forked from flutter/engine
-
Notifications
You must be signed in to change notification settings - Fork 0
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
DlAttribute base class (flutter#31672)
- Loading branch information
Showing
15 changed files
with
226 additions
and
251 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,120 @@ | ||
| // Copyright 2013 The Flutter Authors. All rights reserved. | ||
| // Use of this source code is governed by a BSD-style license that can be | ||
| // found in the LICENSE file. | ||
|
|
||
| #ifndef FLUTTER_DISPLAY_LIST_DISPLAY_LIST_ATTRIBUTES_H_ | ||
| #define FLUTTER_DISPLAY_LIST_DISPLAY_LIST_ATTRIBUTES_H_ | ||
|
|
||
| #include "flutter/display_list/types.h" | ||
|
|
||
| namespace flutter { | ||
|
|
||
| // =========================================================================== | ||
|
|
||
| // The base class for a family of DisplayList attribute classes. | ||
| // | ||
| // This class is designed to support the following properties for any | ||
| // attribute to facilitate the storage of the attribute in a DisplayList | ||
| // and for use in code that inspects or creates DisplayList objects: | ||
| // | ||
| // - Typed: | ||
| // Even though most references and pointers are passed around as the | ||
| // attribute's base class, a Type property can be queried using the |type| | ||
| // method to determine which type of the attribute is being used. For | ||
| // example, the Blend type of ColorFilter will return DlColorFilter::kBlend | ||
| // from its type method. | ||
| // | ||
| // - Inspectable: | ||
| // Any parameters required to full specify the action of the attribute are | ||
| // provided on the type-specific classes. | ||
| // | ||
| // - Safely Downcast: | ||
| // For the subclasses that have specific data to query, methods are | ||
| // provided to safely downcast the reference for inspection. The down | ||
| // casting method will either return a pointer to the instance with | ||
| // its type-specific class type, or nullptr if it is executed on the | ||
| // wrong type of instance. | ||
| // (eg. DlColorFilter::asBlend() or DlMaskFilter::asBlur()) | ||
| // | ||
| // - Skiafiable: | ||
| // The classes override an |skia_object| method to easily obtain a Skia | ||
| // version of the attribute on demand. | ||
| // | ||
| // - Immutable: | ||
| // Neither the base class or any of the subclasses specify any mutation | ||
| // methods. Instances are often passed around as const as a reminder, | ||
| // but the classes have no mutation methods anyway. | ||
| // | ||
| // - Flat and Embeddable: | ||
| // Bulk freed + bulk compared + zero memory fragmentation. | ||
| // | ||
| // All of these classes are designed to be stored in the DisplayList | ||
| // buffer allocated in-line with the rest of the data to avoid dangling | ||
| // pointers that require explicit freeing when the DisplayList goes | ||
| // away, or that fragment the memory needed to read the operations in | ||
| // the DisplayList. Furthermore, the data in the classes can be bulk | ||
| // compared using a |memcmp| when performing a |DisplayList::Equals|. | ||
| // | ||
| // - Passed by Pointer: | ||
| // The data shared via the |Dispatcher::set<Attribute>| calls are stored | ||
| // in the buffer itself and so their lifetime is controlled by the | ||
| // DisplayList. That memory cannot be shared as by a |shared_ptr| | ||
| // because the memory may be freed outside the control of the shared | ||
| // pointer. Creating a shared version of the object would require a | ||
| // new instantiation which we'd like to avoid on every dispatch call, | ||
| // so a raw (const) pointer is shared in those dispatch calls instead, | ||
| // with all of the responsibilities of non-ownership in the called method. | ||
| // | ||
| // But, for methods that need to keep a copy of the data... | ||
| // | ||
| // - Shared_Ptr-able: | ||
| // The classes support a method to return a |std::shared_ptr| version of | ||
| // themselves, safely instantiating a new copy of the object into a | ||
| // shared_ptr using |std::make_shared|. For those dispatcher objects | ||
| // that may want to hold on to the contents of the object (typically | ||
| // in a |current_attribute_| field), they can obtain a shared_ptr | ||
| // copy safely and easily using the |shared| method. | ||
|
|
||
| // =========================================================================== | ||
|
|
||
| // |D| is the base type for the attribute | ||
| // (i.e. DlColorFilter, etc.) | ||
| // |S| is the base type for the Skia version of the attribute | ||
| // (i.e. SkColorFilter, etc.) | ||
| // |T| is the enum that describes the specific subclasses | ||
| // (i.e DlColorFilterType, etc.) | ||
| template <class D, class S, typename T> | ||
| class DlAttribute { | ||
| public: | ||
| // Return the recognized specific type of the attribute. | ||
| virtual T type() const = 0; | ||
|
|
||
| // Return the size of the instantiated data (typically used to allocate) | ||
| // storage in the DisplayList buffer. | ||
| virtual size_t size() const = 0; | ||
|
|
||
| // Return a shared version of |this| attribute. The |shared_ptr| returned | ||
| // will reference a copy of this object so that the lifetime of the shared | ||
| // version is not tied to the storage of this particular instance. | ||
| virtual std::shared_ptr<D> shared() const = 0; | ||
|
|
||
| // Return an equivalent sk_sp<Skia> version of this object. | ||
| virtual sk_sp<S> skia_object() const = 0; | ||
|
|
||
| // Perform a content aware |==| comparison of the ColorFilter. | ||
| bool operator==(D const& other) const { | ||
| return type() == other.type() && equals_(other); | ||
| } | ||
| // Perform a content aware |!=| comparison of the ColorFilter. | ||
| bool operator!=(D const& other) const { return !(*this == other); } | ||
|
|
||
| virtual ~DlAttribute() = default; | ||
|
|
||
| protected: | ||
| // Virtual comparison method to support |==| and |!=|. | ||
| virtual bool equals_(D const& other) const = 0; | ||
| }; | ||
|
|
||
| } // namespace flutter | ||
|
|
||
| #endif // FLUTTER_DISPLAY_LIST_DISPLAY_LIST_ATTRIBUTES_H_ |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Oops, something went wrong.