SWT应用之：随机RGB颜色、ScrolledComposite控件的使用

在项目中要用到SWT中我不熟悉的随机产生RGB颜色和ScrolledComosite的应用。因此，我学着做了一个包含这两个技巧的用法的DEMO分享出来。

A. SWT中产生随机RGB颜色的方法，由于RGB颜色是由红、绿、蓝三种颜色组成的，因此在产生的时候只需要随机产生这三种颜色的值就可以了。

（1）在SWT中提供了一个Color类，它的构造函数为 new Color(Display.getDefault(),new RGB());

（2）其中RGB对象的构造函数为 new RGB(int red,int green,int blue);

（3）因此，只需要随机产生RGB构造函数中的三个颜色值，就能生成随机的Color对象了

（4）产生随机数就很简单了，使用Random类提供的nextInt(int i)方法就能够产生随机的一定范围的int随机数了。

class ProduceColor {      public Color produceColor() {          Random random = new Random();          int red = random.nextInt(255);          int green = random.nextInt(255);          int blue = random.nextInt(255);          System.out.println("(" + red + "," + green + "," + blue + ")");          RGB rgb = new RGB(red, green, blue);          Color color = new Color(Display.getDefault(), rgb);          return color;      }  }  

B,介绍ScrolledComosite控件的时候，由于这个Composite控件虽然提供了ScrooledBar，但是需要手动添加相应的响应事件处理，才能实现像Tree和Table那样的ScrolledBar的功能。因此，ScrolledComosite控件能够实现这个功能，但是麻烦程度和手动添加事件处理彻滑功能不相上下。

