Shim to enforce that canvas virtuals are overridden

Change-Id: Iad70d449bbc43195baefd70d20c41996a8435e6e
Reviewed-on: https://skia-review.googlesource.com/113320
Reviewed-by: Mike Reed <reed@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Brian Osman <brianosman@google.com>

6 files changed, 128 insertions, 31 deletions

diff --git a/include/core/SkCanvas.h b/include/core/SkCanvas.h
index a9adc48722..f1081bfa83 100644
--- a/include/core/SkCanvas.h
+++ b/include/core/SkCanvas.h
@@ -2476,48 +2476,41 @@ protected:
         this->didConcat(SkMatrix::MakeTrans(dx, dy));
     }
 
-    virtual void onDrawAnnotation(const SkRect& rect, const char key[], SkData* value);
+    // NOTE: If you are adding a new onDraw virtual to SkCanvas, PLEASE add an override to
+    // SkCanvasVirtualEnforcer (in SkCanvasVirtualEnforcer.h). This ensures that subclasses using
+    // that mechanism  will be required to implement the new function.
+    virtual void onDrawPaint(const SkPaint& paint);
+    virtual void onDrawRect(const SkRect& rect, const SkPaint& paint);
+    virtual void onDrawRRect(const SkRRect& rrect, const SkPaint& paint);
     virtual void onDrawDRRect(const SkRRect& outer, const SkRRect& inner, const SkPaint& paint);
+    virtual void onDrawOval(const SkRect& rect, const SkPaint& paint);
+    virtual void onDrawArc(const SkRect& rect, SkScalar startAngle, SkScalar sweepAngle,
+                           bool useCenter, const SkPaint& paint);
+    virtual void onDrawPath(const SkPath& path, const SkPaint& paint);
+    virtual void onDrawRegion(const SkRegion& region, const SkPaint& paint);
 
     virtual void onDrawText(const void* text, size_t byteLength, SkScalar x,
                             SkScalar y, const SkPaint& paint);
-
     virtual void onDrawPosText(const void* text, size_t byteLength,
                                const SkPoint pos[], const SkPaint& paint);
-
     virtual void onDrawPosTextH(const void* text, size_t byteLength,
                                 const SkScalar xpos[], SkScalar constY,
                                 const SkPaint& paint);
-
     virtual void onDrawTextOnPath(const void* text, size_t byteLength,
                                   const SkPath& path, const SkMatrix* matrix,
                                   const SkPaint& paint);
     virtual void onDrawTextRSXform(const void* text, size_t byteLength, const SkRSXform xform[],
                                    const SkRect* cullRect, const SkPaint& paint);
-
     virtual void onDrawTextBlob(const SkTextBlob* blob, SkScalar x, SkScalar y,
                                 const SkPaint& paint);
 
     virtual void onDrawPatch(const SkPoint cubics[12], const SkColor colors[4],
                            const SkPoint texCoords[4], SkBlendMode mode, const SkPaint& paint);
-
-    virtual void onDrawDrawable(SkDrawable* drawable, const SkMatrix* matrix);
-
-    virtual void onDrawPaint(const SkPaint& paint);
-    virtual void onDrawRect(const SkRect& rect, const SkPaint& paint);
-    virtual void onDrawRegion(const SkRegion& region, const SkPaint& paint);
-    virtual void onDrawOval(const SkRect& rect, const SkPaint& paint);
-    virtual void onDrawArc(const SkRect& rect, SkScalar startAngle, SkScalar sweepAngle,
-                           bool useCenter, const SkPaint& paint);
-    virtual void onDrawRRect(const SkRRect& rrect, const SkPaint& paint);
     virtual void onDrawPoints(PointMode mode, size_t count, const SkPoint pts[],
                               const SkPaint& paint);
     virtual void onDrawVerticesObject(const SkVertices* vertices, SkBlendMode mode,
                                       const SkPaint& paint);
-    virtual void onDrawAtlas(const SkImage* atlas, const SkRSXform xform[], const SkRect rect[],
-                             const SkColor colors[], int count, SkBlendMode mode,
-                             const SkRect* cull, const SkPaint* paint);
-    virtual void onDrawPath(const SkPath& path, const SkPaint& paint);
+
     virtual void onDrawImage(const SkImage* image, SkScalar dx, SkScalar dy, const SkPaint* paint);
     virtual void onDrawImageRect(const SkImage* image, const SkRect* src, const SkRect& dst,
                                  const SkPaint* paint, SrcRectConstraint constraint);
@@ -2534,8 +2527,18 @@ protected:
                                   const SkPaint* paint);
     virtual void onDrawBitmapLattice(const SkBitmap& bitmap, const Lattice& lattice,
                                      const SkRect& dst, const SkPaint* paint);
+
+    virtual void onDrawAtlas(const SkImage* atlas, const SkRSXform xform[], const SkRect rect[],
+                             const SkColor colors[], int count, SkBlendMode mode,
+                             const SkRect* cull, const SkPaint* paint);
+
+    virtual void onDrawAnnotation(const SkRect& rect, const char key[], SkData* value);
     virtual void onDrawShadowRec(const SkPath&, const SkDrawShadowRec&);
 
