很简单的一个类，一个rect放置在另一个rect中如何放置。只是没有考虑边距等，估且认为是在外层作考虑吧。然后认为是外框比内框大，所以外层怕是要进行检查才行
#ifndef JUCE_JUSTIFICATION_H_INCLUDED#define JUCE_JUSTIFICATION_H_INCLUDED//==============================================================================/** Represents a type of justification to be used when positioning graphical items. e.g. it indicates whether something should be placed top-left, top-right, centred, etc. It is used in various places wherever this kind of information is needed.*/class Justification{public: //============================================================================== /** Creates a Justification object using a combination of flags from the Flags enum. */ Justification (int justificationFlags) noexcept : flags (justificationFlags) {} /** Creates a copy of another Justification object. */ Justification (const Justification& other) noexcept : flags (other.flags) {} /** Copies another Justification object. */ Justification& operator= (const Justification& other) noexcept { flags = other.flags; return *this; } bool operator== (const Justification& other) const noexcept { return flags == other.flags; } bool operator!= (const Justification& other) const noexcept { return flags != other.flags; } //============================================================================== /** Returns the raw flags that are set for this Justification object. */ inline int getFlags() const noexcept { return flags; } /** Tests a set of flags for this object. @returns true if any of the flags passed in are set on this object. */ inline bool testFlags (int flagsToTest) const noexcept { return (flags & flagsToTest) != 0; } /** Returns just the flags from this object that deal with vertical layout. */ int getOnlyVerticalFlags() const noexcept { return flags & (top | bottom | verticallyCentred); } /** Returns just the flags from this object that deal with horizontal layout. */ int getOnlyHorizontalFlags() const noexcept { return flags & (left | right | horizontallyCentred | horizontallyJustified); } //============================================================================== /** Adjusts the position of a rectangle to fit it into a space. The (x, y) position of the rectangle will be updated to position it inside the given space according to the justification flags. */ template void applyToRectangle (ValueType& x, ValueType& y, ValueType w, ValueType h, ValueType spaceX, ValueType spaceY, ValueType spaceW, ValueType spaceH) const noexcept { x = spaceX; if ((flags & horizontallyCentred) != 0) x += (spaceW - w) / (ValueType) 2; else if ((flags & right) != 0) x += spaceW - w; y = spaceY; if ((flags & verticallyCentred) != 0) y += (spaceH - h) / (ValueType) 2; else if ((flags & bottom) != 0) y += spaceH - h; } /** Returns the new position of a rectangle that has been justified to fit within a given space. */ template const Rectangle appliedToRectangle (const Rectangle & areaToAdjust, const Rectangle & targetSpace) const noexcept { ValueType x = areaToAdjust.getX(), y = areaToAdjust.getY(); applyToRectangle (x, y, areaToAdjust.getWidth(), areaToAdjust.getHeight(), targetSpace.getX(), targetSpace.getY(), targetSpace.getWidth(), targetSpace.getHeight()); return areaToAdjust.withPosition (x, y); } //============================================================================== /** Flag values that can be combined and used in the constructor. */ enum Flags { //============================================================================== /** Indicates that the item should be aligned against the left edge of the available space. */ left = 1, /** Indicates that the item should be aligned against the right edge of the available space. */ right = 2, /** Indicates that the item should be placed in the centre between the left and right sides of the available space. */ horizontallyCentred = 4, //============================================================================== /** Indicates that the item should be aligned against the top edge of the available space. */ top = 8, /** Indicates that the item should be aligned against the bottom edge of the available space. */ bottom = 16, /** Indicates that the item should be placed in the centre between the top and bottom sides of the available space. */ verticallyCentred = 32, //============================================================================== /** Indicates that lines of text should be spread out to fill the maximum width available, so that both margins are aligned vertically. */ horizontallyJustified = 64, //============================================================================== /** Indicates that the item should be centred vertically and horizontally. This is equivalent to (horizontallyCentred | verticallyCentred) */ centred = 36, /** Indicates that the item should be centred vertically but placed on the left hand side. This is equivalent to (left | verticallyCentred) */ centredLeft = 33, /** Indicates that the item should be centred vertically but placed on the right hand side. This is equivalent to (right | verticallyCentred) */ centredRight = 34, /** Indicates that the item should be centred horizontally and placed at the top. This is equivalent to (horizontallyCentred | top) */ centredTop = 12, /** Indicates that the item should be centred horizontally and placed at the bottom. This is equivalent to (horizontallyCentred | bottom) */ centredBottom = 20, /** Indicates that the item should be placed in the top-left corner. This is equivalent to (left | top) */ topLeft = 9, /** Indicates that the item should be placed in the top-right corner. This is equivalent to (right | top) */ topRight = 10, /** Indicates that the item should be placed in the bottom-left corner. This is equivalent to (left | bottom) */ bottomLeft = 17, /** Indicates that the item should be placed in the bottom-left corner. This is equivalent to (right | bottom) */ bottomRight = 18 };private: //============================================================================== int flags;};#endif // JUCE_JUSTIFICATION_H_INCLUDED