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432 lines
16 KiB
C++
432 lines
16 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef MOZILLA_GFX_BASERECT_H_
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#define MOZILLA_GFX_BASERECT_H_
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#include <cmath>
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#include <mozilla/Assertions.h>
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#include <algorithm>
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namespace mozilla {
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namespace gfx {
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/**
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* Rectangles have two interpretations: a set of (zero-size) points,
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* and a rectangular area of the plane. Most rectangle operations behave
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* the same no matter what interpretation is being used, but some operations
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* differ:
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* -- Equality tests behave differently. When a rectangle represents an area,
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* all zero-width and zero-height rectangles are equal to each other since they
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* represent the empty area. But when a rectangle represents a set of
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* mathematical points, zero-width and zero-height rectangles can be unequal.
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* -- The union operation can behave differently. When rectangles represent
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* areas, taking the union of a zero-width or zero-height rectangle with
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* another rectangle can just ignore the empty rectangle. But when rectangles
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* represent sets of mathematical points, we may need to extend the latter
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* rectangle to include the points of a zero-width or zero-height rectangle.
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*
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* To ensure that these interpretations are explicitly disambiguated, we
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* deny access to the == and != operators and require use of IsEqualEdges and
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* IsEqualInterior instead. Similarly we provide separate Union and UnionEdges
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* methods.
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*
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* Do not use this class directly. Subclass it, pass that subclass as the
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* Sub parameter, and only use that subclass.
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*/
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template <class T, class Sub, class Point, class SizeT, class Margin>
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struct BaseRect {
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T x, y, width, height;
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// Constructors
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BaseRect() : x(0), y(0), width(0), height(0) {}
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BaseRect(const Point& aOrigin, const SizeT &aSize) :
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x(aOrigin.x), y(aOrigin.y), width(aSize.width), height(aSize.height)
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{
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}
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BaseRect(T aX, T aY, T aWidth, T aHeight) :
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x(aX), y(aY), width(aWidth), height(aHeight)
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{
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}
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// Emptiness. An empty rect is one that has no area, i.e. its height or width
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// is <= 0
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bool IsEmpty() const { return height <= 0 || width <= 0; }
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void SetEmpty() { width = height = 0; }
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// Returns true if this rectangle contains the interior of aRect. Always
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// returns true if aRect is empty, and always returns false is aRect is
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// nonempty but this rect is empty.
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bool Contains(const Sub& aRect) const
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{
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return aRect.IsEmpty() ||
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(x <= aRect.x && aRect.XMost() <= XMost() &&
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y <= aRect.y && aRect.YMost() <= YMost());
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}
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// Returns true if this rectangle contains the rectangle (aX,aY,1,1).
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bool Contains(T aX, T aY) const
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{
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return x <= aX && aX + 1 <= XMost() &&
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y <= aY && aY + 1 <= YMost();
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}
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// Returns true if this rectangle contains the rectangle (aPoint.x,aPoint.y,1,1).
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bool Contains(const Point& aPoint) const { return Contains(aPoint.x, aPoint.y); }
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// Intersection. Returns TRUE if the receiver's area has non-empty
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// intersection with aRect's area, and FALSE otherwise.
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// Always returns false if aRect is empty or 'this' is empty.
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bool Intersects(const Sub& aRect) const
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{
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return x < aRect.XMost() && aRect.x < XMost() &&
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y < aRect.YMost() && aRect.y < YMost();
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}
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// Returns the rectangle containing the intersection of the points
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// (including edges) of *this and aRect. If there are no points in that
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// intersection, returns an empty rectangle with x/y set to the std::max of the x/y
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// of *this and aRect.
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Sub Intersect(const Sub& aRect) const
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{
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Sub result;
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result.x = std::max(x, aRect.x);
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result.y = std::max(y, aRect.y);
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result.width = std::min(XMost(), aRect.XMost()) - result.x;
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result.height = std::min(YMost(), aRect.YMost()) - result.y;
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if (result.width < 0 || result.height < 0) {
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result.SizeTo(0, 0);
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}
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return result;
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}
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// Sets *this to be the rectangle containing the intersection of the points
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// (including edges) of *this and aRect. If there are no points in that
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// intersection, sets *this to be an empty rectangle with x/y set to the std::max
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// of the x/y of *this and aRect.
