skia WIPjarred/canvas

1 files changed, 382 insertions, 0 deletions

diff --git a/src/deps/skia/include/core/SkRefCnt.h b/src/deps/skia/include/core/SkRefCnt.h
new file mode 100644
index 000000000..bcb75d769
--- /dev/null
+++ b/src/deps/skia/include/core/SkRefCnt.h
@@ -0,0 +1,382 @@
+/*
+ * Copyright 2006 The Android Open Source Project
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkRefCnt_DEFINED
+#define SkRefCnt_DEFINED
+
+#include "include/core/SkTypes.h"
+
+#include <atomic>       // std::atomic, std::memory_order_*
+#include <cstddef>      // std::nullptr_t
+#include <iosfwd>       // std::basic_ostream
+#include <memory>       // TODO: unused
+#include <type_traits>  // std::enable_if, std::is_convertible
+#include <utility>      // std::forward, std::swap
+
+/** \class SkRefCntBase
+
+    SkRefCntBase is the base class for objects that may be shared by multiple
+    objects. When an existing owner wants to share a reference, it calls ref().
+    When an owner wants to release its reference, it calls unref(). When the
+    shared object's reference count goes to zero as the result of an unref()
+    call, its (virtual) destructor is called. It is an error for the
+    destructor to be called explicitly (or via the object going out of scope on
+    the stack or calling delete) if getRefCnt() > 1.
+*/
+class SK_API SkRefCntBase {
+public:
+    /** Default construct, initializing the reference count to 1.
+    */
+    SkRefCntBase() : fRefCnt(1) {}
+
+    /** Destruct, asserting that the reference count is 1.
+    */
+    virtual ~SkRefCntBase() {
+    #ifdef SK_DEBUG
+        SkASSERTF(this->getRefCnt() == 1, "fRefCnt was %d", this->getRefCnt());
+        // illegal value, to catch us if we reuse after delete
+        fRefCnt.store(0, std::memory_order_relaxed);
+    #endif
+    }
+
+    /** May return true if the caller is the only owner.
+     *  Ensures that all previous owner's actions are complete.
+     */
+    bool unique() const {
+        if (1 == fRefCnt.load(std::memory_order_acquire)) {
+            // The acquire barrier is only really needed if we return true.  It
+            // prevents code conditioned on the result of unique() from running
+            // until previous owners are all totally done calling unref().
+            return true;
+        }
+        return false;
+    }
+
+    /** Increment the reference count. Must be balanced by a call to unref().
+    */
+    void ref() const {
+        SkASSERT(this->getRefCnt() > 0);
+        // No barrier required.
+        (void)fRefCnt.fetch_add(+1, std::memory_order_relaxed);
+    }
+
+    /** Decrement the reference count. If the reference count is 1 before the
+        decrement, then delete the object. Note that if this is the case, then
+        the object needs to have been allocated via new, and not on the stack.
+    */
+    void unref() const {
+        SkASSERT(this->getRefCnt() > 0);
+        // A release here acts in place of all releases we "should" have been doing in ref().
+        if (1 == fRefCnt.fetch_add(-1, std::memory_order_acq_rel)) {
+            // Like unique(), the acquire is only needed on success, to make sure
+            // code in internal_dispose() doesn't happen before the decrement.
+            this->internal_dispose();
+        }
+    }
+
+private:
+
+#ifdef SK_DEBUG
+    /** Return the reference count. Use only for debugging. */
+    int32_t getRefCnt() const {
+        return fRefCnt.load(std::memory_order_relaxed);
+    }
+#endif
+
+    /**
+     *  Called when the ref count goes to 0.
+     */
+    virtual void internal_dispose() const {
+    #ifdef SK_DEBUG
+        SkASSERT(0 == this->getRefCnt());
+        fRefCnt.store(1, std::memory_order_relaxed);
+    #endif
+        delete this;
+    }
+
+    // The following friends are those which override internal_dispose()
+    // and conditionally call SkRefCnt::internal_dispose().
+    friend class SkWeakRefCnt;
+
+    mutable std::atomic<int32_t> fRefCnt;
+
+    SkRefCntBase(SkRefCntBase&&) = delete;
+    SkRefCntBase(const SkRefCntBase&) = delete;
+    SkRefCntBase& operator=(SkRefCntBase&&) = delete;
+    SkRefCntBase& operator=(const SkRefCntBase&) = delete;
+};
+
+#ifdef SK_REF_CNT_MIXIN_INCLUDE
+// It is the responsibility of the following include to define the type SkRefCnt.
+// This SkRefCnt should normally derive from SkRefCntBase.
+#include SK_REF_CNT_MIXIN_INCLUDE
+#else
+class SK_API SkRefCnt : public SkRefCntBase {
+    // "#include SK_REF_CNT_MIXIN_INCLUDE" doesn't work with this build system.
+    #if defined(SK_BUILD_FOR_GOOGLE3)
+    public:
+        void deref() const { this->unref(); }
+    #endif
+};
+#endif
+
+///////////////////////////////////////////////////////////////////////////////
+
+/** Call obj->ref() and return obj. The obj must not be nullptr.
