dll inno-setup pascalscript bitmapimage inno-setup-v6

Why are the images/descriptions from "Enlarge Inno Setup component page only with preview and description" not loading in my script?

Introducing the problem

Firstly, this might be a long post (sorry in advance), but after trying to implement the image previews and component descriptions from the question mentioned in the title, I've run into some problems: the aforementioned images/descriptions are not loading at all, and while the components page is longer, it's missing the Next and Cancel buttons.

Example image:

Minimal Reproducible Example

Before fully implementing with my project's main script I decided to work on it with it's own separate script to minimize conflicts and resolve bugs that may occur faster and with more precision.

All bitmap images are fully functional bitmap exports, they should work perfectly fine (non-transparent).

And yes, I did download InnoCallback.dll and place it in my SourceDir.

Here is some of the source code in my Image_Preview_Test.iss script:

[Files]

Source: "1.bmp"; Flags: dontcopy
Source: "2.bmp"; Flags: dontcopy
Source: "3.bmp"; Flags: dontcopy
Source: "InnoCallback.dll"; Flags: dontcopy

[Components]

Name: "Component1"; Description: "1*"; Types: Component1;
Name: "Component2"; Description: "2*"; Types: Component2;
Name: "Component3"; Description: "3*"; Types: Component3;

[Code]

var
  LastMouse: TPoint;

type
  TTimerProc = procedure(H: LongWord; Msg: LongWord; IdEvent: LongWord; Time: LongWord);

function GetCursorPos(var lpPoint: TPoint): BOOL; external 'GetCursorPos@user32.dll stdcall';
function SetTimer(hWnd: longword; nIDEvent, uElapse: LongWord; lpTimerFunc: LongWord): LongWord; external 'SetTimer@user32.dll stdcall';
function ScreenToClient(hWnd: HWND; var lpPoint: TPoint): BOOL; external 'ScreenToClient@user32.dll stdcall';
function ClientToScreen(hWnd: HWND; var lpPoint: TPoint): BOOL; external 'ClientToScreen@user32.dll stdcall';
function ListBox_GetItemRect(const hWnd: HWND; const Msg: Integer; Index: LongInt; var Rect: TRect): LongInt; external 'SendMessageW@user32.dll stdcall';  

const
  LB_GETITEMRECT = $0198;
  LB_GETTOPINDEX = $018E;

function WrapTimerProc(Callback: TTimerProc; ParamCount: Integer): LongWord; external 'wrapcallback@files:InnoCallback.dll stdcall';

function FindControl(Parent: TWinControl; P: TPoint): TControl;
var
  Control: TControl;
  WinControl: TWinControl;
  I: Integer;
  P2: TPoint;
begin
  for I := 0 to Parent.ControlCount - 1 do
  begin
    Control := Parent.Controls[I];
    if Control.Visible and
       (Control.Left <= P.X) and (P.X < Control.Left + Control.Width) and
       (Control.Top <= P.Y) and (P.Y < Control.Top + Control.Height) then
    begin
      if Control is TWinControl then
      begin
        P2 := P;
        ClientToScreen(Parent.Handle, P2);
        WinControl := TWinControl(Control);
        ScreenToClient(WinControl.Handle, P2);
        Result := FindControl(WinControl, P2);
        if Result <> nil then Exit;
      end;

      Result := Control;
      Exit;
    end;
  end;

  Result := nil;
end;

function PointInRect(const Rect: TRect; const Point: TPoint): Boolean;
begin
  Result := (Point.X >= Rect.Left) and (Point.X <= Rect.Right) and
    (Point.Y >= Rect.Top) and (Point.Y <= Rect.Bottom);
end;

function ListBoxItemAtPos(ListBox: TCustomListBox; Pos: TPoint): Integer;
var
  Count: Integer;
  ItemRect: TRect;
begin
  Result := SendMessage(ListBox.Handle, LB_GETTOPINDEX, 0, 0);
  Count := ListBox.Items.Count;
  while Result < Count do
  begin
    ListBox_GetItemRect(ListBox.Handle, LB_GETITEMRECT, Result, ItemRect);
    if PointInRect(ItemRect, Pos) then Exit;
    Inc(Result);
  end;
  Result := -1;
end;

var
  CompLabel: TLabel;
  CompImage: TBitmapImage;
  LoadingImage: Boolean;

procedure HoverComponentChanged(Index: Integer);
var 
  Description: string;
  Image: string;
  ImagePath: string;
begin
  case Index of
    0: begin Description := 'Component 1'; Image := '1.bmp'; end;
    1: begin Description := 'Component 2'; Image := '2.bmp'; end;
    2: begin Description := 'Component 3'; Image := '3.bmp'; end;

  else
    Description := 'Move your mouse over a component to see its description.';
  end;
  CompLabel.Caption := Description;

  if Image <> '' then
  begin
    // The ExtractTemporaryFile pumps the message queue, prevent recursion
    if not LoadingImage then
    begin
      LoadingImage := True;
      try
        ImagePath := ExpandConstant('{tmp}\' + Image);
        if not FileExists(ImagePath) then
        begin
          ExtractTemporaryFile(Image);
        end;
        CompImage.Bitmap.LoadFromFile(ImagePath);
      finally
        LoadingImage := False;
      end;
    end;
    CompImage.Visible := True;
  end
    else
  begin
    CompImage.Visible := False;
  end;
end;

procedure HoverTimerProc(H: LongWord; Msg: LongWord; IdEvent: LongWord; Time: LongWord);
var
  P: TPoint;
  Control: TControl; 
  Index: Integer;
begin
  GetCursorPos(P);
  if P <> LastMouse then // just optimization
  begin
    LastMouse := P;
    ScreenToClient(WizardForm.Handle, P);

    if (P.X < 0) or (P.Y < 0) or
       (P.X > WizardForm.ClientWidth) or (P.Y > WizardForm.ClientHeight) then
    begin
      Control := nil;
    end
      else
    begin
      Control := FindControl(WizardForm, P);
    end;

