Css Calc Parent Width

As the screen gets larger, the value of 1vw would be added to the minimum font size of 1em. tooltip div - this is the actual element that is being hovered; the message box or the ::after selector - we'll use this to display the message in the corresponding position (left, right, top, bottom). Topic: HTML / CSS Prev|Next Answer: Set the 100% height for parents too. c, /trunk/liblwgeom/lwgeodetic_tree. (This can be changed if need be). padding-bottom-1 { padding-bottom: 1px; }. The CSS we write offers suggestions and guidelines for how a browser could lay elements out on the screen, but that is all they are… suggestions. So you end up with the element sticking out of the right margin of your design. これを防ぐことはできますか?. Fixed Dimensions. As of jQuery 1. Content "div" Height - Fill Page Height - Pure CSS Solutions If you prefer a cross-browser and responsive CSS solution to fill available height of page, here are some tips. The image is larger than its parent element. , with a font-size of 18px, an em height glyph would be 18px tall. The number of columns will be the minimum number of columns needed to show all the content across the element. @chall8908 It doesen't work. This gives you the box model you want. CSS: Animation Using CSS Transforms Tweet 1 Share 0 Tweets 40 Comments. We know that y is the font-size, and that if we want to do basic operations in CSS we need calc(). It's pulled from used 2010 Chevrolet Malibu 2010 LT 2. r=heycam ☠☠ backed out by 8fe7716a118b ☠ ☠ author. #widthExample {width: calc(75% - 30px)}. Max-width: 100%; will essentially create a one-column mobile version of the email. How to Centre a DIV Block Using CSS by Christopher Heng, thesitewizard. clac() is the computational function in css. What's sweet about flexbox is you can add padding, border, and margin to the child elements without needing to worry about a column spilling over to the next row. CSS: Animation Using CSS Transforms Tweet 1 Share 0 Tweets 40 Comments. parent { padding: 0; } [/code]While the above is not possible, there are various ways to mitigate a parent's padding with CSS: Approach 1: Create a modifier cl. HTML CSS Two 2-column tables side by side with same height and width. But it's not. CSS Setting height and width. (Oh wait, I've said that before. Join a community of over 2. The units in CSS are critical as we work with these all the time. You can apply CSS to your Pen from any stylesheet on the web. mask element is then scaled up to reveal the project featured image and the project content is loaded (more in the Events handling section). In plain CSS, we select child elements by first targeting the parent in every rule set, which is considerably redundant if we follow the “best practices” principle. Requirement #1: A scrollable view with fixed header and footer with 50px of height ( should work for multiple resolutions ). calc()width: calc(75% - 20px) Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. There are some styles in my parent theme that I would simply remove from the stylesheet if I was not using a child theme. I don't think this happens very often. For example, height: 100%; applied to an element is relative to the size of its parent. @font-face{font-family:Argent CF;src:url(/wp-content/themes/indiewire/assets/build/css/. Nested calc() functions work fine in the development environment. When using percentage (%) for width, authors must be aware that the percentage is based on the element's parent, or in other words, the width of the containing block. percentage or calc(); Canonical order: the length or. Externe Quellen. child) * (total number of. Q==n(y {@E1 ADD16rr set_gdbarch_frame_red_zone_size (D9d$X Previewgammablue: -p:pid [email protected] font-size:100% is a relative value to the font-size of the elements' parent. I've tried most types from the first iPod upwards. /* Restrict all div elements to a min-width of 100px */ div { min-width: 100px } Constrain the width of a div element using min-width and max-width attributes. This article describes the CSS3 calc() value. Q==n(y {@E1 ADD16rr set_gdbarch_frame_red_zone_size (D9d$X Previewgammablue: -p:pid [email protected] Obviously, I do not want to remove them from the parent css, but is there a way to effectively "remove" the styles using my child theme?. Fixed Dimensions. A discussion of how front-end web developers can use the calc() property in CSS to perform mathematical. I want to make a note you need to know how large the actual box is for the fixed size element. Consider this piece of code:. For example, in the following CSS code, the container is 75% of the available space minus 30 pixels. CSS Paint API (also known as “CSS Custom Paint” or “Houdini’s paint worklet”) is enabled by default starting in Chrome 65. Why doesn't the CSS calc() function work for me? The operator "-" must be surrounded by spaces: #abc {width: calc (100%-20px)}. But in a couple of years when the CSS calc() spec finally gets submitted into recommendation status by WHATWG and the W3C. calc()width: calc(75% - 20px) Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. You might notice that in this case, I chose not to use negative margin, and