Use Path Ops to generate PDF clips

src/pdf/SkPDFDevice.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkPDFDevice.h"
 
 #include "SkAnnotation.h"
@@ skipping 309 matching lines @@
 
     NOT_IMPLEMENTED(clipFill == SkPath::kInverseEvenOdd_FillType, false);
     NOT_IMPLEMENTED(clipFill == SkPath::kInverseWinding_FillType, false);
     if (clipFill == SkPath::kEvenOdd_FillType) {
         contentStream->writeText("W* n\n");
     } else {
         contentStream->writeText("W n\n");
     }
 }
 
+/* Calculate an inverted path's equivalent non-inverted path, given the
+ * canvas bounds.
+ * outPath may alias with invPath (since this is supported by PathOps).
+ */
+static bool calculate_inverse_path(const SkRect& bounds, const SkPath& invPath,

[vandebo (ex-Chrome), 2013/08/05 16:38:08]

nit: put this and handleInversePath() inside the SK_PDF_USE_PATHOPS

[ducky, 2013/08/05 17:54:19]

Done.

+                                   SkPath* outPath) {
+    SkASSERT(invPath.isInverseFillType());
+
+    SkPath clipPath;
+    clipPath.addRect(bounds);
+
+    return Op(clipPath, invPath, kIntersect_PathOp, outPath);
+}
+
+#ifdef SK_PDF_USE_PATHOPS
+// Sanity check the numerical values of the SkRegion ops and PathOps ops
+// enums so region_op_to_pathops_op can do a straight passthrough cast.
+// If these are failing, it may be necessary to make region_op_to_pathops_op
+// do more.
+SK_COMPILE_ASSERT(SkRegion::kDifference_Op == (int)kDifference_PathOp,
+                  region_pathop_mismatch);
+SK_COMPILE_ASSERT(SkRegion::kIntersect_Op == (int)kIntersect_PathOp,
+                  region_pathop_mismatch);
+SK_COMPILE_ASSERT(SkRegion::kUnion_Op == (int)kUnion_PathOp,
+                  region_pathop_mismatch);
+SK_COMPILE_ASSERT(SkRegion::kXOR_Op == (int)kXOR_PathOp,
+                  region_pathop_mismatch);
+SK_COMPILE_ASSERT(SkRegion::kReverseDifference_Op ==
+                  (int)kReverseDifference_PathOp,
+                  region_pathop_mismatch);
+
+static SkPathOp region_op_to_pathops_op(SkRegion::Op op) {
+    SkASSERT(op >= 0);
+    SkASSERT(op <= SkRegion::kReverseDifference_Op);
+    return (SkPathOp)op;
+}
+
+/* Uses Path Ops to calculate a vector SkPath clip from a clip stack.
+ * Returns true if successful, or false if not successful.
+ * If successful, the resulting clip is stored in outClipPath.
+ * If not successful, outClipPath is undefined, and a fallback method
+ * should be used.
+ */
+static bool get_clip_stack_path(const SkMatrix& transform,
+                                const SkClipStack& clipStack,
+                                const SkRegion& clipRegion,
+                                SkPath* outClipPath) {
+    outClipPath->reset();
+    outClipPath->setFillType(SkPath::kInverseWinding_FillType);
+
+    const SkClipStack::Element* clipEntry;
+    SkClipStack::Iter iter;
+    iter.reset(clipStack, SkClipStack::Iter::kBottom_IterStart);
+    for (clipEntry = iter.next(); clipEntry; clipEntry = iter.next()) {
+        SkPath entryPath;
+        if (SkClipStack::Element::kEmpty_Type == clipEntry->getType()) {
+            outClipPath->reset();
+            outClipPath->setFillType(SkPath::kInverseWinding_FillType);
+            continue;
+        } else if (SkClipStack::Element::kRect_Type == clipEntry->getType()) {
+            entryPath.addRect(clipEntry->getRect());
+        } else if (SkClipStack::Element::kPath_Type == clipEntry->getType()) {
+            entryPath = clipEntry->getPath();
+        }
+        entryPath.transform(transform);
+
+        if (SkRegion::kReplace_Op == clipEntry->getOp()) {
+            *outClipPath = entryPath;
+        } else {
+            SkPathOp op = region_op_to_pathops_op(clipEntry->getOp());
+            if (!Op(*outClipPath, entryPath, op, outClipPath)) {
+                return false;
+            }
+        }
+    }
+
+    if (outClipPath->isInverseFillType()) {
+        // The bounds are slightly outset to ensure this is correct in the
+        // face of floating-point accuracy and possible SkRegion bitmap
+        // approximations.
+        SkRect clipBounds = SkRect::Make(clipRegion.getBounds());
+        clipBounds.outset(SK_Scalar1, SK_Scalar1);
+        if (!calculate_inverse_path(clipBounds, *outClipPath, outClipPath)) {
+            return false;
+        }
+    }
+    return true;
+}
+#endif
+
 // TODO(vandebo): Take advantage of SkClipStack::getSaveCount(), the PDF
 // graphic state stack, and the fact that we can know all the clips used
 // on the page to optimize this.
 void GraphicStackState::updateClip(const SkClipStack& clipStack,
                                    const SkRegion& clipRegion,
                                    const SkPoint& translation) {
     if (clipStack == currentEntry()->fClipStack) {
         return;
     }
 
     while (fStackDepth > 0) {
         pop();
         if (clipStack == currentEntry()->fClipStack) {
             return;
         }
     }
     push();
 
