From ba5d6f9610d6bb352eecfa3ded1bb99bc9892916 Mon Sep 17 00:00:00 2001 From: Peter Bengtsson Date: Fri, 11 Dec 2020 19:00:14 -0500 Subject: dump 2020-12-11 --- .../index.html" | 132 +++++++++++++++++++++ 1 file changed, 132 insertions(+) create mode 100644 "files/zh-cn/web/css/css_logical_properties/\346\265\256\345\212\250\345\222\214\345\256\232\344\275\215/index.html" (limited to 'files/zh-cn/web/css') diff --git "a/files/zh-cn/web/css/css_logical_properties/\346\265\256\345\212\250\345\222\214\345\256\232\344\275\215/index.html" "b/files/zh-cn/web/css/css_logical_properties/\346\265\256\345\212\250\345\222\214\345\256\232\344\275\215/index.html" new file mode 100644 index 0000000000..b96f3f6c88 --- /dev/null +++ "b/files/zh-cn/web/css/css_logical_properties/\346\265\256\345\212\250\345\222\214\345\256\232\344\275\215/index.html" @@ -0,0 +1,132 @@ +--- +title: 浮动和定位的逻辑属性 +slug: Web/CSS/CSS_Logical_Properties/浮动和定位 +translation_of: Web/CSS/CSS_Logical_Properties/Floating_and_positioning +--- +
{{CSSRef}}
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逻辑属性和值指南 包含了 {{cssxref("float")}} 和{{cssxref("clear")}}逻辑属性到物理属性的映射, 以及与定位布局一起使用的定位属性. 通过本文，我们来看看如何使用它们。

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Mapped properties and values

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The table below details the properties and values discussed in this guide along with their physical mappings. They assume a horizontal {{cssxref("writing-mode")}}, with a left-to-right direction.

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Logical property or valuePhysical property or value
{{cssxref("float")}}: inline-start{{cssxref("float")}}: left
{{cssxref("float")}}: inline-end{{cssxref("float")}}: right
{{cssxref("clear")}}: inline-start{{cssxref("clear")}}: left
{{cssxref("clear")}}: inline-end{{cssxref("clear")}}: right
{{cssxref("inset-inline-start")}}{{cssxref("left")}}
{{cssxref("inset-inline-end")}}{{cssxref("right")}}
{{cssxref("inset-block-start")}}{{cssxref("top")}}
{{cssxref("inset-block-end")}}{{cssxref("bottom")}}
{{cssxref("text-align")}}: start{{cssxref("text-align")}}: left
{{cssxref("text-align")}}: end{{cssxref("text-align")}}: right
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In addition to these mapped properties there are some additional shorthand properties made possible by being able to address block and inline dimensions. These have no mapping to physical properties, aside from the {{cssxref("inset")}} property.

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Logical propertyPurpose
{{cssxref("inset-inline")}}Sets both of the above inset values for the inline dimension simultaneously.
{{cssxref("inset-block")}}Sets both of the above inset values for the block dimension simultaneously.
{{cssxref("inset")}}Sets all four inset values simultaneously with physical mapping of multi-value.
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Float and clear example

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The physical values used with the {{cssxref("float")}} and {{cssxref("clear")}} properties are left, right and both. The Logical Properties specification defines the values inline-start and inline-end as mappings for left and right.

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In the example below I have two boxes — the first has the box floated with float: left, the second with float: inline-start. If you change the writing-mode to vertical-rl or the direction to rtl you will see that the left-floated box always sticks to the left, whereas the inline-start-floated item follows the direction and writing-mode.

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{{EmbedGHLiveSample("css-examples/logical/float.html", '100%', 700)}}

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Example: Inset properties for positioned layout

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Positioning generally allows us to position an element in a manner relative to its containing block — we essentially inset the item relative to where it would fall based on normal flow. To do this we have historically used the physical properties {{cssxref("top")}}, {{cssxref("right")}}, {{cssxref("bottom")}} and {{cssxref("left")}}.

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These properties take a length or a percentage as a value, and relate to the user's screen dimensions.

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New properties have been created in the Logical Properties specification for when you want the positioning to relate to the flow of text in your writing mode. These are as follows: {{cssxref("inset-block-start")}}, {{cssxref("inset-block-end")}}, {{cssxref("inset-inline-start")}} and {{cssxref("inset-inline-end")}}.

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In the below example I have used the inset-block-start and inset-inline-end properties to position the blue box using absolute positioning inside the area with the grey dotted border, which has position: relative. Change the writing-mode property to vertical-rl, or add direction: rtl, and see how the flow relative box stays with the text direction.

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{{EmbedGHLiveSample("css-examples/logical/positioning-inset.html", '100%', 700)}}

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New two- and four-value shorthands

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As with other properties in the specification we have some new shorthand properties, which give the ability to set two or four values at once.

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Note: The browsers that have implemented the Logical Properties specification have so far implemented the direct mappings and not the new shorthands. Look to the browser compatibility data section on each property page reference for more details.

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Example: Logical values for text-align

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The {{cssxref("text-align")}} property has logical values that relate to text direction — rather than using left and right we can use start and end. In the below example I have set text-align: right in the first block and text-align: end in the second.

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If you change the value of direction to rtl you will see that the alignment stays to the right for the first block, but goes to the logical end on the left in the second.

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{{EmbedGHLiveSample("css-examples/logical/text-align.html", '100%', 700)}}

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This works in a more consistent way when using box alignment that uses start and end rather than physical directions for alignment.

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