【SWT】滚动容器实现商品列表样式

缺乏、安全感 2023-10-05 23:04 45阅读 0赞

## 目的 ##

![滚动容器实现商品列表样式][2d6196d2d113475aad4529103004c770.png]

如图实现一个商品列表，纵向支持滚动，当横向宽度变化时，商品自动向右向上填充。  
当鼠标悬浮在商品上时，商品边框显示。当点击商品时，控制台打印商品名称。

## 分析 ##

滚动容器依然使用 `ScrolledComposite` ，容器中的内容要随着容器宽度变化自动填充，需要是使用 `Rowlayout` 布局方式。在Rowlayout 布局中，每一个商品信息及特效使用 GC 实现。具体见项目 [ https://gitee.com/xzbd/epx][https_gitee.com_xzbd_epx]

## 关键实现 ##

该功能依然集成在RCP中，大致步骤如下：

*  plugin.xml中配置编辑器

<editor
                class="com.xzbd.editors.ScrollGoodListEditor"
                default="false"
                extensions="scgl"
                icon="icons/20220721/16/paobing.png"
                id="com.xzbd.editors.ScrollGoodListEditor"
                name="编辑器-滚动容器-商品列表">
          </editor>

*  定义编辑器

package com.xzbd.editors;
    
    import org.eclipse.core.runtime.IProgressMonitor;
    import org.eclipse.swt.widgets.Composite;
    import org.eclipse.ui.IEditorInput;
    import org.eclipse.ui.IEditorSite;
    import org.eclipse.ui.PartInitException;
    import org.eclipse.ui.part.EditorPart;
    
    import com.xzbd.views.ScrollGoodListEditorViewer;
    
    public class ScrollGoodListEditor extends EditorPart {
        
    
    	public static String ID = "com.xzbd.editors.ScrollGoodListEditor";
    
    	public boolean isDirty = false;
    	private ScrollGoodListEditorViewer viewer;
    
    	@Override
    	public void doSave(IProgressMonitor monitor) {
        
    		clearDirty();
    	}
    
    	@Override
    	public void doSaveAs() {
        
    
    	}
    
    	@Override
    	public void init(IEditorSite site, IEditorInput input) throws PartInitException {
        
    		this.setSite(site);
    		this.setInput(input);
    	}
    
    	@Override
    	public boolean isDirty() {
        
    		return isDirty;
    	}
    
    	@Override
    	public boolean isSaveAsAllowed() {
        
    		return false;
    	}
    
    	@Override
    	public void createPartControl(Composite parent) {
        
    		viewer = new ScrollGoodListEditorViewer(parent, this);
    
    	}
    
    	@Override
    	public void setFocus() {
        
    
    	}
    
    	/**
    	 * 转换编辑器状态
    	 * 
    	 * @param isDirty
    	 */
    	public void changeDirtyState(boolean isDirty) {
        
    		this.isDirty = isDirty;
    		firePropertyChange(PROP_DIRTY);
    	}
    	
    	public void toDirty() {
        
    		changeDirtyState(true);
    	}
    
    	public void clearDirty() {
        
    		changeDirtyState(false);
    	}
    }

*  实现编辑器视图

package com.xzbd.views;
    
    import org.apache.commons.lang.math.RandomUtils;
    import org.eclipse.swt.SWT;
    import org.eclipse.swt.graphics.Font;
    import org.eclipse.swt.graphics.GC;
    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.RowData;
    import org.eclipse.swt.widgets.Composite;
    import org.eclipse.swt.widgets.Listener;
    import org.eclipse.swt.widgets.Widget;
    
    import com.xzbd.constants.ColorConstant;
    import com.xzbd.editors.ScrollGoodListEditor;
    import com.xzbd.utils.AppPrinter;
    import com.xzbd.utils.CompositeUtil;
    import com.xzbd.utils.SWTResourceManager;
    
    /**
     * 
     * 滚动容器--商品列表示例
     *
     */
    public class ScrollGoodListEditorViewer {
        
    
    	private String[] iconNames = {
         "bingkuai.png", "ganlan.png", "guodong.png", "jiroujuan.png", "kafei.png",
    			"kele.png", "mantou.png", "meishikafei.png", "mianhuatang.png", "nailao.png", "paobing.png", "qishui.png",
    			"shutiao.png", "tiantong.png", "xuegao.png", "zhenzhunaicha.png" };
    
    	private ScrollGoodListEditor editor;
    	private Composite parent;
    
    	public ScrollGoodListEditorViewer(Composite parent, ScrollGoodListEditor editor) {
        
    		this.parent = parent;
    		// 缓存 Editor
    		setEditor(editor);
    
    		// 绘制UI
    		buildPageUI();
    	}
    
    	// 创建UI
    	private void buildPageUI() {
        
    		// 设置 parent 布局
    		parent.setLayout(new FillLayout());
    
