skia2/include/core/SkPoint.h

/*
 * Copyright (C) 2006 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef SkPoint_DEFINED
#define SkPoint_DEFINED

#include "SkMath.h"
#include "SkScalar.h"

/** \struct SkIPoint

    SkIPoint holds two 32 bit integer coordinates
*/
struct SkIPoint {
    int32_t fX, fY;
    
    static SkIPoint Make(int32_t x, int32_t y) {
        SkIPoint pt;
        pt.set(x, y);
        return pt;
    }

    /** Set the x and y values of the point. */
    void set(int32_t x, int32_t y) { fX = x; fY = y; }

    /** Rotate the point clockwise, writing the new point into dst
        It is legal for dst == this
    */
    void rotateCW(SkIPoint* dst) const;

    /** Rotate the point clockwise, writing the new point back into the point
    */

    void rotateCW() { this->rotateCW(this); }

    /** Rotate the point counter-clockwise, writing the new point into dst.
        It is legal for dst == this
    */
    void rotateCCW(SkIPoint* dst) const;

    /** Rotate the point counter-clockwise, writing the new point back into
        the point
    */
    void rotateCCW() { this->rotateCCW(this); }
    
    /** Negate the X and Y coordinates of the point.
    */
    void negate() { fX = -fX; fY = -fY; }
    
    /** Return a new point whose X and Y coordinates are the negative of the
        original point's
    */
    SkIPoint operator-() const {
        SkIPoint neg;
        neg.fX = -fX;
        neg.fY = -fY;
        return neg;
    }

    /** Add v's coordinates to this point's */
    void operator+=(const SkIPoint& v) {
        fX += v.fX;
        fY += v.fY;
    }
    
    /** Subtract v's coordinates from this point's */
    void operator-=(const SkIPoint& v) {
        fX -= v.fX;
        fY -= v.fY;
    }

    /** Returns true if the point's coordinates equal (x,y) */
    bool equals(int32_t x, int32_t y) const {
        return fX == x && fY == y;
    }

    friend bool operator==(const SkIPoint& a, const SkIPoint& b) {
        return a.fX == b.fX && a.fY == b.fY;
    }
    
    friend bool operator!=(const SkIPoint& a, const SkIPoint& b) {
        return a.fX != b.fX || a.fY != b.fY;
    }

    /** Returns a new point whose coordinates are the difference between
        a and b (i.e. a - b)
    */
    friend SkIPoint operator-(const SkIPoint& a, const SkIPoint& b) {
        SkIPoint v;
        v.set(a.fX - b.fX, a.fY - b.fY);
        return v;
    }

    /** Returns a new point whose coordinates are the sum of a and b (a + b)
    */
    friend SkIPoint operator+(const SkIPoint& a, const SkIPoint& b) {
        SkIPoint v;
        v.set(a.fX + b.fX, a.fY + b.fY);
        return v;
    }
    
    /** Returns the dot product of a and b, treating them as 2D vectors
    */
    static int32_t DotProduct(const SkIPoint& a, const SkIPoint& b) {
        return a.fX * b.fX + a.fY * b.fY;
    }

    /** Returns the cross product of a and b, treating them as 2D vectors
    */
    static int32_t CrossProduct(const SkIPoint& a, const SkIPoint& b) {
        return a.fX * b.fY - a.fY * b.fX;
    }
};

struct SkPoint {
    SkScalar    fX, fY;

    static SkPoint Make(SkScalar x, SkScalar y) {
        SkPoint pt;
        pt.set(x, y);
        return pt;
    }
    
    /** Set the point's X and Y coordinates */
    void set(SkScalar x, SkScalar y) { fX = x; fY = y; }
    
    /** Set the point's X and Y coordinates by automatically promoting (x,y) to
        SkScalar values.
    */
    void iset(int32_t x, int32_t y) {
        fX = SkIntToScalar(x);
        fY = SkIntToScalar(y);
    }
    
    /** Set the point's X and Y coordinates by automatically promoting p's
        coordinates to SkScalar values.
    */
    void iset(const SkIPoint& p) {
        fX = SkIntToScalar(p.fX);
        fY = SkIntToScalar(p.fY);
    }

    /** Return the euclidian distance from (0,0) to the point
    */
    SkScalar length() const { return SkPoint::Length(fX, fY); }

    /** Set the point (vector) to be unit-length in the same direction as it
        currently is, and return its old length. If the old length is
        degenerately small (nearly zero), do nothing and return false, otherwise
        return true.
    */
    bool normalize();
    
