如何在RCP程序中添加一个banner栏

前言：这段时间还算比较空闲，我准备把过去做过的有些形形色色，甚至有些奇怪的研究总结一下，也许刚好有人用的着也不一定，不枉为之抓耳挠腮的时光和浪费的电力。以前有个客户提出要在RCP程序中添加一个banner栏，研究了很久才搞定。代码是基于eclipse4.3.2的。

先看一下效果预览：

为了添加一个banner栏，我们必须重写RCP程序最外层的layout类，即TrimmedPartLayout.java。这个layout类是用来控制menu，toolbar等最基本的layout布局的。我们写一个CustomTrimmedPartLayout 类，继承自TrimmedPartLayout：

public class CustomTrimmedPartLayout extends TrimmedPartLayout {

    public Composite banner;

    /**
     * This layout is used to support parts that want trim for their containing
     * composites.
     *
     * @param trimOwner
     */
    public CustomTrimmedPartLayout(Composite parent) {
        super(parent);
        banner 

= new Composite(parent, SWT.NONE); GridLayout gridLayout = new GridLayout(1, false); gridLayout.horizontalSpacing=0; gridLayout.verticalSpacing = 0; gridLayout.marginHeight = 0; gridLayout.marginWidth = 0

;
        banner.setLayout(gridLayout);
        //banner.setLayoutData(new GridData(GridData.FILL_BOTH));
    }

    protected void layout(Composite composite, boolean flushCache) {
        Rectangle ca = composite.getClientArea();
        Rectangle caRect = new Rectangle(ca.x, ca.y, ca.width, ca.height);

// 'banner' spans the entire area if (banner != null && banner.isVisible() ) { Point bannerSize = banner.computeSize(caRect.width, SWT.DEFAULT, true); // Don't layout unless we've changed Rectangle newBounds = new Rectangle(caRect.x, caRect.y, bannerSize.x, bannerSize.y); caRect.y += bannerSize.y; caRect.height -= bannerSize.y; if (!

newBounds.equals(banner.getBounds())) {
                    banner.setBounds(newBounds);
            }
        }

        // 'Top' spans the entire area

         if (top != null && top.isVisible()) {
            Point topSize = top.computeSize(caRect.width, SWT.DEFAULT, true);

            // Don't layout unless we've changed
            Rectangle newBounds = new Rectangle(caRect.x, caRect.y, caRect.width,
                    topSize.y);
            if (!newBounds.equals(top.getBounds())) {
                top.setBounds(newBounds);
            }

            caRect.y += topSize.y;
            caRect.height -= topSize.y;
        }

        // Include the gutter whether there is a top area or not.
        caRect.y += gutterTop;
        caRect.height -= gutterTop;

        // 'Bottom' spans the entire area
        if (bottom != null && bottom.isVisible()) {
            Point bottomSize = bottom.computeSize(caRect.width, SWT.DEFAULT,
                    true);
            caRect.height -= bottomSize.y;

            // Don't layout unless we've changed
            Rectangle newBounds = new Rectangle(caRect.x, caRect.y
                    + caRect.height, caRect.width, bottomSize.y);
            if (!newBounds.equals(bottom.getBounds())) {
                bottom.setBounds(newBounds);
            }
        }
        caRect.height -= gutterBottom;

        // 'Left' spans between 'top' and 'bottom'
        if (left != null && left.isVisible()) {
            Point leftSize = left.computeSize(SWT.DEFAULT, caRect.height, true);
            caRect.x += leftSize.x;
            caRect.width -= leftSize.x;

            // Don't layout unless we've changed
            Rectangle newBounds = new Rectangle(caRect.x - leftSize.x,
                    caRect.y, leftSize.x, caRect.height);
            if (!newBounds.equals(left.getBounds())) {
                left.setBounds(newBounds);
            }
        }
        caRect.x += gutterLeft;
        caRect.width -= gutterLeft;

        // 'Right' spans between 'top' and 'bottom'
        if (right != null && right.isVisible()) {
            Point rightSize = right.computeSize(SWT.DEFAULT, caRect.height,
                    true);
            caRect.width -= rightSize.x;

            // Don't layout unless we've changed
            Rectangle newBounds = new Rectangle(caRect.x + caRect.width,
                    caRect.y, rightSize.x, caRect.height);
            if (!newBounds.equals(right.getBounds())) {
                right.setBounds(newBounds);
            }
        }
        caRect.width -= gutterRight;

        // Don't layout unless we've changed
        if (!caRect.equals(clientArea.getBounds())) {
            clientArea.setBounds(caRect);
        }
    }
}

如果我们希望Banner放在工具栏下面，而不是上面，只要稍微修改一下代码的位置

public class CustomTrimmedPartLayout extends TrimmedPartLayout {

public Composite banner;

    /**
     * This layout is used to support parts that want trim for their containing
     * composites.
     *
     * @param trimOwner
     */
    public CustomTrimmedPartLayout(Composite parent) {
        super(parent);
        banner 

= new Composite(parent, SWT.NONE); GridLayout gridLayout = new GridLayout(1, false); gridLayout.horizontalSpacing=0; gridLayout.verticalSpacing = 0; gridLayout.marginHeight = 0; gridLayout.marginWidth = 0

;
        banner.setLayout(gridLayout);
        //banner.setLayoutData(new GridData(GridData.FILL_BOTH));
    }

    protected void layout(Composite composite, boolean flushCache) {
        Rectangle ca = composite.getClientArea();
        Rectangle caRect = new Rectangle(ca.x, ca.y, ca.width, ca.height);

        // 'Top' spans the entire area

         if (top != null && top.isVisible()) {
            Point topSize = top.computeSize(caRect.width, SWT.DEFAULT, true);

            // Don't layout unless we've changed
            Rectangle newBounds = new Rectangle(caRect.x, caRect.y, caRect.width,
                    topSize.y);
            if (!newBounds.equals(top.getBounds())) {
                top.setBounds(newBounds);
            }

            caRect.y += topSize.y;
            caRect.height -= topSize.y;
        }

// 'banner' spans the entire area if (banner != null && banner.isVisible()) { Point bannerSize = banner.computeSize(caRect.width, SWT.DEFAULT, true); // Don't layout unless we've changed Rectangle newBounds = new Rectangle(caRect.x, caRect.y, bannerSize.x, bannerSize.y); caRect.y += bannerSize.y; caRect.height -= bannerSize.y; if (!

newBounds.equals(banner.getBounds())) {
                        banner.setBounds(newBounds);
                }
            }

        // Include the gutter whether there is a top area or not.
        caRect.y += gutterTop;
        caRect.height -= gutterTop;

        // 'Bottom' spans the entire area
        if (bottom != null && bottom.isVisible()) {
            Point bottomSize = bottom.computeSize(caRect.width, SWT.DEFAULT,
                    true);
            caRect.height -= bottomSize.y;

            // Don't layout unless we've changed
            Rectangle newBounds = new Rectangle(caRect.x, caRect.y
                    + caRect.height, caRect.width, bottomSize.y);
            if (!newBounds.equals(bottom.getBounds())) {
                bottom.setBounds(newBounds);
            }
        }
        caRect.height -= gutterBottom;

        // 'Left' spans between 'top' and 'bottom'
        if (left != null && left.isVisible()) {
            Point leftSize = left.computeSize(SWT.DEFAULT, caRect.height, true);
            caRect.x += leftSize.x;
            caRect.width -= leftSize.x;

            // Don't layout unless we've changed
            Rectangle newBounds = new Rectangle(caRect.x - leftSize.x,
                    caRect.y, leftSize.x, caRect.height);
            if (!newBounds.equals(left.getBounds())) {
                left.setBounds(newBounds);
            }
        }
        caRect.x += gutterLeft;
        caRect.width -= gutterLeft;

        // 'Right' spans between 'top' and 'bottom'
        if (right != null && right.isVisible()) {
            Point rightSize = right.computeSize(SWT.DEFAULT, caRect.height,
                    true);
            caRect.width -= rightSize.x;

            // Don't layout unless we've changed
            Rectangle newBounds = new Rectangle(caRect.x + caRect.width,
                    caRect.y, rightSize.x, caRect.height);
            if (!newBounds.equals(right.getBounds())) {
                right.setBounds(newBounds);
            }
        }
        caRect.width -= gutterRight;

        // Don't layout unless we've changed
        if (!caRect.equals(clientArea.getBounds())) {
            clientArea.setBounds(caRect);
        }
    }
}

最后，我们需要把shell加载的layout从TrimmedPartLayout替换为CustomTrimmedPartLayout。

在ApplicationWorkbenchWindowAdvisor 的preWindowOpen中添加如下代码：

public class ApplicationWorkbenchWindowAdvisor extends WorkbenchWindowAdvisor {
...

    public void preWindowOpen() {
        IWorkbenchWindowConfigurer configurer = getWindowConfigurer();
        configurer.setInitialSize(new Point(600, 400));
        configurer.setShowCoolBar(true);
        configurer.setShowPerspectiveBar(true);
        configurer.setShowStatusLine(true);
        configurer.setShowProgressIndicator(false);
        configurer.setShowFastViewBars(false);

        IWorkbenchWindow workbenchWindow=  configurer.getWindow();
        workbenchWindow=  configurer.getWindow();

        Shell shell 

= workbenchWindow.getShell(); TrimmedPartLayout layout = (TrimmedPartLayout)shell.getLayout(); CustomTrimmedPartLayout customLayout = new CustomTrimmedPartLayout(layout.clientArea.getParent()); customLayout.clientArea =

 layout.clientArea;
        shell.setLayout(customLayout);

        Label bannerLabel 

= new Label(customLayout.banner, SWT.SIMPLE|SWT.CENTER); customLayout.banner.setBackground(…); GridData gridData = new GridData(SWT.FILL, SWT.FILL, true, true); bannerLabel.setLayoutData(gridData); Image image =

 Activator.getImageDescriptor(bannerExtensionPoint.getImage()).createImage();
        bannerLabel.setImage(image);
    }
....
}

其中 ---

标记为绿色的代码是用来替换Layout类的

标记为蓝色的代码是用来在banner中创建一个Label，并加载一张作为banner的图片。