How to make Delphi 10.2 Tokyo honor ICON_SMALL (window title icon) in addition to ICON_BIG?

How to achieve the next goal in Delphi 10.2 Tokyo: I need Delphi to automatically set not only the large icon, but also the large and small icons for each window. I need to be able for some forms and for TApplication to change icons at runtime. I want this to be done unchanged VCL.Forms.pas

(the little icon is the one that appears in the window title bar, to the left of the window title).

There TCustomForm

is a function:

function GetIconHandle: HICON;

      

        
        
        
      

    

Unfortunately Delphi only sets a large icon handle, for example, here's a quote from VCL.Forms.pas

:

  SendMessage(Handle, WM_SETICON, ICON_BIG, GetIconHandle);

      

        
        
        
      

    

As you can see, the above code only sets the large icon handle, but I also need to set the small icon handle as the .ICO files used contain different images for the big and small icons.

Let me briefly describe the differences between large and small icons, as even Microsoft's documentation says almost nothing about it. Here are the main differences:

• A small icon image is displayed in the title bar of the window.

• A large icon is displayed on the Windows taskbar (usually at the bottom of the screen) if the taskbar is thick; the large icon image is also displayed when you press Alt + Tab.

See https://blog.barthe.ph/2009/07/17/wmseticon/ for more information on large and small icons .

Delphi, by setting only a large window handle, effectively disables the alternate image for the smaller icon displayed in the window titles. If only a large icon is specified, but not a small one, Windows will cancel the image from the larger icon to the smaller one, the quality will deteriorate, and the basic idea of ​​the smaller, simpler image will be lost.

See example image courtesy of sanyok. The left column labeled v7.4.16, is a screenshot of the program compiled with the code that sets both ICON_BIG

and ICON_SMALL

. The right column labeled v7.4.16.22 is a screenshot from the same program which does not explicitly set both small and large icons, but simply assigns to the form to the TIcon

form, and then Delphi, using its standard code, simply assigns only the large icon. so the image from the windows title bar is resized with a large icon. You can see how poor quality results from standard Delphi behavior.

In the past, I've changed the GetIconHandle in the interface section VCL.Forms.pas

from static to virtual, changing it from function

to procedure

and adding two parameters:

procedure GetIconHandle(var Big, Small: HICON); virtual;

      

        
        
        
      

    

So the following code in VCL.Forms.pas was as follows:

var
  Big, Small: HICON;
begin    
  [...]
  GetIconHandle(Big, Small);
  SendMessage(Handle, WM_SETICON, ICON_BIG, LParam(Big));
  SendMessage(Handle, WM_SETICON, ICON_SMALL, LParam(Small));
  [...]

      

        
        
        
      

    

Is it easy to accomplish this without changing VCL.Forms.pas

?

I solved the problem in Delphi 2007 by changing VCL units, but I can no longer change VCL units in Delphi 10.20 Tokyo for the following reasons:

• VCL compilations are compiled, but then when I compile my application I get "Internal error: AV0047C6C7-R000004CC-0" regardless of target targets (Win32 / Win64; Debug / Release), see https: //quality.embarcadero. com / browse / RSP-18455 - the first part of the error number (address) is different, and the second - R000004CC-0 - is always the same.

• I need to manually add (TObject) to each of the classes that do not inherit from any class; otherwise I am reporting an error that Create
  
  or Destroy
  
  not found in the base class. In previous versions of Delphi, writing simple class
  
  without any ancestor implicitly inherited it from TObject
  
  , but when I compile the code from the command line dcc32
  
  with command line parameters dcc32 -Q -M -$D- -$M+
  
  , this error occurs when Create
  
  or is Destroy
  
  not found in the base class.

This is how I loaded icons in the past:

procedure LoadIconPair(var Big, Small: hIcon; AName: PChar);
begin
  if Win32MajorVersion < 4 then
  begin
    Big := LoadIcon(hInstance, AName);
    Small := 0;
  end
  else
  begin
    Big := LoadImage(hInstance, AName, IMAGE_ICON, 32, 32, LR_DEFAULTCOLOR);
    Small := LoadImage(hInstance, AName, IMAGE_ICON, 16, 16, LR_DEFAULTCOLOR);
  end;
end;

      

        
        
        
      

    

This code can be further improved: hardcoded dimensions 32x32 and 16x16 can be modified as suggested in https://blog.barthe.ph/2009/07/17/wmseticon/ , in GetSystemMetrics(SM_CXICON)

, GetSystemMetrics(SM_CYICON)

for large and icons GetSystemMetrics(SM_CXSMICON)

and GetSystemMetrics(SM_CYSMICON)

small icons.

So, each form is essentially called LoadIconPair

and then returns the descriptors via the overwritten one procedure GetIconHandle(var Big, Small: HICON); override;

.

So the questions are:

• Is it possible to let Delphi set both small and large icons without much hassle and without changingVCL.Forms.pas?
  
  (this is the main question) - I need to be able, for some forms and for TApplication, to change icons at runtime.

• If not, how to add the modified VCL source to your application in Delphi 10.2 Tokyo where the device interface section changes? Are there any instructions or official guidelines? If someone succeeded, how did you do it? Have you compiled them from the GUI IDE? Or using the dcc32 / dcc64 command line? Or with msbuild? Or otherwise? Do you also need to manually add (TObject) classes that do not inherit from any class to avoid Create
  
  or Destroy
  
  not found in the base class error?

Update # 1: Installing icons again after installing VCL.Forms.pas is not a complete solution: we also have to take care of the application icon, not just the form icons; also, VCL.Forms.pas installs icons anyway, but only ICON_BIG

, we have to install icons again, this time setting both small and large. Do you have an idea on how we can fix the VCL.Forms.pas to add a parameter ICON_SMALL

whenever it sets a large icon, so we are only fixing the section implementation

and will be calling some messages, even WM_USER + N to request icon handles from the form. and will our TForm descendant execute this message handler?

Update # 2: TApplication and TForm have similar interfaces with regard to icons, but TApplication is a descendant of TComponent which has no window handle and thus no message handlers. What we can do with TForm, we cannot do with TApplication.

Update # 3: I have implemented a solution that is a mixture of what kobik has suggested in his post and Sertac Akyuz suggested in his later post . Thanks also to those who contributed to the comments. I compiled the program and gave it to the beta testers and they confirmed that the problem was fixed, the icon now looks good, and the animation of the icon in TApplication by changing the icons by timer also works correctly. Thanks everyone!