+    virtual void onDrawDrawable(SkDrawable* drawable, const SkMatrix* matrix);
+    virtual void onDrawPicture(const SkPicture* picture, const SkMatrix* matrix,
+                               const SkPaint* paint);
+
     enum ClipEdgeStyle {
         kHard_ClipEdgeStyle,
         kSoft_ClipEdgeStyle
@@ -2548,9 +2551,6 @@ protected:
 
     virtual void onDiscard();
 
-    virtual void onDrawPicture(const SkPicture* picture, const SkMatrix* matrix,
-                               const SkPaint* paint);
-
     // Clip rectangle bounds. Called internally by saveLayer.
     // returns false if the entire rectangle is entirely clipped out
     // If non-NULL, The imageFilter parameter will be used to expand the clip
@@ -2673,7 +2673,10 @@ private:
         kDefault_InitFlags                  = 0,
         kConservativeRasterClip_InitFlag    = 1 << 0,
     };
+protected:
+    // For use by SkNoDrawCanvas (via SkCanvasVirtualEnforcer, which can't be a friend)
     SkCanvas(const SkIRect& bounds, InitFlags);
+private:
     SkCanvas(SkBaseDevice* device, InitFlags);
     SkCanvas(const SkBitmap&, std::unique_ptr<SkRasterHandleAllocator>,
              SkRasterHandleAllocator::Handle);
diff --git a/include/core/SkCanvasVirtualEnforcer.h b/include/core/SkCanvasVirtualEnforcer.h
new file mode 100644
index 0000000000..1999802170
--- /dev/null
+++ b/include/core/SkCanvasVirtualEnforcer.h
@@ -0,0 +1,85 @@
+/*
+ * Copyright 2018 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkCanvasVirtualEnforcer_DEFINED
+#define SkCanvasVirtualEnforcer_DEFINED
+
+#include "SkCanvas.h"
+
+// If you would ordinarily want to inherit from Base (eg SkCanvas, SkNWayCanvas), instead
+// inherit from SkCanvasVirtualEnforcer<Base>, which will make the build fail if you forget
+// to override one of SkCanvas' key virtual hooks.
+template <typename Base>
+class SkCanvasVirtualEnforcer : public Base {
+public:
+    using Base::Base;
+
+protected:
+    void onDrawPaint(const SkPaint& paint) override = 0;
+    void onDrawRect(const SkRect& rect, const SkPaint& paint) override = 0;
+    void onDrawRRect(const SkRRect& rrect, const SkPaint& paint) override = 0;
+    void onDrawDRRect(const SkRRect& outer, const SkRRect& inner,
+                      const SkPaint& paint) override = 0;
+    void onDrawOval(const SkRect& rect, const SkPaint& paint) override = 0;
+    void onDrawArc(const SkRect& rect, SkScalar startAngle, SkScalar sweepAngle, bool useCenter,
+                   const SkPaint& paint) override = 0;
+    void onDrawPath(const SkPath& path, const SkPaint& paint) override = 0;
+    void onDrawRegion(const SkRegion& region, const SkPaint& paint) override = 0;
+
+    void onDrawText(const void* text, size_t byteLength, SkScalar x, SkScalar y,
+                    const SkPaint& paint) override = 0;
+    void onDrawPosText(const void* text, size_t byteLength, const SkPoint pos[],
+                       const SkPaint& paint) override = 0;
+    void onDrawPosTextH(const void* text, size_t byteLength, const SkScalar xpos[],
+                        SkScalar constY, const SkPaint& paint) override = 0;
+    void onDrawTextOnPath(const void* text, size_t byteLength, const SkPath& path,
+                          const SkMatrix* matrix, const SkPaint& paint) override = 0;
+    void onDrawTextRSXform(const void* text, size_t byteLength, const SkRSXform xform[],
+                           const SkRect* cullRect, const SkPaint& paint) override = 0;
+    void onDrawTextBlob(const SkTextBlob* blob, SkScalar x, SkScalar y,
+                        const SkPaint& paint) override = 0;
+
+    void onDrawPatch(const SkPoint cubics[12], const SkColor colors[4],
+                     const SkPoint texCoords[4], SkBlendMode mode,
+                     const SkPaint& paint) override = 0;
+    void onDrawPoints(SkCanvas::PointMode mode, size_t count, const SkPoint pts[],
+                      const SkPaint& paint) override = 0;
+    void onDrawVerticesObject(const SkVertices* vertices, SkBlendMode mode,
+                              const SkPaint& paint) override = 0;
+
+    void onDrawImage(const SkImage* image, SkScalar dx, SkScalar dy,
+                     const SkPaint* paint) override = 0;
+    void onDrawImageRect(const SkImage* image, const SkRect* src, const SkRect& dst,
+                         const SkPaint* paint, SkCanvas::SrcRectConstraint constraint) override = 0;
+    void onDrawImageNine(const SkImage* image, const SkIRect& center, const SkRect& dst,
+                         const SkPaint* paint) override = 0;
+    void onDrawImageLattice(const SkImage* image, const SkCanvas::Lattice& lattice,
+                            const SkRect& dst, const SkPaint* paint) override = 0;
+
+    void onDrawBitmap(const SkBitmap& bitmap, SkScalar dx, SkScalar dy,
+                      const SkPaint* paint) override = 0;
+    void onDrawBitmapRect(const SkBitmap& bitmap, const SkRect* src, const SkRect& dst,
+                          const SkPaint* paint,
+                          SkCanvas::SrcRectConstraint constraint) override = 0;
+    void onDrawBitmapNine(const SkBitmap& bitmap, const SkIRect& center, const SkRect& dst,
+                          const SkPaint* paint) override = 0;
+    void onDrawBitmapLattice(const SkBitmap& bitmap, const SkCanvas::Lattice& lattice,
+                             const SkRect& dst, const SkPaint* paint) override = 0;
+
+    void onDrawAtlas(const SkImage* atlas, const SkRSXform xform[], const SkRect rect[],
+                     const SkColor colors[], int count, SkBlendMode mode, const SkRect* cull,
+                     const SkPaint* paint) override = 0;
+
+    void onDrawAnnotation(const SkRect& rect, const char key[], SkData* value) override = 0;
+    void onDrawShadowRec(const SkPath&, const SkDrawShadowRec&) override = 0;
+
+    void onDrawDrawable(SkDrawable* drawable, const SkMatrix* matrix) override = 0;
+    void onDrawPicture(const SkPicture* picture, const SkMatrix* matrix,
+                       const SkPaint* paint) override = 0;
+};
+
+#endif
diff --git a/include/core/SkOverdrawCanvas.h b/include/core/SkOverdrawCanvas.h
index 284fe6cd97..47b5e04872 100644
--- a/include/core/SkOverdrawCanvas.h
+++ b/include/core/SkOverdrawCanvas.h
@@ -8,6 +8,7 @@
 #ifndef SkOverdrawCanvas_DEFINED
 #define SkOverdrawCanvas_DEFINED
 
