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
17SkDWriteGeometrySink::SkDWriteGeometrySink(SkPath* path) : fRefCount(1), fPath(path) { }
18
19SkDWriteGeometrySink::~SkDWriteGeometrySink() { }
20
21HRESULT 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
35ULONG STDMETHODCALLTYPE SkDWriteGeometrySink::AddRef(void) {
36    return static_cast<ULONG>(InterlockedIncrement(&fRefCount));
37}
38
39ULONG 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
47void 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
61void 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
67void 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
74void 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
80static bool approximately_equal(float a, float b) {
81    const SkFloatingPoint<float, 10> lhs(a), rhs(b);
82    return lhs.AlmostEquals(rhs);
83}
84
85typedef struct {
86    float x;
87    float y;
88} Cubic[4], Quadratic[3];
89
90static 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
112void 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
135void STDMETHODCALLTYPE SkDWriteGeometrySink::EndFigure(D2D1_FIGURE_END figureEnd) {
136    fPath->close();
137}
138
139HRESULT SkDWriteGeometrySink::Close() {
140    return S_OK;
141}
142
143HRESULT SkDWriteGeometrySink::Create(SkPath* path, IDWriteGeometrySink** geometryToPath) {
144    *geometryToPath = new SkDWriteGeometrySink(path);
145    return S_OK;
146}
147