systemScale.c

/*
 * Copyright (c) 2016, 2021, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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#include "systemScale.h"
#include <stdlib.h>

static int getScale(const char *name) {
    char *uiScale = getenv(name);
    if (uiScale != NULL) {
        double scale = strtod(uiScale, NULL);
        if (scale < 1) {
            return -1;
        }
        return (int) scale;
    }
    return -1;
}

double getNativeScaleFactor() {
    static int scale = -2.0;

    if (scale == -2) {
        scale = getScale("J2D_UISCALE");
    }

    if (scale > 0) {
        return scale;
    }

    return getScale("GDK_SCALE");
}