Ticket #5717: toon_magnify_clipping.txt

diff --git a/engines/toon/toon.cpp b/engines/toon/toon.cpp
index 44c747c..30c4239 100644
--- a/engines/toon/toon.cpp
+++ b/engines/toon/toon.cpp
@@ -464,24 +464,42 @@ void ToonEngine::doMagnifierEffect() {
                11, 11, 11, 11, 12
        };
 
+       // clip the range so that it doesn't go outside the screen
+       int32 minY = -12, maxY = 12, minX = -12, maxX = 12;
+       if (minY + posY < 0)
+               minY = -posY;
+       if (maxY + posY >= surface.h)
+               maxY = surface.h - posY - 1;
+       if (minX + posX < 0)
+               minX = -posX;
+       if (maxX + posX >= surface.w)
+               maxX = surface.w - posX - 1;
+
        byte tempBuffer[25 * 25];
-       for (int32 y = -12; y <= 12; y++) {
-               for (int32 x = -12; x <= 12; x++) {
+       for (int32 y = minY; y <= maxY; y++) {
+               for (int32 x = minX; x <= maxX; x++) {
                        int32 destPitch = surface.pitch;
                        uint8 *curRow = (uint8 *)surface.pixels + (posY + y) * destPitch + (posX + x);
                        tempBuffer[(y + 12) * 25 + x + 12] = *curRow;
                }
        }
 
-       for (int32 y = -12; y <= 12; y++) {
-               for (int32 x = -12; x <= 12; x++) {
+       for (int32 y = minY; y <= maxY; y++) {
+               for (int32 x = minX; x <= maxX; x++) {
                        int32 dist = y * y + x * x;
                        if (dist > 144)
                                continue;
                        int32 destPitch = surface.pitch;
                        uint8 *curRow = (uint8 *)surface.pixels + (posY + y) * destPitch + (posX + x);
+
+                       // force the magnification source to only use pixels which are present
                        int32 lerp = (512 + intSqrt[dist] * 256 / 12);
-                       *curRow = tempBuffer[(y * lerp / 1024 + 12) * 25 + x * lerp / 1024 + 12];
+                       int32 srcX = (x * lerp / 1024);
+                       srcX = MAX(MIN(srcX, maxX), minX);
+                       int32 srcY = (y * lerp / 1024);
+                       srcY = MAX(MIN(srcY, maxY), minY);
+
+                       *curRow = tempBuffer[(srcY + 12) * 25 + srcX + 12];
                }
        }
 }