    /** Set the point (vector) to be unit-length in the same direction as the
        x,y params. If the vector (x,y) has a degenerate length (i.e. nearly 0)
        then return false and do nothing, otherwise return true.
    */
    bool setNormalize(SkScalar x, SkScalar y);
    
    /** Scale the point (vector) to have the specified length, and return that
        length. If the original length is degenerately small (nearly zero),
        do nothing and return false, otherwise return true.
    */
    bool setLength(SkScalar length);
    
    /** Set the point (vector) to have the specified length in the same
     direction as (x,y). If the vector (x,y) has a degenerate length
     (i.e. nearly 0) then return false and do nothing, otherwise return true.
    */
    bool setLength(SkScalar x, SkScalar y, SkScalar length);

    /** Scale the point's coordinates by scale, writing the answer into dst.
        It is legal for dst == this.
    */
    void scale(SkScalar scale, SkPoint* dst) const;
    
    /** Scale the point's coordinates by scale, writing the answer back into
        the point.
    */
    void scale(SkScalar value) { this->scale(value, this); }

    /** Rotate the point clockwise by 90 degrees, writing the answer into dst.
        It is legal for dst == this.
    */
    void rotateCW(SkPoint* dst) const;
    
    /** Rotate the point clockwise by 90 degrees, writing the answer back into
        the point.
    */
    void rotateCW() { this->rotateCW(this); }
    
    /** Rotate the point counter-clockwise by 90 degrees, writing the answer
        into dst. It is legal for dst == this.
    */
    void rotateCCW(SkPoint* dst) const;
    
    /** Rotate the point counter-clockwise by 90 degrees, writing the answer
        back into the point.
    */
    void rotateCCW() { this->rotateCCW(this); }
    
    /** Negate the point's coordinates
    */
    void negate() {
        fX = -fX;
        fY = -fY;
    }
    
    /** Returns a new point whose coordinates are the negative of the point's
    */
    SkPoint operator-() const {
        SkPoint neg;
        neg.fX = -fX;
        neg.fY = -fY;
        return neg;
    }

    /** Add v's coordinates to the point's
    */
    void operator+=(const SkPoint& v) {
        fX += v.fX;
        fY += v.fY;
    }
    
    /** Subtract v's coordinates from the point's
    */
    void operator-=(const SkPoint& v) {
        fX -= v.fX;
        fY -= v.fY;
    }

    /** Returns true if the point's coordinates equal (x,y)
    */
    bool equals(SkScalar x, SkScalar y) const { return fX == x && fY == y; }

    friend bool operator==(const SkPoint& a, const SkPoint& b) {
        return a.fX == b.fX && a.fY == b.fY;
    }
    
    friend bool operator!=(const SkPoint& a, const SkPoint& b) {
        return a.fX != b.fX || a.fY != b.fY;
    }

    /** Returns a new point whose coordinates are the difference between
        a's and b's (a - b)
    */
    friend SkPoint operator-(const SkPoint& a, const SkPoint& b) {
        SkPoint v;
        v.set(a.fX - b.fX, a.fY - b.fY);
        return v;
    }

    /** Returns a new point whose coordinates are the sum of a's and b's (a + b)
    */
    friend SkPoint operator+(const SkPoint& a, const SkPoint& b) {
        SkPoint v;
        v.set(a.fX + b.fX, a.fY + b.fY);
        return v;
    }

    /** Returns the euclidian distance from (0,0) to (x,y)
    */
    static SkScalar Length(SkScalar x, SkScalar y);

    /** Normalize pt, returning its previous length. If the prev length is too
        small (degenerate), return 0 and leave pt unchanged.
     */
    static SkScalar Normalize(SkPoint* pt);

    /** Returns the euclidian distance between a and b
    */
    static SkScalar Distance(const SkPoint& a, const SkPoint& b) {
        return Length(a.fX - b.fX, a.fY - b.fY);
    }

    /** Returns the dot product of a and b, treating them as 2D vectors
    */
    static SkScalar DotProduct(const SkPoint& a, const SkPoint& b) {
        return SkScalarMul(a.fX, b.fX) + SkScalarMul(a.fY, b.fY);
    }

    /** Returns the cross product of a and b, treating them as 2D vectors
    */
    static SkScalar CrossProduct(const SkPoint& a, const SkPoint& b) {
        return SkScalarMul(a.fX, b.fY) - SkScalarMul(a.fY, b.fX);
    }
};

typedef SkPoint SkVector;

#endif