+ */
+template <typename T> static inline T* SkRef(T* obj) {
+    SkASSERT(obj);
+    obj->ref();
+    return obj;
+}
+
+/** Check if the argument is non-null, and if so, call obj->ref() and return obj.
+ */
+template <typename T> static inline T* SkSafeRef(T* obj) {
+    if (obj) {
+        obj->ref();
+    }
+    return obj;
+}
+
+/** Check if the argument is non-null, and if so, call obj->unref()
+ */
+template <typename T> static inline void SkSafeUnref(T* obj) {
+    if (obj) {
+        obj->unref();
+    }
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+// This is a variant of SkRefCnt that's Not Virtual, so weighs 4 bytes instead of 8 or 16.
+// There's only benefit to using this if the deriving class does not otherwise need a vtable.
+template <typename Derived>
+class SkNVRefCnt {
+public:
+    SkNVRefCnt() : fRefCnt(1) {}
+    ~SkNVRefCnt() {
+    #ifdef SK_DEBUG
+        int rc = fRefCnt.load(std::memory_order_relaxed);
+        SkASSERTF(rc == 1, "NVRefCnt was %d", rc);
+    #endif
+    }
+
+    // Implementation is pretty much the same as SkRefCntBase. All required barriers are the same:
+    //   - unique() needs acquire when it returns true, and no barrier if it returns false;
+    //   - ref() doesn't need any barrier;
+    //   - unref() needs a release barrier, and an acquire if it's going to call delete.
+
+    bool unique() const { return 1 == fRefCnt.load(std::memory_order_acquire); }
+    void ref() const { (void)fRefCnt.fetch_add(+1, std::memory_order_relaxed); }
+    void  unref() const {
+        if (1 == fRefCnt.fetch_add(-1, std::memory_order_acq_rel)) {
+            // restore the 1 for our destructor's assert
+            SkDEBUGCODE(fRefCnt.store(1, std::memory_order_relaxed));
+            delete (const Derived*)this;
+        }
+    }
+    void  deref() const { this->unref(); }
+
+    // This must be used with caution. It is only valid to call this when 'threadIsolatedTestCnt'
+    // refs are known to be isolated to the current thread. That is, it is known that there are at
+    // least 'threadIsolatedTestCnt' refs for which no other thread may make a balancing unref()
+    // call. Assuming the contract is followed, if this returns false then no other thread has
+    // ownership of this. If it returns true then another thread *may* have ownership.
+    bool refCntGreaterThan(int32_t threadIsolatedTestCnt) const {
+        int cnt = fRefCnt.load(std::memory_order_acquire);
+        // If this fails then the above contract has been violated.
+        SkASSERT(cnt >= threadIsolatedTestCnt);
+        return cnt > threadIsolatedTestCnt;
+    }
+
+private:
+    mutable std::atomic<int32_t> fRefCnt;
+
+    SkNVRefCnt(SkNVRefCnt&&) = delete;
+    SkNVRefCnt(const SkNVRefCnt&) = delete;
+    SkNVRefCnt& operator=(SkNVRefCnt&&) = delete;
+    SkNVRefCnt& operator=(const SkNVRefCnt&) = delete;
+};
+
+///////////////////////////////////////////////////////////////////////////////////////////////////
+
+/**
+ *  Shared pointer class to wrap classes that support a ref()/unref() interface.
+ *
+ *  This can be used for classes inheriting from SkRefCnt, but it also works for other
+ *  classes that match the interface, but have different internal choices: e.g. the hosted class
+ *  may have its ref/unref be thread-safe, but that is not assumed/imposed by sk_sp.
+ */
+template <typename T> class sk_sp {
+public:
+    using element_type = T;
+
+    constexpr sk_sp() : fPtr(nullptr) {}
+    constexpr sk_sp(std::nullptr_t) : fPtr(nullptr) {}
+
+    /**
+     *  Shares the underlying object by calling ref(), so that both the argument and the newly
+     *  created sk_sp both have a reference to it.
+     */
+    sk_sp(const sk_sp<T>& that) : fPtr(SkSafeRef(that.get())) {}
+    template <typename U,
+              typename = typename std::enable_if<std::is_convertible<U*, T*>::value>::type>
+    sk_sp(const sk_sp<U>& that) : fPtr(SkSafeRef(that.get())) {}
+
+    /**
+     *  Move the underlying object from the argument to the newly created sk_sp. Afterwards only
+     *  the new sk_sp will have a reference to the object, and the argument will point to null.
+     *  No call to ref() or unref() will be made.
+     */
+    sk_sp(sk_sp<T>&& that) : fPtr(that.release()) {}
+    template <typename U,
+              typename = typename std::enable_if<std::is_convertible<U*, T*>::value>::type>
+    sk_sp(sk_sp<U>&& that) : fPtr(that.release()) {}
+
+    /**
+     *  Adopt the bare pointer into the newly created sk_sp.
+     *  No call to ref() or unref() will be made.