instead, opted for a negative value on the left property (paired with relative positioning). Elements are given a width and height using CSS, ensuring their square shape. Comment by mattiacci — June 10, 2010. (This can be changed if need be). Multiplication and Division Division. Intro to calc() 5:52 with Guil Hernandez. Lets you to inform the browser which elements and what properties will change, which allows the browser to optimize animations. What is calc()? It is a CSS construct that allows us to make calculations at runtime. Microsoft Edge doesn’t support those math operations though, so if you need to support it, just pass some static values instead, like this:. width: calc(100% - 200px); Would work as expected with the strict math option enabled. Years of obsession completely wiped away by this beautiful little CSS rule. The Sass Core Team has worked endlessly to not only keep up, but stay ahead. The height and width properties are used to set the height and width of an element. Elements are given a width and height using CSS, ensuring their square shape. These divs both have height: auto as well so the text mainly decides. The 'inherit' value is allowed on every CSS property. But a variable is a variable: a name that refers to a value, and variables in CSS helps reduce repetition and inconsistencies in your CSS, by centralizing the values definition. So simple that most of us are convinced to fully understand how they work and how to use them. Furthermore, this can greatly help out people to avoid using too much !important and reduce the overall design usability. How to Centre a DIV Block Using CSS by Christopher Heng, thesitewizard. CSS (Cascading Style Sheets) is a style sheet language that describes the presentation of web pages. If you look at the CSS box model spec, you'll observe the following: The [margin] percentage is calculated with respect to the width of the generated box's containing block. A width of value auto will have 0px margins. One of my least favorite parts about layout with CSS is the relationship of width and padding. Sass has been actively supported for over 13 years by its loving Core Team. You write CSS? Then no variables for you. All dimensions in React Native are unitless, and represent density-independent pixels. The site was built and is maintained by Alexis Deveria, with occasional updates provided by the web development community. A block element’s width typically covers its container’s when it is auto or 100% and hence a margin auto will be computed to 0px in such a case. by Rémi Parmentier The Fab Four technique to create Responsive Emails without Media Queries I think I found a new way to create responsive emails, without media queries. CSS3 Click Chart. When using percentage (%) for width, authors must be aware that the percentage is based on the element's parent, or in other words, the width of the containing block. We know that y is the font-size, and that if we want to do basic operations in CSS we need calc(). See the Pen CSS Calc Feature by Josh Johnson (@secondfret) on CodePen. There are many ways you can use calc() in your projects. Vous pourrez tester vos réponses sur le simulateur fourni plus bas. There are too many variables to consider. calc() & width & min-width & max-width, aka The Fab Four. In older browsers you will see either no effects, or the transforms taking place without any animation. If the element you want to be “sticky” is currently position: relative; and responsive to the container (width: 100%) and then you swap to position: fixed, you’ll get an element that is 100% of the window or at width auto depending on your CSS. In the case of Sass, we use that syntax mostly when inside of a CSS function. The em unit refers to the font size of the parent element. In this article we will see how to create a dynamic and responsive container with HTML / CSS. Define some constraints. CSS calc() function. outerWidth() can be used on table elements, it may give unexpected results on tables using the. There are some details that apply when using customScroll on elements with size set by css flex. Six Questions to Understand the CSS Box Model. CSS is designed to enable the separation of presentation and content, including layout, colors, and fonts. This CSS tutorial explains how to use the CSS selector called :nth-child with syntax and examples. So for line-height and most other properties, it's 1 time the element's computed font-size. Just like with calc(a * b) in standard CSS. child) * (total number of. half as there will be no need for it in a future update, as well as removing margin-left and margin-top from. So you end up with the element sticking out of the right margin of your design. A script inside the iframe informs the parent that the size of the content has changed. Based on CSS Flexbox module, Gridlex is a simple CSS grid system to quickly create modern layouts and submodules. I had made a note in the CSS that it was just to show that floats are. The amount we want to "pull" to the left and right is half the width of the browser window plus half the width of the parent. Site stylesheets often feature a mixture of units, all interacting with each other to create a design. CSS variables cascades from parent to child views. Table of Content Introduction Often times when developing CSS for a WordPress child theme or just when working with someone elses stylesheets in general, it can be desirable to "breakout" of the parent element and draw a full width element that stretches the entire width of the page. Save Your Code. el { width: calc(100% - 50% / 3); }. calc() is particularly useful for calculating relative values, such as relative widths and heights. This value is relative to the viewport width, and so 10vw is 10 percent of the width of the viewport. 