serumalt/Source/GUI/Knob.cpp

#include "Knob.h"

namespace serum
{

namespace
{
    // One shared look-and-feel for every knob. It outlives every Knob because
    // it is a function-local static and the GUI owns the knobs.
    KnobLookAndFeel& knobStyle()
    {
        static KnobLookAndFeel style;
        return style;
    }
}

Knob::Knob (const juce::String& name, std::function<juce::String (float)> fmt)
    : formatter (std::move (fmt))
{
    setSliderStyle (juce::Slider::RotaryVerticalDrag);
    setTextBoxStyle (juce::Slider::NoTextBox, false, 0, 0);
    setRange (0.0, 1.0);
    setDoubleClickReturnValue (true, 0.5);
    setName (name);
    setComponentID (name);

    // Draw the dial and the name strip through the theme, not through the
    // shared default look-and-feel.
    setLookAndFeel (&knobStyle());
}

juce::String Knob::getTextFromValue (double value)
{
    if (formatter)
        return formatter ((float) value);
    return formatPercent ((float) value);
}

// The dial takes the top of the footprint and the name takes a strip at the
// bottom, so the name is always visible without a tooltip hover.
void Knob::resized()
{
    juce::Slider::resized();
    textArea = getLocalBounds().removeFromBottom (
        juce::jmin (KnobLookAndFeel::labelHeight, getHeight() / 2));
}

void Knob::paint (juce::Graphics& g)
{
    juce::Slider::paint (g);

    if (textArea.isEmpty())
        return;

    // Dim while disabled, bright while hovered, otherwise the normal label
    // colour, so the three states are distinguishable without colour alone.
    const auto colour = isEnabled() ? (isMouseOverOrDragging() ? theme::text : theme::textDim)
                                    : theme::outline;

    g.setColour (colour);
    g.setFont (juce::Font (11.0f));
    g.drawText (getName(), textArea, juce::Justification::centred, false);
}

void Knob::mouseDown (const juce::MouseEvent& e)
{
    juce::Slider::mouseDown (e);
    showValuePopup (e);
}

void Knob::mouseDrag (const juce::MouseEvent& e)
{
    juce::Slider::mouseDrag (e);
    showValuePopup (e);
}

void Knob::mouseUp (const juce::MouseEvent& e)
{
    juce::Slider::mouseUp (e);
    hideValuePopup();
}

void Knob::mouseExit (const juce::MouseEvent& e)
{
    juce::Slider::mouseExit (e);
    hideValuePopup();
}

// ---------------------------------------------------------------------------
// The floating readout lives as a child of the top-level component so it can
// follow the cursor outside this knob's own bounds without being clipped, and
// it never intercepts mouse clicks so it can't block interaction.
// ---------------------------------------------------------------------------
void Knob::showValuePopup (const juce::MouseEvent& e)
{
    auto* topLevel = getTopLevelComponent();
    if (topLevel == nullptr)
        return;

    constexpr int baseW = 84;
    constexpr int baseH = 24;
    constexpr int gap = 10;

    // The interface scale is applied to a parent component, not to this slider.
    // Measure it from the local-space distance between two neighbouring points,
    // so a scaled interface does not leave the readout at a fixed size.
    float scale = 1.0f;
    if (auto* parent = getParentComponent())
    {
        const auto origin = getLocalPoint (parent, juce::Point<int> (0, 0)).toFloat();
        const auto unitX  = getLocalPoint (parent, juce::Point<int> (1, 0)).toFloat();
        scale = origin.getDistanceFrom (unitX);
    }
    scale = juce::jlimit (0.5f, 2.5f, scale);
    const int w = juce::roundToInt (baseW * scale);
    const int h = juce::roundToInt (baseH * scale);

    if (valuePopup == nullptr)
    {
        valuePopup = std::make_unique<juce::Label>();
        valuePopup->setAlwaysOnTop (true);
        valuePopup->setInterceptsMouseClicks (false, false);
        valuePopup->setColour (juce::Label::backgroundColourId, juce::Colours::transparentBlack);
        valuePopup->setColour (juce::Label::textColourId, theme::text);
        valuePopup->setJustificationType (juce::Justification::centred);
        topLevel->addAndMakeVisible (valuePopup.get());
    }

    valuePopup->setFont (juce::Font (14.0f * scale, juce::Font::bold));
    valuePopup->setText (getTextFromValue (getValue()), juce::dontSendNotification);

    // Keep the readout inside the window so a knob near an edge still shows it.
    const auto popupPos = topLevel->getLocalPoint (nullptr, e.getScreenPosition());
    valuePopup->setBounds (juce::jlimit (0, juce::jmax (0, topLevel->getWidth() - w),
                                         popupPos.getX() - w / 2),
                           juce::jlimit (0, juce::jmax (0, topLevel->getHeight() - h),
                                         popupPos.getY() - h - gap),
                           w, h);
}

void Knob::hideValuePopup()
{
    valuePopup.reset();
}

// A section switch can hide the view holding this knob mid-drag. The popup is a
// sibling of that view, so it has to be taken down here or it stays on screen.
void Knob::visibilityChanged()
{
    if (! isVisible())
        hideValuePopup();
}

} // namespace serum