1 files changed, 108 insertions, 0 deletions
diff --git a/src/VBox/Frontends/VBoxFB/Helper.cpp b/src/VBox/Frontends/VBoxFB/Helper.cpp
new file mode 100644
index 00000000..bdc8ff8c
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+++ b/src/VBox/Frontends/VBoxFB/Helper.cpp
@@ -0,0 +1,108 @@
+/** @file
+ *
+ * VBox frontends: Framebuffer (FB, DirectFB):
+ * Helper routines
+ */
+
+/*
+ * Copyright (C) 2006-2022 Oracle and/or its affiliates.
+ *
+ * This file is part of VirtualBox base platform packages, as
+ * available from https://www.virtualbox.org.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, in version 3 of the
+ * License.
+ *
+ * This program 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 for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <https://www.gnu.org/licenses>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-only
+ */
+
+#include "VBoxFB.h"
+#include "Helper.h"
+
+/**
+ * Globals
+ */
+videoMode videoModes[MAX_VIDEOMODES] = {{0}};
+uint32_t numVideoModes = 0;
+
+/**
+ * callback handler for populating the supported video modes
+ *
+ * @returns callback success indicator
+ * @param   width        width in pixels of the current video mode
+ * @param   height       height in pixels of the current video mode
+ * @param   bpp          bits per pixel of the current video mode
+ * @param   callbackdata user data pointer
+ */
+DFBEnumerationResult enumVideoModesHandler(int width, int height, int bpp, void *callbackdata)
+{
+    if (numVideoModes >= MAX_VIDEOMODES)
+    {
+        return DFENUM_CANCEL;
+    }
+    // don't take palette based modes
+    if (bpp >= 16)
+    {
+        // don't take modes we already have (I have seen many cases where
+        // DirectFB returns the same modes several times)
+        int32_t existingMode = getBestVideoMode(width, height, bpp);
+        if ((existingMode == -1) ||
+            ((videoModes[existingMode].width != (uint32_t)width) ||
+             (videoModes[existingMode].height != (uint32_t)height) ||
+             (videoModes[existingMode].bpp != (uint32_t)bpp)))
+        {
+            videoModes[numVideoModes].width  = (uint32_t)width;
+            videoModes[numVideoModes].height = (uint32_t)height;
+            videoModes[numVideoModes].bpp    = (uint32_t)bpp;
+            numVideoModes++;
+        }
+    }
+    return DFENUM_OK;
+}
+
+/**
+ * Returns the best fitting video mode for the given characteristics.
+ *
+ * @returns index of the best video mode, -1 if no suitable mode found
+ * @param   width  requested width
+ * @param   height requested height
+ * @param   bpp    requested bit depth
+ */
+int32_t getBestVideoMode(uint32_t width, uint32_t height, uint32_t bpp)
+{
+    int32_t bestMode = -1;
+
+    for (uint32_t i = 0; i < numVideoModes; i++)
+    {
+        // is this mode compatible?
+        if ((videoModes[i].width >= width) && (videoModes[i].height >= height) &&
+            (videoModes[i].bpp >= bpp))
+        {
+            // first suitable mode?
+            if (bestMode == -1)
+            {
+                bestMode = i;
+            } else
+            {
+                // is it better than the one we got before?
+                if ((videoModes[i].width  < videoModes[bestMode].width) ||
+                    (videoModes[i].height < videoModes[bestMode].height) ||
+                    (videoModes[i].bpp    < videoModes[bestMode].bpp))
+                {
+                    bestMode = i;
+                }
+            }
+        }
+    }
+    return bestMode;
+}