skia/ext/platform_device_mac.cc

   1 // Copyright (c) 2006-2008 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 #include "skia/ext/bitmap_platform_device.h"
   7
   8 #import <ApplicationServices/ApplicationServices.h>
   9 #include "skia/ext/skia_utils_mac.h"
  10 #include "third_party/skia/include/core/SkMatrix.h"
  11 #include "third_party/skia/include/core/SkPath.h"
  12 #include "third_party/skia/include/core/SkTypes.h"
  13 #include "third_party/skia/include/core/SkUtils.h"
  14
  15 namespace skia {
  16
  17 CGContextRef GetBitmapContext(SkBaseDevice* device) {
  18   PlatformDevice* platform_device = GetPlatformDevice(device);
  19   if (platform_device)
  20     return platform_device->GetBitmapContext();
  21
  22   return NULL;
  23 }
  24
  25 CGContextRef PlatformDevice::BeginPlatformPaint() {
  26   return GetBitmapContext();
  27 }
  28
  29 void PlatformDevice::EndPlatformPaint() {
  30   // Flushing will be done in onAccessBitmap.
  31 }
  32
  33 // Set up the CGContextRef for peaceful coexistence with Skia
  34 void PlatformDevice::InitializeCGContext(CGContextRef context) {
  35   // CG defaults to the same settings as Skia
  36 }
  37
  38 // static
  39 void PlatformDevice::LoadPathToCGContext(CGContextRef context,
  40                                          const SkPath& path) {
  41   // instead of a persistent attribute of the context, CG specifies the fill
  42   // type per call, so we just have to load up the geometry.
  43   CGContextBeginPath(context);
  44
  45   SkPoint points[4] = { {0, 0}, {0, 0}, {0, 0}, {0, 0} };
  46   SkPath::Iter iter(path, false);
  47   for (SkPath::Verb verb = iter.next(points); verb != SkPath::kDone_Verb;
  48        verb = iter.next(points)) {
  49     switch (verb) {
  50       case SkPath::kMove_Verb: {  // iter.next returns 1 point
  51         CGContextMoveToPoint(context, points[0].fX, points[0].fY);
  52         break;
  53       }
  54       case SkPath::kLine_Verb: {  // iter.next returns 2 points
  55         CGContextAddLineToPoint(context, points[1].fX, points[1].fY);
  56         break;
  57       }
  58       case SkPath::kQuad_Verb: {  // iter.next returns 3 points
  59         CGContextAddQuadCurveToPoint(context, points[1].fX, points[1].fY,
  60                                      points[2].fX, points[2].fY);
  61         break;
  62       }
  63       case SkPath::kCubic_Verb: {  // iter.next returns 4 points
  64         CGContextAddCurveToPoint(context, points[1].fX, points[1].fY,
  65                                  points[2].fX, points[2].fY,
  66                                  points[3].fX, points[3].fY);
  67         break;
  68       }
  69       case SkPath::kClose_Verb: {  // iter.next returns 1 point (the last point)
  70         break;
  71       }
  72       case SkPath::kDone_Verb:  // iter.next returns 0 points
  73       default: {
  74         SkASSERT(false);
  75         break;
  76       }
  77     }
  78   }
  79   CGContextClosePath(context);
  80 }
  81
  82 // static
  83 void PlatformDevice::LoadTransformToCGContext(CGContextRef context,
  84                                               const SkMatrix& matrix) {
  85   // CoreGraphics can concatenate transforms, but not reset the current one.
  86   // So in order to get the required behavior here, we need to first make
  87   // the current transformation matrix identity and only then load the new one.
  88
  89   // Reset matrix to identity.
  90   CGAffineTransform orig_cg_matrix = CGContextGetCTM(context);
  91   CGAffineTransform orig_cg_matrix_inv = CGAffineTransformInvert(
  92       orig_cg_matrix);
  93   CGContextConcatCTM(context, orig_cg_matrix_inv);
  94
  95   // assert that we have indeed returned to the identity Matrix.
  96   SkASSERT(CGAffineTransformIsIdentity(CGContextGetCTM(context)));
  97
  98   // Convert xform to CG-land.
  99   // Our coordinate system is flipped to match WebKit's so we need to modify
 100   // the xform to match that.
 101   SkMatrix transformed_matrix = matrix;
 102   SkScalar sy = matrix.getScaleY() * (SkScalar)-1;
 103   transformed_matrix.setScaleY(sy);
 104   size_t height = CGBitmapContextGetHeight(context);
 105   SkScalar ty = -matrix.getTranslateY(); // y axis is flipped.
 106   transformed_matrix.setTranslateY(ty + (SkScalar)height);
 107
 108   CGAffineTransform cg_matrix = gfx::SkMatrixToCGAffineTransform(
 109       transformed_matrix);
 110
 111   // Load final transform into context.
 112   CGContextConcatCTM(context, cg_matrix);
 113 }
 114
 115 // static
 116 void PlatformDevice::LoadClippingRegionToCGContext(
 117          CGContextRef context,
 118          const SkRegion& region,
 119          const SkMatrix& transformation) {
 120   if (region.isEmpty()) {
 121     // region can be empty, in which case everything will be clipped.
 122     SkRect rect;
 123     rect.setEmpty();
 124     CGContextClipToRect(context, gfx::SkRectToCGRect(rect));
 125   } else if (region.isRect()) {
 126     // CoreGraphics applies the current transform to clip rects, which is
 127     // unwanted. Inverse-transform the rect before sending it to CG. This only
 128     // works for translations and scaling, but not for rotations (but the
 129     // viewport is never rotated anyway).
 130     SkMatrix t;
 131     bool did_invert = transformation.invert(&t);
 132     if (!did_invert)
 133       t.reset();
 134     // Do the transformation.
 135     SkRect rect;
 136     rect.set(region.getBounds());
 137     t.mapRect(&rect);
 138     SkIRect irect;
 139     rect.round(&irect);
 140     CGContextClipToRect(context, gfx::SkIRectToCGRect(irect));
 141   } else {
 142     // It is complex.
 143     SkPath path;
 144     region.getBoundaryPath(&path);
 145     // Clip. Note that windows clipping regions are not affected by the
 146     // transform so apply it manually.
 147     path.transform(transformation);
 148     // TODO(playmobil): Implement.
 149     SkASSERT(false);
 150     // LoadPathToDC(context, path);
 151     // hrgn = PathToRegion(context);
 152   }
 153 }
 154
 155 }  // namespace skia