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giáo trình Java By Example phần 5

Tham khảo tài liệu 'giáo trình java by example phần 5', công nghệ thông tin, kỹ thuật lập trình phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Table 17.2 Commonly Used FontMetrics Methods. Method Description charWidth Returns the width of a character. getAscent Returns the font s ascent. getDescent Returns the font s descent. getFont Returns the associated Font object. getHeight Returns the font s height. getLeading Returns the font s leading line spacing . stringWidth Returns the width of a string. toString Returns a string of information about the font. NOTE If you haven t used fonts before some of the terms-leading ascent and descent-used in Table 17.2 may be unfamiliar to you. Leading pronounced ledding is the amount of white space between lines of text. Ascent is the height of a character from the baseline to the top of the character. Descent is the size of the area that accommodates the descending portions of letters such as the tail on a lowercase g. Height is the sum of ascent descent and leading. See Figure 17.3 for examples of each. Figure 17.3 Ascent descent and leading determine the overall height of a font. Example Displaying Font Metrics Most of the methods listed in Table 17.2 are self-explanatory. However you probably want a chance to see them in action. Listing 17.3 is the source code for the MetricsApplet and Listing 17.4 is the applet s HTML document. When you run the MetricsApplet applet you see the window shown in Figure 17.4. At the top of the window is a text box into which you can enter different strings of text. When you press Enter the applet displays the length of the string in pixels. Immediately below the text box is information about the current font. Figure 17.4 This is Appletviewer running the MetricsApplet applet. Listing 17.3 MetricsApplet.java An Applet That Displays Text Metrics. import java.awt. import java.applet. http www.ngohaianh.info public class MetricsApplet extends Applet TextField textField public void init textField new TextField 20 add textField textField.setText Default string public void paint Graphics g Font font getFont FontMetrics fontMetrics .