Define clear regions in terms of GrFixedClip

src/gpu/GrDrawContext.cpp

Index: src/gpu/GrDrawContext.cpp
diff --git a/src/gpu/GrDrawContext.cpp b/src/gpu/GrDrawContext.cpp
index 3b346b6efd302c68541db2a48701360f57aef9e0..bf2f0fc6f9c4cd3f9fcee63be79d9535bc69ccef 100644
--- a/src/gpu/GrDrawContext.cpp
+++ b/src/gpu/GrDrawContext.cpp
@@ -195,45 +195,55 @@ void GrDrawContext::clear(const SkIRect* rect,
     GR_AUDIT_TRAIL_AUTO_FRAME(fAuditTrail, "GrDrawContext::clear");
 
     AutoCheckFlush acf(fDrawingManager);
+    this->internalClear(rect ? GrFixedClip(*rect) : GrFixedClip::Disabled(), color, canIgnoreRect);
+}
 
-    const SkIRect rtRect = SkIRect::MakeWH(this->width(), this->height());
-    SkIRect clippedRect;
-    bool isFull = false;
-    if (!rect ||
-        (canIgnoreRect && fContext->caps()->fullClearIsFree()) ||
-        rect->contains(rtRect)) {
-        rect = &rtRect;
-        isFull = true;
-    } else {
-        clippedRect = *rect;
-        if (!clippedRect.intersect(rtRect)) {
-            return;

[csmartdalton, 2016/08/23 16:31:23]

This is where it used to bail early on a non-intersection case.

-        }
-        rect = &clippedRect;
-    }
+void GrDrawContextPriv::clear(const GrFixedClip& clip,
+                              const GrColor color,
+                              bool canIgnoreClip) {
+    ASSERT_SINGLE_OWNER_PRIV
+    RETURN_IF_ABANDONED_PRIV
+    SkDEBUGCODE(fDrawContext->validate();)
+    GR_AUDIT_TRAIL_AUTO_FRAME(fDrawContext->fAuditTrail, "GrDrawContextPriv::clear");
+
+    AutoCheckFlush acf(fDrawContext->fDrawingManager);
+    fDrawContext->internalClear(clip, color, canIgnoreClip);
+}
+
+void GrDrawContext::internalClear(const GrFixedClip& clip,
+                                  const GrColor color,
+                                  bool canIgnoreClip) {
+    bool isFull = !clip.scissorEnabled() ||
+                  (canIgnoreClip && fContext->caps()->fullClearIsFree()) ||
+                  clip.scissorRect().contains(SkIRect::MakeWH(this->width(), this->height()));
 
     if (fContext->caps()->useDrawInsteadOfClear()) {
         // This works around a driver bug with clear by drawing a rect instead.
         // The driver will ignore a clear if it is the only thing rendered to a
         // target before the target is read.
-        if (rect == &rtRect) {
+        SkRect clearRect = SkRect::MakeIWH(this->width(), this->height());
+        if (isFull) {
             this->discard();
+        } else if (!clearRect.intersect(SkRect::Make(clip.scissorRect()))) {
+            return;

[csmartdalton, 2016/08/23 16:31:23]

Still bails in the "draw instead of clear" case.

         }
 
         GrPaint paint;
         paint.setColor4f(GrColor4f::FromGrColor(color));
         paint.setXPFactory(GrPorterDuffXPFactory::Make(SkXfermode::kSrc_Mode));
 
-        this->drawRect(GrNoClip(), paint, SkMatrix::I(), SkRect::Make(*rect));
+        this->drawRect(clip, paint, SkMatrix::I(), clearRect);
     } else if (isFull) {
         this->getDrawTarget()->fullClear(this->accessRenderTarget(), color);
     } else {
-        sk_sp<GrBatch> batch(GrClearBatch::Make(*rect, color, this->accessRenderTarget()));
+        sk_sp<GrBatch> batch(GrClearBatch::Make(clip, color, this->accessRenderTarget()));
+        if (!batch) {
+            return;

[csmartdalton, 2016/08/23 16:31:23]

But now it relies on GrClearBatch::Make to detect non-intersection in the
"clipped clear" case.

The reason for this that this method now takes a const GrFixedClip&. So it made
more sense to just pass ours along rather than making a temp GrFixedClip on the
stack just so we can fix up the scissor rect. Especially since GrClearBatch will
be copying the GrFixedClip anyway, it may as well do the intersection (and
non-intersection check) itself and save a copy of GrFixedClip.

[bsalomon, 2016/08/23 16:57:29]

Sounds reasonable. lgtm,

+        }
         this->getDrawTarget()->addBatch(std::move(batch));
     }
 }
 
-
 void GrDrawContext::drawPaint(const GrClip& clip,
                               const GrPaint& origPaint,
                               const SkMatrix& viewMatrix) {
@@ -528,14 +538,14 @@ void GrDrawContext::drawRect(const GrClip& clip,
     this->internalDrawPath(clip, paint, viewMatrix, path, *style);
 }
 
-void GrDrawContextPriv::clearStencilClip(const SkIRect& rect, bool insideClip) {
+void GrDrawContextPriv::clearStencilClip(const GrFixedClip& clip, bool insideStencilMask) {
     ASSERT_SINGLE_OWNER_PRIV
     RETURN_IF_ABANDONED_PRIV
     SkDEBUGCODE(fDrawContext->validate();)
     GR_AUDIT_TRAIL_AUTO_FRAME(fDrawContext->fAuditTrail, "GrDrawContextPriv::clearStencilClip");
 
     AutoCheckFlush acf(fDrawContext->fDrawingManager);
-    fDrawContext->getDrawTarget()->clearStencilClip(rect, insideClip,
+    fDrawContext->getDrawTarget()->clearStencilClip(clip, insideStencilMask,
                                                     fDrawContext->accessRenderTarget());
 }