1 files changed, 159 insertions, 0 deletions
diff --git a/src/VBox/Main/src-all/DisplayResampleImage.cpp b/src/VBox/Main/src-all/DisplayResampleImage.cpp
new file mode 100644
index 00000000..04f0cdbe
--- /dev/null
+++ b/src/VBox/Main/src-all/DisplayResampleImage.cpp
@@ -0,0 +1,159 @@
+/* $Id: DisplayResampleImage.cpp $ */
+/** @file
+ * Image resampling code, used for snapshot thumbnails.
+ */
+
+/*
+ * Copyright (C) 2009-2022 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 <iprt/types.h>
+
+DECLINLINE(void) imageSetPixel (uint8_t *im, int x, int y, int color, int w)
+{
+    *(int32_t *)(im + y * w * 4 + x * 4) = color;
+}
+
+#define trueColorGetAlpha(c) (((c) & 0x7F000000) >> 24)
+#define trueColorGetRed(c)   (((c) & 0xFF0000)   >> 16)
+#define trueColorGetGreen(c) (((c) & 0x00FF00)   >> 8)
+#define trueColorGetBlue(c)   ((c) & 0x0000FF)
+
+/* Fast integer implementation for 32 bpp bitmap scaling.
+ * Using fixed point values * 16.
+ */
+typedef int32_t FIXEDPOINT;
+#define INT_TO_FIXEDPOINT(i) (FIXEDPOINT)((i) << 4)
+#define FIXEDPOINT_TO_INT(v) (int)((v) >> 4)
+#define FIXEDPOINT_FLOOR(v) ((v) & ~0xF)
+#define FIXEDPOINT_FRACTION(v) ((v) & 0xF)
+
+/* For 32 bit source only. */
+void BitmapScale32 (uint8_t *dst,
+                    int dstW, int dstH,
+                    const uint8_t *src,
+                    int iDeltaLine,
+                    int srcW, int srcH)
+{
+    int x, y;
+
+    for (y = 0; y < dstH; y++)
+    {
+        FIXEDPOINT sy1 = INT_TO_FIXEDPOINT(y * srcH) / dstH;
+        FIXEDPOINT sy2 = INT_TO_FIXEDPOINT((y + 1) * srcH) / dstH;
+
+        for (x = 0; x < dstW; x++)
+        {
+            FIXEDPOINT red = 0, green = 0, blue = 0;
+
+            FIXEDPOINT sx1 = INT_TO_FIXEDPOINT(x * srcW) / dstW;
+            FIXEDPOINT sx2 = INT_TO_FIXEDPOINT((x + 1) * srcW) / dstW;
+
+            FIXEDPOINT spixels = (sx2 - sx1) * (sy2 - sy1);
+
+            FIXEDPOINT sy = sy1;
+
+            do
+            {
+                FIXEDPOINT yportion;
+                if (FIXEDPOINT_FLOOR (sy) == FIXEDPOINT_FLOOR (sy1))
+                {
+                    yportion = INT_TO_FIXEDPOINT(1) - FIXEDPOINT_FRACTION(sy);
+                    if (yportion > sy2 - sy1)
+                    {
+                        yportion = sy2 - sy1;
+                    }
+                    sy = FIXEDPOINT_FLOOR (sy);
+                }
+                else if (sy == FIXEDPOINT_FLOOR (sy2))
+                {
+                    yportion = FIXEDPOINT_FRACTION(sy2);
+                }
+                else
+                {
+                    yportion = INT_TO_FIXEDPOINT(1);
+                }
+
+                const uint8_t *pu8SrcLine = src + iDeltaLine * FIXEDPOINT_TO_INT(sy);
+                FIXEDPOINT sx = sx1;
+                do
+                {
+                    FIXEDPOINT xportion;
+                    FIXEDPOINT pcontribution;
+                    if (FIXEDPOINT_FLOOR (sx) == FIXEDPOINT_FLOOR (sx1))
+                    {
+                        xportion = INT_TO_FIXEDPOINT(1) - FIXEDPOINT_FRACTION(sx);
+                        if (xportion > sx2 - sx1)
+                        {
+                            xportion = sx2 - sx1;
+                        }
+                        pcontribution = xportion * yportion;
+                        sx = FIXEDPOINT_FLOOR (sx);
+                    }
+                    else if (sx == FIXEDPOINT_FLOOR (sx2))
+                    {
+                        xportion = FIXEDPOINT_FRACTION(sx2);
+                        pcontribution = xportion * yportion;
+                    }
+                    else
+                    {
+                        xportion = INT_TO_FIXEDPOINT(1);
+                        pcontribution = xportion * yportion;
+                    }
+                    /* Color depth specific code begin */
+                    int32_t p = *(int32_t *)(pu8SrcLine + FIXEDPOINT_TO_INT(sx) * 4);
+                    /* Color depth specific code end */
+                    red   += trueColorGetRed (p) * pcontribution;
+                    green += trueColorGetGreen (p) * pcontribution;
+                    blue  += trueColorGetBlue (p) * pcontribution;
+
+                    sx += INT_TO_FIXEDPOINT(1);
+                } while (sx < sx2);
+
+                sy += INT_TO_FIXEDPOINT(1);
+            } while (sy < sy2);
+
+            if (spixels != 0)
+            {
+                red /= spixels;
+                green /= spixels;
+                blue /= spixels;
+            }
+            /* Clamping to allow for rounding errors above */
+            if (red > 255)
+            {
+                red = 255;
+            }
+            if (green > 255)
+            {
+                green = 255;
+            }
+            if (blue > 255)
+            {
+                blue = 255;
+            }
+            imageSetPixel (dst,
+                           x, y,
+                           ( ((int) red) << 16) + (((int) green) << 8) + ((int) blue),
+                           dstW);
+        }
+    }
+}