skia/ext/platform_device_win.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "skia/ext/platform_device.h"
   6
   7 #include "skia/ext/skia_utils_win.h"
   8 #include "third_party/skia/include/core/SkMatrix.h"
   9 #include "third_party/skia/include/core/SkPath.h"
  10 #include "third_party/skia/include/core/SkRegion.h"
  11 #include "third_party/skia/include/core/SkUtils.h"
  12
  13 namespace skia {
  14
  15 void InitializeDC(HDC context) {
  16   // Enables world transformation.
  17   // If the GM_ADVANCED graphics mode is set, GDI always draws arcs in the
  18   // counterclockwise direction in logical space. This is equivalent to the
  19   // statement that, in the GM_ADVANCED graphics mode, both arc control points
  20   // and arcs themselves fully respect the device context's world-to-device
  21   // transformation.
  22   BOOL res = SetGraphicsMode(context, GM_ADVANCED);
  23   SkASSERT(res != 0);
  24
  25   // Enables dithering.
  26   res = SetStretchBltMode(context, HALFTONE);
  27   SkASSERT(res != 0);
  28   // As per SetStretchBltMode() documentation, SetBrushOrgEx() must be called
  29   // right after.
  30   res = SetBrushOrgEx(context, 0, 0, NULL);
  31   SkASSERT(res != 0);
  32
  33   // Sets up default orientation.
  34   res = SetArcDirection(context, AD_CLOCKWISE);
  35   SkASSERT(res != 0);
  36
  37   // Sets up default colors.
  38   res = SetBkColor(context, RGB(255, 255, 255));
  39   SkASSERT(res != CLR_INVALID);
  40   res = SetTextColor(context, RGB(0, 0, 0));
  41   SkASSERT(res != CLR_INVALID);
  42   res = SetDCBrushColor(context, RGB(255, 255, 255));
  43   SkASSERT(res != CLR_INVALID);
  44   res = SetDCPenColor(context, RGB(0, 0, 0));
  45   SkASSERT(res != CLR_INVALID);
  46
  47   // Sets up default transparency.
  48   res = SetBkMode(context, OPAQUE);
  49   SkASSERT(res != 0);
  50   res = SetROP2(context, R2_COPYPEN);
  51   SkASSERT(res != 0);
  52 }
  53
  54 PlatformSurface PlatformDevice::BeginPlatformPaint() {
  55   return 0;
  56 }
  57
  58 void PlatformDevice::EndPlatformPaint() {
  59   // We don't clear the DC here since it will be likely to be used again.
  60   // Flushing will be done in onAccessBitmap.
  61 }
  62
  63 // static
  64 bool PlatformDevice::LoadPathToDC(HDC context, const SkPath& path) {
  65   switch (path.getFillType()) {
  66     case SkPath::kWinding_FillType: {
  67       int res = SetPolyFillMode(context, WINDING);
  68       SkASSERT(res != 0);
  69       break;
  70     }
  71     case SkPath::kEvenOdd_FillType: {
  72       int res = SetPolyFillMode(context, ALTERNATE);
  73       SkASSERT(res != 0);
  74       break;
  75     }
  76     default: {
  77       SkASSERT(false);
  78       break;
  79     }
  80   }
  81   BOOL res = BeginPath(context);
  82   if (!res) {
  83       return false;
  84   }
  85
  86   CubicPaths paths;
  87   if (!SkPathToCubicPaths(&paths, path))
  88     return false;
  89
  90   std::vector<POINT> points;
  91   for (CubicPaths::const_iterator path(paths.begin()); path != paths.end();
  92        ++path) {
  93     if (!path->size())
  94       continue;
  95     points.resize(0);
  96     points.reserve(path->size() * 3 / 4 + 1);
  97     points.push_back(SkPointToPOINT(path->front().p[0]));
  98     for (CubicPath::const_iterator point(path->begin()); point != path->end();
  99        ++point) {
 100       // Never add point->p[0]
 101       points.push_back(SkPointToPOINT(point->p[1]));
 102       points.push_back(SkPointToPOINT(point->p[2]));
 103       points.push_back(SkPointToPOINT(point->p[3]));
 104     }
 105     SkASSERT((points.size() - 1) % 3 == 0);
 106     // This is slightly inefficient since all straight line and quadratic lines
 107     // are "upgraded" to a cubic line.
 108     // TODO(maruel):  http://b/1147346 We should use
 109     // PolyDraw/PolyBezier/Polyline whenever possible.
 110     res = PolyBezier(context, &points.front(),
 111                      static_cast<DWORD>(points.size()));
 112     SkASSERT(res != 0);
 113     if (res == 0)
 114       break;
 115   }
 116   if (res == 0) {
 117     // Make sure the path is discarded.
