【SWT】滚动容器实现商品列表样式

目的

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

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

      <!-- 编辑器-滚动容器-商品列表 -->
      <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

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