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/*******************************************************************************
 * Copyright (c) 2000, 2018 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.opengl;

import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.internal.*;
import org.eclipse.swt.internal.gtk.*;
import org.eclipse.swt.internal.gtk3.*;
import org.eclipse.swt.internal.opengl.glx.*;
import org.eclipse.swt.widgets.*;

/**
 * GLCanvas is a widget capable of displaying OpenGL content.
 *
 * @see GLData
 * @see OpenGL snippets
 * @see Sample code and further information
 *
 * @since 3.2
 */

public class GLCanvas extends Canvas {
	long context;
	long xWindow;
	long glWindow;
	XVisualInfo vinfo;
	static final int MAX_ATTRIBUTES = 32;

/**
 * Create a GLCanvas widget using the attributes described in the GLData
 * object provided.
 *
 * @param parent a composite widget
 * @param style the bitwise OR'ing of widget styles
 * @param data the requested attributes of the GLCanvas
 *
 * @exception IllegalArgumentException
 * ERROR_NULL_ARGUMENT when the data is null
 *     ERROR_UNSUPPORTED_DEPTH when the requested attributes cannot be provided
 * 
 */
public GLCanvas (Composite parent, int style, GLData data) {
	super (parent, style);
	if (data == null) SWT.error (SWT.ERROR_NULL_ARGUMENT);
	int glxAttrib [] = new int [MAX_ATTRIBUTES];
	int pos = 0;
	glxAttrib [pos++] = GLX.GLX_RGBA;
	if (data.doubleBuffer) glxAttrib [pos++] = GLX.GLX_DOUBLEBUFFER;
	if (data.stereo) glxAttrib [pos++] = GLX.GLX_STEREO;
	if (data.redSize > 0) {
		glxAttrib [pos++] = GLX.GLX_RED_SIZE;
		glxAttrib [pos++] = data.redSize;
	}
	if (data.greenSize > 0) {
		glxAttrib [pos++] = GLX.GLX_GREEN_SIZE;
		glxAttrib [pos++] = data.greenSize;
	}
	if (data.blueSize > 0) {
		glxAttrib [pos++] = GLX.GLX_BLUE_SIZE;
		glxAttrib [pos++] = data.blueSize;
	}
	if (data.alphaSize > 0) {
		glxAttrib [pos++] = GLX.GLX_ALPHA_SIZE;
		glxAttrib [pos++] = data.alphaSize;
	}
	if (data.depthSize > 0) {
		glxAttrib [pos++] = GLX.GLX_DEPTH_SIZE;
		glxAttrib [pos++] = data.depthSize;
	}
	if (data.stencilSize > 0) {
		glxAttrib [pos++] = GLX.GLX_STENCIL_SIZE;
		glxAttrib [pos++] = data.stencilSize;
	}
	if (data.accumRedSize > 0) {
		glxAttrib [pos++] = GLX.GLX_ACCUM_RED_SIZE;
		glxAttrib [pos++] = data.accumRedSize;
	}
	if (data.accumGreenSize > 0) {
		glxAttrib [pos++] = GLX.GLX_ACCUM_GREEN_SIZE;
		glxAttrib [pos++] = data.accumGreenSize;
	}
	if (data.accumBlueSize > 0) {
		glxAttrib [pos++] = GLX.GLX_ACCUM_BLUE_SIZE;
		glxAttrib [pos++] = data.accumBlueSize;
	}
	if (data.accumAlphaSize > 0) {
		glxAttrib [pos++] = GLX.GLX_ACCUM_ALPHA_SIZE;
		glxAttrib [pos++] = data.accumAlphaSize;
	}
	if (data.sampleBuffers > 0) {
		glxAttrib [pos++] = GLX.GLX_SAMPLE_BUFFERS;
		glxAttrib [pos++] = data.sampleBuffers;
	}
	if (data.samples > 0) {
		glxAttrib [pos++] = GLX.GLX_SAMPLES;
		glxAttrib [pos++] = data.samples;
	}
	glxAttrib [pos++] = 0;
	GTK.gtk_widget_realize (handle);
	long window = GTK3.gtk_widget_get_window (handle);

