Inno Setup WizardImageFile looks bad with font scaling on Windows 7

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;

Solution

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.

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

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

Inno Setup can automatically select the best version of the image since 5.6. Just list your versions of the images in the WizardImageFile and WizardSmallImageFile. You can use wildcards:

[Setup]
WizardImageFile=WizardImage *.bmp
WizardImageFile=WizardSmallImage *.bmp

On older versions of Inno Setup (or if your need to customize the selection algorithm or when you have additional custom images in the wizard), you would have to select the images programatically.

The following example does more or less the same what Inno Setup 5.6:

[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 LoadEmbededScaledImage(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
    LoadEmbededScaledImage(WizardForm.WizardBitmapImage, 'WizardImage');
    LoadEmbededScaledImage(WizardForm.WizardBitmapImage2, 'WizardImage');
    LoadEmbededScaledImage(WizardForm.WizardSmallBitmapImage, 'WizardSmallImage');
  end;
end;

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