如何计算文本在JTextArea中的行数（以及每行中的列数）？ [英] How to calculate the number of rows (and columns in each row) a text takes in a JTextArea?
问题描述
对问题
我试图接近它几次但都失败了，我不喜欢这样：）
After getting interested in the problem presented in the question I tried to approach it few times and failed, and I do not like that :)
我认为如果将问题分解为子问题，可能有助于解决问题。
I think if the problem were split into sub issues it might help to solve it.
为简单起见，假设JTextArea不会改变其大小，所以我们不需要担心重新评估等。我认为重要的问题是：
For simplicity lets assume the JTextArea will not change its size, so we do not need to worry about re-evaluation etc. I think the important issues are:
1.如何计算某个文本占用的行数JTextArea？
1.How to calculate the number of rows a certain text takes in a JTextArea?
2. JTextArea中的列数与它可以放在一行中的字符数之间的关系是什么？所以我们可以计算行长。
2.What is the relation between the number of columns in a JTextArea and a number of characters it can fit in a row? So we can calculate row length.
请在下面找到包含要处理的文本区域的示例代码：
Please find including below the sample code presenting the text area to process:
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
public class TextAreaLines
{
public static void main(String[] args)
{
SwingUtilities.invokeLater(new Runnable()
{
@Override
public void run()
{
JPanel p = new JPanel();
JFrame f = new JFrame();
JTextArea ta = new JTextArea("dadsad sasdasdasdasdasd");
ta.setWrapStyleWord(true);
ta.setLineWrap(true);
ta.setRows(5);
ta.setColumns(5);
p.add(ta);
f.setContentPane(p);
f.setSize(400, 300);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
//BTW the code below prints 1
System.out.println("ta.getLineCount()="+ta.getLineCount());
}
});
}
}
EDIT1：所以我已经提出以下代码，但问题是输出不是你看到的，即
So I have come up with the following code but the problem is that the output is not what you see, i.e
//for input
//JTextArea ta = new JTextArea("alfred abcdefghijklmnoprstuwvxyz abcdefg");
//we have output
//s=alfred abcdefghijk
//s=lmnoprstuwvxyz a
//s=bcdefg
FontMetrics fm = ta.getFontMetrics(ta.getFont());
String text = ta.getText();
List<String> texts = new ArrayList<String>();
String line = "";
//no word wrap
for(int i = 0;i < text.length(); i++)
{
char c = text.charAt(i);
if(fm.stringWidth(line +c) <= ta.getPreferredSize().width)
{
//System.out.println("in; line+c ="+(line + c));
line += c;
}
else
{
texts.add(line);//store the text
line = ""+c;//empty the line, add the last char
}
}
texts.add(line);
for(String s: texts)
System.out.println("s="+s);
我做错了什么，我忘记了什么？文本区域没有自动换行。
What am I doing wrong, what am I forgetting about? There is no word wrap on the text area.
EDIT2 ：@trashgod这是我得到的输出。从中可以看出，我们有不同的默认字体。实际上问题可能是字体甚至是系统依赖的。 （PS：我在Win7上）。
EDIT2: @trashgod This is the output I am getting. Apparent from this is that we have different default fonts. And the problem in fact might be either font or even system dependent. (PS: I am on Win7).
line: Twas brillig and the slithy tovesD
line: id gyre and gimble in the wabe;
line count: 2
preferred: java.awt.Dimension[width=179,height=48]
bounds1: java.awt.geom.Rectangle2D$Float[x=0.0,y=-12.064453,w=170.0,h=15.09375]
layout1: java.awt.geom.Rectangle2D$Float[x=0.28125,y=-8.59375,w=168.25,h=11.125]
bounds2: java.awt.geom.Rectangle2D$Float[x=0.0,y=-12.064453,w=179.0,h=15.09375]
layout2: java.awt.geom.Rectangle2D$Float[x=0.921875,y=-8.59375,w=177.34375,h=11.125]
在我的头脑中编译你们所有人大家都在说我认为可能可靠的解决方案可能是破解文本区域设置文本的方式，并完全控制它。通过运行该算法（请注意，正如@trashgod所建议的那样，在该区域的setText中，'<'被更改为'< ='）。
Compiling in my head what all of you guys are saying I think that the possibly reliable solution might be to hack the way in which the text area sets its text, and take a full control over it. By running the algorithm (above one, please notice, as suggested by @trashgod the '<' was changed to '<=') in the setText of the area.
是什么让我这样思考...例如我提供的样本如果你
将textarea的文本改为 JTextArea ta = new JTextArea（alfred abcdefghijkl \ nmnoprstuwvxyz ab\\\因为它在我的情况下计算然后它将完全适合textarea。
cdefg）;
What got me to think like this... for example in the sample I have provided if you
change text of the textarea to JTextArea ta = new JTextArea("alfred abcdefghijkl\nmnoprstuwvxyz ab\ncdefg"); as it is calculated in my case then it will fit perfectly into the textarea.
