JUCE/modules/juce_gui_basics/layout/juce_StretchableLayoutManager.cpp

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

   This file is part of the JUCE 6 technical preview.
   Copyright (c) 2020 - Raw Material Software Limited

   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
{

StretchableLayoutManager::StretchableLayoutManager() {}
StretchableLayoutManager::~StretchableLayoutManager() {}

//==============================================================================
void StretchableLayoutManager::clearAllItems()
{
    items.clear();
    totalSize = 0;
}

void StretchableLayoutManager::setItemLayout (const int itemIndex,
                                              const double minimumSize,
                                              const double maximumSize,
                                              const double preferredSize)
{
    auto* layout = getInfoFor (itemIndex);

    if (layout == nullptr)
    {
        layout = new ItemLayoutProperties();
        layout->itemIndex = itemIndex;

        int i;
        for (i = 0; i < items.size(); ++i)
            if (items.getUnchecked (i)->itemIndex > itemIndex)
                break;

        items.insert (i, layout);
    }

    layout->minSize = minimumSize;
    layout->maxSize = maximumSize;
    layout->preferredSize = preferredSize;
    layout->currentSize = 0;
}

bool StretchableLayoutManager::getItemLayout (const int itemIndex,
                                              double& minimumSize,
                                              double& maximumSize,
                                              double& preferredSize) const
{
    if (auto* layout = getInfoFor (itemIndex))
    {
        minimumSize = layout->minSize;
        maximumSize = layout->maxSize;
        preferredSize = layout->preferredSize;
        return true;
    }

    return false;
}

//==============================================================================
void StretchableLayoutManager::setTotalSize (const int newTotalSize)
{
    totalSize = newTotalSize;

    fitComponentsIntoSpace (0, items.size(), totalSize, 0);
}

int StretchableLayoutManager::getItemCurrentPosition (const int itemIndex) const
{
    int pos = 0;

    for (int i = 0; i < itemIndex; ++i)
        if (auto* layout = getInfoFor (i))
            pos += layout->currentSize;

    return pos;
}

int StretchableLayoutManager::getItemCurrentAbsoluteSize (const int itemIndex) const
{
    if (auto* layout = getInfoFor (itemIndex))
        return layout->currentSize;

    return 0;
}

double StretchableLayoutManager::getItemCurrentRelativeSize (const int itemIndex) const
{
    if (auto* layout = getInfoFor (itemIndex))
        return -layout->currentSize / (double) totalSize;

    return 0;
}

void StretchableLayoutManager::setItemPosition (const int itemIndex,
                                                int newPosition)
{
    for (int i = items.size(); --i >= 0;)
    {
        auto* layout = items.getUnchecked(i);

        if (layout->itemIndex == itemIndex)
        {
            auto realTotalSize = jmax (totalSize, getMinimumSizeOfItems (0, items.size()));
            auto minSizeAfterThisComp = getMinimumSizeOfItems (i, items.size());
            auto maxSizeAfterThisComp = getMaximumSizeOfItems (i + 1, items.size());

            newPosition = jmax (newPosition, totalSize - maxSizeAfterThisComp - layout->currentSize);
            newPosition = jmin (newPosition, realTotalSize - minSizeAfterThisComp);

            auto endPos = fitComponentsIntoSpace (0, i, newPosition, 0);

            endPos += layout->currentSize;

            fitComponentsIntoSpace (i + 1, items.size(), totalSize - endPos, endPos);
            updatePrefSizesToMatchCurrentPositions();
            break;
        }
    }
}

//==============================================================================
void StretchableLayoutManager::layOutComponents (Component** const components,
                                                 int numComponents,
                                                 int x, int y, int w, int h,
                                                 const bool vertically,
                                                 const bool resizeOtherDimension)
{
    setTotalSize (vertically ? h : w);
    int pos = vertically ? y : x;

    for (int i = 0; i < numComponents; ++i)
    {
        if (auto* layout = getInfoFor (i))
        {
            if (auto* c = components[i])
            {
                if (i == numComponents - 1)
                {
                    // if it's the last item, crop it to exactly fit the available space..
                    if (resizeOtherDimension)
                    {
                        if (vertically)
                            c->setBounds (x, pos, w, jmax (layout->currentSize, h - pos));
                        else
                            c->setBounds (pos, y, jmax (layout->currentSize, w - pos), h);
                    }
                    else
                    {
                        if (vertically)
                            c->setBounds (c->getX(), pos, c->getWidth(), jmax (layout->currentSize, h - pos));
                        else
                            c->setBounds (pos, c->getY(), jmax (layout->currentSize, w - pos), c->getHeight());
                    }
                }
                else
                {
                    if (resizeOtherDimension)
                    {
                        if (vertically)
                            c->setBounds (x, pos, w, layout->currentSize);
                        else
                            c->setBounds (pos, y, layout->currentSize, h);
                    }
                    else
                    {
                        if (vertically)
                            c->setBounds (c->getX(), pos, c->getWidth(), layout->currentSize);
                        else
                            c->setBounds (pos, c->getY(), layout->currentSize, c->getHeight());
                    }
                }
            }

