Carla/source/modules/juce_gui_basics/layout/juce_ScrollBar.cpp

/*
  ==============================================================================

   This file is part of the JUCE 6 technical preview.
   Copyright (c) 2017 - ROLI Ltd.

   You may use this code under the terms of the GPL v3
   (see www.gnu.org/licenses).

   For this technical preview, this file is not subject to commercial licensing.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

class ScrollBar::ScrollbarButton  : public Button
{
public:
    ScrollbarButton (int direc, ScrollBar& s)
        : Button (String()), direction (direc), owner (s)
    {
        setWantsKeyboardFocus (false);
    }

    void paintButton (Graphics& g, bool over, bool down) override
    {
        getLookAndFeel().drawScrollbarButton (g, owner, getWidth(), getHeight(),
                                              direction, owner.isVertical(), over, down);
    }

    void clicked() override
    {
        owner.moveScrollbarInSteps ((direction == 1 || direction == 2) ? 1 : -1);
    }

    using Button::clicked;

    int direction;

private:
    ScrollBar& owner;

    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (ScrollbarButton)
};


//==============================================================================
ScrollBar::ScrollBar (bool shouldBeVertical)  : vertical (shouldBeVertical)
{
    setRepaintsOnMouseActivity (true);
    setFocusContainer (true);
}

ScrollBar::~ScrollBar()
{
    upButton.reset();
    downButton.reset();
}

//==============================================================================
void ScrollBar::setRangeLimits (Range<double> newRangeLimit, NotificationType notification)
{
    if (totalRange != newRangeLimit)
    {
        totalRange = newRangeLimit;
        setCurrentRange (visibleRange, notification);
        updateThumbPosition();
    }
}

void ScrollBar::setRangeLimits (double newMinimum, double newMaximum, NotificationType notification)
{
    jassert (newMaximum >= newMinimum); // these can't be the wrong way round!
    setRangeLimits (Range<double> (newMinimum, newMaximum), notification);
}

bool ScrollBar::setCurrentRange (Range<double> newRange, NotificationType notification)
{
    auto constrainedRange = totalRange.constrainRange (newRange);

    if (visibleRange != constrainedRange)
    {
        visibleRange = constrainedRange;

        updateThumbPosition();

        if (notification != dontSendNotification)
            triggerAsyncUpdate();

        if (notification == sendNotificationSync)
            handleUpdateNowIfNeeded();

        return true;
    }

    return false;
}

void ScrollBar::setCurrentRange (double newStart, double newSize, NotificationType notification)
{
    setCurrentRange (Range<double> (newStart, newStart + newSize), notification);
}

void ScrollBar::setCurrentRangeStart (double newStart, NotificationType notification)
{
    setCurrentRange (visibleRange.movedToStartAt (newStart), notification);
}

void ScrollBar::setSingleStepSize (double newSingleStepSize) noexcept
{
    singleStepSize = newSingleStepSize;
}

bool ScrollBar::moveScrollbarInSteps (int howManySteps, NotificationType notification)
{
    return setCurrentRange (visibleRange + howManySteps * singleStepSize, notification);
}

bool ScrollBar::moveScrollbarInPages (int howManyPages, NotificationType notification)
{
    return setCurrentRange (visibleRange + howManyPages * visibleRange.getLength(), notification);
}

bool ScrollBar::scrollToTop (NotificationType notification)
{
    return setCurrentRange (visibleRange.movedToStartAt (getMinimumRangeLimit()), notification);
}

bool ScrollBar::scrollToBottom (NotificationType notification)
{
    return setCurrentRange (visibleRange.movedToEndAt (getMaximumRangeLimit()), notification);
}

void ScrollBar::setButtonRepeatSpeed (int newInitialDelay,
                                      int newRepeatDelay,
                                      int newMinimumDelay)
{
    initialDelayInMillisecs = newInitialDelay;
    repeatDelayInMillisecs  = newRepeatDelay;
    minimumDelayInMillisecs = newMinimumDelay;

    if (upButton != nullptr)
    {
        upButton  ->setRepeatSpeed (newInitialDelay, newRepeatDelay, newMinimumDelay);
        downButton->setRepeatSpeed (newInitialDelay, newRepeatDelay, newMinimumDelay);
    }
}