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//
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// 'this' can be the same object as either aRect1 or aRect2
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bool IntersectRect(const Sub& aRect1, const Sub& aRect2)
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{
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*static_cast<Sub*>(this) = aRect1.Intersect(aRect2);
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return !IsEmpty();
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}
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// Returns the smallest rectangle that contains both the area of both
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// this and aRect2.
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// Thus, empty input rectangles are ignored.
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// If both rectangles are empty, returns this.
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Sub Union(const Sub& aRect) const
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{
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if (IsEmpty()) {
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return aRect;
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} else if (aRect.IsEmpty()) {
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return *static_cast<const Sub*>(this);
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} else {
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return UnionEdges(aRect);
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}
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}
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// Returns the smallest rectangle that contains both the points (including
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// edges) of both aRect1 and aRect2.
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// Thus, empty input rectangles are allowed to affect the result.
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Sub UnionEdges(const Sub& aRect) const
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{
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Sub result;
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result.x = std::min(x, aRect.x);
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result.y = std::min(y, aRect.y);
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result.width = std::max(XMost(), aRect.XMost()) - result.x;
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result.height = std::max(YMost(), aRect.YMost()) - result.y;
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return result;
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}
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// Computes the smallest rectangle that contains both the area of both
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// aRect1 and aRect2, and fills 'this' with the result.
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// Thus, empty input rectangles are ignored.
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// If both rectangles are empty, sets 'this' to aRect2.
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//
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// 'this' can be the same object as either aRect1 or aRect2
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void UnionRect(const Sub& aRect1, const Sub& aRect2)
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{
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*static_cast<Sub*>(this) = aRect1.Union(aRect2);
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}
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// Computes the smallest rectangle that contains both the points (including
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// edges) of both aRect1 and aRect2.
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// Thus, empty input rectangles are allowed to affect the result.
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//
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// 'this' can be the same object as either aRect1 or aRect2
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void UnionRectEdges(const Sub& aRect1, const Sub& aRect2)
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{
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*static_cast<Sub*>(this) = aRect1.UnionEdges(aRect2);
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}
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void SetRect(T aX, T aY, T aWidth, T aHeight)
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{
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x = aX; y = aY; width = aWidth; height = aHeight;
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}
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void SetRect(const Point& aPt, const SizeT& aSize)
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{
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SetRect(aPt.x, aPt.y, aSize.width, aSize.height);
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}
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void MoveTo(T aX, T aY) { x = aX; y = aY; }
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void MoveTo(const Point& aPoint) { x = aPoint.x; y = aPoint.y; }
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void MoveBy(T aDx, T aDy) { x += aDx; y += aDy; }
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void MoveBy(const Point& aPoint) { x += aPoint.x; y += aPoint.y; }
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void SizeTo(T aWidth, T aHeight) { width = aWidth; height = aHeight; }
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void SizeTo(const SizeT& aSize) { width = aSize.width; height = aSize.height; }
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void Inflate(T aD) { Inflate(aD, aD); }
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void Inflate(T aDx, T aDy)
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{
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x -= aDx;
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y -= aDy;
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width += 2 * aDx;
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height += 2 * aDy;
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}
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void Inflate(const Margin& aMargin)
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{
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x -= aMargin.left;
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y -= aMargin.top;
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width += aMargin.LeftRight();
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height += aMargin.TopBottom();
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}
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void Inflate(const SizeT& aSize) { Inflate(aSize.width, aSize.height); }
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void Deflate(T aD) { Deflate(aD, aD); }
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void Deflate(T aDx, T aDy)
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{
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x += aDx;
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y += aDy;
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width = std::max(T(0), width - 2 * aDx);
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height = std::max(T(0), height - 2 * aDy);
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}
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void Deflate(const Margin& aMargin)
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{
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x += aMargin.left;
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y += aMargin.top;
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width = std::max(T(0), width - aMargin.LeftRight());
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height = std::max(T(0), height - aMargin.TopBottom());
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}
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void Deflate(const SizeT& aSize) { Deflate(aSize.width, aSize.height); }
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// Return true if the rectangles contain the same set of points, including
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// points on the edges.
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// Use when we care about the exact x/y/width/height values being
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// equal (i.e. we care about differences in empty rectangles).
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bool IsEqualEdges(const Sub& aRect) const
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{
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return x == aRect.x && y == aRect.y &&
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width == aRect.width && height == aRect.height;
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}
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// Return true if the rectangles contain the same area of the plane.
