The same technique can be used for the CAPS LOCK key ( VK_CAPITAL) and the SCROLL LOCK key ( VK_SCROLL). It takes a Boolean value that indicates whether the light should be turned off ( FALSE) or on ( TRUE). The following sample program toggles the NUM LOCK light by using keybd_event with a virtual key of VK_NUMLOCK. On keydown event alt is pressed - so it returns keycode 18 and true, on keyup alt is not pressed, so the result is 18 and false. To do this, call keybd_event with theīVk parameter set to VK_SNAPSHOT. According to w3c docs altKey event attribute returns true if it's press and false if not, so your code is working right. Return valueĪn application can simulate a press of the PRINTSCRN key in order to obtain a screen snapshot and save it to the clipboard. If not specified, the key is being depressed.Īn additional value associated with the key stroke. If specified, the scan code was preceded by a prefix byte having the value 0圎0 (224). This parameter can be one or more of the following values. For a complete list, see Virtual Key Codes.Ĭontrols various aspects of function operation. The code must be a value in the range 1 to 254. *Updated from an original post written by Thom McGrath.A virtual-key code. Run the project and watch the text change when you hold and release the Option/Alt key. In the Timer subclass, put this code in the KeyDown event: Label1.Value = "You are pressing Option."Īnd in the KeyUp event put this code: Label1.Value = "Normal Text" To test this, add a Label to the Window which will be used to display different text when the Option key is held down. You’ll also want to adjust the period of the timer to something small such as 200 to make sure the events are responsive. Now go to your Window, place a Timer on it and set the super to “OptionTimer” and you can insert code into the events for that timer. In KeyPress you can detect the key pressed and. Although any single character can be used as a key name, its meaning (scan code or virtual keycode) depends on the current keyboard layout. Lastly add the Action event handler with the following code: If Keyboard.AsyncAltKey = True And Pressed = False ThenĮlseIf KeyBoard.AsyncAltKey = False And Pressed = True Then while Alt key is pressed down if user presses any button, two events will be fired KeyUp and KeyPress. Note: The names of the letter and number keys are the same as that single letter or digit.For example: b is B and 5 is 5. Next, add a property “Pressed As Boolean”, an event definition “KeyDown”, and a second event definition “KeyUp” to OptionTimer. Start by creating a new class called “OptionTimer” whose super is “Timer”. Also, the subclass will allow you to call events which can come in handy. For enhanced 101- and 102-key keyboards, extended keys are the right ALT and CTRL keys on the main section of the keyboard the INS, DEL, HOME, END, PAGE UP, PAGE DOWN, and arrow keys in the clusters to the left of the numeric keypad and the divide (/) and ENTER keys in the numeric keypad. Answer: In modern browsers, your script can check whether a keyboard event occurred while the user was pressing any of the Ctrl, Alt, Shift keys. Either technique will work, but the subclass creates reusable code, something I always recommend. The solution is to use a Timer to detect the Option/Alt key, though it could be adapted to read any of the modifier keys.įirst of all, we need to decide whether to create a Timer embedded on a Window, or to create a subclass. The only reason I can see for using keydown or keyup would be to track the shift, ctrl, alt, or other special control characters. The problem is KeyDown/KeyUp does not get called for modifier keys. The goal is to inform the user that option-clicking the button will perform a different task.Īt first glance you might think that simply looking for the option key in a KeyDown event will do the trick. For example, iTunes changes its “Previous Track” button from a rewind icon to a Genius Shuffle icon when the option key is held down. Ctrl + O comes in fine, but I need ALT+o to work too. Then it gets into this code again and I get e.Key is RightAlt or LeftAlt (depending on which one i hit). Sometimes it is necessary, or at least user-friendly, to adjust your interface when the user holds down modifier keys. if ( (Keyboard.Modifiers ModifierKeys.Alt) & (e.Key Key.O)) When I press ALT + o, and step in here, this doesn't evaluate to True- the e.Key is defined as 'System' in the debugger.
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