blocks|key|1669043|text|FontMetrics.getAscent()和FontMetrics.getDescent()可能会做到这一点。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1669044|entityMap|0|LINK|mutability|MUTABLE|url|http://java.sun.com/javase/6/docs/api/java/awt/FontMetrics.html#getAscent()|1|http://java.sun.com/javase/6/docs/api/java/awt/FontMetrics.html#getDescent()^0|0|N|0|O|O|1|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@$A|O|B|P|1|Q]|$A|R|B|S|1|T]]|C|$]]|$1|D|3|-4|5|6|7|U|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]|L|$5|G|H|I|C|$J|M]]]]

<a href="http://java.sun.com/javase/6/docs/api/java/awt/FontMetrics.html#getAscent()" rel="noreferrer">FontMetrics.getAscent()</a> and <a href="http://java.sun.com/javase/6/docs/api/java/awt/FontMetrics.html#getDescent()" rel="noreferrer">FontMetrics.getDescent()</a> might do the trick.

blocks|key|1669103|text|是什么让你认为它返回了错误的值？更有可能的是，您对它返回的内容的期望与规范不符。请注意，如果字体中的某些字形超过或低于这些值，则完全没有问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1669104|对于字体中的任何字形，getMaxDescent()和getMaxAscent()应该会告诉您这些字段的绝对最大值。|offset|length|style|CODE|1669105|如果您想知道特定字符串的度量标准，那么您肯定希望调用getLineMetrics()。|1669106|entityMap^0|0|B|F|R|E|0|Q|G|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|M|8|@$D|N|E|O|F|G]|$D|P|E|Q|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|R|8|@$D|S|E|T|F|G]]|9|@]|A|$]]|$1|J|3|-4|5|6|7|U|8|@]|9|@]|A|$]]]|K|$]]

What makes you think it returns the wrong value? It's far more probable that your expectation of what it returns does not match the specification. Note that it's perfectly fine if some glyphs in the Font go over or under those values.

<code>getMaxDescent()</code> and <code>getMaxAscent()</code> should tell you the absolute maximum values of those fields for any glyph in the Font.

If you want to know the metrics for a specific String, then you definitely want to call <code>getLineMetrics()</code>.

blocks|key|1669208|text|getHeight()不能截断字符串的下部，只有绘制字符串才能做到这一点。您正在以某种方式使用从getHeight返回的高度来绘制字符串，并且很可能误用了高度。例如，如果将字符串的起始点定位在getHeight()高的框的底部，则文本的基线将位于框的底边，并且很可能会裁剪向下的部分。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1669209|文本几何是一个复杂的主题，充满了奇怪的历史文物。正如其他人所建议的，使用getAscent和getDescent尝试在框中正确定位基线。|1669210|entityMap^0|0|B|1C|9|0|10|9|1A|A|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]|$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|I|$]]

<code>getHeight()</code> can't cut off the descenders of a string, only drawing the string can do that. You are using the height returned from <code>getHeight</code> to draw the string somehow, and likely you are misusing the height. For example, if you position the start point of the string at the bottom of a box that is getHeight() high, then the baseline of your text will sit on the bottom edge of the box, and very likely the descenders will be clipped.

Text geometry is a complex topic, infused with bizarre historical artifacts. As others have suggested, use <code>getAscent</code> and <code>getDescent</code> to try to position the baseline properly within your box.

blocks|key|1669317|text|下面的getStringBounds()方法基于当前Graphics2D字体的GlyphVector，它非常适用于一行文本字符串：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1669318|public+class+StringBoundsPanel+extends+JPanel
{
++++public+StringBoundsPanel()
++++{
++++++++setBackground(Color.white);
++++++++setPreferredSize(new+Dimension(400,+247));
++++}

++++@Override
++++protected+void+paintComponent(Graphics+g)
++++{
++++++++super.paintComponent(g);

++++++++Graphics2D+g2+=+(Graphics2D)+g;

++++++++g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
++++++++++++++++++++++++++++RenderingHints.VALUE_ANTIALIAS_ON);

++++++++//+must+be+called+before+getStringBounds()
++++++++g2.setFont(getDesiredFont());

++++++++String+str+=+"My+Text";
++++++++float+x+=+140,+y+=+128;

++++++++Rectangle+bounds+=+getStringBounds(g2,+str,+x,+y);