//==============================================================================
void ScrollBar::addListener (Listener* listener)
{
    listeners.add (listener);
}

void ScrollBar::removeListener (Listener* listener)
{
    listeners.remove (listener);
}

void ScrollBar::handleAsyncUpdate()
{
    auto start = visibleRange.getStart(); // (need to use a temp variable for VC7 compatibility)
    listeners.call ([=] (Listener& l) { l.scrollBarMoved (this, start); });
}

//==============================================================================
void ScrollBar::updateThumbPosition()
{
    auto minimumScrollBarThumbSize = getLookAndFeel().getMinimumScrollbarThumbSize (*this);

    int newThumbSize = roundToInt (totalRange.getLength() > 0 ? (visibleRange.getLength() * thumbAreaSize) / totalRange.getLength()
                                                              : thumbAreaSize);

    if (newThumbSize < minimumScrollBarThumbSize)
        newThumbSize = jmin (minimumScrollBarThumbSize, thumbAreaSize - 1);

    if (newThumbSize > thumbAreaSize)
        newThumbSize = thumbAreaSize;

    int newThumbStart = thumbAreaStart;

    if (totalRange.getLength() > visibleRange.getLength())
        newThumbStart += roundToInt (((visibleRange.getStart() - totalRange.getStart()) * (thumbAreaSize - newThumbSize))
                                         / (totalRange.getLength() - visibleRange.getLength()));

    Component::setVisible (getVisibility());

    if (thumbStart != newThumbStart  || thumbSize != newThumbSize)
    {
        auto repaintStart = jmin (thumbStart, newThumbStart) - 4;
        auto repaintSize = jmax (thumbStart + thumbSize, newThumbStart + newThumbSize) + 8 - repaintStart;

        if (vertical)
            repaint (0, repaintStart, getWidth(), repaintSize);
        else
            repaint (repaintStart, 0, repaintSize, getHeight());

        thumbStart = newThumbStart;
        thumbSize = newThumbSize;
    }
}

void ScrollBar::setOrientation (bool shouldBeVertical)
{
    if (vertical != shouldBeVertical)
    {
        vertical = shouldBeVertical;

        if (upButton != nullptr)
        {
            upButton->direction    = vertical ? 0 : 3;
            downButton->direction  = vertical ? 2 : 1;
        }

        updateThumbPosition();
    }
}

void ScrollBar::setAutoHide (bool shouldHideWhenFullRange)
{
    autohides = shouldHideWhenFullRange;
    updateThumbPosition();
}

bool ScrollBar::autoHides() const noexcept
{
    return autohides;
}

//==============================================================================
void ScrollBar::paint (Graphics& g)
{
    if (thumbAreaSize > 0)
    {
        auto& lf = getLookAndFeel();

        auto thumb = (thumbAreaSize > lf.getMinimumScrollbarThumbSize (*this))
                       ? thumbSize : 0;

        if (vertical)
            lf.drawScrollbar (g, *this, 0, thumbAreaStart, getWidth(), thumbAreaSize,
                              vertical, thumbStart, thumb, isMouseOver(), isMouseButtonDown());
        else
            lf.drawScrollbar (g, *this, thumbAreaStart, 0, thumbAreaSize, getHeight(),
                              vertical, thumbStart, thumb, isMouseOver(), isMouseButtonDown());
    }
}

void ScrollBar::lookAndFeelChanged()
{
    setComponentEffect (getLookAndFeel().getScrollbarEffect());

    if (isVisible())
        resized();
}

void ScrollBar::resized()
{
    auto length = vertical ? getHeight() : getWidth();

    auto& lf = getLookAndFeel();
    bool buttonsVisible = lf.areScrollbarButtonsVisible();
    int buttonSize = 0;

    if (buttonsVisible)
    {
        if (upButton == nullptr)
        {
            upButton  .reset (new ScrollbarButton (vertical ? 0 : 3, *this));
            downButton.reset (new ScrollbarButton (vertical ? 2 : 1, *this));

            addAndMakeVisible (upButton.get());
            addAndMakeVisible (downButton.get());

            setButtonRepeatSpeed (initialDelayInMillisecs, repeatDelayInMillisecs, minimumDelayInMillisecs);
        }

        buttonSize = jmin (lf.getScrollbarButtonSize (*this), length / 2);
    }
    else
    {
        upButton.reset();
        downButton.reset();
    }