    Index := -1;
    if Control = WizardForm.ComponentsList then
    begin
      P := LastMouse;
      ScreenToClient(WizardForm.ComponentsList.Handle, P);
      Index := ListBoxItemAtPos(WizardForm.ComponentsList, P);
    end;

    HoverComponentChanged(Index);
  end;
end;

type
  TPositionStorage = array of Integer;

var
  CompPageModified: Boolean;
  CompPagePositions: TPositionStorage;

procedure SaveComponentsPage(out Storage: TPositionStorage);
begin
  SetArrayLength(Storage, 10);

  Storage[0] := WizardForm.Height;
  Storage[1] := WizardForm.NextButton.Top;
  Storage[2] := WizardForm.BackButton.Top;
  Storage[3] := WizardForm.CancelButton.Top;
  Storage[4] := WizardForm.ComponentsList.Height;
  Storage[5] := WizardForm.OuterNotebook.Height;
  Storage[6] := WizardForm.InnerNotebook.Height;
  Storage[7] := WizardForm.Bevel.Top;
  Storage[8] := WizardForm.BeveledLabel.Top;
  Storage[9] := WizardForm.ComponentsDiskSpaceLabel.Top;
end;

procedure LoadComponentsPage(const Storage: TPositionStorage;
  HeightOffset: Integer);
begin
  if GetArrayLength(Storage) <> 10 then
    RaiseException('Invalid storage array length.');

  WizardForm.Height := Storage[0] + HeightOffset;
  WizardForm.NextButton.Top := Storage[1] + HeightOffset;
  WizardForm.BackButton.Top := Storage[2] + HeightOffset;
  WizardForm.CancelButton.Top := Storage[3] + HeightOffset;
  WizardForm.ComponentsList.Height := Storage[4] + ScaleY(150);
  WizardForm.OuterNotebook.Height := Storage[5] + HeightOffset;
  WizardForm.InnerNotebook.Height := Storage[6] + HeightOffset;
  WizardForm.Bevel.Top := Storage[7] + HeightOffset;
  WizardForm.BeveledLabel.Top := Storage[8] + HeightOffset;
  WizardForm.ComponentsDiskSpaceLabel.Top := Storage[9] + HeightOffset;
end;

procedure InitializeWizard1();
var
  HoverTimerCallback: LongWord;
begin
  HoverTimerCallback := WrapTimerProc(@HoverTimerProc, 4);

  SetTimer(0, 0, 50, HoverTimerCallback);

  CompLabel := TLabel.Create(WizardForm);
  CompLabel.Parent := WizardForm.SelectComponentsPage;
  CompLabel.Left := WizardForm.ComponentsList.Left;
  CompLabel.Width := WizardForm.ComponentsList.Width div 2;
  CompLabel.Height := ScaleY(64);
  CompLabel.Top := WizardForm.ComponentsList.Top + WizardForm.ComponentsList.Height - CompLabel.Height + ScaleY(150);
  CompLabel.AutoSize := false;
  CompLabel.WordWrap := True;

  CompImage := TBitmapImage.Create(WizardForm);
  CompImage.Parent := WizardForm.SelectComponentsPage;
  CompImage.Top := CompLabel.Top;
  CompImage.Width := CompImage.Width + ScaleX(128);
  CompImage.Height := CompLabel.Height + ScaleX(128);
  CompImage.Left := WizardForm.ComponentsList.Left + WizardForm.ComponentsList.Width - CompLabel.Width;

  WizardForm.ComponentsList.Height := WizardForm.ComponentsList.Height - CompLabel.Height - ScaleY(8);
end;

procedure InitializeWizard2();
begin
  CompPageModified := False;
end;

procedure CurPageChanged(CurPageID: Integer);
begin
  if CurpageID = wpSelectComponents then
  begin
    SaveComponentsPage(CompPagePositions);
    LoadComponentsPage(CompPagePositions, ScaleY(250));
    CompPageModified := True;
  end
  else
  if CompPageModified then
  begin
    LoadComponentsPage(CompPagePositions, 0);
    CompPageModified := False;
  end;
end;

procedure InitializeWizard();
begin 
  InitializeWizard1();
  InitializeWizard2();
end;

Solution

I do not think the images are not loading. They are rather obscured by incorrectly resized ComponentsList.

Some of the samples, you have based your code on, are not compatible with larger (and resizable) Inno Setup 6 wizard.

I've updated my answer to:
Add image into the Inno Setup components list - component description
(also note that the answer already uses Inno Setup 6 CreateCallback instead of the obsolete solution based on InnoCallback.dll)
And use my solution to:
Larger "Select Components" page in Inno Setup
... instead of the obsolete solution by @TLama.

Then everything should work:

If you want larger images, just change the CompImage.Height and CompImage.Width.