How to determine programmatically the Windows' Performance settings with Delphi 2010 - windows

Question

The following code is to fade my application on close.
procedure TfrmMain.btnClose1Click(Sender: TObject);
var
i : Integer;
begin
for i := 255 downto 0 do begin
frmMain.AlphaBlendValue := i;
application.ProcessMessages;
end;
Close;
end;
With Windows performance set to “Let Windows choose…”
When closing my Delphi app with the above code the fade is almost
instantaneous (maybe ¼ second at the most, if I blink I miss the
transition).
If I set the performance Option to ‘Adjust for best performance”
When exiting the same app the fade takes over 12 seconds.
Using the same code but commenting out the AlphaBlendValue change removes the delay.
I tested this out on both Delphi 2010 and DelphiXE2 and the results are the same.
This was tested on Windows 7 Ultimate 64bit if that makes any difference.
To say the least this behavior puzzles me.
I thought that the forms Alpha property was handled by the GPU and would therefore not be affected by Windows performance settings that should would be targeted at maximizing CPU performance.
So as far as this is concerned I'm not sure if this is a Windows 7 bug, a Delphi bug or just my lack of knowledge.
As far as a fix...
Is there a way to tell if Windows is running in crap graphics/max performance mode so that I can disable Alpha fade effects in my apps?
Edit for clarity:
While I would like to fix the fade what I am really looking for is a way to determine what the Windows performance setting is.
I am looking for how to determine a specific Windows setting - when you go into Windows Performance Options there are 3 tabs. On the first tab "Visual Effects" there are 3 canned options and a 4th option for 'Custom'. Minimally I am trying to determine if the option chosen is 'Adjust for best performance', if I could determine what the settings are on this tab even better.
Appreciate any help.

Answer 1

The fundamental problem with your code is that you are forcing 256 distinct updates irrespective of the performance characteristics of the machine. You don't have to use every single alpha blend value between 255 and 0. You can skip some values and still have a smooth fade.
You need to account for the actual graphics performance of the machine. Since you cannot predict that, you should account for real time in your fade code. Doing so will give you a consistent rate of fade irrespective of the performance characteristics of your machine.
So, here's a simple example to demonstrate tying the fade rate to real time:
procedure TfrmMain.btnClose1Click(Sender: TObject);
var
Stopwatch: TStopwatch;
NewAlphaBlendValue: Integer;
begin
Stopwatch := TStopwatch.StartNew;
while True do
begin
NewAlphaBlendValue := 255-(Stopwatch.ElapsedMilliseconds div 4);
if NewAlphaBlendValue>0 then
AlphaBlendValue := NewAlphaBlendValue
else
break;
end;
Close;
end;
The fade has a 1 second duration. You can readily adjust the mathematics to modify the duration to your requirements. This code will produce a smooth fade even on your low performing machine.
I would also comment that you should not use the global variable drmMain in a TfrmMain method. The TfrmMain method already has access to the instance. It is Self. And of course you can omit the Self. What's more the call to ProcessMessages is bad. That allows re-entrant handling of queued input messages. You don't want that to happen. So remove the call to ProcessMessages.
You actually ask about detecting the Adjust for best performance setting. But I think that's the wrong question. For a start you should fix your fade code so that the fade duration is independent of graphics performance.
Having done that you may still wish to disable the fade if the user has asked for lower quality appearance settings. I don't think you should look for one of the 3 canned options that you mention. They are quite possibly Windows version specific. Personally I would base the behaviour on the Animate windows when minimizing and maximizing setting. My rationale is that if the user does not want minimize and maximize to be animated, then presumably they don't want window close to be faded.
Here's how to read that setting:
function GetWindowAnimation: Boolean;
var
AnimationInfo: TAnimationInfo;
begin
AnimationInfo.cbSize := SizeOf(AnimationInfo);
if not SystemParametersInfo(SPI_GETANIMATION, AnimationInfo.cbSize,
#AnimationInfo, 0) then
RaiseLastOSError;
Result := AnimationInfo.iMinAnimate<>0;
end;
I think that most of the other settings that you may be concerned with can also be read using SystemParametersInfo. You should be able to work out how to do so by following the documentation.

Answer 2

Sorry for the tardy followup but it took me a while to figure out a working answer to my question and some of the issues behind it.
First, a thank you to David Heffernan for insight on a better way to handle the fade loop and information on the TStopWatch function from the Delphi's Diagnostics unit, much appreciated.
In regards to being able to determine the Windows' Performance settings...
When using the following un-optimized fade loop
procedure TfrmMain.btnFadeNCloseClick(Sender: TObject);
var
i : Integer;
begin
for i := 255 downto 0 do
frmMain.AlphaBlendValue := i;
Close;
end;
the actual Windows Performance Option settings causing the performance issue are "Enable desktop composition" and "Use visual styles on Windows and buttons". If both options are enabled there is no issue, if either setting is not enabled the loop crawls** (about 12 seconds on my system if the form is maximized).
Turns out that turning Aero Glass on or off affects these same 2 settings. So being able to detect if Aero Glass is on or not enables me to determine whether to not to enable the form effects, such as transition fades and other eye candy, in my apps. Plus now I can also capture that information in my bug reports.
**Note this appears to be an NVidia issue/bug, or at least an issue that is much more severe on systems with NVidia graphics cards. On 2
different NVidia systems (with recent, if not latest drivers) I
got similar results for a miximized form fade - less than
.001 seconds if Aero Glass is on, around 12 seconds if Aero Glass is
off. On a system with an Intel graphics card - less than .001 seconds
if Aero Glass is on, about 3.7 seconds if Aero Glass is off. Now
granted my test sampling is small, 3 NVidia systems (counting my
customer who initially reported the issue) and one non-NVidia system
but if I was using a decent NVidia graphic card I would not bother
turning Aero Glass off.
Below is the working code to detect if Aero Glass is enabled via Delphi:
This function has been tested on a Windows7 64 bit system and works with Delphi 2007, 2010 and Xe2 (32 & 64bit).
All of the various versions of the Delphi function below that I found on the net were broken - along with comments of people complaining about getting Access Violation errors.
What finally shed the light on fixing the bad code was Gerry Coll's response to: AccessViolationException in Delphi - impossible (check it, unbelievable...) which was about trying to fix AV errors in a function of the same type.
function ISAeroEnabled: Boolean;
type
_DwmIsCompositionEnabledFunc = function(var IsEnabled: Bool): HRESULT; stdcall;
var
Flag : BOOL;
DllHandle : THandle;
OsVersion : TOSVersionInfo;
DwmIsCompositionEnabledFunc: _DwmIsCompositionEnabledFunc;
begin
Result:=False;
ZeroMemory(#OsVersion, SizeOf(OsVersion));
OsVersion.dwOSVersionInfoSize := SizeOf(TOSVERSIONINFO);
if ((GetVersionEx(OsVersion)) and (OsVersion.dwPlatformId = VER_PLATFORM_WIN32_NT) and
(OsVersion.dwMajorVersion = 6) and (OsVersion.dwMinorVersion < 2)) then //Vista&Win7 only (no Win8)
begin
DllHandle := LoadLibrary('dwmapi.dll');
try
if DllHandle <> 0 then
begin
#DwmIsCompositionEnabledFunc := GetProcAddress(DllHandle, 'DwmIsCompositionEnabled');
if (#DwmIsCompositionEnabledFunc <> nil) then
begin
if DwmIsCompositionEnabledFunc(Flag)= S_OK then
Result:= Flag;
end;
end;
finally
FreeLibrary(DllHandle);
end;
end;
end;