Eclipse Zest一
1. Eclipse Zest
1.1 概述
Eclipse Zest是一个可视化的图形工具。它基于SWT/Draw2D。Zest还支持JFace中Viewer的概念，因此允许模型和视图的分离。这篇文章假设你已经熟悉了Eclipse RCP或Eclipse Plugin开发。
（我注：其实也可以在一个普通的SWT程序中使用Zest）
1.2 组件
Eclipse Zest有以下组件：
- GraphNode -- graph中，带属性的结点
- GraphConnections -- graph中，用来连接两个结点的边线
- GraphContainer -- graph中，用来包含其他结点的容器
- Graph -- 根，用来包含所有其他的结点（nodes，connections，container）
（我注：graph可以理解为画板，用来画这些结点的）
1.3 布局
Zest提供了一些布局管理器，用来决定怎么布局graph上的结点。下面列出的就是所提供的一些布局：
表1 布局管理器
| TreeLayoutAlgorithm | Graph is displayed in the form of a vertical tree |
| HorizontalTreeLayoutAlgorithm | Similar to TreeLayoutAlgorithm, but layout is horizontal |
| RadialLayoutAlgorithm | Root is the center, the others nodes are placed around this node |
| GridLayoutAlgorithm SpringLayoutAlgorithm |
layout the graph, so that all connections should have approx the same length and that the edges overlap minimal |
| HorizontalShift | move overlapping nodes to the right |
| CompositeLayoutAlgorithm | combines other layout algorithms, for example, HorizontalShift can be the second layout algorithm to move nodes which were still overlapping if another algorithm is used. |
1.4 Filter
可以通过调用setFilter(filter)方法，在布局上增加过滤器（org.eclipse.zest.layouts.filter），用于决定哪些结点和边线是可见的。filter收到一个LayoutItem对象，实际的graph结点可以通过方法getGraphData()得到。
2. 安装
（我注：好像现在安装完GEF后，自动就有了，所以这里略了）
3 你的第一个Zest工程
3.1 开始
创建一个Eclipse RCP应用“de.vogella.zest.first”。选择模板"Eclipse RCP with a view“。 增加"org.eclipse.zest.core" 和 "org.eclipse.zest.layouts" 依赖项。
修改"View.java"的代码如下，用于创建一个简单的graph和连接它的元素：
package de.vogella.zest.first;
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.ui.part.ViewPart;
import org.eclipse.zest.core.widgets.Graph;
import org.eclipse.zest.core.widgets.GraphConnection;
import org.eclipse.zest.core.widgets.GraphNode;
import org.eclipse.zest.core.widgets.ZestStyles;
import org.eclipse.zest.layouts.LayoutStyles;
import org.eclipse.zest.layouts.algorithms.SpringLayoutAlgorithm;
import org.eclipse.zest.layouts.algorithms.TreeLayoutAlgorithm;
public class View extends ViewPart {
public static final String ID = "de.vogella.zest.first.view";
private Graph graph;
private int layout = 1;
public void createPartControl(Composite parent) {
// Graph will hold all other objects
graph = new Graph(parent, SWT.NONE);
// Now a few nodes
GraphNode node1 = new GraphNode(graph, SWT.NONE, "Jim");
GraphNode node2 = new GraphNode(graph, SWT.NONE, "Jack");
GraphNode node3 = new GraphNode(graph, SWT.NONE, "Joe");
GraphNode node4 = new GraphNode(graph, SWT.NONE, "Bill");
// Lets have a directed connection
new GraphConnection(graph, ZestStyles.CONNECTIONS_DIRECTED, node1,
node2);
// Lets have a dotted graph connection
new GraphConnection(graph, ZestStyles.CONNECTIONS_DOT, node2, node3);
// Standard connection
new GraphConnection(graph, SWT.NONE, node3, node1);
// Change line color and line width
GraphConnection graphConnection = new GraphConnection(graph, SWT.NONE,
node1, node4);
graphConnection.changeLineColor(parent.getDisplay().getSystemColor(
SWT.COLOR_GREEN));
// Also set a text
graphConnection.setText("This is a text");
graphConnection.setHighlightColor(parent.getDisplay().getSystemColor(
SWT.COLOR_RED));
graphConnection.setLineWidth(3);
graphConnection.addListener(SWT.SELECTED, new Listener() {
@Override
public void handleEvent(Event event) {
System.out.println("Selected");
}
});
graph.setLayoutAlgorithm(new SpringLayoutAlgorithm(
LayoutStyles.NO_LAYOUT_NODE_RESIZING), true);
}
public void setLayoutManager() {
switch (layout) {
case 1:
graph.setLayoutAlgorithm(new TreeLayoutAlgorithm(
LayoutStyles.NO_LAYOUT_NODE_RESIZING), true);
layout++;
break;
case 2:
graph.setLayoutAlgorithm(new SpringLayoutAlgorithm(
LayoutStyles.NO_LAYOUT_NODE_RESIZING), true);
layout = 1;
break;
}
}
/**
* Passing the focus request to the viewer's control.
*/
public void setFocus() {
}
}
运行以后，得到下图：
3.2 通过command来改变布局
创建一个command，并把以下"de.vogella.zest.first.handler.ChangeLayout"作为它的handler，此handler用于更改布局。最后把这个command加到一个menu上：
package de.vogella.zest.first.handler;
import org.eclipse.core.commands.AbstractHandler;
import org.eclipse.core.commands.ExecutionEvent;
import org.eclipse.core.commands.ExecutionException;
import org.eclipse.ui.IViewPart;
import org.eclipse.ui.handlers.HandlerUtil;
import de.vogella.zest.first.View;
public class ChangeLayout extends AbstractHandler {
@Override
public Object execute(ExecutionEvent event) throws ExecutionException {
IViewPart findView = HandlerUtil.getActiveWorkbenchWindow(event)
.getActivePage().findView("de.vogella.zest.first.view");
View view = (View) findView;
view.setLayoutManager();
return null;
}
}
运行应用，如果你选择了上面的菜单，视图的布局将会改变
4.Zest和JFace
JFace提供了viewers用于分离数据和展现。请看Eclipse JFace TableViewer 或 Eclipse JFace TreeViewer 。JFace要求一个content provider和一个label provider。Zest提供了一个"GraphViewer“作为一个viewer。content provider则是基于connections或者是nodes的。
标准的Zest content providers有：
| IGraphContentProvider | Based on the connections. The connections contain the information which nodes they refer to. Cannot display nodes without connections. |
| IGraphEntityContentProvider | Based on the Node which contain the information about which relationship they have. These relationship are available in the label provider as EntityConnectionData objects. |
| IGraphEntityRelationshipContentProvider | Node based, the content provider defines getRelationShips(sourceNode, destinationNode) which determines the connections. The advantages compared with IGraphEntityContentProvider is that you decide which objects you return. |
Zest的label provider可以是一个标准的JFace的 ILabelProvider，也可以是Zest特定的IEntityStyleProvider。