+    SkMatrix transform;
+    transform.setTranslate(translation.fX, translation.fY);
+
+#ifdef SK_PDF_USE_PATHOPS
+    SkPath clipPath;
+    if (get_clip_stack_path(transform, clipStack, clipRegion, &clipPath)) {
+        emit_clip(&clipPath, NULL, fContentStream);
+
+        currentEntry()->fClipStack = clipStack;
+        currentEntry()->fClipRegion = clipRegion;
+        return;
+    }
+#endif
     // gsState->initialEntry()->fClipStack/Region specifies the clip that has
     // already been applied.  (If this is a top level device, then it specifies
     // a clip to the content area.  If this is a layer, then it specifies
     // the clip in effect when the layer was created.)  There's no need to
     // reapply that clip; SKCanvas's SkDrawIter will draw anything outside the
     // initial clip on the parent layer.  (This means there's a bug if the user
     // expands the clip and then uses any xfer mode that uses dst:
     // http://code.google.com/p/skia/issues/detail?id=228 )
     SkClipStack::Iter iter;
     skip_clip_stack_prefix(fEntries[0].fClipStack, clipStack, &iter);
 
     // If the clip stack does anything other than intersect or if it uses
     // an inverse fill type, we have to fall back to the clip region.
     bool needRegion = false;
     const SkClipStack::Element* clipEntry;
     for (clipEntry = iter.next(); clipEntry; clipEntry = iter.next()) {
         if (clipEntry->getOp() != SkRegion::kIntersect_Op || clipEntry->isInverseFilled()) {
             needRegion = true;
             break;
         }
     }
 
     if (needRegion) {
         SkPath clipPath;
         SkAssertResult(clipRegion.getBoundaryPath(&clipPath));
         emit_clip(&clipPath, NULL, fContentStream);
     } else {
         skip_clip_stack_prefix(fEntries[0].fClipStack, clipStack, &iter);
-        SkMatrix transform;
-        transform.setTranslate(translation.fX, translation.fY);
         const SkClipStack::Element* clipEntry;
         for (clipEntry = iter.next(); clipEntry; clipEntry = iter.next()) {
             SkASSERT(clipEntry->getOp() == SkRegion::kIntersect_Op);
             switch (clipEntry->getType()) {
                 case SkClipStack::Element::kRect_Type: {
                     SkRect translatedClip;
                     transform.mapRect(&translatedClip, clipEntry->getRect());
                     emit_clip(NULL, &translatedClip, fContentStream);
                     break;
                 }
                 case SkClipStack::Element::kPath_Type: {
                     SkPath translatedPath;
                     clipEntry->getPath().transform(transform, &translatedPath);
                     emit_clip(&translatedPath, NULL, fContentStream);
                     break;
                 }
                 default:
                     SkASSERT(false);
             }
         }
     }
     currentEntry()->fClipStack = clipStack;

[vandebo (ex-Chrome), 2013/08/05 16:38:08]

nit: this is done in all cases, so just pull it up to line 440.

[ducky, 2013/08/05 17:54:19]

Done.

     currentEntry()->fClipRegion = clipRegion;
 }
 
 void GraphicStackState::updateMatrix(const SkMatrix& matrix) {
     if (matrix == currentEntry()->fMatrix) {
         return;
     }
 
     if (currentEntry()->fMatrix.getType() != SkMatrix::kIdentity_Mask) {
         SkASSERT(fStackDepth > 0);
@@ skipping 822 matching lines @@
         emit_clip(NULL, &r, &data);
     }
 
     SkPDFDevice::copyContentEntriesToData(fContentEntries.get(), &data);
 
     // potentially we could cache this SkData, and only rebuild it if we
     // see that our state has changed.
     return data.copyToData();
 }
 
-/* Calculate an inverted path's equivalent non-inverted path, given the
- * canvas bounds.
- */
-static bool calculate_inverse_path(const SkRect& bounds, const SkPath& invPath,
-                                   SkPath* outPath) {
-    SkASSERT(invPath.isInverseFillType());
-
-    SkPath clipPath;
-    clipPath.addRect(bounds);
-
-    return Op(clipPath, invPath, kIntersect_PathOp, outPath);
-}
-
 /* Draws an inverse filled path by using Path Ops to compute the positive
  * inverse using the current clip as the inverse bounds.
  * Return true if this was an inverse path and was properly handled,
  * otherwise returns false and the normal drawing routine should continue,
  * either as a (incorrect) fallback or because the path was not inverse
  * in the first place.
  */
 bool SkPDFDevice::handleInversePath(const SkDraw& d, const SkPath& origPath,
                                     const SkPaint& paint, bool pathIsMutable) {
     if (!origPath.isInverseFillType()) {
@@ skipping 567 matching lines @@
 }
 
 bool SkPDFDevice::onReadPixels(const SkBitmap& bitmap, int x, int y,
                                SkCanvas::Config8888) {
     return false;
 }
 
 bool SkPDFDevice::allowImageFilter(SkImageFilter*) {
     return false;
 }