 118     AbortPath(context);
 119   } else {
 120     res = EndPath(context);
 121     SkASSERT(res != 0);
 122   }
 123   return true;
 124 }
 125
 126 // static
 127 void PlatformDevice::LoadTransformToDC(HDC dc, const SkMatrix& matrix) {
 128   XFORM xf;
 129   xf.eM11 = matrix[SkMatrix::kMScaleX];
 130   xf.eM21 = matrix[SkMatrix::kMSkewX];
 131   xf.eDx = matrix[SkMatrix::kMTransX];
 132   xf.eM12 = matrix[SkMatrix::kMSkewY];
 133   xf.eM22 = matrix[SkMatrix::kMScaleY];
 134   xf.eDy = matrix[SkMatrix::kMTransY];
 135   SetWorldTransform(dc, &xf);
 136 }
 137
 138 // static
 139 bool PlatformDevice::SkPathToCubicPaths(CubicPaths* paths,
 140                                         const SkPath& skpath) {
 141   paths->clear();
 142   CubicPath* current_path = NULL;
 143   SkPoint current_points[4];
 144   CubicPoints points_to_add;
 145   SkPath::Iter iter(skpath, false);
 146   for (SkPath::Verb verb = iter.next(current_points);
 147        verb != SkPath::kDone_Verb;
 148        verb = iter.next(current_points)) {
 149     switch (verb) {
 150       case SkPath::kMove_Verb: {  // iter.next returns 1 point
 151         // Ignores it since the point is copied in the next operation. See
 152         // SkPath::Iter::next() for reference.
 153         paths->push_back(CubicPath());
 154         current_path = &paths->back();
 155         // Skip point addition.
 156         continue;
 157       }
 158       case SkPath::kLine_Verb: {  // iter.next returns 2 points
 159         points_to_add.p[0] = current_points[0];
 160         points_to_add.p[1] = current_points[0];
 161         points_to_add.p[2] = current_points[1];
 162         points_to_add.p[3] = current_points[1];
 163         break;
 164       }
 165       case SkPath::kQuad_Verb: {  // iter.next returns 3 points
 166         points_to_add.p[0] = current_points[0];
 167         points_to_add.p[1] = current_points[1];
 168         points_to_add.p[2] = current_points[2];
 169         points_to_add.p[3] = current_points[2];
 170         break;
 171       }
 172       case SkPath::kCubic_Verb: {  // iter.next returns 4 points
 173         points_to_add.p[0] = current_points[0];
 174         points_to_add.p[1] = current_points[1];
 175         points_to_add.p[2] = current_points[2];
 176         points_to_add.p[3] = current_points[3];
 177         break;
 178       }
 179       case SkPath::kClose_Verb: {  // iter.next returns 1 point (the last point)
 180         paths->push_back(CubicPath());
 181         current_path = &paths->back();
 182         continue;
 183       }
 184       default: {
 185         current_path = NULL;
 186         // Will return false.
 187         break;
 188       }
 189     }
 190     SkASSERT(current_path);
 191     if (!current_path) {
 192       paths->clear();
 193       return false;
 194     }
 195     current_path->push_back(points_to_add);
 196   }
 197   return true;
 198 }
 199
 200 // static
 201 void PlatformDevice::LoadClippingRegionToDC(HDC context,
 202                                             const SkRegion& region,
 203                                             const SkMatrix& transformation) {
 204   HRGN hrgn;
 205   if (region.isEmpty()) {
 206     // region can be empty, in which case everything will be clipped.
 207     hrgn = CreateRectRgn(0, 0, 0, 0);
 208   } else if (region.isRect()) {
 209     // We don't apply transformation, because the translation is already applied
 210     // to the region.
 211     hrgn = CreateRectRgnIndirect(&SkIRectToRECT(region.getBounds()));
 212   } else {
 213     // It is complex.
 214     SkPath path;
 215     region.getBoundaryPath(&path);
 216     // Clip. Note that windows clipping regions are not affected by the
 217     // transform so apply it manually.
 218     // Since the transform is given as the original translation of canvas, we
 219     // should apply it in reverse.
 220     SkMatrix t(transformation);
 221     t.setTranslateX(-t.getTranslateX());
 222     t.setTranslateY(-t.getTranslateY());
 223     path.transform(t);
 224     LoadPathToDC(context, path);
 225     hrgn = PathToRegion(context);
 226   }
 227   int result = SelectClipRgn(context, hrgn);
 228   SkASSERT(result != ERROR);
 229   result = DeleteObject(hrgn);
 230   SkASSERT(result != 0);
 231 }
 232
 233 }  // namespace skia