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JAVA---Graphics2D类

Graphics2D类继承于Graphics类,提供了几何学、坐标转换、颜色管理及文本排列等更高级的控制。Graphics2D类是java平台渲染二维图形,文字及图片的基础类,提供较好的对绘制形状,填充形状、旋转形状、及定义颜色的支持。

在AWT编程接口中,用户通过paint方法接收Graphics对象作为参数,若使用Graphics2D类,就需要在paint方法中进行强制转换。

public  void  paint(Graphics oldg){

                       Graphics2D new=(Graphics2D)oldg;

                                      }

绘制形状:

public   abstract   void  draw(shape s);         空心s;

public  sbstract    void  fill(shape s);           实心s;

Line2D:线     Rectangle2D: 矩形        RoundRectangle2D:画圆角矩形            Ellipse2D:椭圆               GeneralPath:几何路径。

GeneralPath常用的方法有四个:

public void  lineTo(float x,float y);      从当前坐标点到(x,y)画一条直线

public  void  moveTo(float x,float y);    移动到点(x,y)

public  void qualTo(float   x1,float y1,float x2,float y2); 以坐标点(x1,y1)为控制点,在当前坐标点和坐标点(x2,y2)之间插入二次曲线片断。

public  void  curveTo(float   x1,float y1,float x2,float y2,float x3,float y3);   以(x1,y1)和(x2,y2)为控制点,在当前坐标点和(x3,y3)之间插入曲线片断。

在draw方法中提到Graphics2D的环境变量。所谓的环境变量是指设置画图和填充属性等,设置方法分别如下:

public abstract void  setStroke(Stroke s);  设置笔画的粗细。

public BasicStroke(float  width); 创建实线笔画宽度为width。

public abstract  void setPaint(Paint paint);

设置Graphics2D环境的填充属性,其中paint的值可以渐变充值,渐变充值类:java.awt.GradientPaint,也可以为图形填充类java.awt.TexturePaint,构造函数:

public GradientPaint(float x1,flaot y2,Color.Color1,float x2,float y2,Color.Color2,boolean   cyclic);在(x1,y1)和(x2,y2)之间颜色从Color1到Color2之间渐变,当cyclic为真,循序渐变。

eg:
import java.util.awt.*;

import java.applet.*;

import java.awt.geom.*;

public  class GUI2D extends Applet{

           public  void paint(Graphics oldg){

                       Graphics2D g=(Graphics2D)oldg;

                       //设置笔画

                     BasicStroke stroke=new BasicStroke(10);

                     g.setStroke(stroke);

                  //画线

                     Line2D line=new Line2D.Float(0,0,20,30);

                    g.draw(line);

                   line=new Line2D.Float(50,50,100,50);

                    g.draw(line);

                  line=new Line2D.Float(50,50,50,100);

                    g.draw(line);

                  stroke=new BasicStroke(5);

                    g.setStroke(stroke);

               //设置渐变填充

                   GradientPaint gt=new GradientPaint(0,0,Color.green,50,30,Color.blue,true);

                      g.setPaint((Paint)gt);

              //画矩形

              Rectangle2D rect=new Rectangle2D.Float(80,80,40,40);

              g.draw(rect);

              rect=new Rectangle2D.Float(100,100,40,40);

              g.draw(rect);

              //画椭圆

              Ellipse2D ellipse=new Ellipse2D.Float(120,120,30,40);

              g.draw(ellipse);

               gt=new GradientPaint(0,0,Color.red,30,30,Color.yellow,true);

              g.setPaint((Paint)gt);

              ellipse=new Ellipse2D.Float(140,140,20,20);

              g.draw(ellipse);

             //画圆角矩形

               RoundRectangle roundrect=new RoundRectangle2D.Float(160,160,40,40,20,20);

               g.draw(roundrect);

               roundrect=new RoundRectangle2D.Float(180,180,40,40,20,20);

              g.fill(roundrect);

            //画几何图形

              GeneralPath path=new GeneralPath();

              path.moveTo(150,0);

              path.lineTo(160,50);

              path.curveTo(190,200,240,140,200,100);

             g.fill(path);