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// Use when we do not care about differences in empty rectangles.
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bool IsEqualInterior(const Sub& aRect) const
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{
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return IsEqualEdges(aRect) || (IsEmpty() && aRect.IsEmpty());
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}
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Sub operator+(const Point& aPoint) const
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{
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return Sub(x + aPoint.x, y + aPoint.y, width, height);
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}
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Sub operator-(const Point& aPoint) const
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{
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return Sub(x - aPoint.x, y - aPoint.y, width, height);
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}
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Sub& operator+=(const Point& aPoint)
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{
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MoveBy(aPoint);
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return *static_cast<Sub*>(this);
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}
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Sub& operator-=(const Point& aPoint)
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{
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MoveBy(-aPoint);
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return *static_cast<Sub*>(this);
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}
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// Find difference as a Margin
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Margin operator-(const Sub& aRect) const
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{
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return Margin(aRect.y - y,
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XMost() - aRect.XMost(),
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YMost() - aRect.YMost(),
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aRect.x - x);
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}
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// Helpers for accessing the vertices
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Point TopLeft() const { return Point(x, y); }
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Point TopRight() const { return Point(XMost(), y); }
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Point BottomLeft() const { return Point(x, YMost()); }
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Point BottomRight() const { return Point(XMost(), YMost()); }
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Point Center() const { return Point(x, y) + Point(width, height)/2; }
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SizeT Size() const { return SizeT(width, height); }
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// Helper methods for computing the extents
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T X() const { return x; }
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T Y() const { return y; }
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T Width() const { return width; }
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T Height() const { return height; }
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T XMost() const { return x + width; }
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T YMost() const { return y + height; }
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// Moves one edge of the rect without moving the opposite edge.
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void SetLeftEdge(T aX) {
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MOZ_ASSERT(aX <= XMost());
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width = XMost() - aX;
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x = aX;
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}
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void SetRightEdge(T aXMost) {
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MOZ_ASSERT(aXMost >= x);
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width = aXMost - x;
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}
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void SetTopEdge(T aY) {
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MOZ_ASSERT(aY <= YMost());
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height = YMost() - aY;
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y = aY;
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}
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void SetBottomEdge(T aYMost) {
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MOZ_ASSERT(aYMost >= y);
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height = aYMost - y;
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}
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// Round the rectangle edges to integer coordinates, such that the rounded
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// rectangle has the same set of pixel centers as the original rectangle.
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// Edges at offset 0.5 round up.
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// Suitable for most places where integral device coordinates
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// are needed, but note that any translation should be applied first to
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// avoid pixel rounding errors.
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// Note that this is *not* rounding to nearest integer if the values are negative.
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// They are always rounding as floor(n + 0.5).
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// See https://bugzilla.mozilla.org/show_bug.cgi?id=410748#c14
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// If you need similar method which is using NS_round(), you should create
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// new |RoundAwayFromZero()| method.
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void Round()
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{
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T x0 = static_cast<T>(floor(T(X()) + 0.5));
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T y0 = static_cast<T>(floor(T(Y()) + 0.5));
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T x1 = static_cast<T>(floor(T(XMost()) + 0.5));
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T y1 = static_cast<T>(floor(T(YMost()) + 0.5));
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x = x0;
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y = y0;
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width = x1 - x0;
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height = y1 - y0;
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}
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// Snap the rectangle edges to integer coordinates, such that the
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// original rectangle contains the resulting rectangle.
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void RoundIn()
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{
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T x0 = static_cast<T>(ceil(T(X())));
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T y0 = static_cast<T>(ceil(T(Y())));
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T x1 = static_cast<T>(floor(T(XMost())));
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T y1 = static_cast<T>(floor(T(YMost())));
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x = x0;
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y = y0;
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width = x1 - x0;
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height = y1 - y0;
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}
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// Snap the rectangle edges to integer coordinates, such that the
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// resulting rectangle contains the original rectangle.
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void RoundOut()
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{
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T x0 = static_cast<T>(floor(T(X())));
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T y0 = static_cast<T>(floor(T(Y())));
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T x1 = static_cast<T>(ceil(T(XMost())));
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T y1 = static_cast<T>(ceil(T(YMost())));
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x = x0;
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y = y0;
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width = x1 - x0;
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height = y1 - y0;
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}
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// Scale 'this' by aScale, converting coordinates to integers so that the result is
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// the smallest integer-coordinate rectangle containing the unrounded result.
