Question

I am trying to set a property that is an enum using an integer value, like

Graphics g = this.CreateGraphics();
int enumValue = 2; // corresponds to SmoothingMode.HighQuality
g.SmoothingMode = (SmoothingMode)2; // does not have expected result
// also tried:
SmoothingMode sm = (SmoothingMode)Enum.ToObject(typeof(SmoothingMode), enumValue); // works correctly
g.SmoothingMode = sm; // still doesn't work!

But the object’s property never gets set to the correct enum value. I’ve run this through VS2010’s debugger and the casting and/or use of Enum.ToObject works correctly, but after the assignment, g.SmoothingMode is AntiAlias instead of HighQuality, for example. In fact, no matter what number I cast, the assignment always results in either AntiAlias (int equivalent 3) or None (int equivalent 4) being assigned to the object’s property.

Is there something different about when an enum is a property of a class that affects casting & assignment, or just something weird about Graphics.SmoothingMode, or what?

Answer 1

Take a look at SmoothingMode Enumeration description.

Quote:

Default , None, and HighSpeed are
equivalent and specify rendering
without smoothing applied.

AntiAlias and HighQuality are
equivalent and specify rendering with
smoothing applied.

So basically there are three modes:

• antialiased rendering (HighQuality, AntiAlias)
• no antialiasing (Default, None, HighSpeed
• invalid (Invalid)

There is no problem with the enumeration in your code. The following line is legit.

g.SmoothingMode = (SmoothingMode)2;

It just internally treats HighQuality the same way as it does AntiAlias.

If you do:

g.SmoothingMode = SmoothingMode.HighQuality;
var x = g.SmoothingMode;

x will return SmoothingMode.AntiAlias as this basically the same.