如何在 Java 中居中 Graphics.drawString()？
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How can I center Graphics.drawString() in Java?
提问by Daniel Kvist
I'm currently working on the menu system for my Javagame, and I wonder how I can center the text from Graphics.drawString(), so that if I want to draw a text whose center point is at X: 50and Y: 50, and the text is 30pixels wide and 10pixels tall, the text will start at X: 35and Y: 45.
我目前正在为我的菜单系统上的Java游戏，我不知道如何可以从中心的文本Graphics.drawString()，因此，如果我想画一个文本，其中心点是在X: 50和Y: 50，和文字30像素宽，10像素高，文本将从X: 35和开始Y: 45。
Can I determine the width of the text before I draw it?
Then it would be easy maths.
我可以在绘制之前确定文本的宽度吗？
那么数学就很简单了。
EDIT:I also wonder if I can get the height of the text, so that I can center it vertically too.
编辑：我也想知道是否可以获得文本的高度，以便我也可以将其垂直居中。
Any help is appreciated!
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采纳答案by Daniel Kvist
I used the answer on this question.
我在这个问题上使用了答案。
The code I used looks something like this:
我使用的代码如下所示：
/**
* Draw a String centered in the middle of a Rectangle.
*
* @param g The Graphics instance.
* @param text The String to draw.
* @param rect The Rectangle to center the text in.
*/
public void drawCenteredString(Graphics g, String text, Rectangle rect, Font font) {
// Get the FontMetrics
FontMetrics metrics = g.getFontMetrics(font);
// Determine the X coordinate for the text
int x = rect.x + (rect.width - metrics.stringWidth(text)) / 2;
// Determine the Y coordinate for the text (note we add the ascent, as in java 2d 0 is top of the screen)
int y = rect.y + ((rect.height - metrics.getHeight()) / 2) + metrics.getAscent();
// Set the font
g.setFont(font);
// Draw the String
g.drawString(text, x, y);
}
回答by Gilbert Le Blanc
When I have to draw text, I usually need to center the text in a bounding rectangle.
当我必须绘制文本时，我通常需要将文本居中放置在一个边界矩形中。
/**
* This method centers a <code>String</code> in
* a bounding <code>Rectangle</code>.
* @param g - The <code>Graphics</code> instance.
* @param r - The bounding <code>Rectangle</code>.
* @param s - The <code>String</code> to center in the
* bounding rectangle.
* @param font - The display font of the <code>String</code>
*
* @see java.awt.Graphics
* @see java.awt.Rectangle
* @see java.lang.String
*/
public void centerString(Graphics g, Rectangle r, String s,
Font font) {
FontRenderContext frc =
new FontRenderContext(null, true, true);
Rectangle2D r2D = font.getStringBounds(s, frc);
int rWidth = (int) Math.round(r2D.getWidth());
int rHeight = (int) Math.round(r2D.getHeight());
int rX = (int) Math.round(r2D.getX());
int rY = (int) Math.round(r2D.getY());
int a = (r.width / 2) - (rWidth / 2) - rX;
int b = (r.height / 2) - (rHeight / 2) - rY;
g.setFont(font);
g.drawString(s, r.x + a, r.y + b);
}
