| Flutter Impeller |

Public Member Functions | List of all members
impeller::OpacityPeepholePassDelegate Class Referencefinal

`#include <paint_pass_delegate.h>`

Inheritance diagram for impeller::OpacityPeepholePassDelegate:

## Public Member Functions
| OpacityPeepholePassDelegate (Paint paint)
| ~OpacityPeepholePassDelegate () override
bool | CanElide () override
bool | CanCollapseIntoParentPass (EntityPass *entity_pass) override
| Whether or not this entity pass can be collapsed into the parent. If true, this method may modify the entities for the current pass. More...
std::shared_ptr< Contents > | CreateContentsForSubpassTarget (std::shared_ptr< Texture > target, const Matrix &effect_transform) override
std::shared_ptr< FilterContents > | WithImageFilter (const FilterInput::Variant &input, const Matrix &effect_transform) const override
Public Member Functions inherited from impeller::EntityPassDelegate
| EntityPassDelegate ()
virtual | ~EntityPassDelegate ()

## Additional Inherited Members
Static Public Member Functions inherited from impeller::EntityPassDelegate
static std::unique_ptr< EntityPassDelegate > | MakeDefault ()

## Detailed Description

A delegate that attempts to forward opacity from a save layer to child contents.

Currently this has a hardcoded limit of 3 entities in a pass, and cannot forward to child subpass delegates.

Definition at line 52 of file paint_pass_delegate.h.

## Constructor & Destructor Documentation

## ◆ OpacityPeepholePassDelegate()

impeller::OpacityPeepholePassDelegate::OpacityPeepholePassDelegate | ( | Paint | paint | ) |
| explicit

## OpacityPeepholePassDelegate

Definition at line 60 of file paint_pass_delegate.cc.

61 : paint_(std::move(paint)) {}

## ◆ ~OpacityPeepholePassDelegate()

impeller::OpacityPeepholePassDelegate::~OpacityPeepholePassDelegate | ( |  | ) |
| override default

## Member Function Documentation

## ◆ CanCollapseIntoParentPass()

bool impeller::OpacityPeepholePassDelegate::CanCollapseIntoParentPass | ( | EntityPass * | entity_pass | ) |
| override virtual

Whether or not this entity pass can be collapsed into the parent. If true, this method may modify the entities for the current pass.

Implements impeller::EntityPassDelegate.

Definition at line 72 of file paint_pass_delegate.cc.

73 {
74 // Passes with absorbed clips can not be safely collapsed.
75 if (entity_pass->GetBoundsLimit().has_value()) {
76 return false;
77 }
78
79 // OpacityPeepholePassDelegate will only get used if the pass's blend mode is
80 // SourceOver, so no need to check here.
81 if (paint_.color.alpha <= 0.0 || paint_.color.alpha >= 1.0 ||
82 paint_.image_filter || paint_.color_filter) {
83 return false;
84 }
85
86 // Note: determing whether any coverage intersects has quadradic complexity in
87 // the number of rectangles, and depending on whether or not we cache at
88 // different levels of the entity tree may end up cubic. In the interest of
89 // proving whether or not this optimization is valuable, we only consider very
90 // simple peephole optimizations here - where there is a single drawing
91 // command wrapped in save layer. This would indicate something like an
92 // Opacity or FadeTransition wrapping a very simple widget, like in the
93 // CupertinoPicker.
94 if (entity_pass->GetElementCount() > 3) {
95 // Single paint command with a save layer would be:
96 // 1. clip
97 // 2. draw command
98 // 3. restore.
99 return false;
100 }
101 bool all_can_accept = true;
102 std::vector<Rect> all_coverages;
103 auto had_subpass = entity_pass->IterateUntilSubpass(
104 [&all_coverages, &all_can_accept](Entity& entity) {
105 const auto& contents = entity.GetContents();
106 if (!entity.CanInheritOpacity()) {
107 all_can_accept = false;
108 return false;
109 }
110 auto maybe_coverage = contents->GetCoverage(entity);
111 if (maybe_coverage.has_value()) {
112 auto coverage = maybe_coverage.value();
113 for (const auto& cv : all_coverages) {
114 if (cv.IntersectsWithRect(coverage)) {
115 all_can_accept = false;
116 return false;
117 }
118 }
119 all_coverages.push_back(coverage);
120 }
121 return true;
122 });
123 if (had_subpass || !all_can_accept) {
124 return false;
125 }
126 auto alpha = paint_.color.alpha;
127 entity_pass->IterateUntilSubpass([&alpha](Entity& entity) {
128 entity.SetInheritedOpacity(alpha);
129 return true;
130 });
131 return true;
132 }