03125x + 10px ); Not too bad. ` inherits our max-width styles, and prevents the image from extending beyond the content column. FREE next day delivery available, free collection in 5 minutes. The default width of a child element is ‘auto’, not ‘inherit’. It offers a means of dynamically positioning elements at runtime and promises to change the way web developers approach layout design from this point onwards. Div (short for division) divides the content into individual sections. width() instead. Here is an example for an HTML structure before using customScroll:. @eyelidlessness: Yup - and in box model choice and this will be excellent. During a recent project I came upon an interesting CSS problem. This can be remedied by using the CSS calc function to subtract 2px from each div. In LESS CSS, we can simplify the rule sets by nesting the child elements inside the parents, as follows;. Use the var() function to elicit the pre-defined size variables that of the parent element. This site uses cookies for analytics, personalized content and ads. In the last lesson we discovered the limitations of using pixels, and I showed an example of using a percentage to make the container relative to the size of the viewport. auto will also not work on a typical block element if it doesn’t have a width. the parent. Umrechnen von Pixel zu EM / % / Points; Type Scale Übersicht über das Zusammenwirken von. Here the width of the div will be 50% of the width of it's parent div + 30px extra. child) * (total number of. CSS variables get even more powerful, when we combine them with the calc() function. One of the most confusing aspects of CSS styling is the application of the font. Home / Blog / CSS / 6 Methods For Vertical Centering With CSS. It allows developers to have the benefits of both absolute units and percentages in CSS positioning. This means it will stay as wide as you specified and not react to resizing the window or viewing the page on different-sized screens. -2 post processed context, before the compiled css output is returned-1 preparation context, before the compiler. Hey! Today we are going to go over CSS variables. But sadly, CSS has lacked support for native variables from the very beginning. Used on parent to create the flex container. Using a subtle mix of round and sharp elements, the theme is fierce, yet elegant. For instance, if you needed a 7-column float-based grid (don't ask), it's cleaner and more intuitive:. height() will always return the content height, regardless of the value of the CSS box-sizing property. vh stands for viewport height and vw is for viewport width. Then we'll discuss layout, painting, and composition. The em unit refers to the font size of the parent element. For example, the pixel unit represents CSS pixels and not physical pixels. Manage your showings wherever you are! Take CSS on the road with our CSS Mobile App available for Android & Apple. The parent on receiving such a message updates the CSS width and height of the element, thus preventing scrollbars from coming up. In CSS there are a large number of units to choose from, but we tend to fall into the habit of using a particular one because that is how we learned CSS, or we've just gotten used to working with it. (Assuming the parent is centered. For example, in the following CSS code, the container is 75% of the available space minus 30 pixels. If you change the calc value to 50vw - 1 , then the width seems to correctly render at about 50% of the screen width. CSS calc() is used for calculations inside the stylesheet. CSS pro tips: responsive font-sizes and when to use which units. Being able to do math in CSS is a very useful feature, especially when creating complex layouts. Our wide width image spans the 100% of its parent container, plus an extra 20 viewport width units. ` inherits our max-width styles, and prevents the image from extending beyond the content column. This article describes the CSS3 calc() value. css` - remove the conditional comments - remove any CSS rule that use selectors with `. This means the browser decides based on what that child element is / contains. Simple Way To Set The Height/Width Dynamically Using CSS While working on the HTML designs, I came across some of the design issues that I would like to share them along with the solutions. Re: css Calc() problem by David Scotson - Thursday, 16 August 2018, 2:00 PM There's some workarounds listed in the bug tracker commemts for MDL-61879 and it seems the issue is now fixed in the CSS parser library that Moodle uses, so