Add device space "nudge" to gpu draws

This CL nudges all the GPU draws and clips slightly to match raster's round behavior for BW draws. We assume the effect will be negligible and do it for AA draws too.

BUG=423834

Review URL: https://codereview.chromium.org/877473005

1 files changed, 66 insertions, 59 deletions

diff --git a/samplecode/SampleClipDrawMatch.cpp b/samplecode/SampleClipDrawMatch.cpp
index 8e2fb46dc9..f897b7185e 100644
--- a/samplecode/SampleClipDrawMatch.cpp
+++ b/samplecode/SampleClipDrawMatch.cpp
@@ -16,6 +16,7 @@
 // fractionally (via an animator) to expose snapping bugs. The key bindings are:
 //      1-9: the different geometries
 //      t:   toggle which is drawn first the clip or the normal geometry
+//      f:   flip-flops which corner the bottom AA clip rect occupies in the complex clip cases
 
 // The possible geometric combinations to test
 enum Geometry {
@@ -35,6 +36,10 @@ static const float kMin = 100.5f;
 static const float kMid = 200.0f;
 static const float kMax = 299.5f;
 
+// The translation applied to the base AA rect  in the combination cases
+// (i.e., kRectAndRect through kRectAndConcave)
+static const float kXlate = 100.0f;
+
 SkRect create_rect(const SkPoint& offset) {
     SkRect r = SkRect::MakeLTRB(kMin, kMin, kMax, kMax);
     r.offset(offset);
@@ -79,62 +84,6 @@ SkPath create_concave_path(const SkPoint& offset) {
     return concavePath;
 }
 
-static void draw_clipped_geom(SkCanvas* canvas, const SkPoint& offset, int geom, bool useAA) {
-
-    int count = canvas->save();
-
-    switch (geom) {
-    case kRect_Geometry:
-        canvas->clipRect(create_rect(offset), SkRegion::kReplace_Op, useAA);
-        break;
-    case kRRect_Geometry:
-        canvas->clipRRect(create_rrect(offset), SkRegion::kReplace_Op, useAA);
-        break;
-    case kCircle_Geometry:
-        canvas->clipRRect(create_circle(offset), SkRegion::kReplace_Op, useAA);
-        break;
-    case kConvexPath_Geometry:
-        canvas->clipPath(create_convex_path(offset), SkRegion::kReplace_Op, useAA);
-        break;
-    case kConcavePath_Geometry:
-        canvas->clipPath(create_concave_path(offset), SkRegion::kReplace_Op, useAA);
-        break;
-    case kRectAndRect_Geometry: {
-        SkRect r = create_rect(offset);
-        r.offset(-100.0f, -100.0f);
-        canvas->clipRect(r, SkRegion::kReplace_Op, true); // AA here forces shader clips
-        canvas->clipRect(create_rect(offset), SkRegion::kIntersect_Op, useAA);
-        } break;
-    case kRectAndRRect_Geometry: {
-        SkRect r = create_rect(offset);
-        r.offset(-100.0f, -100.0f);
-        canvas->clipRect(r, SkRegion::kReplace_Op, true); // AA here forces shader clips
-        canvas->clipRRect(create_rrect(offset), SkRegion::kIntersect_Op, useAA);
-        } break;
-    case kRectAndConvex_Geometry: {
-        SkRect r = create_rect(offset);
-        r.offset(-100.0f, -100.0f);
-        canvas->clipRect(r, SkRegion::kReplace_Op, true); // AA here forces shader clips
-        canvas->clipPath(create_convex_path(offset), SkRegion::kIntersect_Op, useAA);
-        } break;
-    case kRectAndConcave_Geometry: {
-        SkRect r = create_rect(offset);
-        r.offset(-100.0f, -100.0f);
-        canvas->clipRect(r, SkRegion::kReplace_Op, true); // AA here forces shader clips
-        canvas->clipPath(create_concave_path(offset), SkRegion::kIntersect_Op, useAA);
-        } break;
-    } 
-
-    SkISize size = canvas->getDeviceSize();
-    SkRect bigR = SkRect::MakeWH(SkIntToScalar(size.width()), SkIntToScalar(size.height()));
-
-    SkPaint p;
-    p.setColor(SK_ColorRED);
-
-    canvas->drawRect(bigR, p);
-    canvas->restoreToCount(count);
-}
-
 static void draw_normal_geom(SkCanvas* canvas, const SkPoint& offset, int geom, bool useAA) {
     SkPaint p;
     p.setAntiAlias(useAA);
@@ -165,7 +114,7 @@ static void draw_normal_geom(SkCanvas* canvas, const SkPoint& offset, int geom,
 