在这里就介绍ScrolledComosite控件的实现，以后接触到了手动添加彻滑事件的处理，再分享出来。

具体怎样实现，就不细谈了，直接贴出代码。

package testEntity;import java.io.File;import java.io.FileInputStream;import java.io.IOException;import java.util.Random;import org.eclipse.swt.widgets.Display;import org.eclipse.swt.widgets.ScrollBar;import org.eclipse.swt.widgets.Shell;import org.eclipse.swt.widgets.Composite;import org.eclipse.swt.SWT;import org.eclipse.swt.layout.FillLayout;import org.eclipse.swt.layout.GridLayout;import org.eclipse.swt.widgets.Group;import org.eclipse.swt.layout.grouplayout.GroupLayout;import org.eclipse.swt.widgets.Canvas;import org.eclipse.swt.widgets.Button;import org.eclipse.swt.events.SelectionAdapter;import org.eclipse.swt.events.SelectionEvent;import org.eclipse.swt.events.MouseAdapter;import org.eclipse.swt.events.MouseEvent;import org.eclipse.swt.events.SelectionListener;import org.eclipse.swt.graphics.Color;import org.eclipse.swt.graphics.Font;import org.eclipse.swt.graphics.GC;import org.eclipse.swt.graphics.Image;import org.eclipse.swt.graphics.ImageData;import org.eclipse.swt.graphics.RGB;import org.eclipse.swt.graphics.Rectangle;import org.eclipse.swt.custom.ScrolledComposite;import org.eclipse.swt.widgets.Label;import org.eclipse.swt.layout.GridData;import org.eclipse.swt.layout.grouplayout.LayoutStyle;public class SWTColorDemo {protected Shell shell;private Group group;private Color color = null;private Composite composite_1;private Composite composite;private int count = 300;private ScrolledComposite scrolledComposite;/** * Launch the application. *  * @param args */public static void main(String[] args) {try {SWTColorDemo window = new SWTColorDemo();window.open();} catch (Exception e) {e.printStackTrace();}}/** * Open the window. */public void open() {Display display = Display.getDefault();createContents();shell.open();shell.layout();while (!shell.isDisposed()) {if (!display.readAndDispatch()) {display.sleep();}}}/** * Create contents of the window. */protected void createContents() {shell = new Shell();shell.setSize(944, 664);shell.setText("SWT Application");shell.setLayout(new FillLayout(SWT.HORIZONTAL));{composite = new Composite(shell, SWT.BORDER);Button button = new Button(composite, SWT.NONE);button.setSize(200, 200);button.addSelectionListener(new SelectionAdapter() {@Overridepublic void widgetSelected(SelectionEvent e) {color = (new ProduceColor()).produceColor();}});button.setText("改变字体颜色");{group = new Group(composite, SWT.NULL);group.setLayout(new FillLayout(SWT.HORIZONTAL));{final Canvas canvas = new Canvas(group, SWT.NONE);canvas.setBackground(new Color(Display.getDefault(), 200,200, 200));Button btnButton = new Button(composite, SWT.NONE);btnButton.addSelectionListener(new SelectionAdapter() {@Overridepublic void widgetSelected(SelectionEvent e) {showSomething(500);}});btnButton.setText("500 BUTTON");GroupLayout gl_composite = new GroupLayout(composite);gl_composite.setHorizontalGroup(gl_composite.createParallelGroup(GroupLayout.LEADING).add(group, GroupLayout.DEFAULT_SIZE, 464,Short.MAX_VALUE).add(gl_composite.createSequentialGroup().add(122).add(button).add(28).add(btnButton).addContainerGap(158,Short.MAX_VALUE)));gl_composite.setVerticalGroup(gl_composite.createParallelGroup(GroupLayout.LEADING).add(gl_composite.createSequentialGroup().add(group, GroupLayout.DEFAULT_SIZE,529, Short.MAX_VALUE).add(41).add(gl_composite.createParallelGroup(GroupLayout.BASELINE).add(button).add(btnButton)).add(34)));composite.setLayout(gl_composite);canvas.addMouseListener(new MouseAdapter() {@Overridepublic void mouseDown(MouseEvent e) {if (color != null) {GC gc = new GC(canvas);Rectangle rect = canvas.getClientArea();gc.fillRectangle(rect.x, rect.y, rect.width,rect.height);gc.setForeground(color);Font font = new Font(Display.getDefault(),"Arial", 32, SWT.BOLD);gc.setFont(font);gc.drawText("SHOW TEXT", e.x, e.y);}}});}}}showSomething(300);}public void showSomething(int count) {if (scrolledComposite == null) {scrolledComposite = new ScrolledComposite(shell, SWT.BORDER| SWT.H_SCROLL | SWT.V_SCROLL);}composite_1 = new Composite(scrolledComposite, SWT.NONE);GridLayout gridLayout = new GridLayout();gridLayout.numColumns = 5;composite_1.setLayout(gridLayout);{for (int i = 0; i < count; i++) {Group group_1 = new Group(composite_1, SWT.NONE);Button button2 = new Button(group_1, SWT.NONE);Label label2 = new Label(group_1, SWT.NONE);group_1.setLayoutData(new GridData(SWT.CENTER, SWT.CENTER,true, true, 1, 1));{FileInputStream inputStream = null;try {inputStream = new FileInputStream(new File(".\\IMAGE\\a.jpg"));ImageData imageData = new ImageData(inputStream);button2.setImage(new Image(Display.getDefault(),imageData));inputStream.close();} catch (IOException e) {e.printStackTrace();}button2.addSelectionListener(new SelectionListener() {@Overridepublic void widgetSelected(SelectionEvent e) {color = new ProduceColor().produceColor();}@Overridepublic void widgetDefaultSelected(SelectionEvent e) {}});}{label2.setBounds(10, 40, 54, 12);label2.setText("Label" + i);}GroupLayout gl_group_1 = new GroupLayout(group_1);gl_group_1.setHorizontalGroup(gl_group_1.createParallelGroup(GroupLayout.LEADING).add(button2,GroupLayout.DEFAULT_SIZE, 90, Short.MAX_VALUE).add(GroupLayout.TRAILING,gl_group_1.createSequentialGroup().add(10).add(label2,GroupLayout.DEFAULT_SIZE, 101, Short.MAX_VALUE).addContainerGap()));gl_group_1.setVerticalGroup(gl_group_1.createParallelGroup(GroupLayout.LEADING).add(GroupLayout.TRAILING,gl_group_1.createSequentialGroup().addContainerGap().add(button2, GroupLayout.DEFAULT_SIZE, 84,Short.MAX_VALUE).addPreferredGap(LayoutStyle.UNRELATED).add(label2).addContainerGap()));group_1.setLayout(gl_group_1);}}ScrollBar vscrollBar = scrolledComposite.getVerticalBar();vscrollBar.setIncrement(100);scrolledComposite.setContent(composite_1);scrolledComposite.setExpandHorizontal(true);scrolledComposite.setExpandVertical(true);scrolledComposite.setMinSize(composite_1.computeSize(SWT.DEFAULT,SWT.DEFAULT));scrolledComposite.setFocus();}}class ProduceColor {public Color produceColor() {Random random = new Random();int red = random.nextInt(255);int green = random.nextInt(255);int blue = random.nextInt(255);System.out.println("(" + red + "," + green + "," + blue + ")");RGB rgb = new RGB(red, green, blue);Color color = new Color(Display.getDefault(), rgb);return color;}}

效果图：

初始显示的是300个Button

点击500 Button按钮后，显示了500个Button

点击“改变字体颜色”按钮，或者是点击右边的任何一个按钮，在灰色Canvas中点击显示的字体的颜色是随机显示的。

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