upgrading that is probably a solution if you have that kind of server access. The CSS calc() function is not even a CSS property that you animate, it is a computed equation value that gets parsed by the CSS parser in the browser like @Visual-Q advised above. This means it will stay as wide as you specified and not react to resizing the window or viewing the page on different-sized screens. New here? Start with our free trials. Don't get me wrong i love using CSS calc(), since CSS is my first love. You can't build anything without using these so we must know the units properly. After more testing, it turns out the 1em in a calc function equals 1em for the current property and the current element. When calc() is used for controlling text size, be sure that one of the values includes a relative length unit, for example: h1 { font-size: calc(1. Join Ray Villalobos for an in-depth discussion in this video Use calc() function for simple calculations in CSS, part of Building a Responsive Single-Page Design with PostCSS. Preprocessors like Sass sell the use of variables as a big add-on. Compatibilité La compatibilité de cette fonction est encore un peu limitée aux navigateurs récents. small in place of any. Our wide width image spans the 100% of its parent container, plus an extra 20 viewport width units. It has four simple math operators: add (+), subtract (-), multiply (*), and divide (/). One CSS selector has width : auto ;. I also have a…. Let me show you. Make Iframe to fit 100% of container's remaining height. Returns the width of the element, including left and right padding, border, and optionally margin, in pixels. However, if you haven't set the font size anywhere on the page, then it is the browser default, which. You can use calc() anywhere a CSS length or number can be used. Content "div" Height - Fill Page Height - Pure CSS Solutions If you prefer a cross-browser and responsive CSS solution to fill available height of page, here are some tips. child) * (total number of. This information can then be used by the browser in optimizing the rendering. We could use the width of the browser window in our CSS math. Set of keywords that are interpreted as relative to the font size of the parent object. This method is not applicable to window and document objects; for these, use. So simple that most of us are convinced to fully understand how they work and how to use them. use(true) or disabled after that through stylis. The CSS calc() property will takes care of the proper width calculation based on. In the world of CSS, the. There are many hidden gems in the modular CSS3 specifications. The number of columns will be the minimum number of columns needed to show all the content across the element. el { width: calc(100% - 50% / 3); }. Cascading Style Sheets define a webpage element's appearance by hooking into the attributes that you apply to that element. Less runs on both the server-side (with Node. A pixel is a physical dot on your monitor’s screen which size is always the same …. Being a base, this theme is meant to be extended, mainly by adding colors. However, if you haven't set the font size anywhere on the page, then it is the browser default, which. Accessibility concerns. height() will always return the content height, regardless of the value of the CSS box-sizing property. NativeScript supports CSS variables (also known as custom properties or cascading variables) for reusable values through the CSS used in the app. Though we could use CSS to force the size, why have them if their not being used — less code is beautiful code. Animatable as a length, percentage, or calc(). The desired effect is that the 3 lists would be at 3 different scales but as demo'd on codepen all 3 lists are the same scale. but it doesn't feel at all intuitive to have the CSS width and height of an element affected by its padding and borders. Let me show you. eot);src:url(/wp-content/themes/indiewire/assets. calc() is particularly useful for calculating relative values, such as relative widths and heights. We’re also working on adding calc() for angle and frequency properties soon. - You are bidding on a used 2008-2012 Chevrolet Malibu Hose 25946498 OEM - Has been used previously. width defined as a percentage + absolute length in shrink-to-fit containers is to treat the entire calc expression as zero when determining the parent container's width, but then evaluate the calc for the children normally after the parent width is set (so the child elements now overflow the too-small parent). In LESS CSS, we can simplify the rule sets by nesting the child elements inside the parents, as follows;. New here? Start with our free trials. Inside a CSS Rule there is a set of CSS. width() will always return the content width, regardless of the value of the CSS box-sizing property. font-size:100% is a relative value to the font-size of the elements' parent. Users can author their own stylesheets that tailor our content to their needs. Essentially, 50% of the parent's height - 50% of the children's height, done. Then we will see better behavior cross browser. Bug 1140623 - Correct mochitest failures that occur when the layout. One CSS