Tesselate path once for tiled offscreen AA
Review URL: http://codereview.appspot.com/4661062/
git-svn-id: http://skia.googlecode.com/svn/trunk@1777 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gpu/include/GrPathRenderer.h b/gpu/include/GrPathRenderer.h
index d77aad6..6bc91b5 100644
--- a/gpu/include/GrPathRenderer.h
+++ b/gpu/include/GrPathRenderer.h
@@ -18,57 +18,46 @@
#define GrPathRenderer_DEFINED
#include "GrDrawTarget.h"
+#include "SkTemplates.h"
class SkPath;
struct GrPoint;
/**
* Base class for drawing paths into a GrDrawTarget.
+ * Paths may be drawn multiple times as when tiling for supersampling. The
+ * calls on GrPathRenderer to draw a path will look like this:
+ *
+ * pr->setPath(target, path, fill, translate); // sets the path to draw
+ * pr->drawPath(...); // draw the path
+ * pr->drawPath(...);
+ * ...
+ * pr->clearPath(); // finished with the path
*/
class GR_API GrPathRenderer : public GrRefCnt {
public:
GrPathRenderer(void);
-
/**
* Returns true if this path renderer is able to render the path.
* Returning false allows the caller to fallback to another path renderer.
*
- * @param target The target to draw into
* @param path The path to draw
* @param fill The fill rule to use
*
* @return true if the path can be drawn by this object, false otherwise.
*/
- virtual bool canDrawPath(const GrDrawTarget* target, const SkPath& path,
- GrPathFill fill) const = 0;
-
- /**
- * Draws a path into the draw target. The target will already have its draw
- * state configured for the draw.
- * @param target the target to draw into.
- * @param stages indicates which stages the are already
- * in use. All enabled stages expect positions
- * as texture coordinates. The path renderer
- * use the remaining stages for its path
- * filling algorithm.
- * @param path the path to draw.
- * @param fill the fill rule to apply.
- * @param translate optional additional translation to apply to
- * the path. NULL means (0,0).
- */
- virtual void drawPath(GrDrawTarget* target,
- GrDrawTarget::StageBitfield stages,
- const SkPath& path,
- GrPathFill fill,
- const GrPoint* translate) = 0;
+ virtual bool canDrawPath(const SkPath& path, GrPathFill fill) const = 0;
/**
* For complex clips Gr uses the stencil buffer. The path renderer must be
* able to render paths into the stencil buffer. However, the path renderer
- * itself may require the stencil buffer to resolve the path fill rule. This
- * function queries whether the path render needs its own stencil
+ * itself may require the stencil buffer to resolve the path fill rule.
+ * This function queries whether the path render needs its own stencil
* pass. If this returns false then drawPath() should not modify the
- * the target's stencil settings but use those already set on target.
+ * the target's stencil settings but use those already set on target. The
+ * target is passed as a param in case the answer depends upon draw state.
+ * The view matrix and render target set on the draw target may change
+ * before setPath/drawPath is called and so shouldn't be considered.
*
* @param target target that the path will be rendered to
* @param path the path that will be drawn
@@ -85,7 +74,59 @@
GrPathFill fill) const { return false; }
/**
- * Draws a path to the stencil buffer. Assume the writable stencil bits
+ * @return true if the path renderer can perform anti-aliasing (aside from
+ * having FSAA enabled for a render target). Target is provided to
+ * communicate the draw state (blend mode, stage settings, etc).
+ */
+ virtual bool supportsAA(GrDrawTarget* target,
+ const SkPath& path,
+ GrPathFill fill) { return false; }
+
+ /**
+ * Sets the path to render and target to render into. All calls to drawPath
+ * and drawPathToStencil must occur between setPath and clearPath. The
+ * path cannot be modified externally between setPath and clearPath. The
+ * path may be drawn several times (e.g. tiled supersampler). The target's
+ * state may change between setPath and drawPath* calls. However, if the
+ * path renderer specified vertices/indices during setPath or drawPath*
+ * they will still be set at subsequent drawPath* calls until the next
+ * clearPath. The target's draw state may change between drawPath* calls
+ * so if the subclass does any caching of tesselation, etc. then it must
+ * validate that target parameters that guided the decisions still hold.
+ *
+ * @param target the target to draw into.
+ * @param path the path to draw.
+ * @param fill the fill rule to apply.
+ * @param translate optional additional translation to apply to
+ * the path. NULL means (0,0).
+ */
+ void setPath(GrDrawTarget* target,
+ const SkPath* path,
+ GrPathFill fill,
+ const GrPoint* translate);
+
+ /**
+ * Notifies path renderer that path set in setPath is no longer in use.
+ */
+ void clearPath();
+
+ /**
+ * Draws the path into the draw target. If requiresStencilBuffer returned
+ * false then the target may be setup for stencil rendering (since the
+ * path renderer didn't claim that it needs to use the stencil internally).
