| |
| /* |
| * Copyright 2011 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #ifndef GrPathRenderer_DEFINED |
| #define GrPathRenderer_DEFINED |
| |
| #include "GrDrawTarget.h" |
| #include "GrPathRendererChain.h" |
| #include "GrStencil.h" |
| |
| #include "SkDrawProcs.h" |
| #include "SkStrokeRec.h" |
| #include "SkTArray.h" |
| |
| class SkPath; |
| |
| struct GrPoint; |
| |
| /** |
| * Base class for drawing paths into a GrDrawTarget. |
| * |
| * Derived classes can use stages GrPaint::kTotalStages through GrDrawState::kNumStages-1. The |
| * stages before GrPaint::kTotalStages are reserved for setting up the draw (i.e., textures and |
| * filter masks). |
| */ |
| class SK_API GrPathRenderer : public SkRefCnt { |
| public: |
| SK_DECLARE_INST_COUNT(GrPathRenderer) |
| |
| /** |
| * This is called to install custom path renderers in every GrContext at create time. The |
| * default implementation in GrCreatePathRenderer_none.cpp does not add any additional |
| * renderers. Link against another implementation to install your own. The first added is the |
| * most preferred path renderer, second is second most preferred, etc. |
| * |
| * @param context the context that will use the path renderer |
| * @param prChain the chain to add path renderers to. |
| */ |
| static void AddPathRenderers(GrContext* context, GrPathRendererChain* prChain); |
| |
| |
| GrPathRenderer(); |
| |
| /** |
| * A caller may wish to use a path renderer to draw a path into the stencil buffer. However, |
| * the path renderer itself may require use of the stencil buffer. Also a path renderer may |
| * use a GrEffect coverage stage that sets coverage to zero to eliminate pixels that are covered |
| * by bounding geometry but outside the path. These exterior pixels would still be rendered into |
| * the stencil. |
| * |
| * A GrPathRenderer can provide three levels of support for stenciling paths: |
| * 1) kNoRestriction: This is the most general. The caller sets up the GrDrawState on the target |
| * and calls drawPath(). The path is rendered exactly as the draw state |
| * indicates including support for simultaneous color and stenciling with |
| * arbitrary stenciling rules. Pixels partially covered by AA paths are |
| * affected by the stencil settings. |
| * 2) kStencilOnly: The path renderer cannot apply arbitrary stencil rules nor shade and stencil |
| * simultaneously. The path renderer does support the stencilPath() function |
| * which performs no color writes and writes a non-zero stencil value to pixels |
| * covered by the path. |
| * 3) kNoSupport: This path renderer cannot be used to stencil the path. |
| */ |
| typedef GrPathRendererChain::StencilSupport StencilSupport; |
| static const StencilSupport kNoSupport_StencilSupport = |
| GrPathRendererChain::kNoSupport_StencilSupport; |
| static const StencilSupport kStencilOnly_StencilSupport = |
| GrPathRendererChain::kStencilOnly_StencilSupport; |
| static const StencilSupport kNoRestriction_StencilSupport = |
| GrPathRendererChain::kNoRestriction_StencilSupport; |
| |
| /** |
| * This function is to get the stencil support for the current path. The path's fill must |
| * not be an inverse type. |
| * |
| * @param stroke the stroke information (width, join, cap). |
| * @param target target that the path will be rendered to |
| */ |
| StencilSupport getStencilSupport(const SkStrokeRec& stroke, |
| const GrDrawTarget* target) const { |
| SkASSERT(!fPath.isInverseFillType()); |
| return this->onGetStencilSupport(stroke, target); |
| } |
| |
| // Set the path and fill type the path renderer is to use. |
| // 'fillType' is included as a parameter b.c. we often want to draw |
| // inverse filled paths normally filled. |
| void setPath(const SkPath& path, SkPath::FillType fillType) { |
| SkASSERT(fPath.isEmpty()); |
| fPath = path; |
| fPath.setFillType(fillType); |
| } |
| |
| void resetPath() { |
| fPath.reset(); |
| } |
| |
| /** |
| * Returns true if this path renderer is able to render the current path. Returning false |
| * allows the caller to fallback to another path renderer This function is called when |
| * searching for a path renderer capable of rendering a path. |
| * |
| * @param stroke The stroke information (width, join, cap) |
| * @param target The target that the path will be rendered to |
| * @param antiAlias True if anti-aliasing is required. |
| * |
| * @return true if the path can be drawn by this object, false otherwise. |
| */ |
| virtual bool canDrawPath(const SkStrokeRec& stroke, |