selector has width : auto ;. Setting Font Size with EM. Line-height and vertical-align are simple CSS properties. How we can create a flat to do list app with minimal design? Solution: See this Minimal To Do App Using jQuery and CSS, To-Do List Program. Using CSS variables. /fonts/ArgentCF-DemiBold. Fixed Dimensions. My understanding of specifying font-size in an absolute length (like px) was that the font would be scaled to match that length, e. The usual suspects are playing catch-up (IE9 is nearly there, but ignores calc() when display:table is used). All elements have the CSS property position: absolute and CSS for corresponding top and left values are generated with SCSS as follows:. Diego Díaz. This causes problems in responsive layouts when the screen size is smaller than the width of the iframe. The solution involves the CSS calc() function and the three width, min-width and max-width properties. This site uses cookies for analytics, personalized content and ads. Keeping those attributes forces the content to stay at that size regardless of the screen size. One of the most versatile is undoubtedly the calc() function. For example, font: 24/32px defines a font with size of 25px and line-height of 32px. These attributes can be either an ID or a class and, like all attributes, they add helpful information to the elements that they are attached to. And I know what you are thinking, "Inlining CSS is bad!!!", but this was the least ugly solution. Join Ray Villalobos for an in-depth discussion in this video Use calc() function for simple calculations in CSS, part of Building a Responsive Single-Page Design with PostCSS. It allows developers to have the benefits of both absolute units and percentages in CSS positioning. You've seen so many implementations, but is there a best way? Comment your way to stardom with your best implementation. Calc() can also eliminate the need for “inner wrapper”-type elements (as in, for instance, 100% width background with fixed width content) by applying padding: 0 calc(50% - sitewidth / 2) to the parent element. and also the width and height of the parent div cannot be removed. min-width: calc (50% - 1rem);} It's important to note the negative margin on the intermediary wrapper makes that element 1rem wider than its parent. Note: Since the newline context is intended for source-map plugins by default stylis will not execute plugins in this context unless enabled, this can be done through stylis. ) So, you've heard about px, pt, em, and the fancy new rem. For instance, if you needed a 7-column float-based grid (don't ask), it's cleaner and more intuitive:. Firstly, I'm guessing that as you are setting the headers of the tables as width:200px; that the width of the two columns are 100px. In this post you will find out how to make a HTML element fills the height of any screen with CSS There are many ways to make the height of your HTML elements to be exactly as the height of the browser screen, regardless of the screen resolution, browser, device, etc. “box-sizing: border-box” in CSS3 will make this less useful, since padding and margin will be included in the width when that style is applied. One CSS selector has width : auto ;. The CSS :nth-child selector allows you to target an element that is the nth child element within its parent. Even for height values, I may have used a 100% value for a hack, but nothing else. By using max-width: 100%, the width of the image won’t exceed the width of its parent. If your parent is set at 480px - as demonstrated by our demo - then the percentage is based on that value. You might also like: Pinterest Like Glowing Input Fields with CSS3; Pinterest-Like Dynamic & Responsive Grid Layout Plugin - BlocksIt. See the Overview for a quick summary of Less. One for how to create CSS variables and one for how to use CSS variables. Over and over again, the industry is choosing Sass as the premier CSS. A script inside the iframe informs the parent that the size of the content has changed. Farewell grid systems. The fit-content() CSS function clamps a given size to an available size according to the formula min(maximum size, max(minimum size, argument)). This is the case, for example, when inside a parent div of fixed size I want to center vertically a child div with a variable number of rows of images, and sometimes there is 1 row, and other times it could be 2 or 3. AjaxService=function(n,t){"use strict";var i,r,u=null;return r=function(){return u=function(){var r=this,i=[],u={url. Microsoft Edge doesn’t support those math operations though, so if you need to support it, just pass some static values instead, like this:. Users can change the font size in their browser or their operating system. Applying a width of 100vw alone doesn’t do the trick because the elements still start on the left edge of the parent container. Schriftgröße anpassen mit vw min-font-size, max-font-size gibt es zwar nicht, aber mit vw und CSS calc gehts dann trotzdem. So you end up with the element sticking out of the right margin of your design. New here? Start with our free trials. Here is a JSBin illustrating the problem. Join Ray Villalobos for an in-depth discussion in