(施工中)所见即所得

  本文介紹的是一般意義上的所見即所得。關於維基百科的所見即所得編輯器，請參見Wikipedia:可視化編輯器。

現在，所見即所得技術通常是文書處理器所必需的。

所見即所得（英語：What You See Is What You Get，縮寫：WYSIWYG） 是一種計算機方面的概念，它讓用戶編輯時可以在屏幕上直接預覽成品的效果。所見即所得的編輯器中的內容（如文字和圖形）在編輯期間屏幕上顯示的形式和作為成品打印或演示時的相似。其中編輯的內容可以是用以列印的文檔、網頁、表格或演示文稿。

含義

左邊的程序使用所見即所得的編輯器製作一篇Lorem Ipsum文檔，右邊的文檔則用到了LaTeX代碼。右邊的文檔編譯後會產生一個和左邊看起來很相似的文件。編譯格式化的代碼不是所見即所得的過程。

所見即所得意味着這種軟件包括了一種用戶界面，用戶編輯時看見的和文檔處理好後的差異很小。用戶能在視圖中直接編輯文本、圖形或文檔中的其他元素。一般情況下，用戶不必去記布局指令就能直接操作設置文件排版。更具體的說，它的意義取決於使用場景，比如：

• 在幻燈片裡、夾雜圖表等的複雜文檔中或是網頁上，所見即所得指的是最終使用時的效果就顯示在編輯者的界面上。（這種情況要求不高，比如隨着打印機和軟件的不同，顯示和打印的效果會有差異。）
• 在文字處理和桌面排版方面，所見即所得的意思是使用特定打印機，顯示時就能模擬出印刷後的字體、換行、分頁的樣式。故而，比如一份500頁文檔上，第一頁的一個引用可以引向300頁之後，不用擔心頁碼出差錯。
• 另外，所見即所得也用來描述類似的操作立體化學、計算機輔助設計和三維計算機圖形中3D模型的界面。

有些情況下，避免用戶「所見」和「所得」間差異是次要的，通常程序會提供多種所見即所得模式顯示不同的技術細節，如編輯時顯示換行符、輔助線等，另外提供一個預覽模式等。

History

File:Xerox 8010 compound document.jpg

Compound document displayed on Xerox 8010 Star system

Before the adoption of WYSIWYG techniques, text appeared in editors using the system standard typeface and style with little indication of layout (margins, spacing etc.). Users were required to enter special non-printing control codes (now referred to as markup code tags) to indicate that some text should be in boldface, italics, or a different typeface or size. In this environment there was very little distinction between text editors and word processors.

These applications typically used an arbitrary markup language to define the codes/tags. Each program had its own special way to format a document, and it was a difficult and time consuming process to change from one word processor to another.

The use of markup tags and codes remains popular today in some applications due to their ability to store complex formatting information. When the tags are made visible in the editor, however, they occupy space in the unformatted text and so disrupt the desired layout and flow.

Bravo, a document preparation program for the Alto produced at Xerox PARC by Butler Lampson, Charles Simonyi and colleagues in 1974, is generally considered the first program to incorporate WYSIWYG technology, displaying text with formatting (e.g. with justification, fonts, and proportional spacing of characters). The Alto monitor (72 PPI) was designed so that one full page of text could be seen and then printed on the first laser printers. When the text was laid out on the screen, 72 PPI font metric files were used, but when printed 300 PPI files were used—thus one would occasionally find characters and words slightly off, a problem that continues to this day. (72 PPI came from a new measure of 72 "PostScript points" per inch. Prior to this, the standard measure of 72.27 points per inch was used in typeface design, graphic design, typesetting and printing.)

Bravo was never released commercially, but the software eventually included in the Xerox Star can be seen as a direct descendant of it.

In parallel with but independent of the work at Xerox PARC, Hewlett Packard developed and released in late 1978 the first commercial WYSIWYG software application for producing overhead slides or what today are called presentation graphics. The first release, named BRUNO (after an HP sales training puppet), ran on the HP 1000 minicomputer taking advantage of HP's first bitmapped computer terminal the HP 2640. BRUNO was then ported to the HP-3000 and re-released as "HP Draw".

By 1981 MicroPro advertised that its WordStar word processor had WYSIWYG, and in 1983 the Weekly Reader advertised its Stickybear educational software with the slogan "What You See Is What You Get", with photographs of its Apple II graphics. In the 1970s and early 1980s, however, most popular home computers lacked the sophisticated graphics capabilities necessary to display WYSIWYG documents, meaning that such applications were usually confined to limited-purpose, high-end workstations (such as the IBM Displaywriter System) that were too expensive for the general public to afford. Towards the mid-1980s, however, things began to change. Improving technology allowed the production of cheaper bitmapped displays, and WYSIWYG software started to appear for more popular computers, including LisaWrite for the Apple Lisa, released in 1983, and MacWrite for the Apple Macintosh, released in 1984.