+#include "SkCanvasVirtualEnforcer.h"
 #include "SkNWayCanvas.h"
 
 /**
@@ -15,7 +16,7 @@
  *  increments the alpha channel of each pixel every time it would have been touched
  *  by a draw call.  This is useful for detecting overdraw.
  */
-class SK_API SkOverdrawCanvas : public SkNWayCanvas {
+class SK_API SkOverdrawCanvas : public SkCanvasVirtualEnforcer<SkNWayCanvas> {
 public:
     /* Does not take ownership of canvas */
     SkOverdrawCanvas(SkCanvas*);
@@ -56,6 +57,9 @@ public:
     void onDrawDrawable(SkDrawable*, const SkMatrix*) override;
     void onDrawPicture(const SkPicture*, const SkMatrix*, const SkPaint*) override;
 
+    void onDrawAnnotation(const SkRect&, const char key[], SkData* value) override;
+    void onDrawShadowRec(const SkPath&, const SkDrawShadowRec&) override;
+
 private:
     void drawPosTextCommon(const void*, size_t, const SkScalar[], int, const SkPoint&,
                            const SkPaint&);
@@ -64,7 +68,7 @@ private:
 
     SkPaint   fPaint;
 
-    typedef SkNWayCanvas INHERITED;
+    typedef SkCanvasVirtualEnforcer<SkNWayCanvas> INHERITED;
 };
 
 #endif
diff --git a/include/utils/SkNWayCanvas.h b/include/utils/SkNWayCanvas.h
index ca57e59f58..e6a6b9962e 100644
--- a/include/utils/SkNWayCanvas.h
+++ b/include/utils/SkNWayCanvas.h
@@ -10,9 +10,10 @@
 #define SkNWayCanvas_DEFINED
 
