mirror of
https://github.com/facebook/react-native.git
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Valentin Shergin
791d0973cc
Summary:
This diff changes the value of `EmptyLayoutMetrics` to make it as unusual and useless as possible. This helps when we need to compare sub-values of `LayoutMetrics` to apply only changed ones.
For example, let say we need to make a transition between two `LayoutMetrics` values. Let's say the first (the source) one equals `EmptyLayoutMetrics`. In order to apply only changed part, we need to compare individual sub-values, like `frame` or `displayType`. Before this change, the default value of `borderWidth` was `{0, 0, 0, 0}`. So in case if the second (the destination) value is also `{0, 0, 0, 0}`, the operation will be skipped.
This is undesirable because all new values have to be applied anyway because `EmptyLayoutMetrics` designates that the actual previous values are unknowns.
This fixes some visual issues on iOS caused by this issue because recycled views sometimes have non-default layout values where the transition from `EmptyLayoutMetrics` to some arbitrary value skips some sub-values.
Reviewed By: JoshuaGross
Differential Revision: D17312176
fbshipit-source-id: 7f311baea202ec2662ca87be0ae0ae6c6dd42712
86 lines
2.6 KiB
C++
86 lines
2.6 KiB
C++
/**
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#pragma once
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#include <react/core/LayoutPrimitives.h>
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#include <react/graphics/Geometry.h>
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namespace facebook {
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namespace react {
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/*
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* Describes results of layout process for particular shadow node.
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*/
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struct LayoutMetrics {
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Rect frame;
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EdgeInsets contentInsets{0};
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EdgeInsets borderWidth{0};
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DisplayType displayType{DisplayType::Flex};
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LayoutDirection layoutDirection{LayoutDirection::Undefined};
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Float pointScaleFactor{1.0};
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Rect getContentFrame() const {
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return Rect{
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Point{contentInsets.left, contentInsets.top},
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Size{frame.size.width - contentInsets.left - contentInsets.right,
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frame.size.height - contentInsets.top - contentInsets.bottom}};
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}
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bool operator==(const LayoutMetrics &rhs) const {
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return std::tie(
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this->frame,
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this->contentInsets,
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this->borderWidth,
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this->displayType,
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this->layoutDirection,
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this->pointScaleFactor) ==
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std::tie(
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rhs.frame,
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rhs.contentInsets,
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rhs.borderWidth,
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rhs.displayType,
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rhs.layoutDirection,
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rhs.pointScaleFactor);
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}
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bool operator!=(const LayoutMetrics &rhs) const {
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return !(*this == rhs);
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}
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};
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/*
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* Represents some undefined, not-yet-computed or meaningless value of
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* `LayoutMetrics` type.
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* The value is comparable by equality with any other `LayoutMetrics` value.
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* All individual sub-properties of `EmptyLayoutMetrics` have the most possible
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* "invalid" values; this is useful when we compare them with some valid values.
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*/
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static const LayoutMetrics EmptyLayoutMetrics = {
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/* .frame = */ {
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/* .origin = */ {std::numeric_limits<Float>::min(),
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std::numeric_limits<Float>::min()},
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/* .size = */
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{std::numeric_limits<Float>::min(), std::numeric_limits<Float>::min()},
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},
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/* .contentInsets = */
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{std::numeric_limits<Float>::min(),
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std::numeric_limits<Float>::min(),
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std::numeric_limits<Float>::min(),
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std::numeric_limits<Float>::min()},
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/* .borderWidth = */
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{std::numeric_limits<Float>::min(),
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std::numeric_limits<Float>::min(),
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std::numeric_limits<Float>::min(),
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std::numeric_limits<Float>::min()},
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/* .displayType = */ (DisplayType)-1,
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/* .layoutDirection = */ (LayoutDirection)-1,
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/* .pointScaleFactor = */ std::numeric_limits<Float>::min()};
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} // namespace react
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} // namespace facebook
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