The Apple Macintosh system was originally designed so that the screen resolution and the resolution of the ImageWriter dot-matrix printers sold by Apple were easily scaled: 72 PPI for the screen and 144 DPI for the printers. Thus, the scale and dimensions of the on-screen display in programs such as MacWrite and MacPaint were easily translated to the printed output—if the paper were held up to the screen, the printed image would be the same size as the on screen image, but at a higher resolution. As the ImageWriter was the only model of printer physically compatible with the Macintosh printer port, this created an effective, closed system. Later, when Macs using external displays became available, the resolution was fixed to the size of the screen to achieve 72 DPI. These resolutions often differed from the VGA-standard resolutions common in the PC world at the time. Thus, while a Macintosh 14" monitor had the same 640x480 resolution as a PC, a 16" screen would be fixed at 832x624 rather than the 800x600 resolution used by PCs. With the introduction of third-party dot-matrix printers as well as laser printers and multisync monitors, resolutions deviated from even multiples of the screen resolution, making true WYSIWYG harder to achieve.

In 2012, Wikipedia offered a WYSIWYG editor called VisualEditor, which allowed edits to Wikipedia to be performed without seeing the page source.

Etymology

The phrase "What you see is what you get", from which the acronym derives, was a catchphrase popularized by Flip Wilson's drag persona Geraldine, first appearing in September 1969, then regularly in the early '70s on The Flip Wilson Show. The phrase was a statement demanding acceptance of Geraldine's entire personality and appearance.

As it relates to computing, there are multiple claims to first use of the phrase:

• In mid-1975, John W. Seybold, the founder of Seybold Publications, and researchers at PARC, incorporated Gypsy software into Bravo to create Bravo 3, which allowed text to be printed as displayed. Charles Simonyi and the other engineers appropriated Flip Wilson's popular phrase around that time.
• The phrase was coined in 1982 by Larry Sinclair, an engineer at Information International, Inc. ("Triple I") to express the idea that what the user sees on the screen is what the user gets on the printer while using the "page layout system", a pre-press typesetting system first shown at ANPS in Las Vegas.

Problems of implementation

Because designers of WYSIWYG applications typically have to account for a variety of different output devices, each of which has different capabilities, there are a number of problems that must be solved in each implementation. These can be seen as tradeoffs between multiple design goals, and hence applications that use different solutions may be suitable for different purposes.

Typically, the design goals of a WYSIWYG application may include the following:

• Provide high-quality printed output on a particular printer
• Provide high-quality printed output on a variety of printers
• Provide high-quality on-screen output
• Allow the user to visualize what the document will look like when printed

It is not usually possible to achieve all of these goals at once.

The major problem to be overcome is that of varying output resolution. As of 2007, monitors typically have a resolution of between 92 and 125 pixels per inch. Printers generally have resolutions between 240 and 1440 pixels per inch; in some printers the horizontal resolution is different from the vertical. This becomes a problem when trying to lay out text; because older output technologies require the spacing between characters to be a whole number of pixels, rounding errors will cause the same text to require different amounts of space in different resolutions.

Solutions to this include the following:

• Always laying out the text using a resolution higher than the user is likely to use in practice. This can result in poor quality output for lower resolution devices (although techniques such as spatial anti-aliasing may help mitigate this), but provides a fixed layout, allowing easy user visualisation. This is the method used by Adobe Acrobat.
• Laying out the text at the resolution of the printer on which the document will be printed. This can result in low quality on-screen output, and the layout may sometimes change if the document is printed on a different printer (although this problem occurs less frequently with higher resolution printers, as rounding errors are smaller). This is the method used by Microsoft Word.
• Laying out the text at the resolution of a specific printer (in most cases the default one) on which the document will be printed using the same font information and kerning. The character positions and number of characters in a line are exactly similar to the printed document.
• Laying out the text at the resolution for the output device to which it will be sent. This often results in changes in layout between the on-screen display and printed output, so is rarely used. It is common in web page designing tools that claim to be WYSIWYG, however.

Other problems that have been faced in the past include differences in the fonts used by the printer and the on-screen display (largely solved by the use of downloadable font technologies like TrueType) and differences in color profiles between devices (mostly solved by printer drivers with good color model conversion software).

See also

•  (纯文本) 
• 無表格網頁設計
• HTML編輯器