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      1 /*
      2  * Copyright 2015 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #include "SkCanvas.h"
      9 #include "SkTLazy.h"
     10 #include "SkMiniRecorder.h"
     11 #include "SkOnce.h"
     12 #include "SkPicture.h"
     13 #include "SkPictureCommon.h"
     14 #include "SkRecordDraw.h"
     15 #include "SkRectPriv.h"
     16 #include "SkTextBlob.h"
     17 #include <new>
     18 
     19 using namespace SkRecords;
     20 
     21 class SkEmptyPicture final : public SkPicture {
     22 public:
     23     void playback(SkCanvas*, AbortCallback*) const override { }
     24 
     25     size_t approximateBytesUsed() const override { return sizeof(*this); }
     26     int    approximateOpCount()   const override { return 0; }
     27     SkRect cullRect()             const override { return SkRect::MakeEmpty(); }
     28 };
     29 
     30 // Calculate conservative bounds for each type of draw op that can be its own mini picture.
     31 // These are fairly easy because we know they can't be affected by any matrix or saveLayers.
     32 static SkRect adjust_for_paint(SkRect bounds, const SkPaint& paint) {
     33     return paint.canComputeFastBounds() ? paint.computeFastBounds(bounds, &bounds)
     34                                         : SkRectPriv::MakeLargest();
     35 }
     36 static SkRect bounds(const DrawRect& op) {
     37     return adjust_for_paint(op.rect, op.paint);
     38 }
     39 static SkRect bounds(const DrawPath& op) {
     40     return op.path.isInverseFillType() ? SkRectPriv::MakeLargest()
     41                                        : adjust_for_paint(op.path.getBounds(), op.paint);
     42 }
     43 static SkRect bounds(const DrawTextBlob& op) {
     44     return adjust_for_paint(op.blob->bounds().makeOffset(op.x, op.y), op.paint);
     45 }
     46 
     47 template <typename T>
     48 class SkMiniPicture final : public SkPicture {
     49 public:
     50     SkMiniPicture(const SkRect* cull, T* op) : fCull(cull ? *cull : bounds(*op)) {
     51         memcpy(&fOp, op, sizeof(fOp));  // We take ownership of op's guts.
     52     }
     53 
     54     void playback(SkCanvas* c, AbortCallback*) const override {
     55         SkRecords::Draw(c, nullptr, nullptr, 0, nullptr)(fOp);
     56     }
     57 
     58     size_t approximateBytesUsed() const override { return sizeof(*this); }
     59     int    approximateOpCount()   const override { return 1; }
     60     SkRect cullRect()             const override { return fCull; }
     61 
     62 private:
     63     SkRect fCull;
     64     T      fOp;
     65 };
     66 
     67 
     68 SkMiniRecorder::SkMiniRecorder() : fState(State::kEmpty) {}
     69 SkMiniRecorder::~SkMiniRecorder() {
     70     if (fState != State::kEmpty) {
     71         // We have internal state pending.
     72         // Detaching then deleting a picture is an easy way to clean up.
     73         (void)this->detachAsPicture(nullptr);
     74     }
     75     SkASSERT(fState == State::kEmpty);
     76 }
     77 
     78 #define TRY_TO_STORE(Type, ...)                    \
     79     if (fState != State::kEmpty) { return false; } \
     80     fState = State::k##Type;                       \
     81     new (fBuffer.get()) Type{__VA_ARGS__};         \
     82     return true
     83 
     84 bool SkMiniRecorder::drawRect(const SkRect& rect, const SkPaint& paint) {
     85     TRY_TO_STORE(DrawRect, paint, rect);
     86 }
     87 
     88 bool SkMiniRecorder::drawPath(const SkPath& path, const SkPaint& paint) {
     89     TRY_TO_STORE(DrawPath, paint, path);
     90 }
     91 
     92 bool SkMiniRecorder::drawTextBlob(const SkTextBlob* b, SkScalar x, SkScalar y, const SkPaint& p) {
     93     TRY_TO_STORE(DrawTextBlob, p, sk_ref_sp(b), x, y);
     94 }
     95 #undef TRY_TO_STORE
     96 
     97 
     98 sk_sp<SkPicture> SkMiniRecorder::detachAsPicture(const SkRect* cull) {
     99 #define CASE(Type)              \
    100     case State::k##Type:        \
    101         fState = State::kEmpty; \
    102         return sk_make_sp<SkMiniPicture<Type>>(cull, reinterpret_cast<Type*>(fBuffer.get()))
    103 
    104     static SkOnce once;
    105     static SkPicture* empty;
    106 
    107     switch (fState) {
    108         case State::kEmpty:
    109             once([]{ empty = new SkEmptyPicture; });
    110             return sk_ref_sp(empty);
    111         CASE(DrawPath);
    112         CASE(DrawRect);
    113         CASE(DrawTextBlob);
    114     }
    115     SkASSERT(false);
    116     return nullptr;
    117 #undef CASE
    118 }
    119 
    120 void SkMiniRecorder::flushAndReset(SkCanvas* canvas) {
    121 #define CASE(Type)                                                  \
    122     case State::k##Type: {                                          \
    123         fState = State::kEmpty;                                     \
    124         Type* op = reinterpret_cast<Type*>(fBuffer.get());          \
    125         SkRecords::Draw(canvas, nullptr, nullptr, 0, nullptr)(*op); \
    126         op->~Type();                                                \
    127     } return
    128 
    129     switch (fState) {
    130         case State::kEmpty: return;
    131         CASE(DrawPath);
    132         CASE(DrawRect);
    133         CASE(DrawTextBlob);
    134     }
    135     SkASSERT(false);
    136 #undef CASE
    137 }
    138