linebreakmeasurer.html
来自「API資料大全」· HTML 代码 · 共 649 行 · 第 1/3 页
HTML
649 行
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Frameset//EN""http://www.w3.org/TR/REC-html40/frameset.dtd"><!--NewPage--><HTML><HEAD><!-- Generated by javadoc on Thu Apr 27 23:33:33 PDT 2000 --><TITLE>Java 2 Platform SE v1.3: Class LineBreakMeasurer</TITLE><LINK REL ="stylesheet" TYPE="text/css" HREF="../../../stylesheet.css" TITLE="Style"></HEAD><BODY BGCOLOR="white"><!-- ========== START OF NAVBAR ========== --><A NAME="navbar_top"><!-- --></A><TABLE BORDER="0" WIDTH="100%" CELLPADDING="1" CELLSPACING="0"><TR><TD COLSPAN=2 BGCOLOR="#EEEEFF" CLASS="NavBarCell1"><A NAME="navbar_top_firstrow"><!-- --></A><TABLE BORDER="0" CELLPADDING="0" CELLSPACING="3"> <TR ALIGN="center" VALIGN="top"> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../overview-summary.html"><FONT CLASS="NavBarFont1"><B>Overview</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-summary.html"><FONT CLASS="NavBarFont1"><B>Package</B></FONT></A> </TD> <TD BGCOLOR="#FFFFFF" CLASS="NavBarCell1Rev"> <FONT CLASS="NavBarFont1Rev"><B>Class</B></FONT> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="class-use/LineBreakMeasurer.html"><FONT CLASS="NavBarFont1"><B>Use</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="package-tree.html"><FONT CLASS="NavBarFont1"><B>Tree</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../deprecated-list.html"><FONT CLASS="NavBarFont1"><B>Deprecated</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../index-files/index-1.html"><FONT CLASS="NavBarFont1"><B>Index</B></FONT></A> </TD> <TD BGCOLOR="#EEEEFF" CLASS="NavBarCell1"> <A HREF="../../../help-doc.html"><FONT CLASS="NavBarFont1"><B>Help</B></FONT></A> </TD> </TR></TABLE></TD><TD ALIGN="right" VALIGN="top" ROWSPAN=3><EM><b>Java<sup><font size=-2>TM</font></sup> 2 Platform<br>Std. Ed. v1.3</b></EM></TD></TR><TR><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../../java/awt/font/ImageGraphicAttribute.html"><B>PREV CLASS</B></A> <A HREF="../../../java/awt/font/LineMetrics.html"><B>NEXT CLASS</B></A></FONT></TD><TD BGCOLOR="white" CLASS="NavBarCell2"><FONT SIZE="-2"> <A HREF="../../../index.html" TARGET="_top"><B>FRAMES</B></A> <A HREF="LineBreakMeasurer.html" TARGET="_top"><B>NO FRAMES</B></A></FONT></TD></TR><TR><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2"> SUMMARY: INNER | FIELD | <A HREF="#constructor_summary">CONSTR</A> | <A HREF="#method_summary">METHOD</A></FONT></TD><TD VALIGN="top" CLASS="NavBarCell3"><FONT SIZE="-2">DETAIL: FIELD | <A HREF="#constructor_detail">CONSTR</A> | <A HREF="#method_detail">METHOD</A></FONT></TD></TR></TABLE><!-- =========== END OF NAVBAR =========== --><HR><!-- ======== START OF CLASS DATA ======== --><H2><FONT SIZE="-1">java.awt.font</FONT><BR>Class LineBreakMeasurer</H2><PRE><A HREF="../../../java/lang/Object.html">java.lang.Object</A> | +--<B>java.awt.font.LineBreakMeasurer</B></PRE><HR><DL><DT>public final class <B>LineBreakMeasurer</B><DT>extends <A HREF="../../../java/lang/Object.html">Object</A></DL><P>The <code>LineBreakMeasurer</code> class allows styled text to be broken into lines (or segments) that fit within a particular visual advance. This is useful for clients who wish to display a paragraph of text that fits within a specific width, called the <b>wrapping width</b>. <p> <code>LineBreakMeasurer</code> is constructed with an iterator over styled text. The iterator's range should be a single paragraph in the text. <code>LineBreakMeasurer</code> maintains a position in the text for the start of the next text segment. Initially, this position is the start of text. Paragraphs are assigned an overall direction (either left-to-right or right-to-left) according to the bidirectional formatting rules. All segments obtained from a paragraph have the same direction as the paragraph. <p> Segments of text are obtained by calling the method <code>nextLayout</code>, which returns a <A HREF="../../../java/awt/font/TextLayout.html"><CODE>TextLayout</CODE></A> representing the text that fits within the wrapping width. The <code>nextLayout</code> method moves the current position to the end of the layout returned from <code>nextLayout</code>. <p> <code>LineBreakMeasurer</code> implements the most commonly used line-breaking policy: Every word that fits within the wrapping width is placed on the line. If the first word does not fit, then