();
+        const double width = double(this->width()) / slices;
+        for (int slice = 0; slice < slices; ++slice) {
+            const double hue = double(slice) / slices * 360;
+            const double shown = m_after ? HueSaturationFilter::shiftedHue(hue, settings) : hue;
+            painter.fillRect(QRectF(slice * width, 0, width + 0.5, height()), QColor::fromHsvF(float(shown / 360), 1, 1));
+        }
+    }
+
+private:
+    const std::function<HueSaturationSettings()> m_value;
+    const bool m_after;
+};
+
+// Swift's handles: shoulders as blocks, the core's ends as bars.
+class SpectrumHandles : public QWidget {
+public:
+    SpectrumHandles(std::function<HueSaturationSettings()> value, std::function<void(double, double, bool)> drag, QWidget *parent)
+        : QWidget(parent), m_value(std::move(value)), m_drag(std::move(drag))
+    {
+        setFixedHeight(12);
+    }
+
+protected:
+    void paintEvent(QPaintEvent *) override
+    {
+        QPainter painter(this);
+        painter.setRenderHint(QPainter::Antialiasing);
+        const std::array<double, 4> handles = m_value().band().handles();
+        for (size_t index = 0; index < handles.size(); ++index) {
+            const double x = handles[index] / 360 * width();
+            const bool inner = index == 1 || index == 2;
+            painter.fillRect(inner ? QRectF(x - 1, 0, 2, height()) : QRectF(x - 3.5, height() / 2.0 - 2.5, 7, 5), palette().color(QPalette::WindowText));
+        }
+    }
+    void mousePressEvent(QMouseEvent *event) override
+    {
+        if (event->button() == Qt::LeftButton)
+            m_drag(event->position().x(), width(), true);
+    }
+    void mouseMoveEvent(QMouseEvent *event) override
+    {
+        if (event->buttons().testFlag(Qt::LeftButton))
+            m_drag(event->position().x(), width(), false);
+    }
+
+private:
+    const std::function<HueSaturationSettings()> m_value;
+    const std::function<void(double, double, bool)> m_drag;
+};
+
+// The nearest handle round the circle; ties take the first.
+int nearestHandle(const HueBand &band, double degrees)
+{
+    const std::array<double, 4> handles = band.handles();
+    std::array<double, 4> distances{};
+    for (size_t index = 0; index < handles.size(); ++index) {
+        const double gap = std::fmod(std::abs(handles[index] - degrees), 360);
+        distances[index] = std::min(gap, 360 - gap);
+    }
+    return int(std::min_element(distances.begin(), distances.end()) - distances.begin());
+}
+}
+
+SpectrumEditor::SpectrumEditor(std::function<HueSaturationSettings()> value, std::function<void(const HueSaturationSettings &)> change, QWidget *parent)
+    : QWidget(parent), m_value(std::move(value)), m_change(std::move(change)),
+      m_handles(new SpectrumHandles(m_value, [this](double x, double width, bool pressed) { drag(x, width, pressed); }, this)),
+      m_after(new Spectrum(m_value, true, this)), m_readout(new QLabel(this))
+{
+    auto *before = new Spectrum(m_value, false, this);
+    before->setObjectName(QStringLiteral("spectrumBefore"));
+    m_handles->setObjectName(QStringLiteral("spectrumHandles"));
+    m_after->setObjectName(QStringLiteral("spectrumAfter"));
+    m_readout->setObjectName(QStringLiteral("spectrumReadout"));
+    // Swift's .caption in the secondary ink.
+    QFont small = m_readout->font();
+    small.setPixelSize(10);
+    m_readout->setFont(small);
+    m_readout->setForegroundRole(QPalette::PlaceholderText);
+    auto *column = new QVBoxLayout(this);
+    column->setContentsMargins(0, 0, 0, 0);
+    column->setSpacing(5);
+    column->addWidget(before);
+    column->addWidget(m_handles);
+    column->addWidget(m_after);
+    column->addWidget(m_readout, 0, Qt::AlignHCenter);
+    synchronize();
+}
+
+void SpectrumEditor::synchronize()
+{
+    QStringList degrees;
+    for (const double handle : m_value().band().handles())
+        degrees << QStringLiteral("%1°").arg(std::lround(handle));
+    m_readout->setText(degrees.join(QStringLiteral("   ")));
+    m_handles->update();
+    m_after->update();
+}
+
+void SpectrumEditor::drag(double x, double width, bool pressed)
+{
+    // A press starts afresh: Qt can lose a release.
+    if (pressed)
+        m_dragging.reset();
+    const double degrees = std::clamp(x, 0.0, width) / width * 360;
+    HueSaturationSettings settings = m_value();
+    HueBand band = settings.band();
+    const int index = m_dragging.value_or(nearestHandle(band, degrees));
+    m_dragging = index;
+    band.setHandle(index, degrees);
+    settings.setBand(band);
+    m_change(settings);
+}