this video Use calc() function for simple calculations in CSS, part of Building a Responsive Single-Page Design with PostCSS. And you know what? It’s a pretty darn good reason. It looks like it's forcing width: calc(50% - ( 0. You might notice that in this case, I chose not to use negative margin, and instead, opted for a negative value on the left property (paired with relative positioning). This gives you the box model you want. Go dancing on the Z-axis this party season!. It is hard to align something to the bottom of the parent box. Now that we’ve computed everything on paper, we need to move all this stuff to the stylesheet. Well the web is. AjaxService=function(n,t){"use strict";var i,r,u=null;return r=function(){return u=function(){var r=this,i=[],u={url. The CSS we write offers suggestions and guidelines for how a browser could lay elements out on the screen, but that is all they are… suggestions. You can use it to calculate values using basic math operations ( addition , substration, multiplication, division) Here is a practical example that can be used in real projects. CSS has become more efficient and closer to the features we’d normally implement using JavaScript and other web programming languages. CSS column-rule-width Property The column-rule-width property specifies the width of the rule Inherits this property from its parent element. When the user selects a project, the class. project-view (added to the wrapper. How we can create a flat to do list app with minimal design? Solution: See this Minimal To Do App Using jQuery and CSS, To-Do List Program. The CSS calc() property will takes care of the proper width calculation based on. A component's height and width determine its size on the screen. Again, without seeing your code I cannot be sure, but this would be my guess. , with a font-size of 18px, an em height glyph would be 18px tall. >> sudo lshw -C cpu|grep width * Show current pathname in title of terminal >> export view - * Go to parent directory of filename edited in last command >> cd. Instead of declaring, for example, static pixel values for an element's width, we can use calc() to specify that the width be the result of the addition of two or more numeric values. CSS3 Menu v1. Well organized and easy to understand Web building tutorials with lots of examples of how to use HTML, CSS, JavaScript, SQL, PHP, Python, Bootstrap, Java and XML. Unlike margin properties, values for padding values cannot be negative. You can see this below ():. We all know well our favorite unit which is the pixel. いいえ、あなたがすることはできません。 max()とmin()はCSS3の値とユニットから削除されました。しかし、それらはCSS4値とユニットに再導入されるかもしれません。 現在のところ仕様はなく、 calc()仕様ではどちらかがcalc()関数内で有効であることは記述されていません。. resize according to pixel size of device. There are many hidden gems in the modular CSS3 specifications. You can set the width based on the vw (viewport width). I also have a…. To set the height of a DIV in CSS, you can simply use the "height: xx" attribute, where xx is the length, in pixels. Though we could use CSS to force the size, why have them if their not being used — less code is beautiful code. ) So, so our parent is 500px wide:. outerWidth() can be used on table elements, it may give unexpected results on tables using the. What is calc()? It is a CSS construct that allows us to make calculations at runtime. Element Queries. The CSS calc routine bucks that trend, providing developers an ounce of programming ability within CSS. - You are bidding on a used 2008-2012 Chevrolet Malibu Hose 25946498 OEM - Has been used previously. It allows developers to have the benefits of both absolute units and percentages in CSS positioning. The Browser use the static CSS code to compute the value for the CSS properties. el { width: calc(100% - 50% / 3); }. CSS calc() is used for calculations inside the stylesheet. Content "div" Height - Fill Page Height - Pure CSS Solutions If you prefer a cross-browser and responsive CSS solution to fill available height of page, here are some tips. But in our linear function, x represents the viewport width, which can be expressed in CSS as 100vw. These apply to font size, padding, margin, height, max-width, positioning, border-radius, etc. 这篇文章主要为大家详细介绍了css实现等分布局的4种方式,等分布局是指子元素平均分配父元素宽度的布局方式,本文将介绍实现等分布局的4种方式,感兴趣的小伙伴们可以参考一下. Table of Content Introduction Often times when developing CSS for a WordPress child theme or just when working with someone elses stylesheets in general, it can be desirable to "breakout" of the parent element and draw a full width element that stretches the entire width of the page. Manage your showings wherever you are! Take CSS on the road with our CSS Mobile App available for Android & Apple. Designers and developers need to understand the role of each CSS measurement system. Six Questions to Understand the CSS Box Model. Animatable as a length, percentage, or calc(). Perhaps you are thinking rem units?. A script inside the iframe informs the parent that the size of the content has changed. font-size:100%. All solutions are CSS only and the pros and cons are outlined too. Learn how font-size works in CSS. calc()对大家来说,或许很陌生,不太会相信calc()是css中的部分。但它却是就是css3的一部分,下面这篇文章主要给大家介绍了关于css3中calc函数的相关资料,文中通过示例代.