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      1 /*
      2  * Copyright 2012 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #include "SkTypes.h"
      9 
     10 #include "SkDWriteGeometrySink.h"
     11 #include "SkFloatUtils.h"
     12 #include "SkPath.h"
     13 
     14 #include <dwrite.h>
     15 #include <d2d1.h>
     16 
     17 SkDWriteGeometrySink::SkDWriteGeometrySink(SkPath* path) : fRefCount(1), fPath(path) { }
     18 
     19 SkDWriteGeometrySink::~SkDWriteGeometrySink() { }
     20 
     21 HRESULT STDMETHODCALLTYPE SkDWriteGeometrySink::QueryInterface(REFIID iid, void **object) {
     22     if (NULL == object) {
     23         return E_INVALIDARG;
     24     }
     25     if (iid == __uuidof(IUnknown) || iid == __uuidof(IDWriteGeometrySink)) {
     26         *object = static_cast<IDWriteGeometrySink*>(this);
     27         this->AddRef();
     28         return S_OK;
     29     } else {
     30         *object = NULL;
     31         return E_NOINTERFACE;
     32     }
     33 }
     34 
     35 ULONG STDMETHODCALLTYPE SkDWriteGeometrySink::AddRef(void) {
     36     return static_cast<ULONG>(InterlockedIncrement(&fRefCount));
     37 }
     38 
     39 ULONG STDMETHODCALLTYPE SkDWriteGeometrySink::Release(void) {
     40     ULONG res = static_cast<ULONG>(InterlockedDecrement(&fRefCount));
     41     if (0 == res) {
     42         delete this;
     43     }
     44     return res;
     45 }
     46 
     47 void STDMETHODCALLTYPE SkDWriteGeometrySink::SetFillMode(D2D1_FILL_MODE fillMode) {
     48     switch (fillMode) {
     49     case D2D1_FILL_MODE_ALTERNATE:
     50         fPath->setFillType(SkPath::kEvenOdd_FillType);
     51         break;
     52     case D2D1_FILL_MODE_WINDING:
     53         fPath->setFillType(SkPath::kWinding_FillType);
     54         break;
     55     default:
     56         SkDEBUGFAIL("Unknown D2D1_FILL_MODE.");
     57         break;
     58     }
     59 }
     60 
     61 void STDMETHODCALLTYPE SkDWriteGeometrySink::SetSegmentFlags(D2D1_PATH_SEGMENT vertexFlags) {
     62     if (vertexFlags == D2D1_PATH_SEGMENT_NONE || vertexFlags == D2D1_PATH_SEGMENT_FORCE_ROUND_LINE_JOIN) {
     63         SkDEBUGFAIL("Invalid D2D1_PATH_SEGMENT value.");
     64     }
     65 }
     66 
     67 void STDMETHODCALLTYPE SkDWriteGeometrySink::BeginFigure(D2D1_POINT_2F startPoint, D2D1_FIGURE_BEGIN figureBegin) {
     68     fPath->moveTo(startPoint.x, startPoint.y);
     69     if (figureBegin == D2D1_FIGURE_BEGIN_HOLLOW) {
     70         SkDEBUGFAIL("Invalid D2D1_FIGURE_BEGIN value.");
     71     }
     72 }
     73 
     74 void STDMETHODCALLTYPE SkDWriteGeometrySink::AddLines(const D2D1_POINT_2F *points, UINT pointsCount) {
     75     for (const D2D1_POINT_2F *end = &points[pointsCount]; points < end; ++points) {
     76         fPath->lineTo(points->x, points->y);
     77     }
     78 }
     79 
     80 static bool approximately_equal(float a, float b) {
     81     const SkFloatingPoint<float, 10> lhs(a), rhs(b);
     82     return lhs.AlmostEquals(rhs);
     83 }
     84 
     85 typedef struct {
     86     float x;
     87     float y;
     88 } Cubic[4], Quadratic[3];
     89 
     90 static bool check_quadratic(const Cubic& cubic, Quadratic& reduction) {
     91     float dx10 = cubic[1].x - cubic[0].x;
     92     float dx23 = cubic[2].x - cubic[3].x;
     93     float midX = cubic[0].x + dx10 * 3 / 2;
     94     //NOTE: !approximately_equal(midX - cubic[3].x, dx23 * 3 / 2)
     95     //does not work as subnormals get in between the left side and 0.
     96     if (!approximately_equal(midX, (dx23 * 3 / 2) + cubic[3].x)) {
     97         return false;
     98     }
     99     float dy10 = cubic[1].y - cubic[0].y;
    100     float dy23 = cubic[2].y - cubic[3].y;
    101     float midY = cubic[0].y + dy10 * 3 / 2;
    102     if (!approximately_equal(midY, (dy23 * 3 / 2) + cubic[3].y)) {
    103         return false;
    104     }
    105     reduction[0] = cubic[0];
    106     reduction[1].x = midX;
    107     reduction[1].y = midY;
    108     reduction[2] = cubic[3];
    109     return true;
    110 }
    111 
    112 void STDMETHODCALLTYPE SkDWriteGeometrySink::AddBeziers(const D2D1_BEZIER_SEGMENT *beziers, UINT beziersCount) {
    113     SkPoint lastPt;
    114     fPath->getLastPt(&lastPt);
    115     D2D1_POINT_2F prevPt = { SkScalarToFloat(lastPt.fX), SkScalarToFloat(lastPt.fY) };
    116 
    117     for (const D2D1_BEZIER_SEGMENT *end = &beziers[beziersCount]; beziers < end; ++beziers) {
    118         Cubic cubic = { { prevPt.x, prevPt.y },
    119                         { beziers->point1.x, beziers->point1.y },
    120                         { beziers->point2.x, beziers->point2.y },
    121                         { beziers->point3.x, beziers->point3.y }, };
    122         Quadratic quadratic;
    123         if (check_quadratic(cubic, quadratic)) {
    124             fPath->quadTo(quadratic[1].x, quadratic[1].y,
    125                           quadratic[2].x, quadratic[2].y);
    126         } else {
    127             fPath->cubicTo(beziers->point1.x, beziers->point1.y,
    128                            beziers->point2.x, beziers->point2.y,
    129                            beziers->point3.x, beziers->point3.y);
    130         }
    131         prevPt = beziers->point3;
    132     }
    133 }
    134 
    135 void STDMETHODCALLTYPE SkDWriteGeometrySink::EndFigure(D2D1_FIGURE_END figureEnd) {
    136     fPath->close();
    137 }
    138 
    139 HRESULT SkDWriteGeometrySink::Close() {
    140     return S_OK;
    141 }
    142 
    143 HRESULT SkDWriteGeometrySink::Create(SkPath* path, IDWriteGeometrySink** geometryToPath) {
    144     *geometryToPath = new SkDWriteGeometrySink(path);
    145     return S_OK;
    146 }
    147