android中的textview控件默认是做不到两端对齐的，都是左对齐。可能的原因是安卓默认数字、字母不能为第一行以后每行的开头字符，因为数字、字母为半角字符，还有就是文字中的英文字符占用1个字节，而一个汉字占用两个字节。下面我就介绍下实现两端对齐的原理：
- 1、测量一个中文汉字所占用的宽度
- 2、根据textview的宽度和一个汉字所占用的宽度以及字符之间的间隔计算出总行数。
- 3、根据padding和margin以及行高计算出textview的总高度。
- 4、绘制每一行的每一个字符
效果如下：
具体代码如下：
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package com.wedroid.framework.module.ui;import android.content.context;import android.graphics.canvas;import android.graphics.paint;import android.text.textpaint;import android.text.textutils;import android.util.attributeset;import android.view.viewgroup.marginlayoutparams;import android.view.viewtreeobserver.onpredrawlistener;import android.widget.textview;public class wedroidaligntextview extends textview { private boolean first = true; public wedroidaligntextview(context context, attributeset attrs, int defstyle) { super(context, attrs, defstyle); getviewtreeobserver().addonpredrawlistener(new onpredrawlistener() { @override public boolean onpredraw() { inittextinfo(); return true; } }); } public wedroidaligntextview(context context, attributeset attrs) { this(context, attrs, 0); } public wedroidaligntextview(context context) { this(context, null, 0); } private float textsize; private float textlineheight; private int top; private int y; private int lines; private int bottom; private int right; private int left; private int linedrawwords; private char[] textchararray; private float singlewordwidth; private float linespacingextra; public void inittextinfo() { textsize = gettextsize(); textlineheight = getlineheight(); left = 0; right = getright(); y = gettop(); // 要画的宽度 int drawtotalwidth = right - left; string text = gettext().tostring(); if (!textutils.isempty(text) && first) { textchararray = text.tochararray(); textpaint mtextpaint = new textpaint(paint.anti_alias_flag); mtextpaint.density = getresources().getdisplaymetrics().density; mtextpaint.settextsize(textsize); // 一个单词的的宽度 singlewordwidth = mtextpaint.measuretext("一") + linespacingextra; // 一行可以放多少个字符 linedrawwords = (int) (drawtotalwidth / singlewordwidth); int length = textchararray.length; lines = length / linedrawwords; if ((length % linedrawwords) > 0) { lines = lines + 1; } first = false; marginlayoutparams layoutparams = (marginlayoutparams) getlayoutparams(); int totalheight = (int) (lines*textlineheight+textlineheight*2 + getpaddingbottom()+getpaddingtop()+layoutparams.bottommargin+layoutparams.topmargin); setheight(totalheight); } } @override protected void ondraw(canvas canvas) { bottom = getbottom(); int drawtotalline = lines; if(maxline!=0&&drawtotalline>maxline){ drawtotalline = maxline; } for (int i = 0; i < drawtotalline; i++) { try { int length = textchararray.length; int mleft = left; // 第i+1行开始的字符index int startindex = (i * 1) * linedrawwords; // 第i+1行结束的字符index int endtextindex = startindex + linedrawwords; if (endtextindex > length) { endtextindex = length; y += textlineheight; } else { y += textlineheight; } for (; startindex < endtextindex; startindex++) { char c = textchararray[startindex];// if (c == ' ') {// c = '\u3000';// } else if (c < '\177') {// c = (char) (c + 65248);// } canvas.drawtext(string.valueof(c), mleft, y, getpaint()); mleft += singlewordwidth; } } catch (exception e) { e.printstacktrace(); } } } int maxline; public void setmaxlines(int max){ this.maxline = max; } public void setlinespacingextra(int linespacingextra){ this.linespacingextra = linespacingextra; } /** * 判断是否为中文 * @return */ public static boolean containchinese(string string){ boolean flag = false; for (int i = 0; i < string.length(); i++) { char c = string.charat(i); if ((c >= 0x4e00) && (c <= 0x9fa5)) { flag = true; } } return flag; } public static string todbc(string input) { // 导致textview异常换行的原因：安卓默认数字、字母不能为第一行以后每行的开头字符，因为数字、字母为半角字符 // 所以我们只需要将半角字符转换为全角字符即可 char c[] = input.tochararray(); for (int i = 0; i < c.length; i++) { if (c[i] == ' ') { c[i] = '\u3000'; } else if (c[i] < '\177') { c[i] = (char) (c[i] + 65248); } } return new string(c); }} |
希望本文所述对大家学习android程序设计有所帮助。
