Sketch splitting SkPicture into an interface and SkBigPicture.

src/core/SkPictureCommon.h

+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+// Some shared code used by both SkBigPicture and SkMiniPicture.
+//   SkTextHunter   -- SkRecord visitor that returns true when the op draws text.
+//   SkBitmapHunter -- SkRecord visitor that returns true when the op draws a bitmap.
+//   SkPathCounter  -- SkRecord visitor that counts paths that draw slowly on the GPU.
+
+#include "SkPathEffect.h"
+#include "SkRecords.h"
+#include "SkTLogic.h"
+
+struct SkTextHunter {
+    // Most ops never have text.  Some always do.  Subpictures know themeselves.
+    template <typename T> bool operator()(const T&) { return false; }
+    bool operator()(const SkRecords::DrawPosText&)    { return true; }
+    bool operator()(const SkRecords::DrawPosTextH&)   { return true; }
+    bool operator()(const SkRecords::DrawText&)       { return true; }
+    bool operator()(const SkRecords::DrawTextBlob&)   { return true; }
+    bool operator()(const SkRecords::DrawTextOnPath&) { return true; }
+    bool operator()(const SkRecords::DrawPicture& op) { return op.picture->hasText(); }
+};
+
+
+struct SkBitmapHunter {
+    // Helpers.  These create HasMember_bitmap and HasMember_paint.
+    SK_CREATE_MEMBER_DETECTOR(bitmap);
+    SK_CREATE_MEMBER_DETECTOR(paint);
+
+    // Some ops have a paint, some have an optional paint.  Either way, get back a pointer.
+    static const SkPaint* AsPtr(const SkPaint& p) { return &p; }
+    static const SkPaint* AsPtr(const SkRecords::Optional<SkPaint>& p) { return p; }
+
+    // Main entry for visitor:
+    // If the op is a DrawPicture, recurse.
+    // If the op has a bitmap directly, return true.
+    // If the op has a paint and the paint has a bitmap, return true.
+    // Otherwise, return false.
+    bool operator()(const SkRecords::DrawPicture& op) { return op.picture->willPlayBackBitmaps(); }
+
+    template <typename T>
+    bool operator()(const T& r) { return CheckBitmap(r); }
+
+    // If the op has a bitmap, of course we're going to play back bitmaps.
+    template <typename T>
+    static SK_WHEN(HasMember_bitmap<T>, bool) CheckBitmap(const T&) { return true; }
+
+    // If not, look for one in its paint (if it has a paint).
+    template <typename T>
+    static SK_WHEN(!HasMember_bitmap<T>, bool) CheckBitmap(const T& r) { return CheckPaint(r); }
+
+    // If we have a paint, dig down into the effects looking for a bitmap.
+    template <typename T>
+    static SK_WHEN(HasMember_paint<T>, bool) CheckPaint(const T& r) {
+        const SkPaint* paint = AsPtr(r.paint);
+        if (paint) {
+            const SkShader* shader = paint->getShader();
+            if (shader &&
+                shader->asABitmap(nullptr, nullptr, nullptr) == SkShader::kDefault_BitmapType) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    // If we don't have a paint, that non-paint has no bitmap.
+    template <typename T>
+    static SK_WHEN(!HasMember_paint<T>, bool) CheckPaint(const T&) { return false; }
+};
+
+// TODO: might be nicer to have operator() return an int (the number of slow paths) ?
+struct SkPathCounter {
+    SK_CREATE_MEMBER_DETECTOR(paint);
+
+    // Some ops have a paint, some have an optional paint.  Either way, get back a pointer.
+    static const SkPaint* AsPtr(const SkPaint& p) { return &p; }
+    static const SkPaint* AsPtr(const SkRecords::Optional<SkPaint>& p) { return p; }
+
+    SkPathCounter() : fNumSlowPathsAndDashEffects(0) {}
+
+    // Recurse into nested pictures.
+    void operator()(const SkRecords::DrawPicture& op) {
+        fNumSlowPathsAndDashEffects += op.picture->numSlowPaths();
+    }
+
+    void checkPaint(const SkPaint* paint) {
+        if (paint && paint->getPathEffect()) {
+            // Initially assume it's slow.
+            fNumSlowPathsAndDashEffects++;
+        }
+    }
+
+    void operator()(const SkRecords::DrawPoints& op) {
+        this->checkPaint(&op.paint);
+        const SkPathEffect* effect = op.paint.getPathEffect();
+        if (effect) {
+            SkPathEffect::DashInfo info;
+            SkPathEffect::DashType dashType = effect->asADash(&info);
+            if (2 == op.count && SkPaint::kRound_Cap != op.paint.getStrokeCap() &&
+                SkPathEffect::kDash_DashType == dashType && 2 == info.fCount) {
+                fNumSlowPathsAndDashEffects--;
+            }
+        }
+    }
+
+    void operator()(const SkRecords::DrawPath& op) {
+        this->checkPaint(&op.paint);
+        if (op.paint.isAntiAlias() && !op.path.isConvex()) {
+            SkPaint::Style paintStyle = op.paint.getStyle();
+            const SkRect& pathBounds = op.path.getBounds();
+            if (SkPaint::kStroke_Style == paintStyle &&
+                0 == op.paint.getStrokeWidth()) {
+                // AA hairline concave path is not slow.
+            } else if (SkPaint::kFill_Style == paintStyle && pathBounds.width() < 64.f &&
+                       pathBounds.height() < 64.f && !op.path.isVolatile()) {
+                // AADF eligible concave path is not slow.
+            } else {
+                fNumSlowPathsAndDashEffects++;
+            }
+        }
+    }
+
+    template <typename T>
+    SK_WHEN(HasMember_paint<T>, void) operator()(const T& op) {
+        this->checkPaint(AsPtr(op.paint));
+    }
+
+    template <typename T>
+    SK_WHEN(!HasMember_paint<T>, void) operator()(const T& op) { /* do nothing */ }
+
+    int fNumSlowPathsAndDashEffects;
+};