	long xDisplay = GDK.gdk_x11_display_get_xdisplay(GDK.gdk_window_get_display(window));
	long infoPtr = GLX.glXChooseVisual (xDisplay, OS.XDefaultScreen (xDisplay), glxAttrib);
	if (infoPtr == 0) {
		dispose ();
		SWT.error (SWT.ERROR_UNSUPPORTED_DEPTH);
	}
	vinfo = new XVisualInfo ();
	GLX.memmove (vinfo, infoPtr, XVisualInfo.sizeof);
	OS.XFree (infoPtr);
	long screen = GDK.gdk_screen_get_default ();
	long gdkvisual = GDK.gdk_x11_screen_lookup_visual (screen, vinfo.visualid);
	long share = data.shareContext != null ? data.shareContext.context : 0;
	context = GLX.glXCreateContext (xDisplay, vinfo, share, true);
	if (context == 0) SWT.error (SWT.ERROR_NO_HANDLES);
	GdkWindowAttr attrs = new GdkWindowAttr ();
	attrs.width = 1;
	attrs.height = 1;
	attrs.event_mask = GDK.GDK_KEY_PRESS_MASK | GDK.GDK_KEY_RELEASE_MASK |
		GDK.GDK_FOCUS_CHANGE_MASK | GDK.GDK_POINTER_MOTION_MASK |
		GDK.GDK_BUTTON_PRESS_MASK | GDK.GDK_BUTTON_RELEASE_MASK |
		GDK.GDK_ENTER_NOTIFY_MASK | GDK.GDK_LEAVE_NOTIFY_MASK |
		GDK.GDK_EXPOSURE_MASK | GDK.GDK_POINTER_MOTION_HINT_MASK;
	attrs.window_type = GDK.GDK_WINDOW_CHILD;
	attrs.visual = gdkvisual;
	glWindow = GTK3.gdk_window_new (window, attrs, GDK.GDK_WA_VISUAL);
	GDK.gdk_window_set_user_data (glWindow, handle);
	if ((style & SWT.NO_BACKGROUND) != 0) {
		//TODO: implement this on GTK3 as pixmaps are gone.
	}

	if (GTK.GTK4) {
		// TODO: Enable when the GdkWindow to GdkSurface changes are in
		//xWindow = GDK.gdk_x11_surface_get_xid(glWindow);
	} else {
		xWindow = GDK.gdk_x11_window_get_xid (glWindow);
	}

	GDK.gdk_window_show (glWindow);

	Listener listener = event -> {
		switch (event.type) {
		case SWT.Paint:
			/**
			* Bug in MESA.  MESA does some nasty sort of polling to try
			* and ensure that their buffer sizes match the current X state.
			* This state can be updated using glViewport().
			* FIXME: There has to be a better way of doing this.
			*/
			int [] viewport = new int [4];
			GLX.glGetIntegerv (GLX.GL_VIEWPORT, viewport);
			GLX.glViewport (viewport [0],viewport [1],viewport [2],viewport [3]);
			break;
		case SWT.Resize:
			Rectangle clientArea = DPIUtil.autoScaleUp(getClientArea());
			GDK.gdk_window_move (glWindow, clientArea.x, clientArea.y);
			GDK.gdk_window_resize (glWindow, clientArea.width, clientArea.height);
			break;
		case SWT.Dispose:
			long window1 = GTK3.gtk_widget_get_window (handle);
			long xDisplay1 = gdk_x11_display_get_xdisplay (window1);
			if (context != 0) {
				if (GLX.glXGetCurrentContext () == context) {
					GLX.glXMakeCurrent (xDisplay1, 0, 0);
				}
				GLX.glXDestroyContext (xDisplay1, context);
				context = 0;
			}
			if (glWindow != 0) {
				GDK.gdk_window_destroy (glWindow);
				glWindow = 0;
			}
			break;
		}
	};
	addListener (SWT.Resize, listener);
	addListener (SWT.Paint, listener);
	addListener (SWT.Dispose, listener);
}

