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KEYUP + Shift key

Started by JeremyCAFE Sep 17, 2006 at 10:53 PM 11 replies 2.1k views

Original Post

Sep 17, 2006 at 10:53 PM

Im having trouble determining when a key is let up. [edit - correction] I used WM_CHAR to check for the input, but I'm not sure what command to check that takes the shift/capslock keys into consideration with KEYUP. The following method worked for letters, but other spots on the ascii chart do not use the same positioning so I am a little confused of how to offset the value.


char c = (char)wparam;
if((c >= 65) && (c <= 90))
	pInput->SetKeyUp(c + 32);

pInput->SetKeyUp(c);

[Edited by - JeremyCAFE on September 17, 2006 11:39:37 PM]

Colin Jeanne

Sep 17, 2006 at 11:25 PM

~~You can use the GetKeyState() function with VK_SHIFT to see if the shift key is currently active. There is also a VK_CAPITAL.~~

Forget what I said. Programmer16 is right

Programmer16

Sep 17, 2006 at 11:34 PM

Quote:
Original post by JeremyCAFE
Im having trouble determining when a key is let up. I used WM_CHAR to check for the input, but I'm not sure what command to check that takes the shift/capslock keys into consideration.

The following method worked for letters, but other spots on the ascii chart do not use the same positioning so I am a little confused of how to offset the value.

*** Source Snippet Removed ***

WM_CHAR automatically takes the shift key and caps-lock into consideration.

JeremyCAFE

Sep 17, 2006 at 11:38 PM

I am using WM_CHAR to check for a key press, but I need to determine when the key us unpressed. I was just hoping there was a way to do it without having to check the character and then translate.

I can turn a letter off no matter what. My problem is the rest of the ascii chart.

edit: Sorry, I realized my initial post was misleading as to what I was asking.

Nypyren

Sep 17, 2006 at 11:44 PM

Would using WM_KEYDOWN instead of WM_CHAR make things easier? WM_KEYDOWN corresponds more closely to WM_KEYUP than WM_CHAR does.

Think about it this way: You can't have a lowercase 'c' and a capital 'C' pressed at the same time, nor a capital 'A' and a lowercase 'z'.

JeremyCAFE

Sep 17, 2006 at 11:53 PM

Let me better explain my issue.

I have my buffer of input that stores if a key has been pressed. When WM_CHAR tells me a key is pressed, it flag the character in the buffer as down.

My problem is, when I get WM_KEYUP it is only returning one version of the key. Say if 1 was pressed and let go. If KEYUP tells me ! has been released, I need to manually check which key is pressed and hardcode the partner key to turn off also.

Servant of the Lord

Sep 18, 2006 at 12:12 AM

I'm not the best programmer in the world, but couldn't you just...

        case WM_KEYDOWN:        {            bool IsShift = false;            if(GetAsyncKeyState(VK_SHIFT)) IsShift = true;            switch(LOWORD(wParam))            {                case VK_LEFT: //Left arrow key                    //Move cursor back along buffer                break;                case VK_RIGHT: //Right arrow key                    //Move cursor forward along char buffer                break;                case 0x43: //Or whatever is 'A' charactor...                     if(IsShift)                     {                         //Add 'A' (capilized) to buffer                     }                     else                     {                         //Add 'a' (lowercase) to buffer                     }                break;                case VK_ESCAPE:                    //Exit app                break;            }        }

Pardon my ignorance, if this is not what you're looking for.

Nypyren

Sep 18, 2006 at 12:46 AM

Why does your input state need to know whether a capitalized key is down? What if you pressed shift, pressed 'c', released shift, and keep holding 'c' down? Is capital C down or up? Is lowercase c down or up? They are the same physical key!

Your 'buffer' that you mention is not a sequential buffer, but a state table, correct?

Use WM_KEYDOWN since it will not care whether shift or caps is down.

Nypyren

Sep 18, 2006 at 1:09 AM

There are three main ways of dealing with WM_KEYDOWN, WM_KEYUP, and WM_CHAR.

1: WM_CHAR is supposed to be used in situations where you need human-readability taking keyboard layout and language settings into account. In a game development scenario, WM_CHAR should only be used for command prompts and chat dialogs. In these cases, shift state matters only when a key is pressed, and is automatically factored into WM_CHAR for programmer ease. There is no need to deal with key-ups.

2: WM_KEYDOWN and WM_KEYUP can be used when you need to know when multiple keys are being held at the same time (such as walking forward and turning/strafing at the same time). You don't care about shift+key combos because shift is simply treated as just another physical key.

3: WM_KEYDOWN and WM_KEYUP can be used to record the exact sequence of keys pressed and released and incorporate delays, which allows a macro utility to play the same sequence back exactly. Shift keys are also treated as yet-another-key.

#2 sounds like what you're trying to do, but you mention 'buffer', which implies a stored sequence, which is #3.

JeremyCAFE

Sep 18, 2006 at 7:47 AM

^^ that is me, login failed.

swiftcoder

Sep 18, 2006 at 7:56 AM

Quote:
Original post by Anonymous Poster
I was trying to mock the way every text editor works with holding a key down. I noticed it pauses for a second, and then continues to spam. To do this I set a flag that the key was down and when it was pressed. I only spam the key when it has been down for longer than .5 seconds. I am 100% sure this is a poor way of doing it. I just couldn't think of any other way.

Can't you request the OS to send you repeat keydown events? This is how it is done on a Mac, and it gives you the users keyboard repeat rate settings too (sorry, not familiar with the Windows API).

JeremyCAFE

Sep 18, 2006 at 8:04 AM

[edit] After checking to see what happens if I just add to the input string straight out of wm_char I noticed it does in fact implement the pause. Thank you everyone for the help.

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