DirectWrite font host for skia.

https://codereview.appspot.com/5417063/


git-svn-id: http://skia.googlecode.com/svn/trunk@5128 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 146 insertions, 0 deletions

diff --git a/src/utils/win/SkDWriteGeometrySink.cpp b/src/utils/win/SkDWriteGeometrySink.cpp
new file mode 100644
index 0000000000..4aec3bb778
--- /dev/null
+++ b/src/utils/win/SkDWriteGeometrySink.cpp
@@ -0,0 +1,146 @@
+/*
+ * Copyright 2012 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkTypes.h"
+
+#include "SkDWriteGeometrySink.h"
+#include "SkFloatUtils.h"
+#include "SkPath.h"
+
+#include <dwrite.h>
+#include <d2d1.h>
+
+SkDWriteGeometrySink::SkDWriteGeometrySink(SkPath* path) : fRefCount(1), fPath(path) { }
+
+SkDWriteGeometrySink::~SkDWriteGeometrySink() { }
+
+HRESULT STDMETHODCALLTYPE SkDWriteGeometrySink::QueryInterface(REFIID iid, void **object) {
+    if (NULL == object) {
+        return E_INVALIDARG;
+    }
+    if (iid == __uuidof(IUnknown) || iid == __uuidof(IDWriteGeometrySink)) {
+        *object = static_cast<IDWriteGeometrySink*>(this);
+        this->AddRef();
+        return S_OK;
+    } else {
+        *object = NULL;
+        return E_NOINTERFACE; 
+    }
+}
+
+ULONG STDMETHODCALLTYPE SkDWriteGeometrySink::AddRef(void) {
+    return static_cast<ULONG>(InterlockedIncrement(&fRefCount));
+}
+
+ULONG STDMETHODCALLTYPE SkDWriteGeometrySink::Release(void) {
+    ULONG res = static_cast<ULONG>(InterlockedDecrement(&fRefCount));
+    if (0 == res) {
+        delete this;
+    }
+    return res;
+}
+
+void STDMETHODCALLTYPE SkDWriteGeometrySink::SetFillMode(D2D1_FILL_MODE fillMode) {
+    switch (fillMode) {
+    case D2D1_FILL_MODE_ALTERNATE:
+        fPath->setFillType(SkPath::kEvenOdd_FillType);
+        break;
+    case D2D1_FILL_MODE_WINDING:
+        fPath->setFillType(SkPath::kWinding_FillType);
+        break;
+    default:
+        SkASSERT(!"Unknown D2D1_FILL_MODE.");
+        break;
+    }
+}
+
+void STDMETHODCALLTYPE SkDWriteGeometrySink::SetSegmentFlags(D2D1_PATH_SEGMENT vertexFlags) {
+    if (vertexFlags == D2D1_PATH_SEGMENT_NONE || vertexFlags == D2D1_PATH_SEGMENT_FORCE_ROUND_LINE_JOIN) {
+        SkASSERT(!"Invalid D2D1_PATH_SEGMENT value.");
+    }
+}
+
+void STDMETHODCALLTYPE SkDWriteGeometrySink::BeginFigure(D2D1_POINT_2F startPoint, D2D1_FIGURE_BEGIN figureBegin) {
+    fPath->moveTo(SkFloatToScalar(startPoint.x), SkFloatToScalar(startPoint.y));
+    if (figureBegin == D2D1_FIGURE_BEGIN_HOLLOW) {
+        SkASSERT(!"Invalid D2D1_FIGURE_BEGIN value.");
+    }
+}
+
+void STDMETHODCALLTYPE SkDWriteGeometrySink::AddLines(const D2D1_POINT_2F *points, UINT pointsCount) {
+    for (const D2D1_POINT_2F *end = &points[pointsCount]; points < end; ++points) {
+        fPath->lineTo(SkFloatToScalar(points->x), SkFloatToScalar(points->y));
+    }
+}
+
+static bool approximately_equal(float a, float b) {
+    const SkFloatingPoint<float, 10> lhs(a), rhs(b);
+    return lhs.AlmostEquals(rhs);
+}
+
+typedef struct {
+    float x;
+    float y;
+} Cubic[4], Quadratic[3];
+
+static bool check_quadratic(const Cubic& cubic, Quadratic& reduction) {
+    float dx10 = cubic[1].x - cubic[0].x;
+    float dx23 = cubic[2].x - cubic[3].x;
+    float midX = cubic[0].x + dx10 * 3 / 2;
+    //NOTE: !approximately_equal(midX - cubic[3].x, dx23 * 3 / 2)
+    //does not work as subnormals get in between the left side and 0.
+    if (!approximately_equal(midX, (dx23 * 3 / 2) + cubic[3].x)) {
+        return false;
+    }
+    float dy10 = cubic[1].y - cubic[0].y;
+    float dy23 = cubic[2].y - cubic[3].y;
+    float midY = cubic[0].y + dy10 * 3 / 2;
+    if (!approximately_equal(midY, (dy23 * 3 / 2) + cubic[3].y)) {
+        return false;
+    }
+    reduction[0] = cubic[0];
+    reduction[1].x = midX;
+    reduction[1].y = midY;
+    reduction[2] = cubic[3];
+    return true;
+}
+
+void STDMETHODCALLTYPE SkDWriteGeometrySink::AddBeziers(const D2D1_BEZIER_SEGMENT *beziers, UINT beziersCount) {
+    SkPoint lastPt;
+    fPath->getLastPt(&lastPt);
+    D2D1_POINT_2F prevPt = { SkScalarToFloat(lastPt.fX), SkScalarToFloat(lastPt.fY) };
+
+    for (const D2D1_BEZIER_SEGMENT *end = &beziers[beziersCount]; beziers < end; ++beziers) {
+        Cubic cubic = { { prevPt.x, prevPt.y },
+                        { beziers->point1.x, beziers->point1.y },
+                        { beziers->point2.x, beziers->point2.y },
+                        { beziers->point3.x, beziers->point3.y }, };
+        Quadratic quadratic;
+        if (check_quadratic(cubic, quadratic)) {
+            fPath->quadTo(SkFloatToScalar(quadratic[1].x), SkFloatToScalar(quadratic[1].y),
+                          SkFloatToScalar(quadratic[2].x), SkFloatToScalar(quadratic[2].y));
+        } else {
+            fPath->cubicTo(SkFloatToScalar(beziers->point1.x), SkFloatToScalar(beziers->point1.y),
+                           SkFloatToScalar(beziers->point2.x), SkFloatToScalar(beziers->point2.y),
+                           SkFloatToScalar(beziers->point3.x), SkFloatToScalar(beziers->point3.y));
+        }
+        prevPt = beziers->point3;
+    }
+}
+
+void STDMETHODCALLTYPE SkDWriteGeometrySink::EndFigure(D2D1_FIGURE_END figureEnd) {
+    fPath->close();
+}
+
+HRESULT SkDWriteGeometrySink::Close() {
+    return S_OK;
+}
+
+HRESULT SkDWriteGeometrySink::Create(SkPath* path, IDWriteGeometrySink** geometryToPath) {
+    *geometryToPath = new SkDWriteGeometrySink(path);
+    return S_OK;
+}