java: Make SVWindow more robust (fix three CID issues)

1386093 Division or modulo by zero
1386096 Division or modulo by float zero
1386101 Division or modulo by float zero

A division by zero would have occurred if both sizeX and canvasSizeX or
sizeY and canvasSizeY were 0.

Catch also negative sizes which don't raise a division by zero exception
but which are also invalid.

Signed-off-by: Stefan Weil <[email protected]>

Author: stweil

java/com/google/scrollview/ui/SVWindow.java

@@ -204,10 +204,20 @@ public SVWindow(String name, int hash, int posX, int posY, int sizeX,
     super(name);
 
     // Provide defaults for sizes.
-    if (sizeX == 0) sizeX = canvasSizeX;
-    if (sizeY == 0) sizeY = canvasSizeY;
-    if (canvasSizeX == 0) canvasSizeX = sizeX;
-    if (canvasSizeY == 0) canvasSizeY = sizeY;
+    if (sizeX <= 0) sizeX = canvasSizeX;
+    if (sizeY <= 0) sizeY = canvasSizeY;
+    if (canvasSizeX <= 0) canvasSizeX = sizeX;
+    if (canvasSizeY <= 0) canvasSizeY = sizeY;
+
+    // Avoid later division by zero.
+    if (sizeX <= 0) {
+      sizeX = 1;
+      canvasSizeX = sizeX;
+    }
+    if (sizeY <= 0) {
+      sizeY = 1;
+      canvasSizeY = sizeY;
+    }
 
     // Initialize variables
     nrWindows++;