path: root/src/classes/javax/media/opengl/GLDrawableFactory.java

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 * This software is provided "AS IS," without a warranty of any kind. ALL
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package javax.media.opengl;

import java.lang.reflect.*;
import java.security.*;
import com.sun.opengl.impl.*;

/** <P> Provides a virtual machine- and operating system-independent
    mechanism for creating {@link GLDrawable}s. </P>

    <P> The {@link javax.media.opengl.GLCapabilities} objects passed
    in to the various factory methods are used as a hint for the
    properties of the returned drawable. The default capabilities
    selection algorithm (equivalent to passing in a null {@link
    GLCapabilitiesChooser}) is described in {@link
    DefaultGLCapabilitiesChooser}. Sophisticated applications needing
    to change the selection algorithm may pass in their own {@link
    GLCapabilitiesChooser} which can select from the available pixel
    formats. The GLCapabilitiesChooser mechanism may not be supported
    by all implementations or on all platforms, in which case any
    passed GLCapabilitiesChooser will be ignored. </P>

    <P> Because of the multithreaded nature of the Java platform's
    Abstract Window Toolkit, it is typically not possible to immediately
    reject a given {@link GLCapabilities} as being unsupportable by
    either returning <code>null</code> from the creation routines or
    raising a {@link GLException}. The semantics of the rejection
    process are (unfortunately) left unspecified for now. The current
    implementation will cause a {@link GLException} to be raised
    during the first repaint of the {@link GLCanvas} or {@link
    GLJPanel} if the capabilities can not be met. Pbuffers are always
    created immediately and their creation will fail with a {@link
    GLException} if errors occur. </P>

    <P> The concrete GLDrawableFactory subclass instantiated by {@link
    #getFactory getFactory} can be changed by setting the system
    property <code>opengl.factory.class.name</code> to the
    fully-qualified name of the desired class. </P>
*/

public abstract class GLDrawableFactory {
  private static GLDrawableFactory factory;

  /** Creates a new GLDrawableFactory instance. End users do not need
      to call this method. */
  protected GLDrawableFactory() {
  }

  /** Returns the sole GLDrawableFactory instance. The {@link
      GLProfile GLProfile} must be configured before calling this
      method. */
  public static GLDrawableFactory getFactory() throws GLException {
    if (null == factory) {
      if (null == GLProfile.getProfile()) {
        throw new GLException("GLProfile was not properly initialized");
      }

      // See if the user is requesting one of the embedded profiles,
      // and if so, try to instantiate the EGLDrawableFactory
      if (GLProfile.isGLES()) {
        try {
          factory = (GLDrawableFactory) GLReflection.createInstance("com.sun.opengl.impl.egl.EGLDrawableFactory");
        } catch (Exception e) {
          e.printStackTrace();
        }
      } else if (!GLProfile.isGL2() && !GLProfile.isGL2ES12()) {
        // We require that the user passes in one of the known profiles
        throw new GLException("Unknown or unsupported profile \"" + GLProfile.getProfile() + "\"");
      }

      if (null == factory) {
        // Use the desktop OpenGL as the fallback always
        try {
          String factoryClassName =
            (String) AccessController.doPrivileged(new PrivilegedAction() {
                public Object run() {
                  return System.getProperty("opengl.factory.class.name");
                }
              });
          String osName = System.getProperty("os.name");
          String osNameLowerCase = osName.toLowerCase();

          if (factoryClassName == null) {
            if (osNameLowerCase.startsWith("windows")) {
              factoryClassName = "com.sun.opengl.impl.windows.wgl.WindowsWGLDrawableFactory";
            } else if (osNameLowerCase.startsWith("mac os x")) {
              // FIXME: remove this residual dependence on the AWT
              factoryClassName = "com.sun.opengl.impl.macosx.cgl.awt.MacOSXAWTCGLDrawableFactory";
            } else {
              // Assume Linux, Solaris, etc. Should probably test for these explicitly.
              factoryClassName = "com.sun.opengl.impl.x11.glx.X11GLXDrawableFactory";
            }
          }

          factory = (GLDrawableFactory) GLReflection.createInstance(factoryClassName);
        } catch (Exception e) {
          throw new GLException(e);
        }
      }
    }

    return factory;
  }

  /** Shuts down this GLDrawableFactory, releasing resources
      associated with it. Before calling this method you should first
      destroy any GLContexts and GLDrawables that have been created
      and are still in use. No further OpenGL calls may be made after
      shutting down the GLDrawableFactory. */
  public void shutdown() {
  }

