自定义的SWT控件

来源：互联网发布：模拟买基金软件编辑：程序博客网时间：2024/04/25 03:09

效果图：

为了在SWT中实现像Windows桌面图标那样的效果，自定义了一个控件，该控件继承自org.eclipse.swt.widgets.Composite，由一个缩略图标(CLabel)和一个图标名称(Label)构成。
缩略图是由图片文件提供，并缩放到固定尺寸。
创建该控件需要向其构造函数传递一个Image和String，分别是缩略图的原图和即将在图标下方显示的名称。
控件的代码如下，很简单：

Java代码

Source

```
import java.io.File;    
```

import org.eclipse.jface.resource.ImageDescriptor;

```
import org.eclipse.swt.SWT;    
```

import org.eclipse.swt.custom.CLabel;

import org.eclipse.swt.events.MouseListener;

import org.eclipse.swt.events.PaintEvent;

import org.eclipse.swt.events.PaintListener;

import org.eclipse.swt.graphics.Image;

import org.eclipse.swt.graphics.Point;

import org.eclipse.swt.graphics.Rectangle;

import org.eclipse.swt.layout.FillLayout;

import org.eclipse.swt.layout.GridData;

import org.eclipse.swt.layout.GridLayout;

import org.eclipse.swt.widgets.Composite;

import org.eclipse.swt.widgets.Display;

import org.eclipse.swt.widgets.Label;

import org.eclipse.swt.widgets.Shell;

```
   
```

public class Thumbnails extends Composite {

```
    private CLabel cLabelImage;    
```
```
    private Image image;    
```
```
    private Label label;    
```
```
    private String labelText;    
```
```
   
```

    private final int IMAGE_SIZE = 164;//缩放后的图片最长的边长为定值。

```
   
```
```
       
```

    public Thumbnails(Composite parent, int style, Image image, String labelText) {

```
        super(parent, style);    
```
```
        this.image = image;    
```
```
        this.labelText = labelText;    
```
```
        initGUI();    
```
```
    }    
```
```
   
```
```
    private void initGUI() {    
```

        GridData data = new GridData ();

```
        data.widthHint = 170;    
```
```
        data.heightHint = 180;    
```
```
        this.setLayoutData(data);    
```
```
        try {    
```

            GridLayout thisLayout = new GridLayout();

            this.setLayout(thisLayout);

```
   
```
```
            {    
```

                GridData cLabelImageGridData = new GridData();

                cLabelImageGridData.horizontalAlignment = GridData.FILL;

                cLabelImageGridData.verticalAlignment = GridData.FILL;

                cLabelImageGridData.grabExcessVerticalSpace = true;

                cLabelImageGridData.grabExcessHorizontalSpace = true;

                cLabelImage = new CLabel(this, SWT.NONE);

                cLabelImage.setLayoutData(cLabelImageGridData);

```
   
```

//              cLabelImage.setImage(this.image);

                cLabelImage.addPaintListener(new PaintListener() {

                    public void paintControl(PaintEvent evt) {

                        cLabelImagePaintControl(evt);

```
                    }    
```
```
                });    
```
```
            }    
```
```
            {    
```

                label = new Label(this, SWT.NONE);

                GridData labelGridData = new GridData();

                labelGridData.horizontalAlignment = GridData.CENTER;

                label.setLayoutData(labelGridData);

                label.setText(this.labelText);

```
            }    
```
```
            this.layout();    
```
```
        } catch (Exception e) {    
```
```
            e.printStackTrace();    
```
```
        }    
```
```
    }    
```
```
   
```
```
       
```

    private void cLabelImagePaintControl(PaintEvent evt) {

        Rectangle bounds = image.getBounds();

        int imageWidth = bounds.width;

        int imageHeight = bounds.height;

```
   
```

        int thumbWidth = IMAGE_SIZE;// TODO: 缩放后的图片最大宽度

        int thumbHeight = IMAGE_SIZE;// TODO: 缩放后的图片最大高度

```
   
```

        double ratio = (double)imageWidth/(double)imageHeight;

```
   
```
```
        //若宽大于高    
```
```
        if(ratio>(double)1){    
```

            thumbHeight = (int)(thumbWidth/ratio);

```
        }else {    
```

            thumbWidth = (int)(thumbHeight*ratio);

```
        }    
```
```
   
```

        // 如果图片小于所略图大小, 不作处理

        if (imageWidth < IMAGE_SIZE && imageHeight < IMAGE_SIZE) {

            thumbWidth = imageWidth;

            thumbHeight = imageHeight;

```
        }    
```
```
   
```

        evt.gc.drawImage(image, 0, 0, bounds.width, bounds.height, 0, 0,

                thumbWidth, thumbHeight);

        //   evt.gc.drawImage(image, srcX, srcY, srcWidth, srcHeight, destX, destY, destWidth, destHeight)

```
    }    
```
```
   
```
```
   
```
```
    @Override   
```

    public void addMouseListener(MouseListener listener) {

        super.addMouseListener(listener);

        //这样在点击图标或标题的时候，整个控件才能被选中。

        cLabelImage.addMouseListener(listener);

        label.addMouseListener(listener);

```
    }    
```
```
   
```
```
    @Override   
```
```
    public void dispose() {    
```

        if(null !=image && !image.isDisposed()){

```
            image.dispose();    
```
```
        }    
```

        if(null !=cLabelImage && !cLabelImage.isDisposed()){

```
            cLabelImage.dispose();    
```
```
        }    
```

        if(null !=label && !label.isDisposed()){

```
            label.dispose();    
```
```
        }    
```
```
   
```
```
        super.dispose();    
```
```
    }    
```
```
       
```
```
       
```

    public static void main(String[] args) {

```
        showGUI();    
```
```
    }    
```
```
   
```
```
       
```
```
    public static void showGUI() {    
```

        Display display = Display.getDefault();

        Shell shell = new Shell(display);

```
   
```

        File imageFile = new File("D://sb.jpg");

```
        Image localImage = null;    
```
```
        if (imageFile.exists()) {    
```

            ImageDescriptor imageDescriptor = ImageDescriptor.createFromFile(

                    null, imageFile.getAbsolutePath());

            localImage = imageDescriptor.createImage();

```
        }    
```
```
   
```

        Thumbnails inst = new Thumbnails(shell, SWT.NULL, localImage, "hello");

```
   
```

        Point size = inst.getSize();

        shell.setLayout(new GridLayout());

```
        shell.layout();    
```

        if (size.x == 0 && size.y == 0) {

```
            inst.pack();    
```
```
            shell.pack();    
```
```
        } else {    
```

            Rectangle shellBounds = shell.computeTrim(0, 0, size.x, size.y);

            shell.setSize(shellBounds.width, shellBounds.height);

```
        }    
```
```
        shell.open();    
```

        while (!shell.isDisposed()) {

            if (!display.readAndDispatch())

```
                display.sleep();    
```
```
        }    
```
```
    }    
```
```
}   
```

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