 class ClipDrawMatchView : public SampleView {
 public:
-    ClipDrawMatchView() : fTrans(2, 5), fGeom(kRect_Geometry), fClipFirst(true) {
+    ClipDrawMatchView() : fTrans(2, 5), fGeom(kRect_Geometry), fClipFirst(true), fSign(1) {
         SkScalar values[2];
 
         fTrans.setRepeatCount(999);
@@ -199,6 +148,7 @@ protected:
                 case '7': fGeom = kRectAndRRect_Geometry; this->inval(NULL); return true;
                 case '8': fGeom = kRectAndConvex_Geometry; this->inval(NULL); return true;
                 case '9': fGeom = kRectAndConcave_Geometry; this->inval(NULL); return true;
+                case 'f': fSign = -fSign; this->inval(NULL); return true;
                 case 't': fClipFirst = !fClipFirst; this->inval(NULL); return true;
                 default: break;
             }
@@ -206,18 +156,74 @@ protected:
         return this->INHERITED::onQuery(evt);
     }
 
+    void drawClippedGeom(SkCanvas* canvas, const SkPoint& offset, bool useAA) {
+
+        int count = canvas->save();
+
+        switch (fGeom) {
+        case kRect_Geometry:
+            canvas->clipRect(create_rect(offset), SkRegion::kReplace_Op, useAA);
+            break;
+        case kRRect_Geometry:
+            canvas->clipRRect(create_rrect(offset), SkRegion::kReplace_Op, useAA);
+            break;
+        case kCircle_Geometry:
+            canvas->clipRRect(create_circle(offset), SkRegion::kReplace_Op, useAA);
+            break;
+        case kConvexPath_Geometry:
+            canvas->clipPath(create_convex_path(offset), SkRegion::kReplace_Op, useAA);
+            break;
+        case kConcavePath_Geometry:
+            canvas->clipPath(create_concave_path(offset), SkRegion::kReplace_Op, useAA);
+            break;
+        case kRectAndRect_Geometry: {
+            SkRect r = create_rect(offset);
+            r.offset(fSign * kXlate, fSign * kXlate);
+            canvas->clipRect(r, SkRegion::kReplace_Op, true); // AA here forces shader clips
+            canvas->clipRect(create_rect(offset), SkRegion::kIntersect_Op, useAA);
+            } break;
+        case kRectAndRRect_Geometry: {
+            SkRect r = create_rect(offset);
+            r.offset(fSign * kXlate, fSign * kXlate);
+            canvas->clipRect(r, SkRegion::kReplace_Op, true); // AA here forces shader clips
+            canvas->clipRRect(create_rrect(offset), SkRegion::kIntersect_Op, useAA);
+            } break;
+        case kRectAndConvex_Geometry: {
+            SkRect r = create_rect(offset);
+            r.offset(fSign * kXlate, fSign * kXlate);
+            canvas->clipRect(r, SkRegion::kReplace_Op, true); // AA here forces shader clips
+            canvas->clipPath(create_convex_path(offset), SkRegion::kIntersect_Op, useAA);
+            } break;
+        case kRectAndConcave_Geometry: {
+            SkRect r = create_rect(offset);
+            r.offset(fSign * kXlate, fSign * kXlate);
+            canvas->clipRect(r, SkRegion::kReplace_Op, true); // AA here forces shader clips
+            canvas->clipPath(create_concave_path(offset), SkRegion::kIntersect_Op, useAA);
+            } break;
+        } 
+
+        SkISize size = canvas->getDeviceSize();
+        SkRect bigR = SkRect::MakeWH(SkIntToScalar(size.width()), SkIntToScalar(size.height()));
+
+        SkPaint p;
+        p.setColor(SK_ColorRED);
+
+        canvas->drawRect(bigR, p);
+        canvas->restoreToCount(count);
+    }
+
     // Draw a big red rect through some clip geometry and also draw that same
     // geometry in black. The order in which they are drawn can be swapped.
     // This tests whether the clip and normally drawn geometry match up.
     void drawGeometry(SkCanvas* canvas, const SkPoint& offset, bool useAA) {
         if (fClipFirst) {
-            draw_clipped_geom(canvas, offset, fGeom, useAA);
+            this->drawClippedGeom(canvas, offset, useAA);
         }
 
         draw_normal_geom(canvas, offset, fGeom, useAA);
 
         if (!fClipFirst) {
-            draw_clipped_geom(canvas, offset, fGeom, useAA);
+            this->drawClippedGeom(canvas, offset, useAA);
         }
     }
 
@@ -239,6 +245,7 @@ private:
     SkInterpolator  fTrans;
     Geometry        fGeom;
     bool            fClipFirst;
+    int             fSign;
 
     typedef SampleView INHERITED;
 };