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12.1 概述

12.1 General

为了触发事件 E（进入）、X（退出）、D（按下）和 U（释放）的目的，术语鼠标指的是具有以下特性的通用指向设备：

  • 有一个选择按钮，该按钮可以被按下、按住和释放。如果有多个鼠标按键，选择按钮通常是左键。
  • 有位置的概念——即指示设备在屏幕上的指向位置。位置通常由屏幕光标表示。
  • 有焦点的概念——即文档中当前与用户进行交互的元素。在许多系统中，该元素由闪烁的光标、焦点矩形或颜色变化来表示。

本条款描述了 PDF 的功能，这些功能允许用户使用鼠标和键盘（多媒体功能除外，多媒体功能见13“多媒体功能”）在屏幕上与文档进行交互：

For purposes of the trigger events E (enter), X (exit), D (down), and U (up), the term mouse denotes a generic pointing device with the following characteristics:

  • A selection button that can be pressed, held down, and released. If there is more than one mouse button, the selection button is typically the left button.
  • A notion of location—that is, an indication of where on the screen the device is pointing. Location is typically denoted by a screen cursor.
  • A notion of focus—that is, which element in the document is currently interacting with the with the user. In many systems, this element is denoted by a blinking caret, a focus rectangle, or a colour change.

This clause describes the PDF features that allow a user to interact with a document on the screen, using the mouse and keyboard (with the exception of multimedia features, which are described in 13, “Multimedia Features”):