+ *
+ * Only called between setPath / clearPath.
+ *
+ * @param stages bitfield that indicates which stages are
+ * in use. All enabled stages expect positions
+ * as texture coordinates. The path renderer
+ * use the remaining stages for its path
+ * filling algorithm.
+ */
+ virtual void drawPath(GrDrawTarget::StageBitfield stages) = 0;
+
+ /**
+ * Draws the path to the stencil buffer. Assume the writable stencil bits
* are already initialized to zero. Fill will always be either
* kWinding_PathFill or kEvenOdd_PathFill.
*
@@ -95,27 +136,11 @@
* The default implementation assumes the path filling algorithm doesn't
* require a separate stencil pass and so crashes.
*
- *
- * @param target the target to draw into.
- * @param path the path to draw.
- * @param fill the fill rule to apply.
- * @param translate optional additional translation to apply to
- * the path. NULL means (0,0).
+ * Only called between setPath / clearPath.
*/
- virtual void drawPathToStencil(GrDrawTarget* target,
- const SkPath& path,
- GrPathFill fill,
- const GrPoint* translate) {
+ virtual void drawPathToStencil() {
GrCrash("Unexpected call to drawPathToStencil.");
}
-
- /**
- * @return true if the path renderer can perform anti-aliasing (aside from
- * having FSAA enabled for a render target)
- */
- virtual bool supportsAA(GrDrawTarget* target,
- const SkPath& path,
- GrPathFill fill) { return false; }
/**
* This is called to install a custom path renderer in every GrContext at
@@ -134,8 +159,56 @@
fCurveTolerance = SkScalarMul(fCurveTolerance, multiplier);
}
+ /**
+ * Helper that sets a path and automatically remove it in destructor.
+ */
+ class AutoClearPath {
+ public:
+ AutoClearPath() {
+ fPathRenderer = NULL;
+ }
+ AutoClearPath(GrPathRenderer* pr,
+ GrDrawTarget* target,
+ const SkPath* path,
+ GrPathFill fill,
+ const GrPoint* translate) {
+ GrAssert(NULL != pr);
+ pr->setPath(target, path, fill, translate);
+ fPathRenderer = pr;
+ }
+ void set(GrPathRenderer* pr,
+ GrDrawTarget* target,
+ const SkPath* path,
+ GrPathFill fill,
+ const GrPoint* translate) {
+ if (NULL != fPathRenderer) {
+ fPathRenderer->clearPath();
+ }
+ GrAssert(NULL != pr);
+ pr->setPath(target, path, fill, translate);
+ fPathRenderer = pr;
+ }
+ ~AutoClearPath() {
+ if (NULL != fPathRenderer) {
+ fPathRenderer->clearPath();
+ }
+ }
+ private:
+ GrPathRenderer* fPathRenderer;
+ };
+
protected:
+
+ // subclass can override these to be notified just after a path is set
+ // and just before the path is cleared.
+ virtual void pathWasSet() {}
+ virtual void pathWillClear() {}
+
GrScalar fCurveTolerance;
+ const SkPath* fPath;
+ GrDrawTarget* fTarget;
+ GrPathFill fFill;
+ GrPoint fTranslate;
private:
@@ -151,35 +224,37 @@
GrDefaultPathRenderer(bool separateStencilSupport,
bool stencilWrapOpsSupport);
- virtual bool canDrawPath(const GrDrawTarget* target,
- const SkPath& path,
+ virtual bool canDrawPath(const SkPath& path,
GrPathFill fill) const { return true; }
- virtual void drawPath(GrDrawTarget* target,
- GrDrawTarget::StageBitfield stages,
- const SkPath& path,
- GrPathFill fill,
- const GrPoint* translate);
virtual bool requiresStencilPass(const GrDrawTarget* target,
const SkPath& path,
GrPathFill fill) const;
- virtual void drawPathToStencil(GrDrawTarget* target,
- const SkPath& path,
- GrPathFill fill,
- const GrPoint* translate);
+
+ virtual void drawPath(GrDrawTarget::StageBitfield stages);
+ virtual void drawPathToStencil();
+
+protected:
+ virtual void pathWillClear();
+
private:
- void onDrawPath(GrDrawTarget* target,
- GrDrawTarget::StageBitfield stages,
- const SkPath& path,
- GrPathFill fill,
- const GrPoint* translate,
- bool stencilOnly);
+ void onDrawPath(GrDrawTarget::StageBitfield stages, bool stencilOnly);
+
+ void createGeom(GrScalar srcSpaceTolSqd,
+ GrDrawTarget::StageBitfield stages);
bool fSeparateStencil;
bool fStencilWrapOps;
+ int fSubpathCount;
+ SkAutoSTMalloc<8, uint16_t> fSubpathVertCount;
+ GrScalar fPreviousSrcTol;
+ GrDrawTarget::StageBitfield fPreviousStages;
+
+
typedef GrPathRenderer INHERITED;
};
#endif
+