/****************************************************************************
**
** Copyright (C) 2015 The Qt Company Ltd.
** Contact: http://www.qt.io/licensing/
**
** This file is part of the plugins of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL21$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see http://www.qt.io/terms-conditions. For further
** information use the contact form at http://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 or version 3 as published by the Free
** Software Foundation and appearing in the file LICENSE.LGPLv21 and
** LICENSE.LGPLv3 included in the packaging of this file. Please review the
** following information to ensure the GNU Lesser General Public License
** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** As a special exception, The Qt Company gives you certain additional
** rights. These rights are described in The Qt Company LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include <QLoggingCategory>
#include "qxlibeglintegration_p.h"

Q_LOGGING_CATEGORY(lcXlibEglDebug, "qt.egl.xlib.debug")

VisualID QXlibEglIntegration::getCompatibleVisualId(Display *display, EGLDisplay eglDisplay, EGLConfig config)
{
    VisualID    visualId = 0;
    EGLint      eglValue = 0;

    EGLint configRedSize = 0;
    eglGetConfigAttrib(eglDisplay, config, EGL_RED_SIZE, &configRedSize);

    EGLint configGreenSize = 0;
    eglGetConfigAttrib(eglDisplay, config, EGL_GREEN_SIZE, &configGreenSize);

    EGLint configBlueSize = 0;
    eglGetConfigAttrib(eglDisplay, config, EGL_BLUE_SIZE, &configBlueSize);

    EGLint configAlphaSize = 0;
    eglGetConfigAttrib(eglDisplay, config, EGL_ALPHA_SIZE, &configAlphaSize);

    eglGetConfigAttrib(eglDisplay, config, EGL_CONFIG_ID, &eglValue);
    int configId = eglValue;

    // See if EGL provided a valid VisualID:
    eglGetConfigAttrib(eglDisplay, config, EGL_NATIVE_VISUAL_ID, &eglValue);
    visualId = (VisualID)eglValue;
    if (visualId) {
        // EGL has suggested a visual id, so get the rest of the visual info for that id:
        XVisualInfo visualInfoTemplate;
        memset(&visualInfoTemplate, 0, sizeof(XVisualInfo));
        visualInfoTemplate.visualid = visualId;

        XVisualInfo *chosenVisualInfo;
        int matchingCount = 0;
        chosenVisualInfo = XGetVisualInfo(display, VisualIDMask, &visualInfoTemplate, &matchingCount);
        if (chosenVisualInfo) {
            // Skip size checks if implementation supports non-matching visual
            // and config (QTBUG-9444).
            if (q_hasEglExtension(eglDisplay,"EGL_NV_post_convert_rounding")) {
                XFree(chosenVisualInfo);
                return visualId;
            }
            // Skip also for i.MX6 where 565 visuals are suggested for the default 444 configs and it works just fine.
            const char *vendor = eglQueryString(eglDisplay, EGL_VENDOR);
            if (vendor && strstr(vendor, "Vivante")) {
                XFree(chosenVisualInfo);
                return visualId;
            }

            int visualRedSize = qPopulationCount(chosenVisualInfo->red_mask);
            int visualGreenSize = qPopulationCount(chosenVisualInfo->green_mask);
            int visualBlueSize = qPopulationCount(chosenVisualInfo->blue_mask);
            int visualAlphaSize = chosenVisualInfo->depth == 32 ? 8 : 0;

            const bool visualMatchesConfig = visualRedSize == configRedSize
                && visualGreenSize == configGreenSize
                && visualBlueSize == configBlueSize
                && visualAlphaSize == configAlphaSize;

            // In some cases EGL tends to suggest a 24-bit visual for 8888
            // configs. In such a case we have to fall back to XGetVisualInfo.
            if (!visualMatchesConfig) {
                visualId = 0;
                qCDebug(lcXlibEglDebug,
                        "EGL suggested using X Visual ID %d (%d %d %d depth %d) for EGL config %d"
                        "(%d %d %d %d), but this is incompatible",
                        (int)visualId, visualRedSize, visualGreenSize, visualBlueSize, chosenVisualInfo->depth,
                        configId, configRedSize, configGreenSize, configBlueSize, configAlphaSize);
            }
        } else {
            qCDebug(lcXlibEglDebug, "EGL suggested using X Visual ID %d for EGL config %d, but that isn't a valid ID",
                    (int)visualId, configId);
            visualId = 0;
        }
        XFree(chosenVisualInfo);
    }
    else
        qCDebug(lcXlibEglDebug, "EGL did not suggest a VisualID (EGL_NATIVE_VISUAL_ID was zero) for EGLConfig %d", configId);

    if (visualId) {
        qCDebug(lcXlibEglDebug, configAlphaSize > 0
                ? "Using ARGB Visual ID %d provided by EGL for config %d"
                : "Using Opaque Visual ID %d provided by EGL for config %d", (int)visualId, configId);
        return visualId;
    }

    // Finally, try to use XGetVisualInfo and only use the bit depths to match on:
    if (!visualId) {
        XVisualInfo visualInfoTemplate;
        memset(&visualInfoTemplate, 0, sizeof(XVisualInfo));
        XVisualInfo *matchingVisuals;
        int matchingCount = 0;

        visualInfoTemplate.depth = configRedSize + configGreenSize + configBlueSize + configAlphaSize;
        matchingVisuals = XGetVisualInfo(display,
                                         VisualDepthMask,
                                         &visualInfoTemplate,
                                         &matchingCount);
        if (!matchingVisuals) {
            // Try again without taking the alpha channel into account:
            visualInfoTemplate.depth = configRedSize + configGreenSize + configBlueSize;
            matchingVisuals = XGetVisualInfo(display,
                                             VisualDepthMask,
                                             &visualInfoTemplate,
                                             &matchingCount);
        }

        if (matchingVisuals) {
            visualId = matchingVisuals[0].visualid;
            XFree(matchingVisuals);
        }
    }

    if (visualId) {
        qCDebug(lcXlibEglDebug, "Using Visual ID %d provided by XGetVisualInfo for EGL config %d", (int)visualId, configId);
        return visualId;
    }

    qWarning("Unable to find an X11 visual which matches EGL config %d", configId);
    return (VisualID)0;
}