++++++++g2.setColor(Color.red);
++++++++g2.drawString(str,+x,+y);

++++++++g2.setColor(Color.blue);
++++++++g2.draw(bounds);

++++++++g2.dispose();
++++}

++++private+Rectangle+getStringBounds(Graphics2D+g2,+String+str,
++++++++++++++++++++++++++++++++++++++float+x,+float+y)
++++{
++++++++FontRenderContext+frc+=+g2.getFontRenderContext();
++++++++GlyphVector+gv+=+g2.getFont().createGlyphVector(frc,+str);
++++++++return+gv.getPixelBounds(null,+x,+y);
++++}

++++private+Font+getDesiredFont()
++++{
++++++++return+new+Font(Font.SANS_SERIF,+Font.BOLD,+28);
++++}

++++private+void+startUI()
++++{
++++++++JFrame+frame+=+new+JFrame();
++++++++frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
++++++++frame.add(this);
++++++++frame.pack();
++++++++frame.setLocationRelativeTo(null);
++++++++frame.setVisible(true);
++++}

++++public+static+void+main(String[]+args)+throws+Exception
++++{
++++++++final+StringBoundsPanel+tb+=+new+StringBoundsPanel();

++++++++SwingUtilities.invokeAndWait(new+Runnable()
++++++++{
++++++++++++public+void+run()
++++++++++++{
++++++++++++++++tb.startUI();
++++++++++++}
++++++++});
++++}
}|code-block|syntax|javascript|1669319|请注意，为了清楚起见，我省略了导入。|1669320|结果是：|1669321|​|1669322|📷|atomic|1669323|1669324|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://ask.qcloudimg.com/http-save/yehe-900000/413b0f3bd92e3443f820f7a539d6a3d6.png|imageAlt^0|3|H|Q|A|13|B|0|0|0|0|0|0|1|0|0|0^^$0|@$1|2|3|4|5|6|7|13|8|@$9|14|A|15|B|C]|$9|16|A|17|B|C]|$9|18|A|19|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|1A|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|1B|8|@]|D|@]|E|$]]|$1|M|3|N|5|6|7|1C|8|@]|D|@]|E|$]]|$1|O|3|P|5|6|7|1D|8|@]|D|@]|E|$]]|$1|Q|3|R|5|S|7|1E|8|@]|D|@$9|1F|A|1G|1|1H]]|E|$]]|$1|T|3|P|5|6|7|1I|8|@]|D|@]|E|$]]|$1|U|3|-4|5|6|7|1J|8|@]|D|@]|E|$]]]|V|$W|$5|X|Y|Z|E|$10|11|12|-4]]]]

The <code>getStringBounds()</code> method below is based on the <code>GlyphVector</code> for the current <code>Graphics2D</code> font, which works very well for one line string of text:

<pre><code>public class StringBoundsPanel extends JPanel
{
 public StringBoundsPanel()
 {
 setBackground(Color.white);
 setPreferredSize(new Dimension(400, 247));
 }

 @Override
 protected void paintComponent(Graphics g)
 {
 super.paintComponent(g);

 Graphics2D g2 = (Graphics2D) g;

 g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
 RenderingHints.VALUE_ANTIALIAS_ON);

 // must be called before getStringBounds()
 g2.setFont(getDesiredFont());

 String str = "My Text";
 float x = 140, y = 128;

 Rectangle bounds = getStringBounds(g2, str, x, y);

 g2.setColor(Color.red);
 g2.drawString(str, x, y);

 g2.setColor(Color.blue);
 g2.draw(bounds);

 g2.dispose();
 }

 private Rectangle getStringBounds(Graphics2D g2, String str,
 float x, float y)
 {
 FontRenderContext frc = g2.getFontRenderContext();
 GlyphVector gv = g2.getFont().createGlyphVector(frc, str);
 return gv.getPixelBounds(null, x, y);
 }

 private Font getDesiredFont()
 {
 return new Font(Font.SANS_SERIF, Font.BOLD, 28);
 }

 private void startUI()
 {
 JFrame frame = new JFrame();
 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 frame.add(this);
 frame.pack();
 frame.setLocationRelativeTo(null);
 frame.setVisible(true);
 }

 public static void main(String[] args) throws Exception
 {
 final StringBoundsPanel tb = new StringBoundsPanel();

 SwingUtilities.invokeAndWait(new Runnable()
 {
 public void run()
 {
 tb.startUI();
 }
 });
 }
}
</code></pre>

Note that I've omitted the imports for clarity.