 #include "../private/SkTDArray.h"
+#include "SkCanvasVirtualEnforcer.h"
 #include "SkNoDrawCanvas.h"
 
-class SK_API SkNWayCanvas : public SkNoDrawCanvas {
+class SK_API SkNWayCanvas : public SkCanvasVirtualEnforcer<SkNoDrawCanvas> {
 public:
     SkNWayCanvas(int width, int height);
     ~SkNWayCanvas() override;
@@ -96,7 +97,7 @@ protected:
     class Iter;
 
 private:
-    typedef SkNoDrawCanvas INHERITED;
+    typedef SkCanvasVirtualEnforcer<SkNoDrawCanvas> INHERITED;
 };
 
 
diff --git a/include/utils/SkNoDrawCanvas.h b/include/utils/SkNoDrawCanvas.h
index a261e4a2fa..7475956704 100644
--- a/include/utils/SkNoDrawCanvas.h
+++ b/include/utils/SkNoDrawCanvas.h
@@ -9,6 +9,7 @@
 #define SkNoDrawCanvas_DEFINED
 
 #include "SkCanvas.h"
+#include "SkCanvasVirtualEnforcer.h"
 #include "SkVertices.h"
 
 struct SkIRect;
@@ -21,7 +22,7 @@ struct SkIRect;
 //   * not backed by any device/pixels
 //   * conservative clipping (clipping calls only use rectangles)
 //
-class SK_API SkNoDrawCanvas : public SkCanvas {
+class SK_API SkNoDrawCanvas : public SkCanvasVirtualEnforcer<SkCanvas> {
 public:
     SkNoDrawCanvas(int width, int height);
 
@@ -37,6 +38,7 @@ protected:
     SaveLayerStrategy getSaveLayerStrategy(const SaveLayerRec& rec) override;
 
     // No-op overrides for aborting rasterization earlier than SkNullBlitter.
+    void onDrawAnnotation(const SkRect&, const char[], SkData*) override {}
     void onDrawDRRect(const SkRRect&, const SkRRect&, const SkPaint&) override {}
     void onDrawDrawable(SkDrawable*, const SkMatrix*) override {}
     void onDrawText(const void*, size_t, SkScalar, SkScalar, const SkPaint&) override {}
@@ -75,9 +77,10 @@ protected:
     void onDrawAtlas(const SkImage*, const SkRSXform[], const SkRect[], const SkColor[],
                      int, SkBlendMode, const SkRect*, const SkPaint*) override {}
     void onDrawShadowRec(const SkPath&, const SkDrawShadowRec&) override {}
+    void onDrawPicture(const SkPicture*, const SkMatrix*, const SkPaint*) override {}
 
 private:
-    typedef SkCanvas INHERITED;
+    typedef SkCanvasVirtualEnforcer<SkCanvas> INHERITED;
 };
 
 #endif // SkNoDrawCanvas_DEFINED
diff --git a/include/utils/SkPaintFilterCanvas.h b/include/utils/SkPaintFilterCanvas.h
index 29727a74c9..72c9784725 100644
--- a/include/utils/SkPaintFilterCanvas.h
+++ b/include/utils/SkPaintFilterCanvas.h
@@ -8,6 +8,7 @@
 #ifndef SkPaintFilterCanvas_DEFINED
 #define SkPaintFilterCanvas_DEFINED
 
+#include "SkCanvasVirtualEnforcer.h"
 #include "SkNWayCanvas.h"
 #include "SkTLazy.h"
 
@@ -15,7 +16,7 @@
 
     A utility proxy base class for implementing draw/paint filters.
 */
-class SK_API SkPaintFilterCanvas : public SkNWayCanvas {
+class SK_API SkPaintFilterCanvas : public SkCanvasVirtualEnforcer<SkNWayCanvas> {
 public:
     /**
      * The new SkPaintFilterCanvas is configured for forwarding to the
@@ -108,6 +109,8 @@ protected:
                         const SkPaint& paint) override;
     void onDrawAtlas(const SkImage*, const SkRSXform[], const SkRect[], const SkColor[],
                      int, SkBlendMode, const SkRect*, const SkPaint*) override;
+    void onDrawAnnotation(const SkRect& rect, const char key[], SkData* value) override;
+    void onDrawShadowRec(const SkPath& path, const SkDrawShadowRec& rec) override;
 
     // Forwarded to the wrapped canvas.
     sk_sp<SkSurface> onNewSurface(const SkImageInfo&, const SkSurfaceProps&) override;
@@ -120,8 +123,6 @@ private:
     class AutoPaintFilter;
 
     SkCanvas* proxy() const { SkASSERT(fList.count() == 1); return fList[0]; }
-
-    typedef SkNWayCanvas INHERITED;
 };
 
 #endif