all of the characters that fit within the wrapping width are placed on the line. At least one character is placed on each line. <p> The <code>TextLayout</code> instances returned by <code>LineBreakMeasurer</code> treat tabs like 0-width spaces. Clients who wish to obtain tab-delimited segments for positioning should use the overload of <code>nextLayout</code> which takes a limiting offset in the text. The limiting offset should be the first character after the tab. The <code>TextLayout</code> objects returned from this method end at the limit provided (or before, if the text between the current position and the limit won't fit entirely within the wrapping width). <p> Clients who are laying out tab-delimited text need a slightly different line-breaking policy after the first segment has been placed on a line. Instead of fitting partial words in the remaining space, they should place words which don't fit in the remaining space entirely on the next line. This change of policy can be requested in the overload of <code>nextLayout</code> which takes a <code>boolean</code> parameter. If this parameter is <code>true</code>, <code>nextLayout</code> returns <code>null</code> if the first word won't fit in the given space. See the tab sample below. <p> In general, if the text used to construct the <code>LineBreakMeasurer</code> changes, a new <code>LineBreakMeasurer</code> must be constructed to reflect the change. (The old <code>LineBreakMeasurer</code> continues to function properly, but it won't be aware of the text change.) Nevertheless, if the text change is the insertion or deletion of a single character, an existing <code>LineBreakMeasurer</code> can be 'updated' by calling <code>insertChar</code> or <code>deleteChar</code>. Updating an existing <code>LineBreakMeasurer</code> is much faster than creating a new one. Clients who modify text based on user typing should take advantage of these methods. <p> <strong>Examples</strong>:<p> Rendering a paragraph in a component <blockquote> <pre> public void paint(Graphics graphics) { Point2D pen = new Point2D(10, 20); // let styledText be an AttributedCharacterIterator containing at least // one character LineBreakMeasurer measurer = new LineBreakMeasurer(styledText); float wrappingWidth = getSize().width - 15; while (measurer.getPosition() < fStyledText.length()) { TextLayout layout = measurer.nextLayout(wrappingWidth); pen.y += (layout.getAscent()); float dx = layout.isLeftToRight() ? 0 : (wrappingWidth - layout.getAdvance()); layout.draw(graphics, pen.x + dx, pen.y); pen.y += layout.getDescent() + layout.getLeading(); } } </pre> </blockquote> <p> Rendering text with tabs. For simplicity, the overall text direction is assumed to be left-to-right <blockquote> <pre> public void paint(Graphics graphics) { float leftMargin = 10, rightMargin = 310; float[] tabStops = { 100, 250 }; // assume styledText is an AttributedCharacterIterator, and the number // of tabs in styledText is tabCount int[] tabLocations = new int[tabCount+1]; int i = 0; for (char c = styledText.first(); c != styledText.DONE; c = styledText.next()) { if (c == '\t') { tabLocations[i++] = styledText.getIndex(); } } tabLocations[tabCount] = styledText.getEndIndex() - 1; // Now tabLocations has an entry for every tab's offset in // the text. For convenience, the last entry is tabLocations // is the offset of the last character in the text. LineBreakMeasurer measurer = new LineBreakMeasurer(styledText); int currentTab = 0; float verticalPos = 20; while (measurer.getPosition() < styledText.getEndIndex()) { // Lay out and draw each line. All segments on a line // must be computed before any drawing can occur, since // we must know the largest ascent on the line. // TextLayouts are computed and stored in a Vector; // their horizontal positions are stored in a parallel // Vector. // lineContainsText is true after first segment is drawn boolean lineContainsText = false; boolean lineComplete = false; float maxAscent = 0, maxDescent = 0; float horizontalPos = leftMargin; Vector layouts = new Vector(1); Vector penPositions = new Vector(1); while (!lineComplete) { float wrappingWidth = rightMargin - horizontalPos; TextLayout layout = measurer.nextLayout(wrappingWidth, tabLocations[currentTab]+1, lineContainsText); // layout can be null if lineContainsText is true⌨️ 快捷键说明
复制代码Ctrl + C
搜索代码Ctrl + F
全屏模式F11
增大字号Ctrl + =
减小字号Ctrl + -
显示快捷键?