C# – DwmExtendFrameIntoClientArea without Aero Glass

aerocdwmnetwpf

Using the DwmExtendFrameIntoClientArea API call with Aero Glass enabled works just fine. However, I want it to work when Aero Glass is disabled as well, like how it works in the Windows control panel:

enter image description here

Notice how the frame has extended into the client area, even though Aero Glass is disabled? When I make the DwmExtendFrameIntoClientArea API call in my application, the returned HRESULT is definitely not success, and my application ends up looking like this:

http://img197.imageshack.us/img197/9629/clientapplication.png

Normally, with Aero Glass enabled, the border stretches down to underneath the navigation buttons, like in the control panel. How do I do this? DwmExtendFrameIntoClientArea clearly isn't working.

By the way, if it is relevant, my application is a WPF application.

Best Answer

Nir's answer is correct; when composition is disabled you have to draw that area yourself.

i can show you the code i have in the paint handler of the panel at the top of my form - the panel normally responsible for drawing the 0x00000000 transparent black to make the glass appear:

Psuedo-code:

procedure DrawGlassHeaderArea(g: Graphics; r: Rectangle; IsFormFocused: Boolean);
const
   clFakeGlassColor = $00EAD1B9;  //(185, 209, 234) This is the fake foreground glass color (for use when composition is disabled)
   clFakeGlassColorUnfocused = $00F2E4D7; //(215, 228, 242) This is the fake background glass color (for use when composition is disabled)
begin
   if Dwm.IsCompositionEnabled then
   begin
      g.FillRectangle(r, 0x00000000); //fill rectangle with transparent black
   end
   else
      //Composition disabled; fake it like Microsoft does

      //The color to use depends if the form has focused or not
      Color glassColor;
      if (IsFormFocused) then
         c = clFakeGlassColor 
      else
         c = clFakeGlassColorUnfocused;

      g.FillRectangle(r, glassColor); //fill rectangle with fake color


      //Now we have to draw the two accent lines along the bottom
      Color edgeHighlight = ColorBlend(Colors.White, glassColor, 0.33); //mix 33% of glass color to white
      Color edgeShadow = ColorBlend(Colors.Black, glassColor, 0.33); //mix 33% of glass color to black

      //Draw highlight as 2nd-last row:
      g.DrawLine(edgeHighlight, Point(r.Left, r.Bottom-2), Point(r.Right, r.Bottom-2);

      //Draw shadow on the very last row:
      g.DrawLine(edgeHighlight, Point(r.Left, r.Bottom-1), Point(r.Right, r.Bottom-1);
   end;
end;

Sample usage

procedure MyForm.PaintBox1Paint(PaintEventArgs e)
begin
   DrawGlassHeaderArea(e.Graphics, PaintBox1.ClientRectangle, this.HasFocus); 
end;

Bonus Screenshot

enter image description here

Update 7/9/2014

@JakePetroules was right, and i was wrong. The "blue" used for fake glass is not hard-coded into Windows. And it is accessible using GetThemeColor.

I coded up all the available colors (TMT_COLOR) available for a Window class:

enter image description here

Note: For more information about Classes, Parts, and States, see Aero Style Classes, Parts, and States

When using:

  • Class: Window
  • Part: WP_CAPTION
  • State: n/a (StateID is not used for the Caption part, nor the entire Window class)

and fetch the color code propertyID:

  • TMT_FILLCOLORHINT: for when the window has focus
  • TMT_BORDERCOLORHINT: for when the window does not have focus

you get the two important colors:

enter image description here

The pseudo-code i now use to get the fake glass color:

public Color GetFakeClassColor(Boolean isWindowFocused=true)
{
   static Color fakeGlass= 0x00B8D0E9; //the correct answer anyway

   if ((GetThemeAppProperties() && STAP_ALLOW_CONTROLS) == 0)
      return fakeGlass;

   hTheme = OpenThemeData(GetDesktopWindow(), "Window");
   if (hTheme = 0)
      return fakeGlass;

   Int32 propID;
   if (isWindowFocused)
       propID= TMT_FILLCOLORHINT; //The color used as a fill color hint for custom controls.
   else
       propID= TMT_BORDERCOLORHINT; //The color used as a border color hint for custom controls.

   DWORD rgb;
   if (Failed(GetThemeColor(hTheme, WP_CAPTION, 0, propID, ref rgb))
      return fakeGlass;

   Result = new Color(rgb);
}

In reality, since i use Delphi, my actual code is:

function GetFakeGlassColor(IsWindowFocused: Boolean=True): TColor;
var
    ted: TThemedElement;
    hTheme: THandle;
    propID: Integer;
    rgb: DWORD;
begin
    Result := $00B8D0E9; //the correct answer anyway

    //We can't use the ThemeServcies.ThemesEnabled, as that mistakenly checks for version 6 of the common controls library
    //Themes can be enabled without using ComCtl V6, or common controls at all
    if not ThemeServices.ThemesAvailable then
        Exit;
    if (GetThemeAppProperties and STAP_ALLOW_CONTROLS) = 0 then
        Exit;

    htheme := ThemeServices.Theme[teWindow];
    if hTheme = 0 then
        Exit;

    if IsWindowFocused then
        propID := TMT_FILLCOLORHINT //The color used as a fill color hint for custom controls.
    else
        propID := TMT_BORDERCOLORHINT; //The color used as a border color hint for custom controls.

    if Failed(GetThemeColor(hTheme, WP_CAPTION, 0, propID, {var}rgb)) then
        Exit;

    Result := rgb;
end;
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