/**
 * Returns a GLData object describing the created context.
 *
 * @return GLData description of the OpenGL context attributes
 * @exception SWTException 
 *    ERROR_WIDGET_DISPOSED - if the receiver has been disposed
 *    ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
 * 
 */
public GLData getGLData () {
	checkWidget ();
	long window = GTK3.gtk_widget_get_window (handle);
	long xDisplay = gdk_x11_display_get_xdisplay (window);
	GLData data = new GLData ();
	int [] value = new int [1];
	GLX.glXGetConfig (xDisplay, vinfo, GLX.GLX_DOUBLEBUFFER, value);
	data.doubleBuffer = value [0] != 0;
	GLX.glXGetConfig (xDisplay, vinfo, GLX.GLX_STEREO, value);
	data.stereo = value [0] != 0;
	GLX.glXGetConfig (xDisplay, vinfo, GLX.GLX_RED_SIZE, value);
	data.redSize = value [0];
	GLX.glXGetConfig (xDisplay, vinfo, GLX.GLX_GREEN_SIZE, value);
	data.greenSize = value [0];
	GLX.glXGetConfig (xDisplay, vinfo, GLX.GLX_BLUE_SIZE, value);
	data.blueSize = value [0];
	GLX.glXGetConfig (xDisplay, vinfo, GLX.GLX_ALPHA_SIZE, value);
	data.alphaSize = value [0];
	GLX.glXGetConfig (xDisplay, vinfo, GLX.GLX_DEPTH_SIZE, value);
	data.depthSize = value [0];
	GLX.glXGetConfig (xDisplay, vinfo, GLX.GLX_STENCIL_SIZE, value);
	data.stencilSize = value [0];
	GLX.glXGetConfig (xDisplay, vinfo, GLX.GLX_ACCUM_RED_SIZE, value);
	data.accumRedSize = value [0];
	GLX.glXGetConfig (xDisplay, vinfo, GLX.GLX_ACCUM_GREEN_SIZE, value);
	data.accumGreenSize = value [0];
	GLX.glXGetConfig (xDisplay, vinfo, GLX.GLX_ACCUM_BLUE_SIZE, value);
	data.accumBlueSize = value [0];
	GLX.glXGetConfig (xDisplay, vinfo, GLX.GLX_ACCUM_ALPHA_SIZE, value);
	data.accumAlphaSize = value [0];
	GLX.glXGetConfig (xDisplay, vinfo, GLX.GLX_SAMPLE_BUFFERS, value);
	data.sampleBuffers = value [0];
	GLX.glXGetConfig (xDisplay, vinfo, GLX.GLX_SAMPLES, value);
	data.samples = value [0];
	return data;
}

/**
 * Returns a boolean indicating whether the receiver's OpenGL context
 * is the current context.
 *
 * @return true if the receiver holds the current OpenGL context,
 * false otherwise
 * @exception SWTException 
 *    ERROR_WIDGET_DISPOSED - if the receiver has been disposed
 *    ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
 * 
 */
public boolean isCurrent () {
	checkWidget ();
	return GLX.glXGetCurrentContext () == context;
}

/**
 * Sets the OpenGL context associated with this GLCanvas to be the
 * current GL context.
 *
 * @exception SWTException 
 *    ERROR_WIDGET_DISPOSED - if the receiver has been disposed
 *    ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
 * 
 */
public void setCurrent () {
	checkWidget ();
	if (GLX.glXGetCurrentContext () == context) return;
	long window = GTK3.gtk_widget_get_window (handle);
	long xDisplay = gdk_x11_display_get_xdisplay (window);
	GLX.glXMakeCurrent (xDisplay, xWindow, context);
}

/**
 * Swaps the front and back color buffers.
 *
 * @exception SWTException 
 *    ERROR_WIDGET_DISPOSED - if the receiver has been disposed
 *    ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
 * 
 */
public void swapBuffers () {
	checkWidget ();
	long window = GTK3.gtk_widget_get_window (handle);
	long xDisplay = gdk_x11_display_get_xdisplay (window);
	GLX.glXSwapBuffers (xDisplay, xWindow);
}

private long gdk_x11_display_get_xdisplay(long window) {
	return GDK.gdk_x11_display_get_xdisplay(GDK.gdk_window_get_display(window));
}
}