Java中计算字符串的显示宽度
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Calculate the display width of a string in Java
提问by eflles
How to calculate the length (in pixels) of a string in Java?
如何在 Java 中计算字符串的长度（以像素为单位）？
Preferable without using Swing.
最好不使用 Swing。
EDIT: I would like to draw the string using the drawString() in Java2D and use the length for word wrapping.
编辑：我想在 Java2D 中使用 drawString() 绘制字符串并使用长度进行自动换行。
采纳答案by Jon Skeet
If you just want to use AWT, then use Graphics.getFontMetrics(optionally specifying the font, for a non-default one) to get a FontMetricsand then FontMetrics.stringWidthto find the width for the specified string.
如果您只想使用 AWT，则使用Graphics.getFontMetrics（可选地指定字体，对于非默认字体）获取 aFontMetrics然后FontMetrics.stringWidth查找指定字符串的宽度。
For example, if you have a Graphicsvariable called g, you'd use:
例如，如果您有一个Graphics名为的变量g，您将使用：
int width = g.getFontMetrics().stringWidth(text);
For other toolkits, you'll need to give us more information - it's always going to be toolkit-dependent.
对于其他工具包，您需要向我们提供更多信息——它总是依赖于工具包。
回答by Olofu Mark
It doesn't always need to be toolkit-dependent or one doesn't always need use the FontMetrics approach since it requires one to first obtain a graphics object which is absent in a web container or in a headless enviroment.
它并不总是需要依赖于工具包，或者并不总是需要使用 FontMetrics 方法，因为它需要首先获取 Web 容器或无头环境中不存在的图形对象。
I have tested this in a web servlet and it does calculate the text width.
我已经在 Web servlet 中对此进行了测试，它确实计算了文本宽度。
import java.awt.Font;
import java.awt.font.FontRenderContext;
import java.awt.geom.AffineTransform;
...
String text = "Hello World";
AffineTransform affinetransform = new AffineTransform();
FontRenderContext frc = new FontRenderContext(affinetransform,true,true);
Font font = new Font("Tahoma", Font.PLAIN, 12);
int textwidth = (int)(font.getStringBounds(text, frc).getWidth());
int textheight = (int)(font.getStringBounds(text, frc).getHeight());
Add the necessary values to these dimensions to create any required margin.
将必要的值添加到这些维度以创建任何所需的边距。
回答by Ed Poor
Use the getWidth method in the following class:
在以下类中使用 getWidth 方法：
import java.awt.*;
import java.awt.geom.*;
import java.awt.font.*;
class StringMetrics {
Font font;
FontRenderContext context;
public StringMetrics(Graphics2D g2) {
font = g2.getFont();
context = g2.getFontRenderContext();
}
Rectangle2D getBounds(String message) {
return font.getStringBounds(message, context);
}
double getWidth(String message) {
Rectangle2D bounds = getBounds(message);
return bounds.getWidth();
}
double getHeight(String message) {
Rectangle2D bounds = getBounds(message);
return bounds.getHeight();
}
}
回答by wmioduszewski
I personally was searching for something to let me compute the multiline string area, so I could determine if given area is big enough to print the string - with preserving specific font.
我个人正在寻找一些东西来让我计算多行字符串区域，这样我就可以确定给定的区域是否足够大来打印字符串 - 并保留特定的字体。
I hope it would safe some time to another guy who may want to do similar job in java so just wanted to share the solution:
我希望这对另一个可能想在 Java 中做类似工作的人来说是安全的，所以只想分享解决方案：
private static Hashtable hash = new Hashtable();
private Font font;
private LineBreakMeasurer lineBreakMeasurer;
private int start, end;
public PixelLengthCheck(Font font) {
this.font = font;
}
public boolean tryIfStringFits(String textToMeasure, Dimension areaToFit) {
AttributedString attributedString = new AttributedString(textToMeasure, hash);
attributedString.addAttribute(TextAttribute.FONT, font);
AttributedCharacterIterator attributedCharacterIterator =
attributedString.getIterator();
start = attributedCharacterIterator.getBeginIndex();
end = attributedCharacterIterator.getEndIndex();
lineBreakMeasurer = new LineBreakMeasurer(attributedCharacterIterator,
new FontRenderContext(null, false, false));
float width = (float) areaToFit.width;
float height = 0;
lineBreakMeasurer.setPosition(start);
while (lineBreakMeasurer.getPosition() < end) {
TextLayout textLayout = lineBreakMeasurer.nextLayout(width);
height += textLayout.getAscent();
height += textLayout.getDescent() + textLayout.getLeading();
}
boolean res = height <= areaToFit.getHeight();
return res;
}
回答by John Henckel
And now for something completelydifferent. The following assumes arial font, and makes a wild guess based on a linear interpolation of character vs width.
现在是完全不同的东西。以下假设为 arial 字体，并基于字符与宽度的线性插值进行了粗略的猜测。
// Returns the size in PICA of the string, given space is 200 and 'W' is 1000.
// see https://p2p.wrox.com/access/32197-calculate-character-widths.html
static int picaSize(String s)
{
// the following characters are sorted by width in Arial font
String lookup = " .:,;'^`!|jl/\i-()JfIt[]?{}sr*a\"ce_gFzLxkP+0123456789<=>~qvy$SbduEphonTBCXY#VRKZN%GUAHD@OQ&wmMW";
int result = 0;
for (int i = 0; i < s.length(); ++i)
{
int c = lookup.indexOf(s.charAt(i));
result += (c < 0 ? 60 : c) * 7 + 200;
}
return result;
}
Interesting, but perhaps not very practical.
有趣，但可能不太实用。