References impeller::Color::alpha, impeller::Entity::CanInheritOpacity(), impeller::Paint::color, impeller::Paint::color_filter, impeller::EntityPass::GetBoundsLimit(), impeller::Entity::GetContents(), impeller::EntityPass::GetElementCount(), impeller::Paint::image_filter, and impeller::EntityPass::IterateUntilSubpass().

## ◆ CanElide()

bool impeller::OpacityPeepholePassDelegate::CanElide | ( |  | ) |
| override virtual

Implements impeller::EntityPassDelegate.

Definition at line 67 of file paint_pass_delegate.cc.

67 {
68 return paint_.blend_mode == BlendMode::kDestination;
69 }

References impeller::Paint::blend_mode, and impeller::kDestination.

## ◆ CreateContentsForSubpassTarget()

std::shared_ptr< Contents > impeller::OpacityPeepholePassDelegate::CreateContentsForSubpassTarget | ( | std::shared_ptr< Texture > | target,
|  | const Matrix & | effect_transform
| ) |  |
| override virtual

Implements impeller::EntityPassDelegate.

Definition at line 136 of file paint_pass_delegate.cc.

138 {
139 auto contents = TextureContents::MakeRect(Rect::MakeSize(target->GetSize()));
140 contents->SetLabel("Subpass");
141 contents->SetTexture(target);
142 contents->SetSourceRect(Rect::MakeSize(target->GetSize()));
143 contents->SetOpacity(paint_.color.alpha);
144 contents->SetDeferApplyingOpacity(true);
145
146 return paint_.WithFiltersForSubpassTarget(std::move(contents),
147 effect_transform);
148 }

## ◆ WithImageFilter()

std::shared_ptr< FilterContents > impeller::OpacityPeepholePassDelegate::WithImageFilter | ( | const FilterInput::Variant & | input,
|  | const Matrix & | effect_transform
| ) |  | const
| override virtual

Implements impeller::EntityPassDelegate.

Definition at line 151 of file paint_pass_delegate.cc.

153 {
154 return paint_.WithImageFilter(input, effect_transform,
155 Entity::RenderingMode::kSubpass);
156 }

The documentation for this class was generated from the following files:

- impeller/aiks/paint_pass_delegate.h
- impeller/aiks/paint_pass_delegate.cc

impeller::Paint::color
Color color
Definition: paint.h:51
impeller::BlendMode::kDestination
@ kDestination
impeller::Color::alpha
Scalar alpha
Definition: color.h:143
impeller::Paint::color_filter
std::shared_ptr< ColorFilter > color_filter
Definition: paint.h:64
impeller::Entity::RenderingMode::kSubpass
@ kSubpass
impeller::Paint::WithImageFilter
std::shared_ptr< FilterContents > WithImageFilter(const FilterInput::Variant &input, const Matrix &effect_transform, Entity::RenderingMode rendering_mode) const
Definition: paint.cc:87
impeller::TRect< Scalar >::MakeSize
constexpr static TRect MakeSize(const TSize< U > &size)
Definition: rect.h:44
impeller::TextureContents::MakeRect
static std::shared_ptr< TextureContents > MakeRect(Rect destination)
A common case factory that marks the texture contents as having a destination rectangle....
Definition: texture_contents.cc:27
impeller::Paint::WithFiltersForSubpassTarget
std::shared_ptr< Contents > WithFiltersForSubpassTarget(std::shared_ptr< Contents > input, const Matrix &effect_transform=Matrix()) const
Wrap this paint's configured filters to the given contents of subpass target.
Definition: paint.cc:66
impeller::Paint::blend_mode
BlendMode blend_mode
Definition: paint.h:60
impeller::Paint::image_filter
std::shared_ptr< ImageFilter > image_filter
Definition: paint.h:63