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author | Peter Bengtsson <mail@peterbe.com> | 2020-12-08 14:40:17 -0500 |
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committer | Peter Bengtsson <mail@peterbe.com> | 2020-12-08 14:40:17 -0500 |
commit | 33058f2b292b3a581333bdfb21b8f671898c5060 (patch) | |
tree | 51c3e392513ec574331b2d3f85c394445ea803c6 /files/zh-cn/web/css/text-rendering/index.html | |
parent | 8b66d724f7caf0157093fb09cfec8fbd0c6ad50a (diff) | |
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diff --git a/files/zh-cn/web/css/text-rendering/index.html b/files/zh-cn/web/css/text-rendering/index.html new file mode 100644 index 0000000000..1b48fa93f9 --- /dev/null +++ b/files/zh-cn/web/css/text-rendering/index.html @@ -0,0 +1,211 @@ +--- +title: 文本渲染 +slug: Web/CSS/text-rendering +tags: + - CSS + - SVG + - zh-CN +translation_of: Web/CSS/text-rendering +--- +<p>{{ CSSRef() }}</p> + +<h2 id="概述">概述</h2> + +<p><code>text-rendering</code> CSS 属性定义浏览器渲染引擎如何渲染字体。浏览器会在速度、清晰度、几何精度之间进行权衡。</p> + +<div class="note"> +<p>该属性是 SVG 的属性而不是标准的 CSS 属性。但是 Gecko(Firefox) 和 Webkit(Chrome、Safari) 内核的浏览器允许该属性在 Windows、Mac OS 和 Linux 操作系统中应用于 HTML 和 XML 内容。 </p> +</div> + +<p>一个视觉上很明显的效果是,<code>optimizeLegibility 属性值会在某些字体(比如,微软的 Calibri,</code>Candara,Constantia 和 Corbel 或者 DejaVu 系列字体<code>)小于20px 时把有些相邻字符连接起来</code>(ligatures,比如,ff、fi、fl 等,效果见下面的 LiveExample) 。</p> + +<p>{{cssinfo}}</p> + +<h2 id="语法">语法</h2> + +<pre class="brush: css">/* Keyword values */ +text-rendering: auto; +text-rendering: optimizeSpeed; +text-rendering: optimizeLegibility; +text-rendering: geometricPrecision; + +/* Global values */ +text-rendering: inherit; +text-rendering: initial; +text-rendering: unset; +</pre> + +<h3 id="值">值</h3> + +<dl> + <dt><code>auto</code></dt> + <dd>浏览器依照某些根据去推测在绘制文本时,何时该优化速度,易读性或者几何精度。对于该<font face="Consolas, Liberation Mono, Courier, monospace">值</font>在不同浏览器中解释的差异,请看兼容性表。</dd> + <dt><code>optimizeSpeed</code></dt> + <dd>浏览器在绘制文本时将着重考虑渲染速度,而不是易读性和几何精度. 它会使字间距和连字无效。</dd> + <dt><code>optimizeLegibility</code></dt> + <dd>浏览器在绘制文本时将着重考虑易读性,而不是渲染速度和几何精度.它会使字间距和连字有效。<strong>该属性值在移动设备上会造成比较明显的性能问题</strong>,详细查看<strong> </strong><a href="https://css-tricks.com/almanac/properties/t/text-rendering/">text-rendering</a>。</dd> + <dt><code>geometricPrecision</code></dt> + <dd> + <p>浏览器在绘制文本时将着重考虑几何精度, 而不是渲染速度和易读性。字体的某些方面—比如字间距—不再线性缩放,所以该<font face="Consolas, Liberation Mono, Courier, monospace">值可以使使用某些字体的文本看起来不错。</font></p> + + <p>对于 SVG,当文本缩放时,浏览器会计算文本最终大小(取决于特定的字体大小和相应的缩放比例)并且从操作平台的字体系统中请求一个符合该计算值的字体大小。但如果你请求一个字体大小,比如 9 并且 140% 的缩放,这个最终的字体大小为 12.6,字体系统中明显不存在,所以浏览器会向下取整到 12。这导致文本缩放是阶梯式的。</p> + + <p>但这个 geometricPrecision 特性——当被渲染引擎完全支持时——会使文本缩放是流畅的。对于大比例的缩放,你可能看到并不太漂亮的文本渲染,但这个字体大小是你期望的,而不是被 Windows 或 Linux 系统四舍五入或向下取整的字体大小。</p> + + <p class="note"><strong>提示</strong>: WebKit 准确地的实现了这个值, 但是 Gecko 把这个值按照 <code>optimizeLegibility 处理。</code></p> + </dd> +</dl> + +<h2 id="示例">示例</h2> + +<pre class="brush:css">/* make sure all fonts in the HTML document display in all its glory, + but avoid inadequate ligatures in class foo elements */ + +body { text-rendering: optimizeLegibility; } +.foo { text-rendering: optimizeSpeed; }</pre> + +<h4 id="Live_Example">Live Example</h4> + +<div class="note"> +<p>没有在 Chrome 中看出例子中的区别来,可以移步看看这篇文章 <a href="https://css-tricks.com/almanac/properties/t/text-rendering/">text-rendering</a>。