| const GrDrawTarget* target, |
| bool antiAlias) const = 0; |
| /** |
| * Draws the current path into the draw target. If getStencilSupport() would return |
| * kNoRestriction then the subclass must respect the stencil settings of the |
| * target's draw state. |
| * |
| * @param stroke the stroke information (width, join, cap) |
| * @param target target that the path will be rendered to |
| * @param antiAlias true if anti-aliasing is required. |
| */ |
| bool drawPath(const SkStrokeRec& stroke, |
| GrDrawTarget* target, |
| bool antiAlias) { |
| SkASSERT(!fPath.isEmpty()); |
| SkASSERT(this->canDrawPath(stroke, target, antiAlias)); |
| SkASSERT(target->drawState()->getStencil().isDisabled() || |
| kNoRestriction_StencilSupport == this->getStencilSupport(stroke, target)); |
| return this->onDrawPath(stroke, target, antiAlias); |
| } |
| |
| /** |
| * Draws the current path to the stencil buffer. Assume the writable stencil bits are already |
| * initialized to zero. The pixels inside the path will have non-zero stencil values |
| * afterwards. |
| * |
| * @param stroke the stroke information (width, join, cap) |
| * @param target target that the path will be rendered to |
| */ |
| void stencilPath(const SkStrokeRec& stroke, GrDrawTarget* target) { |
| SkASSERT(!fPath.isEmpty()); |
| SkASSERT(kNoSupport_StencilSupport != this->getStencilSupport(stroke, target)); |
| this->onStencilPath(stroke, target); |
| } |
| |
| class AutoClearPath : ::SkNoncopyable { |
| public: |
| AutoClearPath(GrPathRenderer* renderer) : fRenderer(renderer) {} |
| AutoClearPath() : fRenderer(NULL) {} |
| ~AutoClearPath() { |
| this->reset(); |
| } |
| |
| GrPathRenderer* renderer() { |
| return fRenderer; |
| } |
| |
| void set(GrPathRenderer* renderer) { |
| this->reset(); |
| fRenderer = renderer; |
| } |
| |
| GrPathRenderer* operator->() { return fRenderer; } |
| |
| private: |
| void reset() { |
| if (NULL != fRenderer) { |
| fRenderer->resetPath(); |
| } |
| fRenderer = NULL; |
| } |
| |
| GrPathRenderer* fRenderer; |
| }; |
| |
| // Helper for determining if we can treat a thin stroke as a hairline w/ coverage. |
| // If we can, we draw lots faster (raster device does this same test). |
| static bool IsStrokeHairlineOrEquivalent(const SkStrokeRec& stroke, const SkMatrix& matrix, |
| SkScalar* outCoverage) { |
| if (stroke.isHairlineStyle()) { |
| if (NULL != outCoverage) { |
| *outCoverage = SK_Scalar1; |
| } |
| return true; |
| } |
| return stroke.getStyle() == SkStrokeRec::kStroke_Style && |
| SkDrawTreatAAStrokeAsHairline(stroke.getWidth(), matrix, outCoverage); |
| } |
| |
| protected: |
| const SkPath& path() const { |
| return fPath; |
| } |
| |
| /** |
| * Subclass overrides if it has any limitations of stenciling support. |
| */ |
| virtual StencilSupport onGetStencilSupport(const SkStrokeRec&, |
| const GrDrawTarget*) const { |
| return kNoRestriction_StencilSupport; |
| } |
| |
| /** |
| * Subclass implementation of drawPath() |
| */ |
| virtual bool onDrawPath(const SkStrokeRec& stroke, |
| GrDrawTarget* target, |
| bool antiAlias) = 0; |
| |
| /** |
| * Subclass implementation of stencilPath(). Subclass must override iff it ever returns |
| * kStencilOnly in onGetStencilSupport(). |
| */ |
| virtual void onStencilPath(const SkStrokeRec& stroke, GrDrawTarget* target) { |
| GrDrawTarget::AutoStateRestore asr(target, GrDrawTarget::kPreserve_ASRInit); |
| GrDrawState* drawState = target->drawState(); |
| GR_STATIC_CONST_SAME_STENCIL(kIncrementStencil, |
| kReplace_StencilOp, |
| kReplace_StencilOp, |
| kAlways_StencilFunc, |
| 0xffff, |
| 0xffff, |
| 0xffff); |
| drawState->setStencil(kIncrementStencil); |
| drawState->enableState(GrDrawState::kNoColorWrites_StateBit); |
| this->drawPath(stroke, target, false); |
| } |
| |
| // Helper for getting the device bounds of a path. Inverse filled paths will have bounds set |
| // by devSize. Non-inverse path bounds will not necessarily be clipped to devSize. |
| static void GetPathDevBounds(const SkPath& path, |
| int devW, |
| int devH, |
| const SkMatrix& matrix, |
| SkRect* bounds); |
| |
| // Helper version that gets the dev width and height from a GrSurface. |
| static void GetPathDevBounds(const SkPath& path, |
| const GrSurface* device, |
| const SkMatrix& matrix, |
| SkRect* bounds) { |
| GetPathDevBounds(path, device->width(), device->height(), matrix, bounds); |
| } |
| |
| private: |
| SkPath fPath; |
| |
| typedef SkRefCnt INHERITED; |
| }; |
| |
| #endif |