+     */
+    explicit sk_sp(T* obj) : fPtr(obj) {}
+
+    /**
+     *  Calls unref() on the underlying object pointer.
+     */
+    ~sk_sp() {
+        SkSafeUnref(fPtr);
+        SkDEBUGCODE(fPtr = nullptr);
+    }
+
+    sk_sp<T>& operator=(std::nullptr_t) { this->reset(); return *this; }
+
+    /**
+     *  Shares the underlying object referenced by the argument by calling ref() on it. If this
+     *  sk_sp previously had a reference to an object (i.e. not null) it will call unref() on that
+     *  object.
+     */
+    sk_sp<T>& operator=(const sk_sp<T>& that) {
+        if (this != &that) {
+            this->reset(SkSafeRef(that.get()));
+        }
+        return *this;
+    }
+    template <typename U,
+              typename = typename std::enable_if<std::is_convertible<U*, T*>::value>::type>
+    sk_sp<T>& operator=(const sk_sp<U>& that) {
+        this->reset(SkSafeRef(that.get()));
+        return *this;
+    }
+
+    /**
+     *  Move the underlying object from the argument to the sk_sp. If the sk_sp previously held
+     *  a reference to another object, unref() will be called on that object. No call to ref()
+     *  will be made.
+     */
+    sk_sp<T>& operator=(sk_sp<T>&& that) {
+        this->reset(that.release());
+        return *this;
+    }
+    template <typename U,
+              typename = typename std::enable_if<std::is_convertible<U*, T*>::value>::type>
+    sk_sp<T>& operator=(sk_sp<U>&& that) {
+        this->reset(that.release());
+        return *this;
+    }
+
+    T& operator*() const {
+        SkASSERT(this->get() != nullptr);
+        return *this->get();
+    }
+
+    explicit operator bool() const { return this->get() != nullptr; }
+
+    T* get() const { return fPtr; }
+    T* operator->() const { return fPtr; }
+
+    /**
+     *  Adopt the new bare pointer, and call unref() on any previously held object (if not null).
+     *  No call to ref() will be made.
+     */
+    void reset(T* ptr = nullptr) {
+        // Calling fPtr->unref() may call this->~() or this->reset(T*).
+        // http://wg21.cmeerw.net/lwg/issue998
+        // http://wg21.cmeerw.net/lwg/issue2262
+        T* oldPtr = fPtr;
+        fPtr = ptr;
+        SkSafeUnref(oldPtr);
+    }
+
+    /**
+     *  Return the bare pointer, and set the internal object pointer to nullptr.
+     *  The caller must assume ownership of the object, and manage its reference count directly.
+     *  No call to unref() will be made.
+     */
+    T* SK_WARN_UNUSED_RESULT release() {
+        T* ptr = fPtr;
+        fPtr = nullptr;
+        return ptr;
+    }
+
+    void swap(sk_sp<T>& that) /*noexcept*/ {
+        using std::swap;
+        swap(fPtr, that.fPtr);
+    }
+
+private:
+    T*  fPtr;
+};
+
+template <typename T> inline void swap(sk_sp<T>& a, sk_sp<T>& b) /*noexcept*/ {
+    a.swap(b);
+}
+
+template <typename T, typename U> inline bool operator==(const sk_sp<T>& a, const sk_sp<U>& b) {
+    return a.get() == b.get();
+}
+template <typename T> inline bool operator==(const sk_sp<T>& a, std::nullptr_t) /*noexcept*/ {
+    return !a;
+}
+template <typename T> inline bool operator==(std::nullptr_t, const sk_sp<T>& b) /*noexcept*/ {
+    return !b;
+}
+
+template <typename T, typename U> inline bool operator!=(const sk_sp<T>& a, const sk_sp<U>& b) {
+    return a.get() != b.get();
+}
+template <typename T> inline bool operator!=(const sk_sp<T>& a, std::nullptr_t) /*noexcept*/ {
+    return static_cast<bool>(a);
+}
+template <typename T> inline bool operator!=(std::nullptr_t, const sk_sp<T>& b) /*noexcept*/ {
+    return static_cast<bool>(b);
+}
+
+template <typename C, typename CT, typename T>
+auto operator<<(std::basic_ostream<C, CT>& os, const sk_sp<T>& sp) -> decltype(os << sp.get()) {
+    return os << sp.get();
+}
+
+template <typename T, typename... Args>
+sk_sp<T> sk_make_sp(Args&&... args) {
+    return sk_sp<T>(new T(std::forward<Args>(args)...));
+}
+
+/*
+ *  Returns a sk_sp wrapping the provided ptr AND calls ref on it (if not null).
+ *
+ *  This is different than the semantics of the constructor for sk_sp, which just wraps the ptr,
+ *  effectively "adopting" it.
+ */
+template <typename T> sk_sp<T> sk_ref_sp(T* obj) {
+    return sk_sp<T>(SkSafeRef(obj));
+}
+
+template <typename T> sk_sp<T> sk_ref_sp(const T* obj) {
+    return sk_sp<T>(const_cast<T*>(SkSafeRef(obj)));
+}
+
+#endif