Windows: Allow setting a window Icon

[MTRNord]

It would be nice to set a Window Icon which shows both in the title bar and in the taskbar.

For the exe itself https://github.com/mxre/winres does work fine. For the Window itself this is not yet clear.

[MTRNord]

As a hint I guess this SO awnser for C should give a starting point https://stackoverflow.com/a/45727762/4929236

[MTRNord]

This seems to show the missing pieces in winapi-rs retep998/winapi-rs#122

Seems like https://github.com/linebender/druid/blob/master/druid-shell/src/platform/windows/window.rs#L1209 needs to construct WNDCLASSEXW from scratch instead of using that function as that function does not expose hIcon to us

[MTRNord]

An alternative is to load it after creating the window using https://docs.rs/winapi/0.3.9/winapi/um/winuser/fn.LoadImageW.html

[MTRNord]

Taken from the zulip chat (Just to track it here):

I think we're looking for SetClassLong to the icon offset, or SendMessage(hWnd, WM_SETICON, [big or small], handle).. either way, I do think we'll need to get a handle to it, so LoadImage or LoadIcon will be involved. (source)

[cmyr]

We definitely want to be able to customize the app icon on all platforms. At least in the mac case this is mostly a case of just putting a file with the right name in the right place in the app bundle, and including it in the info.plist file; other platforms may require more code.

[raphlinus]

Setting the desktop icon on Windows similarly requires storing the icon in the application's manifest, which is analogous to Info.plist. That's a different issue than the titlebar/taskbar, but want to clarify because I think these often go together.

[MTRNord]

@raphlinus thats easily done using the above linked winres and a build.rs :) That already works

[Chaostheorie]

The tracking issue for such files and their handling is #397

[Kethku]

Just wanting to chime in here, there are two separate problems with icons: setting them in the application manifest and or app bundle, and setting the icon for the window itself.

The former sets the icon on the executable itself, and the latter sets it on the window like

I think these should be addressed separately.

[kevin406972552]

Very cumbersome method

[zedseven]

I've gotten window icons set up when building for Windows, in my project. I thought I'd share my findings here along with the relevant code, to aid anyone who wants to implement this before Druid officially supports it.

Here's a screencap of the titlebar:

And in the Alt+Tab dialog: (the Windows API supports setting different icons for Alt+Tab than for window titlebars, though I set the same for both here)

Below is the pertinent code.
https://github.com/zedseven/config-loader/blob/878ced0cd4a097652187953facaaaf0f849bb32d/src/gui.rs#L273-L327
https://github.com/zedseven/config-loader/blob/878ced0cd4a097652187953facaaaf0f849bb32d/build.rs#L29-L41

There's a few considerations, however:

• Currently I'm relying on my changes for Send the WindowHandle with AppDelegate::window_added. #2119 to get a WindowHandle upon window creation for setting the icon.
  • As long as you can get a RawWindowHandle though, it doesn't matter how you get it.
• This requires using Druid's raw-window-handle feature.
• The icon being set at runtime is loaded directly from the executable. (though the Windows API does provide support for loading from a file)
  • The icon ID that is loaded is the Windows default icon ID, IDI_APPLICATION (32512).
  • Until Changed the default icon ID to 32512 to be in line with the Windows default. mxre/winres#39 is merged, if using the winres crate to package an icon with the executable, you will have to specify the icon ID to be 32512 manually. (using WindowsResource::set_icon_with_id)

Useful links I found when looking into this:

• https://docs.microsoft.com/en-us/windows/win32/winmsg/wm-seticon
• https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-loadiconw
  • Deprecated in favour of LoadImage, but this page lists IDI_APPLICATION and other values.
• https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-loadimagew

I haven't worked with MacOS or Linux as of yet as GUI support for my project is still in it's early stages, but if I come up with a solution for any other platforms that I'm happy with I'll mention it here.