Inno Setup WizardImageFile looks bad with font sca

Bitmap for Inno Setup WizardImageFile (and WizardSmallImageFile) looks terrible because when Windows 7 has the large system fonts enabled, the Wizard is bigger than usual, but the images are scaled terrible wrong.

Is there a fix?

There is no similar issue if I add own picture somewhere like this:

BitmapImage1.AutoSize := True;
BitmapImage1.Align := alClient;
BitmapImage1.Left := 0;
BitmapImage1.Top := 0;
BitmapImage1.stretch := True;
BitmapImage1.Parent := Splash;

These are bitmap images, they naturally scale badly. You are just lucky that your own images do not look that bad when scaled.

You have to prepare your own set of images for common scaling factors and dynamically select the correct one. There's no native support for this in Inno Setup.

Common scaling factors used nowadays are 100%, 125%, 150% and 200%. So you should have four sizes for the images.

You can use the WizardImageFile and WizardSmallImageFile directives to assign the 100% sized images and use the Pascal Scripting to override that when a large scaling is used.

Say I have these image files:

WizardImage 100.bmp
WizardImage 125.bmp
WizardImage 150.bmp
WizardImage 200.bmp
WizardSmallImage 100.bmp
WizardSmallImage 125.bmp
WizardSmallImage 150.bmp
WizardSmallImage 200.bmp

This is how you use them to show the correct size for the scaling on user's machine:

[Setup]
; Use 100% images by default
WizardImageFile=WizardImage 100.bmp
WizardSmallImageFile=WizardSmallImage 100.bmp

[Files]
; Embed all other sizes to the installer
Source: "WizardImage *.bmp"; Excludes: "* 100.bmp"; Flags: dontcopy
Source: "WizardSmallImage *.bmp"; Excludes: "* 100.bmp"; Flags: dontcopy

[Code]

function GetScalingFactor: Integer;
begin
  if WizardForm.Font.PixelsPerInch >= 192 then Result := 200
    else
  if WizardForm.Font.PixelsPerInch >= 144 then Result := 150
    else
  if WizardForm.Font.PixelsPerInch >= 120 then Result := 125
    else Result := 100;
end;

procedure LoadEmbededScaledBitmap(Image: TBitmapImage; NameBase: string);
var
  Name: String;
  FileName: String;
begin
  Name := Format('%s %d.bmp', [NameBase, GetScalingFactor]);
  ExtractTemporaryFile(Name);
  FileName := ExpandConstant('{tmp}\' + Name);
  Image.Bitmap.LoadFromFile(FileName);
  DeleteFile(FileName);
end;

procedure InitializeWizard;
begin
  { If using larger scaling, load the correct size of images }
  if GetScalingFactor > 100 then 
  begin
    LoadEmbededScaledBitmap(WizardForm.WizardBitmapImage, 'WizardImage');
    LoadEmbededScaledBitmap(WizardForm.WizardBitmapImage2, 'WizardImage');
    LoadEmbededScaledBitmap(WizardForm.WizardSmallBitmapImage, 'WizardSmallImage');
  end;
end;

You might want to do the same for the SelectDirBitmapImage, the SelectGroupBitmapImage and the PreparingErrorBitmapImage.