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I'm porting to SDL2 windows game that has IME support. Game logic implies that no keys are processed during IME composition. This is accomplished by

 if( wParam == VK_PROCESSKEY ) return 0;


condition in WM_KEYDOWN\WM_KEYUP event handlers. I need some way to emulate this behaviour in SDL_KEYDOWN/SDL_KEYUP event handlers. there is no flags in     SDL_KeyboardEvent structure that can be used to filter keys during IME composition. I don't see any composition-started/composition-ended events so i can maintain my own boolean flag. Any ideas how should I accomplish my goal? Should I prepare a patch that adds such functionality? Any opinions are welcome.



Regards, Alexey
 

SDL_TEXTEDITING indicates composition is in progress (and provides the
current text so far), SDL_TEXTINPUT indicates composition has just
finished (and provides the resulting text). Maybe you can do something
with these two?

Note that you can get SDL_TEXTINPUT alone if it's a system without
composition, e.g. letters get entered directly.

2015-03-28 14:15 GMT-03:00, Alexey Petruchik:
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Does the SDL_TEXTEDITING event fire in any useful way here?

--ryan.



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SDL_TEXEDITING seems to be not enough for me. Here is an example (I use Japanese IME) I press Ctrl+Caps to start IME than I write "waruso" and hit enter. Here is a dump of sdl events:

SDL_KEYDOWN: 224 1073742048
SDL_KEYDOWN: 57 1073741881
SDL_KEYUP: 224 1073742048
SDL_KEYUP: 57 1073741881
SDL_KEYDOWN: 26 119
SDL_TEXTEDITING: "ï½—"
SDL_KEYUP: 26 119
SDL_KEYDOWN: 4 97
SDL_TEXTEDITING: "わ"
SDL_KEYUP: 4 97
SDL_KEYDOWN: 21 114
SDL_TEXTEDITING: "わｒ"
SDL_KEYUP: 21 114
SDL_KEYDOWN: 24 117
SDL_TEXTEDITING: "わる"
SDL_KEYUP: 24 117
SDL_KEYDOWN: 22 115
SDL_TEXTEDITING: "わるｓ"
SDL_KEYUP: 22 115
SDL_KEYDOWN: 18 111
SDL_TEXTEDITING: "わるそ"
SDL_KEYUP: 18 111
SDL_KEYDOWN: 40 13
SDL_TEXTINPUT: "わるそ"
SDL_TEXTEDITING: ""
SDL_KEYUP: 40 13



As you see when SDL_KEYDOWN for "w" letter comes I'm already in IME mode (Ctrl+Caps pressed) but SDL_TEXEDITING event hadn't yet come so I can't filter this keydown. Same comes for SDL_KEYUP for Enter after i received textediting with empty string which seems to mean that IME composition is completed.


On 28 March 2015 at 22:10, Ryan C. Gordon wrote:

Here is more detailed log. I've marked keydown events that have wParam equal to VK_PROCESSKEY



SDL_KEYDOWN: 224 1073742048
SDL_KEYDOWN: 57 1073741881 - VK_PROCESSKEY
SDL_KEYUP: 224 1073742048
SDL_KEYUP: 57 1073741881
SDL_KEYDOWN: 26 119 - VK_PROCESSKEY
WM_IME_STARTCOMPOSITION
SDL_TEXTEDITING: "ï½—"
SDL_KEYUP: 26 119
SDL_KEYDOWN: 4 97 - VK_PROCESSKEY
SDL_TEXTEDITING: "わ"
SDL_KEYUP: 4 97
SDL_KEYDOWN: 21 114 - VK_PROCESSKEY
SDL_TEXTEDITING: "わｒ"
SDL_KEYUP: 21 114
SDL_KEYDOWN: 24 117 - VK_PROCESSKEY
SDL_TEXTEDITING: "わる"
SDL_KEYUP: 24 117
SDL_KEYDOWN: 22 115 - VK_PROCESSKEY
SDL_TEXTEDITING: "わるｓ"
SDL_KEYUP: 22 115
SDL_KEYDOWN: 18 111 - VK_PROCESSKEY
SDL_TEXTEDITING: "わるそ"
SDL_KEYUP: 18 111
SDL_KEYDOWN: 40 13 - VK_PROCESSKEY
SDL_TEXTINPUT: "わるそ"
WM_IME_ENDCOMPOSITION
SDL_TEXTEDITING: ""
SDL_KEYUP: 40 13



On 30 March 2015 at 00:21, Alexey Petruchik wrote:

Hi,Not sure if this helps, but to implement the text fields in Quakespasm (the console, chat prompt, etc.),  what we did is:

- when the user focuses a text field, we call SDL_StartTextInput() and set a flag in our code that indicates we're in text editing mode
- when in text editing mode, we ignore all SDL_KEYDOWN/SDL_KEYUP events, except keys that manipulate the cursor, like backspace, delete, and the arrow keys
- any text that comes in via SDL_TEXTINPUT is pasted into the text field.



After experimenting a bit, I think this is the "right" design for doing a text field in a game with SDL2.
Trying to match key and text input/text editing events on a per-character basis is fragile and bound to fail, in my experience.





On Sun, Mar 29, 2015 at 4:13 PM, Alexey Petruchik wrote: