Posted by Wade Walker on Jan 14, 2011; 4:17pm
URL: https://forum.jogamp.org/Render-problems-for-custom-context-menu-in-OpenGL-SWT-tp2255271p2256353.html

Hi Alex,

Here's a complete program that opens a context menu in SWT with the SWT GLCanvas when the user right-clicks. I tested it on Linux 64-bit with GTK just now, but it should work on Windows too. It looks like your problem was you were trying to set the menu on the composite instead of the GLCanvas.

package name.wadewalker.onetriangle;

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.PaintEvent;
import org.eclipse.swt.events.PaintListener;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.opengl.GLCanvas;
import org.eclipse.swt.opengl.GLData;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Event;
import org.eclipse.swt.widgets.Listener;
import org.eclipse.swt.widgets.Menu;
import org.eclipse.swt.widgets.MenuItem;
import org.eclipse.swt.widgets.Shell;

import javax.media.opengl.GL;
import javax.media.opengl.GLProfile;
import javax.media.opengl.GL2;
import javax.media.opengl.GLContext;
import javax.media.opengl.GLDrawableFactory;
import javax.media.opengl.glu.GLU;

public class OneTriangle {

    public static void main(String [] args) {
        GLProfile.initSingleton( true );
        Display display = new Display();
                final Shell shell = new Shell( display );
                shell.setLayout( new FillLayout() );
                final Composite composite = new Composite( shell, SWT.NONE );
        composite.setLayout( new FillLayout() );

        GLData gldata = new GLData();
        gldata.doubleBuffer = true;
        // need SWT.NO_BACKGROUND to prevent SWT from clearing the window
        // at the wrong times (we use glClear for this instead)
        final GLCanvas glcanvas = new GLCanvas( composite, SWT.NO_BACKGROUND, gldata );
        glcanvas.setCurrent();
        GLProfile glprofile = GLProfile.get( GLProfile.GL2 );
        final GLContext glcontext = GLDrawableFactory.getFactory( glprofile ).createExternalGLContext();

        // fix the viewport when the user resizes the window
        glcanvas.addListener( SWT.Resize, new Listener() {
            public void handleEvent(Event event) {
            setup( glcanvas, glcontext );
            }
        });

        // draw the triangle when the OS tells us that any part of the window needs drawing
        glcanvas.addPaintListener( new PaintListener() {
            public void paintControl( PaintEvent paintevent ) {
                render( glcanvas, glcontext );
            }
        });

        final Menu menu = new Menu( shell, SWT.POP_UP );
        MenuItem item = new MenuItem( menu, SWT.PUSH );
        item.setText( "Popup" );
        glcanvas.setMenu( menu );

        glcanvas.addListener( SWT.MenuDetect, new Listener () {
            public void handleEvent( Event event ) {
                // this gets called when the user right-clicks
            }
        });

                shell.setText( "OneTriangle" );
                shell.setSize( 640, 480 );
                shell.open();

                while( !shell.isDisposed() ) {
                        if( !display.readAndDispatch() )
                                display.sleep();
                }

        glcanvas.dispose();
                display.dispose();
    }

    private static void setup( GLCanvas glcanvas, GLContext glcontext ) {
        Rectangle rectangle = glcanvas.getClientArea();

        glcanvas.setCurrent();
        glcontext.makeCurrent();

        GL2 gl = glcontext.getGL().getGL2();
        gl.glMatrixMode( GL2.GL_PROJECTION );
        gl.glLoadIdentity();

        // coordinate system origin at lower left with width and height same as the window
        GLU glu = new GLU();
        glu.gluOrtho2D( 0.0f, rectangle.width, 0.0f, rectangle.height );

        gl.glMatrixMode( GL2.GL_MODELVIEW );
        gl.glLoadIdentity();

        gl.glViewport( 0, 0, rectangle.width, rectangle.height );
        glcontext.release();    
    }

    private static void render( GLCanvas glcanvas, GLContext glcontext ) {
        Rectangle rectangle = glcanvas.getClientArea();

        glcanvas.setCurrent();
        glcontext.makeCurrent();

        GL2 gl = glcontext.getGL().getGL2();
        gl.glClear( GL.GL_COLOR_BUFFER_BIT );

        // draw a triangle filling the window
        gl.glLoadIdentity();
        gl.glBegin( GL.GL_TRIANGLES );
        gl.glColor3f( 1, 0, 0 );
        gl.glVertex2f( 0, 0 );
        gl.glColor3f( 0, 1, 0 );
        gl.glVertex2f( rectangle.width, 0 );
        gl.glColor3f( 0, 0, 1 );
        gl.glVertex2f( rectangle.width / 2, rectangle.height );
        gl.glEnd();

        glcanvas.swapBuffers();
        glcontext.release();    
    }
}

Note that if you're doing the context menu in an Eclipse RCP app, you may want something more like this (this is clipped from a program that opens a context menu in an IEditorPart):

        createMenuActions();
        MenuManager menumanagerPopup = new MenuManager( "#PopupMenu" );
        menumanagerPopup.setRemoveAllWhenShown( false );
        final Menu menu = menumanagerPopup.createContextMenu( glcanvas );
        glcanvas.setMenu( menu );
        placementeditor.getEditorSite().registerContextMenu( menumanagerPopup, this );
        menumanagerPopup.add( createrowaction );