  /**
   * Returns a GLDrawable that wraps a platform-specific window system
   * object, such as an AWT or LCDUI Canvas. On platforms which
   * support it, selects a pixel format compatible with the supplied
   * GLCapabilities, or if the passed GLCapabilities object is null,
   * uses a default set of capabilities. On these platforms, uses
   * either the supplied GLCapabilitiesChooser object, or if the
   * passed GLCapabilitiesChooser object is null, uses a
   * DefaultGLCapabilitiesChooser instance.
   *
   * @throws IllegalArgumentException if the passed target is null
   * @throws GLException if any window system-specific errors caused
   *         the creation of the GLDrawable to fail.
   */
  public abstract GLDrawable createGLDrawable(NativeWindow target,
                                              GLCapabilities capabilities,
                                              GLCapabilitiesChooser chooser)
    throws IllegalArgumentException, GLException;
  
  //----------------------------------------------------------------------
  // Methods to create high-level objects

  /**
   * Returns true if it is possible to create a GLPbuffer. Some older
   * graphics cards do not have this capability.
   */
  public abstract boolean canCreateGLPbuffer();

  /**
   * Creates a GLPbuffer with the given capabilites and dimensions. <P>
   *
   * See the note in the overview documentation on
   * <a href="../../../overview-summary.html#SHARING">context sharing</a>.
   *
   * @throws GLException if any window system-specific errors caused
   *         the creation of the GLPbuffer to fail.
   */
  public abstract GLPbuffer createGLPbuffer(GLCapabilities capabilities,
                                            GLCapabilitiesChooser chooser,
                                            int initialWidth,
                                            int initialHeight,
                                            GLContext shareWith)
    throws GLException;

  //----------------------------------------------------------------------
  // Methods for interacting with third-party OpenGL libraries

  /**
   * <P> Creates a GLContext object representing an existing OpenGL
   * context in an external (third-party) OpenGL-based library. This
   * GLContext object may be used to draw into this preexisting
   * context using its {@link GL} and {@link
   * javax.media.opengl.glu.GLU} objects. New contexts created through
   * {@link GLDrawable}s may share textures and display lists with
   * this external context. </P>
   *
   * <P> The underlying OpenGL context must be current on the current
   * thread at the time this method is called. The user is responsible
   * for the maintenance of the underlying OpenGL context; calls to
   * <code>makeCurrent</code> and <code>release</code> on the returned
   * GLContext object have no effect. If the underlying OpenGL context
   * is destroyed, the <code>destroy</code> method should be called on
   * the <code>GLContext</code>. A new <code>GLContext</code> object
   * should be created for each newly-created underlying OpenGL
   * context.
   *
   * @throws GLException if any window system-specific errors caused
   *         the creation of the external GLContext to fail.
   */
  public abstract GLContext createExternalGLContext()
    throws GLException;

  /**
   * Returns true if it is possible to create an external GLDrawable
   * object via {@link #createExternalGLDrawable}.
   */
  public abstract boolean canCreateExternalGLDrawable();

  /**
   * <P> Creates a {@link GLDrawable} object representing an existing
   * OpenGL drawable in an external (third-party) OpenGL-based
   * library. This GLDrawable object may be used to create new,
   * fully-functional {@link GLContext}s on the OpenGL drawable. This
   * is useful when interoperating with a third-party OpenGL-based
   * library and it is essential to not perturb the state of the
   * library's existing context, even to the point of not sharing
   * textures or display lists with that context. </P>
   *
   * <P> An underlying OpenGL context must be current on the desired
   * drawable and the current thread at the time this method is
   * called. The user is responsible for the maintenance of the
   * underlying drawable. If one or more contexts are created on the
   * drawable using {@link GLDrawable#createContext}, and the drawable
   * is deleted by the third-party library, the user is responsible
   * for calling {@link GLContext#destroy} on these contexts. </P>
   *
   * <P> Calls to <code>setSize</code>, <code>getWidth</code> and
   * <code>getHeight</code> are illegal on the returned GLDrawable. If
   * these operations are required by the user, they must be performed
   * by the third-party library. </P>
   *
   * <P> It is legal to create both an external GLContext and
   * GLDrawable representing the same third-party OpenGL entities.
   * This can be used, for example, to query current state information
   * using the external GLContext and then create and set up new
   * GLContexts using the external GLDrawable. </P>
   *
   * <P> This functionality may not be available on all platforms and
   * {@link #canCreateExternalGLDrawable} should be called first to
   * see if it is present. For example, on X11 platforms, this API
   * requires the presence of GLX 1.3 or later.
   *
   * @throws GLException if any window system-specific errors caused
   *         the creation of the external GLDrawable to fail.
   */
  public abstract GLDrawable createExternalGLDrawable()
    throws GLException;
}