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// Note: this can turn an empty rectangle into a non-empty rectangle
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void ScaleRoundOut(double aScale) { ScaleRoundOut(aScale, aScale); }
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// Scale 'this' by aXScale and aYScale, converting coordinates to integers so
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// that the result is the smallest integer-coordinate rectangle containing the
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// unrounded result.
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// Note: this can turn an empty rectangle into a non-empty rectangle
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void ScaleRoundOut(double aXScale, double aYScale)
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{
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T right = static_cast<T>(ceil(double(XMost()) * aXScale));
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T bottom = static_cast<T>(ceil(double(YMost()) * aYScale));
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x = static_cast<T>(floor(double(x) * aXScale));
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y = static_cast<T>(floor(double(y) * aYScale));
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width = right - x;
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height = bottom - y;
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}
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// Scale 'this' by aScale, converting coordinates to integers so that the result is
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// the largest integer-coordinate rectangle contained by the unrounded result.
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void ScaleRoundIn(double aScale) { ScaleRoundIn(aScale, aScale); }
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// Scale 'this' by aXScale and aYScale, converting coordinates to integers so
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// that the result is the largest integer-coordinate rectangle contained by the
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// unrounded result.
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void ScaleRoundIn(double aXScale, double aYScale)
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{
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T right = static_cast<T>(floor(double(XMost()) * aXScale));
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T bottom = static_cast<T>(floor(double(YMost()) * aYScale));
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x = static_cast<T>(ceil(double(x) * aXScale));
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y = static_cast<T>(ceil(double(y) * aYScale));
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width = std::max<T>(0, right - x);
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height = std::max<T>(0, bottom - y);
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}
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// Scale 'this' by 1/aScale, converting coordinates to integers so that the result is
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// the smallest integer-coordinate rectangle containing the unrounded result.
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// Note: this can turn an empty rectangle into a non-empty rectangle
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void ScaleInverseRoundOut(double aScale) { ScaleInverseRoundOut(aScale, aScale); }
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// Scale 'this' by 1/aXScale and 1/aYScale, converting coordinates to integers so
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// that the result is the smallest integer-coordinate rectangle containing the
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// unrounded result.
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// Note: this can turn an empty rectangle into a non-empty rectangle
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void ScaleInverseRoundOut(double aXScale, double aYScale)
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{
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T right = static_cast<T>(ceil(double(XMost()) / aXScale));
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T bottom = static_cast<T>(ceil(double(YMost()) / aYScale));
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x = static_cast<T>(floor(double(x) / aXScale));
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y = static_cast<T>(floor(double(y) / aYScale));
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width = right - x;
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height = bottom - y;
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}
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// Scale 'this' by 1/aScale, converting coordinates to integers so that the result is
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// the largest integer-coordinate rectangle contained by the unrounded result.
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void ScaleInverseRoundIn(double aScale) { ScaleInverseRoundIn(aScale, aScale); }
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// Scale 'this' by 1/aXScale and 1/aYScale, converting coordinates to integers so
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// that the result is the largest integer-coordinate rectangle contained by the
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// unrounded result.
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void ScaleInverseRoundIn(double aXScale, double aYScale)
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{
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T right = static_cast<T>(floor(double(XMost()) / aXScale));
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T bottom = static_cast<T>(floor(double(YMost()) / aYScale));
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x = static_cast<T>(ceil(double(x) / aXScale));
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y = static_cast<T>(ceil(double(y) / aYScale));
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width = std::max<T>(0, right - x);
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height = std::max<T>(0, bottom - y);
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}
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/**
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* Clamp aPoint to this rectangle. It is allowed to end up on any
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* edge of the rectangle.
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*/
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Point ClampPoint(const Point& aPoint) const
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{
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return Point(std::max(x, std::min(XMost(), aPoint.x)),
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std::max(y, std::min(YMost(), aPoint.y)));
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}
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private:
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// Do not use the default operator== or operator!= !
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// Use IsEqualEdges or IsEqualInterior explicitly.
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bool operator==(const Sub& aRect) const { return false; }
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bool operator!=(const Sub& aRect) const { return false; }
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};
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}
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}
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#endif /* MOZILLA_GFX_BASERECT_H_ */
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