JUCE/modules/juce_gui_basics/layout/juce_FlexBox.h

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

   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
{

/**
    Represents a FlexBox container, which contains and manages the layout of a set
    of FlexItem objects.

    To use this class, set its parameters appropriately (you can search online for
    more help on exactly how the FlexBox protocol works!), then add your sub-items
    to the items array, and call performLayout() in the resized() function of your
    Component.

    @see FlexItem

    @tags{GUI}
*/
class JUCE_API  FlexBox  final
{
public:
    /** Possible values for the flexDirection property. */
    enum class Direction
    {
        row,                  /**< Set the main axis direction from left to right. */
        rowReverse,           /**< Set the main axis direction from right to left. */
        column,               /**< Set the main axis direction from top to bottom. */
        columnReverse         /**< Set the main axis direction from bottom to top. */
    };

    /** Possible values for the flexWrap property. */
    enum class Wrap
    {
        noWrap,               /**< Items are forced into a single line. */
        wrap,                 /**< Items are wrapped onto multiple lines from top to bottom. */
        wrapReverse           /**< Items are wrapped onto multiple lines from bottom to top. */
    };

    /** Possible values for the alignContent property. */
    enum class AlignContent
    {
        stretch,              /**< Lines of items are stretched from start to end of the cross axis. */
        flexStart,            /**< Lines of items are aligned towards the start of the cross axis. */
        flexEnd,              /**< Lines of items are aligned towards the end of the cross axis. */
        center,               /**< Lines of items are aligned towards the center of the cross axis. */
        spaceBetween,         /**< Lines of items are evenly spaced along the cross axis with spaces between them. */
        spaceAround           /**< Lines of items are evenly spaced along the cross axis with spaces around them. */
    };

    /** Possible values for the alignItems property. */
    enum class AlignItems
    {
        stretch,              /**< Items are stretched from start to end of the cross axis. */
        flexStart,            /**< Items are aligned towards the start of the cross axis. */
        flexEnd,              /**< Items are aligned towards the end of the cross axis. */
        center                /**< Items are aligned towards the center of the cross axis. */
    };

    /** Possible values for the justifyContent property. */
    enum class JustifyContent
    {
        flexStart,            /**< Items are justified towards the start of the main axis. */
        flexEnd,              /**< Items are justified towards the end of the main axis. */
        center,               /**< Items are justified towards the center of the main axis. */
        spaceBetween,         /**< Items are evenly spaced along the main axis with spaces between them. */
        spaceAround           /**< Items are evenly spaced along the main axis with spaces around them. */
    };

    //==============================================================================
    /** Creates an empty FlexBox container with default parameters. */
    FlexBox() noexcept;

    /** Creates an empty FlexBox container with these parameters. */
    FlexBox (Direction, Wrap, AlignContent, AlignItems, JustifyContent) noexcept;

    /** Creates an empty FlexBox container with the given content-justification mode. */
    FlexBox (JustifyContent) noexcept;

    /** Destructor. */
    ~FlexBox() noexcept;

    //==============================================================================
    /** Lays-out the box's items within the given rectangle. */
    void performLayout (Rectangle<float> targetArea);

    /** Lays-out the box's items within the given rectangle. */
    void performLayout (Rectangle<int> targetArea);

    //==============================================================================
    /** Specifies how flex items are placed in the flex container, and defines the
        direction of the main axis.
    */
    Direction flexDirection = Direction::row;

    /** Specifies whether items are forced into a single line or can be wrapped onto multiple lines.
        If wrapping is allowed, this property also controls the direction in which lines are stacked.
    */
    Wrap flexWrap = Wrap::noWrap;

    /** Specifies how a flex container's lines are placed within the flex container when
        there is extra space on the cross-axis.
        This property has no effect on single line layouts.
    */
    AlignContent alignContent = AlignContent::stretch;

    /** Specifies the alignment of flex items along the cross-axis of each line. */
    AlignItems alignItems = AlignItems::stretch;

    /** Defines how the container distributes space between and around items along the main-axis.
        The alignment is done after the lengths and auto margins are applied, so that if there is at
        least one flexible element, with flex-grow different from 0, it will have no effect as there
        won't be any available space.
    */
    JustifyContent justifyContent = JustifyContent::flexStart;

    /** The set of items to lay-out. */
    Array<FlexItem> items;

private:
    JUCE_LEAK_DETECTOR (FlexBox)
};

} // namespace juce