The result:

<img src="https://i.stack.imgur.com/fpk48.png" alt="Result screenshot.">

blocks|key|1669418|text|我最近写了下面的代码，因为我需要像素完美的高度测量字体的特定范围(例如:所有较低的字符，或所有数字)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1669419|如果你需要更快的代码(我的有for循环)，我建议在启动时运行一次，以获得数组中的所有值(例如，从1到100)，然后使用数组。|1669420|代码基本上是在一个250x250的位图上重叠的同一位置绘制输入字符串中的所有字符(如果需要，可以增加或减少)，它从顶部开始查找像素，然后从底部开始查找，然后返回找到的最大高度。它适用于普通字符串，即使它是为字符范围设计的。这意味着在计算一些字符重复时的常规字符串时，会有一种冗余。因此，如果您的输入字符串超过了字母表计数(26)，请使用'tRange‘输入："abcd...z“和其他可能使用的字符。它的速度更快。|1669421|希望这能有所帮助。|1669422|public+int+getFontPixelHeight(float+inSize,+Paint+sourcePaint,+String+tRange)
{
++++//+It+is+assumed+that+the+font+is+already+set+in+the+sourcePaint

++++int+bW+=+250,+bH+=+250;+++++++++++++++++++++++++++++++++++++//+bitmap's+width+and+height
++++int+firstContact+=+-1,+lastContact+=+-2;++++++++++++++++++++//+Used+when+scanning+the+pixel+rows.+Initial+values+are+set+so+that+if+no+pixels+found,+the+returned+result+is+zero.
++++int+tX+=+(int)(bW+-+inSize)/2,+tY+=+(int)(bH+-+inSize)/2;+++//+Used+for+a+rough+centering+of+the+displayed+characters

++++int+tSum+=+0;

++++//+Preserve+the+original+paint+attributes
++++float+oldSize+=+sourcePaint.getTextSize();
++++int+oldColor+=+sourcePaint.getColor();
++++//+Set+the+size/color
++++sourcePaint.setTextSize(inSize);+sourcePaint.setColor(Color.WHITE);

++++//+Create+the+temporary+bitmap/canvas
++++Bitmap.Config+bConf+=+Bitmap.Config.ARGB_8888;
++++Bitmap+hld+=+Bitmap.createBitmap(250,+250,+bConf);
++++Canvas+canv+=+new+Canvas(hld);

++++for+(int+i+=+0;+i+<+bH;+i%2B%2B)
++++{
++++++++for+(int+j+=+0;+j+<+bW;+j%2B%2B)
++++++++{
++++++++++++hld.setPixel(j,+i,+0);+//+Zero+all+pixel+values.+This+might+seem+redundant,+but+I+am+not+quite+sure+that+creating+a+blank+bitmap+means+the+pixel+color+value+is+indeed+zero,+and+I+need+them+to+be+zero+so+the+addition+performed+below+is+correct.
++++++++}
++++}

++++//+Display+all+characters+overlapping+at+the+same+position
++++for+(int+i+=+0;+i+<+tRange.length();+i%2B%2B)
++++{
++++++++canv.drawText(""+%2B+tRange.charAt(i),+tX,+tY,+sourcePaint);
++++}

++++for+(int+i+=+0;+i+<+bH;+i%2B%2B)
++++{
++++++++for+(int+j+=+0;+j+<+bW;+j%2B%2B)
++++++++{
++++++++++++tSum+=+tSum+%2B+hld.getPixel(j,+i);
++++++++}

++++++++if+(tSum+>+0)+//+If+we+found+at+least+a+pixel,+save+row+index+and+exit+loop
++++++++{
++++++++++++firstContact+=+i;
++++++++++++tSum+=+0;+++//+Reset
++++++++++++break;
++++++++}+++
++++}

++++for+(int+i+=+bH+-+1;+i+>+0+;+i--)
++++{
++++++++for+(int+j+=+0;+j+<+bW;+j%2B%2B)
++++++++{
++++++++++++tSum+=+tSum+%2B+hld.getPixel(j,+i);
++++++++}