EDIT3：这是我快速入侵的一种解决方案，至少现在所显示的字符与计算完全相同。其他人可以检查一下，让我知道，可能它在其他机器上如何工作，然后Win7？下面的示例已准备好使用您应该能够调整窗口大小并获得与您看到的相同的行的打印输出。
This is a kind of solution I quickly hacked, at least now the shown characters and calculated are exactly the same. Can someone else please check it out and let me know, possibly how it works on other machine then Win7? The example below is ready to use you should be able to resize the window and get the printout of lines the same as you see.
import java.awt.BorderLayout;
import java.awt.FontMetrics;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
public class TextAreaLines
{
public static void main(String[] args)
{
SwingUtilities.invokeLater(new Runnable()
{
@Override
public void run()
{
JPanel p = new JPanel(new BorderLayout());
JFrame f = new JFrame();
final JTextArea ta = new JTextArea("alfred abcdefghijklmnoprstuwvxyz abcdefg");
ta.addComponentListener(new ComponentAdapter()
{
@Override
public void componentResized(ComponentEvent e)
{
super.componentResized(e);
System.out.println("ta componentResized");
reformatTextAreaText(ta);
}
});
//ta.setWrapStyleWord(true);
ta.setLineWrap(true);
p.add(ta);
f.setContentPane(p);
f.setSize(200, 100);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
}
private void reformatTextAreaText(JTextArea ta)
{
String text = ta.getText();
//remove all new line characters since we want to control line braking
text = text.replaceAll("\n", "");
FontMetrics fm = ta.getFontMetrics(ta.getFont());
List<String> texts = new ArrayList<String>();
String line = "";
//no word wrap
for(int i = 0; i < text.length(); i++)
{
char c = text.charAt(i);
if(fm.stringWidth(line + c) <= ta.getPreferredSize().width)
{
//System.out.println("in; line+c ="+(line + c));
line += c;
}
else
{
texts.add(line);//store the text
line = "" + c;//empty the line, add the last char
}
}
texts.add(line);
//print out of the lines
for(String s : texts)
System.out.println("s=" + s);
//build newText for the
String newText = "";
for(String s : texts)
newText += s + "\n";
ta.setText(newText);
}
});
}
}
提前致谢。
推荐答案
我做错了什么，我忘记了什么？
What am I doing wrong, what am I forgetting about?
没什么，真的。我将您的示例修改为在宽度上使用< =并突出显示一些功能：
Nothing, really. I modified your example to use "<=" on the width and to highlight a few features:
-
FontMetrics说明，字符串的前进不一定是孤立测量的字符前进的总和......
FontMetricsnotes, "the advance of aStringis not necessarily the sum of the advances of its characters measured in isolation…"
对于最宽的行，文本组件的首选大小与度量范围相匹配。由于比例间距的原因，这会因字体而异。
The preferred size of the text component matches the metric bounds pretty well for the widest line. This varies by font due to proportional spacing.
TextLayout 显示更严格的边界，但请注意基线相对坐标。
TextLayout shows even tighter bounds, but note the "baseline-relative coordinates."
getLineCount（）方法计算 line.separator 分隔线，没有包裹的行。
The getLineCount() method counts line.separator delimited lines, not wrapped lines.
line: Twas brillig and the slithy toves
line: Did gyre and gimble in the wabe;
line count: 2
preferred: java.awt.Dimension[width=207,height=48]
bounds1: java.awt.geom.Rectangle2D$Float[x=0.0,y=-12.568359,w=205.0,h=15.310547]
layout1: java.awt.geom.Rectangle2D$Float[x=0.0,y=-10.0,w=200.0,h=13.0]
bounds2: java.awt.geom.Rectangle2D$Float[x=0.0,y=-12.568359,w=207.0,h=15.310547]
layout2: java.awt.geom.Rectangle2D$Float[x=1.0,y=-10.0,w=205.0,h=13.0]
import java.awt.Dimension;
import java.awt.FontMetrics;
import java.awt.font.FontRenderContext;
import java.awt.font.TextLayout;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
/** #see http://stackoverflow.com/questions/5979795 */
public class TextAreaLine {
private static final String text1 =
"Twas brillig and the slithy toves\n";
private static final String text2 =
"Did gyre and gimble in the wabe;";
private static final JTextArea ta = new JTextArea(text1 + text2);
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
display();
}
});
}
static void display() {
JFrame f = new JFrame();
ta.setWrapStyleWord(false);
ta.setLineWrap(false);
ta.setRows(3);
f.add(ta);
f.pack();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setLocationRelativeTo(null);
f.setVisible(true);
FontMetrics fm = ta.getFontMetrics(ta.getFont());
List<String> texts = new ArrayList<String>();
Dimension d = ta.getPreferredSize();
String text = ta.getText();
String line = "";
for (int i = 0; i < text.length(); i++) {
char c = text.charAt(i);
if (c != '\n') {
if (fm.stringWidth(line + c) <= d.width) {
line += c;
} else {
texts.add(line);
line = "" + c;
}
}
}
texts.add(line);
for (String s : texts) {
System.out.println("line: " + s);
}
System.out.println("line count: " + ta.getLineCount());
System.out.println("preferred: " + d);
System.out.println("bounds1: " + fm.getStringBounds(text1, null));
FontRenderContext frc = new FontRenderContext(null, false, false);
TextLayout layout = new TextLayout(text1, ta.getFont(), frc);
System.out.println("layout1: " + layout.getBounds());
System.out.println("bounds2: " + fm.getStringBounds(text2, null));
layout = new TextLayout(text2, ta.getFont(), frc);
System.out.println("layout2: " + layout.getBounds());
}
}
这篇关于如何计算文本在JTextArea中的行数（以及每行中的列数）？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