            pos += layout->currentSize;
        }
    }
}


//==============================================================================
StretchableLayoutManager::ItemLayoutProperties* StretchableLayoutManager::getInfoFor (const int itemIndex) const
{
    for (auto* i : items)
        if (i->itemIndex == itemIndex)
            return i;

    return nullptr;
}

int StretchableLayoutManager::fitComponentsIntoSpace (const int startIndex,
                                                      const int endIndex,
                                                      const int availableSpace,
                                                      int startPos)
{
    // calculate the total sizes
    double totalIdealSize = 0.0;
    int totalMinimums = 0;

    for (int i = startIndex; i < endIndex; ++i)
    {
        auto* layout = items.getUnchecked (i);

        layout->currentSize = sizeToRealSize (layout->minSize, totalSize);

        totalMinimums += layout->currentSize;
        totalIdealSize += sizeToRealSize (layout->preferredSize, totalSize);
   }

    if (totalIdealSize <= 0)
        totalIdealSize = 1.0;

    // now calc the best sizes..
    int extraSpace = availableSpace - totalMinimums;

    while (extraSpace > 0)
    {
        int numWantingMoreSpace = 0;
        int numHavingTakenExtraSpace = 0;

        // first figure out how many comps want a slice of the extra space..
        for (int i = startIndex; i < endIndex; ++i)
        {
            auto* layout = items.getUnchecked (i);

            auto sizeWanted = sizeToRealSize (layout->preferredSize, totalSize);

            auto bestSize = jlimit (layout->currentSize,
                                    jmax (layout->currentSize,
                                          sizeToRealSize (layout->maxSize, totalSize)),
                                    roundToInt (sizeWanted * availableSpace / totalIdealSize));

            if (bestSize > layout->currentSize)
                ++numWantingMoreSpace;
        }

        // ..share out the extra space..
        for (int i = startIndex; i < endIndex; ++i)
        {
            auto* layout = items.getUnchecked (i);

            auto sizeWanted = sizeToRealSize (layout->preferredSize, totalSize);

            auto bestSize = jlimit (layout->currentSize,
                                    jmax (layout->currentSize, sizeToRealSize (layout->maxSize, totalSize)),
                                    roundToInt (sizeWanted * availableSpace / totalIdealSize));

            auto extraWanted = bestSize - layout->currentSize;

            if (extraWanted > 0)
            {
                auto extraAllowed = jmin (extraWanted,
                                          extraSpace / jmax (1, numWantingMoreSpace));

                if (extraAllowed > 0)
                {
                    ++numHavingTakenExtraSpace;
                    --numWantingMoreSpace;

                    layout->currentSize += extraAllowed;
                    extraSpace -= extraAllowed;
                }
            }
        }

        if (numHavingTakenExtraSpace <= 0)
            break;
    }

    // ..and calculate the end position
    for (int i = startIndex; i < endIndex; ++i)
    {
        auto* layout = items.getUnchecked(i);
        startPos += layout->currentSize;
    }

    return startPos;
}

int StretchableLayoutManager::getMinimumSizeOfItems (const int startIndex,
                                                     const int endIndex) const
{
    int totalMinimums = 0;

    for (int i = startIndex; i < endIndex; ++i)
        totalMinimums += sizeToRealSize (items.getUnchecked (i)->minSize, totalSize);

    return totalMinimums;
}

int StretchableLayoutManager::getMaximumSizeOfItems (const int startIndex, const int endIndex) const
{
    int totalMaximums = 0;

    for (int i = startIndex; i < endIndex; ++i)
        totalMaximums += sizeToRealSize (items.getUnchecked (i)->maxSize, totalSize);

    return totalMaximums;
}

void StretchableLayoutManager::updatePrefSizesToMatchCurrentPositions()
{
    for (int i = 0; i < items.size(); ++i)
    {
        auto* layout = items.getUnchecked (i);

        layout->preferredSize
            = (layout->preferredSize < 0) ? getItemCurrentRelativeSize (i)
                                          : getItemCurrentAbsoluteSize (i);
    }
}

int StretchableLayoutManager::sizeToRealSize (double size, int totalSpace)
{
    if (size < 0)
        size *= -totalSpace;

    return roundToInt (size);
}

} // namespace juce