    if (length < 32 + lf.getMinimumScrollbarThumbSize (*this))
    {
        thumbAreaStart = length / 2;
        thumbAreaSize = 0;
    }
    else
    {
        thumbAreaStart = buttonSize;
        thumbAreaSize = length - 2 * buttonSize;
    }

    if (upButton != nullptr)
    {
        auto r = getLocalBounds();

        if (vertical)
        {
            upButton->setBounds (r.removeFromTop (buttonSize));
            downButton->setBounds (r.removeFromBottom (buttonSize));
        }
        else
        {
            upButton->setBounds (r.removeFromLeft (buttonSize));
            downButton->setBounds (r.removeFromRight (buttonSize));
        }
    }

    updateThumbPosition();
}

void ScrollBar::parentHierarchyChanged()
{
    lookAndFeelChanged();
}

void ScrollBar::mouseDown (const MouseEvent& e)
{
    isDraggingThumb = false;
    lastMousePos = vertical ? e.y : e.x;
    dragStartMousePos = lastMousePos;
    dragStartRange = visibleRange.getStart();

    if (dragStartMousePos < thumbStart)
    {
        moveScrollbarInPages (-1);
        startTimer (400);
    }
    else if (dragStartMousePos >= thumbStart + thumbSize)
    {
        moveScrollbarInPages (1);
        startTimer (400);
    }
    else
    {
        isDraggingThumb = (thumbAreaSize > getLookAndFeel().getMinimumScrollbarThumbSize (*this))
                            && (thumbAreaSize > thumbSize);
    }
}

void ScrollBar::mouseDrag (const MouseEvent& e)
{
    auto mousePos = vertical ? e.y : e.x;

    if (isDraggingThumb && lastMousePos != mousePos && thumbAreaSize > thumbSize)
    {
        auto deltaPixels = mousePos - dragStartMousePos;

        setCurrentRangeStart (dragStartRange
                                + deltaPixels * (totalRange.getLength() - visibleRange.getLength())
                                    / (thumbAreaSize - thumbSize));
    }

    lastMousePos = mousePos;
}

void ScrollBar::mouseUp (const MouseEvent&)
{
    isDraggingThumb = false;
    stopTimer();
    repaint();
}

void ScrollBar::mouseWheelMove (const MouseEvent&, const MouseWheelDetails& wheel)
{
    float increment = 10.0f * (vertical ? wheel.deltaY : wheel.deltaX);

    if (increment < 0)
        increment = jmin (increment, -1.0f);
    else if (increment > 0)
        increment = jmax (increment, 1.0f);

    setCurrentRange (visibleRange - singleStepSize * increment);
}

void ScrollBar::timerCallback()
{
    if (isMouseButtonDown())
    {
        startTimer (40);

        if (lastMousePos < thumbStart)
            setCurrentRange (visibleRange - visibleRange.getLength());
        else if (lastMousePos > thumbStart + thumbSize)
            setCurrentRangeStart (visibleRange.getEnd());
    }
    else
    {
        stopTimer();
    }
}

bool ScrollBar::keyPressed (const KeyPress& key)
{
    if (isVisible())
    {
        if (key == KeyPress::upKey || key == KeyPress::leftKey)    return moveScrollbarInSteps (-1);
        if (key == KeyPress::downKey || key == KeyPress::rightKey) return moveScrollbarInSteps (1);
        if (key == KeyPress::pageUpKey)                            return moveScrollbarInPages (-1);
        if (key == KeyPress::pageDownKey)                          return moveScrollbarInPages (1);
        if (key == KeyPress::homeKey)                              return scrollToTop();
        if (key == KeyPress::endKey)                               return scrollToBottom();
    }

    return false;
}

void ScrollBar::setVisible (bool shouldBeVisible)
{
    if (userVisibilityFlag != shouldBeVisible)
    {
        userVisibilityFlag = shouldBeVisible;
        Component::setVisible (getVisibility());
    }
}

bool ScrollBar::getVisibility() const noexcept
{
    if (! userVisibilityFlag)
        return false;

    return (! autohides) || (totalRange.getLength() > visibleRange.getLength()
                                    && visibleRange.getLength() > 0.0);
}

} // namespace juce