</p> +</div> + +<table class="standard-table"> + <tbody> + <tr> + <th>CSS code</th> + <th>Kerning</th> + <th>Ligatures</th> + </tr> + <tr style="font: 19.9px 'DejaVu Serif',Constantia;"> + <td style="font: medium monospace;">font: 19.9px 'DejaVu Serif',Constantia;</td> + <td>LYoWAT</td> + <td>ff fi fl ffl</td> + </tr> + <tr style="font: 20px 'DejaVu Serif',Constantia;"> + <td style="font: medium monospace;">font: 20px 'DejaVu Serif',Constantia;</td> + <td>LYoWAT</td> + <td>ff fi fl ffl</td> + </tr> + <tr style="font: 3em 'DejaVu Serif',Constantia; text-rendering: optimizeSpeed;"> + <td style="font: medium monospace;">font: 3em 'DejaVu Serif',Constantia;<br> + text-rendering: optimizeSpeed;</td> + <td>LYoWAT</td> + <td>ff fi fl ffl</td> + </tr> + <tr style="font: 3em 'Dejavu Serif',Constantia; text-rendering: optimizeLegibility;"> + <td style="font: medium monospace;">font: 3em 'Dejavu Serif',Constantia;<br> + text-rendering: optimizeLegibility;</td> + <td>LYoWAT</td> + <td>ff fi fl ffl</td> + </tr> + </tbody> +</table> + +<h3 id="Gecko_注释">Gecko 注释</h3> + +<p>auto 选项的 20px 字体大小的阈值可以被 <code>browser.display.auto_quality_min_font_size</code> 值改变.</p> + +<p><code>optimizeSpeed</code> 选项在 Gecko 2.0 {{ geckoRelease("2.0") }} 上已经没有效果了,因为标准的文字渲染代码已经非常快,而且目前还没有更快的渲染方法。详见 {{ bug(595688) }} .</p> + +<h2 id="说明文档">说明文档</h2> + +<table class="standard-table"> + <thead> + <tr> + <th scope="col">Specification</th> + <th scope="col">Status</th> + <th scope="col">Comment</th> + </tr> + </thead> + <tbody> + <tr> + <td>{{ SpecName('SVG1.1', 'painting.html#TextRenderingProperty', 'text-rendering') }}</td> + <td>{{ Spec2('SVG1.1') }}</td> + <td> </td> + </tr> + </tbody> +</table> + +<div class="note"> +<p>该属性是 SVG 的属性而不是标准的 CSS 属性。但是 Gecko(Firefox) 和 Webkit(Chrome、Safari) 内核的浏览器允许该属性在 Windows、Mac OS 和 Linux 操作系统中应用于 HTML 和 XML 内容。 </p> +</div> + +<h2 id="Browser_Compatibility" name="Browser_Compatibility">浏览器兼容性</h2> + +<p>{{ CompatibilityTable() }}</p> + +<div id="compat-desktop"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari (WebKit)</th> + </tr> + <tr> + <td>Basic support for Windows and Linux</td> + <td> + <p>4.0 but the implementation known bugs on Windows and Linux which can break <a href="http://crbug.com/114719" title="http://crbug.com/114719">font substitition</a>, <a href="http://crbug.com/51973" title="http://crbug.com/51973">small-caps</a>, <a href="http://crbug.com/55458" title="http://crbug.com/55458">letter-spacing</a> or cause <a href="http://crbug.com/149548" title="http://crbug.com/149548">text to overlap</a></p> + </td> + <td><strong>3.0</strong> (1.9)</td> + <td>{{ CompatNo() }}</td> + <td>{{ CompatNo() }}</td> + <td>5.0 (532.5)</td> + </tr> + <tr> + <td>Basic support for other operating systems</td> + <td>{{ CompatNo() }}</td> + <td>{{ CompatNo() }}</td> + <td>{{ CompatNo() }}</td> + <td>{{ CompatNo() }}</td> + <td>{{ CompatNo() }}</td> + </tr> + <tr> + <td><code>auto</code></td> + <td>Chrome treats this as <code>optimizeSpeed</code>.<br> + Work is continuing on{{ Webkitbug("41363") }}</td> + <td>If the font size is 20 px or higher, Gecko browsers use <code>optimizeLegibility</code>; for smaller text, they use <code>optimizeSpeed</code>.</td> + <td>{{ CompatNo() }}</td> + <td>{{ CompatNo() }}</td> + <td>Safari treats this as <code>optimizeSpeed</code>.<br> + Work is continuing on{{ Webkitbug("41363") }}</td> + </tr> + <tr> + <td><code>geometricPrecision</code></td> + <td>13 supports true geometric precision, without rounding up or down to the nearest supported font size in the operating system.<br> + Introduced in WebKit 535.1 {{ Webkitbug("60317") }}</td> + <td>Gecko treats the value the same as <code>optimizeLegibility</code>.</td> + <td> {{ CompatNo() }}</td> + <td> {{ CompatNo() }}</td> + <td> </td> + </tr> + </tbody> +</table> +</div> + +<div id="compat-mobile"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Phone</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{ CompatUnknown() }}</td> + <td>{{ CompatUnknown() }}</td> + <td>{{ CompatUnknown() }}</td> + <td>{{ CompatUnknown() }}</td> + <td>{{ CompatUnknown() }}</td> + </tr> + </tbody> +</table> +</div> |