    		// 生成滚动容器
    		Composite scContent = CompositeUtil.getAutoFillScrollCmp(parent);
    
    		for (int i = 0; i <= 50 + RandomUtils.nextInt(50); i++) {
        
    			Composite itemCmp = new Composite(scContent, SWT.NONE);
    			itemCmp.setLayoutData(new RowData(160, 120));
    
    			// 选定图片
    			String iconName = iconNames[RandomUtils.nextInt(iconNames.length)];
    			String imgPath = "/icons/20220721/32/" + iconName;
    			Image img = SWTResourceManager.getImage(ScrollGoodListEditorViewer.class, imgPath);
    
    			// GC 绘制
    			Boolean[] lineTags = {
         false };
    			itemCmp.addPaintListener(e -> {
        
    				GC gc = e.gc;
    
    				Rectangle clientArea = itemCmp.getClientArea();
    				Rectangle imgBounds = img.getBounds();
    				int imgWidth = (clientArea.width - imgBounds.width) / 2;
    //						int imgHeight = (clientArea.height - imgBounds.height) / 2;
    				gc.drawImage(img, imgWidth, 15);
    
    				String text = iconName.substring(0, iconName.lastIndexOf("."));
    				Font font = SWTResourceManager.getFont("Microsoft YaHei", 14, SWT.NORMAL);
    				if (lineTags[0]) {
        
    					gc.setLineWidth(5);
    					gc.setForeground(ColorConstant.MAIN_BLUE);
    					gc.drawRectangle(0, 0, clientArea.width, clientArea.height);
    					font = SWTResourceManager.getBoldFont(font);
    				}
    
    				gc.setFont(font);
    				Point textExtentPoint = gc.textExtent(text);
    				gc.setForeground(ColorConstant.MAIN_BLUE);
    				int textWidth = (clientArea.width - textExtentPoint.x) / 2;
    				int textHeight = clientArea.height - textExtentPoint.y - 10;
    				gc.drawText(text, textWidth, textHeight, true);
    			});
    
    			// 事件绑定
    			Listener enterListener = e -> {
        
    				lineTags[0] = true;
    				itemCmp.redraw();
    			};
    
    			itemCmp.addListener(SWT.MouseEnter, enterListener);
    
    			Listener exitListener = e -> {
        
    				lineTags[0] = false;
    				itemCmp.redraw();
    			};
    			itemCmp.addListener(SWT.MouseExit, exitListener);
    
    
    			itemCmp.addListener(SWT.MouseUp, e->{
        
    				AppPrinter.println("您挑选了商品： " + iconName);
    			});
    			
    		}
    
    	}
    
    	public ScrollGoodListEditor getEditor() {
        
    		return editor;
    	}
    
    	public void setEditor(ScrollGoodListEditor editor) {
        
    		this.editor = editor;
    	}
    
    	private void addDirtyListener(Widget com) {
        
    		com.addListener(SWT.Modify, e -> {
        
    			editor.toDirty();
    		});
    		
    	}
    
    }

*  滚动容器关键代码

/**
    	 *  生成滚动容器
    	 *  <div>
    	 *  	parent 布局方式需是 FillLayout，返回的容器布局方式是 RowLayout
    	 *  </div>
    	 * @param parent
    	 * @return
    	 */
    	public static Composite getAutoFillScrollCmp(Composite parent) {
        
    		ScrolledComposite scrollComposite = new ScrolledComposite(parent, SWT.V_SCROLL | SWT.BORDER);
    
    		Composite scContent = new Composite(scrollComposite, SWT.NONE);
    		RowLayout rowLayout = new RowLayout();
    		rowLayout.spacing = 16;
    		rowLayout.marginWidth = 24;
    		
    		RowLayout layout = new RowLayout(SWT.HORIZONTAL);
    		layout.wrap = true;
    		scContent.setLayout(layout);
    
    		scrollComposite.setContent(scContent);
    		scrollComposite.setExpandVertical(true);
    		scrollComposite.setExpandHorizontal(true);
    		scrollComposite.addControlListener(ControlListener.controlResizedAdapter(e -> {
        
    			Rectangle r = scrollComposite.getClientArea();
    			scrollComposite.setMinSize(scContent.computeSize(r.width, SWT.DEFAULT));
    		}));
    		
    		return scContent;
    	}

## 效果 ##

![在这里插入图片描述][9bf2488ec9ec40a8b2b10568a179d6b9.gif]

## 总结 ##

依赖 `ScrolledComposite` ，`Rowlayout` ， `GC` 实现了一个滚动容器，该容器支持纵向滚动，横向自动适配填充。适合用于类似与商品列表等展示的场景。

代码详见： [ https://gitee.com/xzbd/epx][https_gitee.com_xzbd_epx]

[2d6196d2d113475aad4529103004c770.png]: https://img-blog.csdnimg.cn/2d6196d2d113475aad4529103004c770.png
[https_gitee.com_xzbd_epx]: https://gitee.com/xzbd/epx
[9bf2488ec9ec40a8b2b10568a179d6b9.gif]: https://img-blog.csdnimg.cn/9bf2488ec9ec40a8b2b10568a179d6b9.gif