           }

}

 绘制文本

Graphics2D提供了一个文本布局(TextLayout)对象,用于实现各种字体或段落文本的绘制。其构造函数为:

public TextLayout(String string,Font font,FontRnderContext frc);          通过字符串string和字体font构造布局。

public void draw(Graphics2D g2,floatx,float y);将这个TextLayout画到Graphics2D对象上的x,y坐标处。

public Rectangle2D getBounds();      返回TextLayout对象的区域。

eg:

import java.awt.*;

import java.applet.*;

import java.awt.geom.*;

import java.awt.font.*;

public class GUIText extends Applet{

           public void paint(Graphics oldg){

                     Graphics2D g=(Graphics2D)oldg;

                      //设置字体

                     Font font1=new Font("Courier",Font.PLAN,24);

                     Font   font2=new Font("helvetica",Font.BOLD,24);

                     FontRenderContext  frc=g.getFontRnderContext();

                     String str=new String("这是一个文本布局类的实现");

                     String str2=new String("扩充绘制文本的功能");

                   //构造文本布局

                    TextLayout   layout=new TextLayout(str,f1,frc);

                      Point2D loc=new Point2D.Float(20,50);

                //绘制文本

                      layout.draw(g,(float)loc.getX(),(float)loc.getY());

                   //设置边框

                 Rectangle2D bounds=layout.getBounds();

                 bounds.setRect(bounds.getX()+loc.getX(),

                                           bounds.getY()+loc.getY(),

                                           bounds.getwidth();

                                           bounds.getheight();

                                           g.draw(bounds);

                                           layout=new Layout(str2,f2,frc);

                                           g.setColor(Color.red);

                                            layout.draw(g,20,80);

                               }

              }

绘制图像

绘制图像用到BufferedImage类,BufferedImage类是用来存放图像数据的可访问的缓冲。构造函数:

public BufferedImage(int width,int height,int iamgeType);    使用宽度(width)、高度(height)和imageType类型构造BufferedImage对象。

public Graphics2D  createGraphics()

用图片填充椭圆的具体过程如下:

(1):创建一个Graphics2D,可以画到BufferedImage中。

BufferedImage   buf=new BufferedImage(img.getWidth(this),img.getHeight(this),BufferedImage.TYPE_INT_ARGB);

创建一个临时Graphics2D对象。

Graphics  tmpG=buf.createGraphics();

将图像画入临时缓冲中:

tmpG.drawImage(img,10,10,this);

(2):用TexturePaint类进行填充

public  TexturePaint(BufferedImage  tetr,Rectangle2D  anchor)        构造TexturePaint对象,需要一个Rectangle2D对象来存放该对象:

Rectangle2D rect=new Rectangle2D.Float(0,0,h,w);

TexturePaint t=new TexturePaint(buf,rect);

(3):然后设置填充模式,并进行填充。

g.setPaint(t);

g.fill(new Ellipse2D.Float(100,50,60,60));

eg:

import java.awt.*;

import java.applet.*;

import java.awt.geom.*;

import java.awt.front.*;

import java.awt.image.*;

import java.net.*;

public class GUIImage  extends Applet{

           public void  paint(Graphics oldg){

                          Graphics2D g=(Graphics2D)oldg;

                         try{

                              URL imgURL=new URL(getDocumentBase(),"simple.gif");

                              Image img=getImage(imgURL);

                              int h=img.getHeight(this);

                              int w=img.getWidth(this);

                              //构造缓冲图像对象

                              BufferedImage buf=new BufferedImage(w,h,BufferedImage.TYPE_INT_ARGB);

                              //放入临时图形类

                             Graphics tmpG=buf.createGraphics();

                             tmpG.drawImage(img,10,10,this);

                             g.drawImage(buf,10,20,this);

                             //设置透明颜色对象

                            Color transBlue=new Color(0,0,255,200);

                            g.setColor(transBlue);

                            GeneralOPath  path=new GeneralPath();

                            path.moveTo(60,0);

                            path.lineTo(50,100);

                            path.curveTo(160,230,240,140,200,100);

                            g.fill(path);

                           transBlue=new Color(0,0,225,140);

                           g.fill(new Ellipse2D.Float(100,100,50,50));

                         Rectangle2D rect=new Rectangle2D.Float(0,0,h,w);

                           //图片填充

                          TexturePaint t=new TexturePaint(buf,rect);

                          g.fill(new Ellipse2D.Float(100,50,60,60));

                            }

                          catch(Exception e){

                            System.out.println("ERROR:"+e.getMessage());

                                       }

                           }

}

                 

                  

 

posted @ 2017-08-25 10:23  Yi_warmth  阅读(2291)  评论(0编辑  收藏  举报
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