++++++++if+(tSum+>+0)+//+If+we+found+at+least+a+pixel,+save+row+index+and+exit+loop
++++++++{
++++++++++++lastContact+=+i;
++++++++++++break;
++++++++}+++
++++}

++++//+Restore+the+initial+attributes,+just+in+case+the+paint+was+passed+byRef+somehow
++++sourcePaint.setTextSize(oldSize);
++++sourcePaint.setColor(oldColor);

++++return+lastContact+-+firstContact+%2B+1;
}|code-block|syntax|javascript|1669423|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|Q|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|R|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|S|8|@]|9|@]|A|$K|L]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

I recently wrote the code below as I needed pixel perfect height measurements for specific ranges of the font (for example: all lower characters, or all numbers).

If you need faster code (mine has for loops) I would recommend running it once at the start-up to get all values (for example from 1 to 100) in an array and then use the array instead.

The code basically draws all characters from the input string at the same place overlapped on a 250x250 bitmap (increase or reduce if needed), it starts looking for pixels from top, then from bottom, then it returns the maximum height found. It works with normal strings even if it was designed for character ranges. This means there is a sort of redundancy when evaluating regular strings as some of the characters repeat. So if your imput string exceeds the alphabet count (26), use as 'tRange' imput: "abcd...z" and other characters that may be used. It is faster.

Hope that helps.

<pre><code>public int getFontPixelHeight(float inSize, Paint sourcePaint, String tRange)
{
 // It is assumed that the font is already set in the sourcePaint

 int bW = 250, bH = 250; // bitmap's width and height
 int firstContact = -1, lastContact = -2; // Used when scanning the pixel rows. Initial values are set so that if no pixels found, the returned result is zero.
 int tX = (int)(bW - inSize)/2, tY = (int)(bH - inSize)/2; // Used for a rough centering of the displayed characters

 int tSum = 0;

 // Preserve the original paint attributes
 float oldSize = sourcePaint.getTextSize();
 int oldColor = sourcePaint.getColor();
 // Set the size/color
 sourcePaint.setTextSize(inSize); sourcePaint.setColor(Color.WHITE);

 // Create the temporary bitmap/canvas
 Bitmap.Config bConf = Bitmap.Config.ARGB_8888;
 Bitmap hld = Bitmap.createBitmap(250, 250, bConf);
 Canvas canv = new Canvas(hld);

 for (int i = 0; i &lt; bH; i++)
 {
 for (int j = 0; j &lt; bW; j++)
 {
 hld.setPixel(j, i, 0); // Zero all pixel values. This might seem redundant, but I am not quite sure that creating a blank bitmap means the pixel color value is indeed zero, and I need them to be zero so the addition performed below is correct.
 }
 }

 // Display all characters overlapping at the same position
 for (int i = 0; i &lt; tRange.length(); i++)
 {
 canv.drawText("" + tRange.charAt(i), tX, tY, sourcePaint);
 }

 for (int i = 0; i &lt; bH; i++)
 {
 for (int j = 0; j &lt; bW; j++)
 {
 tSum = tSum + hld.getPixel(j, i);
 }

 if (tSum &gt; 0) // If we found at least a pixel, save row index and exit loop
 {
 firstContact = i;
 tSum = 0; // Reset
 break;
 } 
 }

 for (int i = bH - 1; i &gt; 0 ; i--)
 {
 for (int j = 0; j &lt; bW; j++)
 {
 tSum = tSum + hld.getPixel(j, i);
 }

 if (tSum &gt; 0) // If we found at least a pixel, save row index and exit loop
 {
 lastContact = i;
 break;
 } 
 }

 // Restore the initial attributes, just in case the paint was passed byRef somehow
 sourcePaint.setTextSize(oldSize);
 sourcePaint.setColor(oldColor);

 return lastContact - firstContact + 1;
}
</code></pre>

I'm using <code>FontMetrics.getHeight()</code> to get the height of the string, but it gives me a wrong value, cutting off the descenders of string characters. Is there a better function I can use?

How to get real string height in Java?

我使用FontMetrics.getHeight()来获取字符串的高度，但是它给出了一个错误的值，切断了字符串字符的后缀。有没有更好的功能可以使用？

问如何在Java中获得真实的字符串高度？
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