I'm reviewing some part of a project written with Qt:
void Editor::keyPressEvent(QKeyEvent* event)
{
int key = event->key();
switch (key) {
case Qt::Key_Tab:
...
I've put a breakpoint at int key = event->key().
Now, I've notice that pressing the minus "-" on the keypad shows me in debug:
Pressed 'Minus' (key:45 vKey:65453)
Qt::Key_Minus (0x002d)
Then, pressing "-" (the hyphen on the hyphen/underscore key gives me:
Pressed 'Minus' (key:45 vKey:45)"
Qt::Key_Minus (0x002d)
1439241440
So they are definitely detected as different (judging from this "vKey" number) but the event is the same: "Key_Minus".
Why can't I get the "Key_hyphen" event? How could I solve this (maybe using this "vKey" number?
Try
event->nativeVirtualKey();
and
event->nativeScanCode();
Related
Platform: Intellij IDEA
Language: JavaFX
I would like to be able to select a line of text where the cursor lies. Similar to SQL Developer, I have a textarea that allows multiples lines of input or queries. It is nice to be able to use the textarea as a query bank while testing queries.
Using the txtOutput.getCaretPosition(), I would like to get the current integer index of the line where the cursor resides and then be able to select all of the text that is within that same line with the same keyboard shortcut as SQL Developer (Ctrl + Enter). Using the .selectForward() or .selectBackward() will not work if there are multiple lines.
Any help or suggestions as to how to limit the selection of text to one line or select text up until a specific character (e.g. ";") would be much appreciated.
public void executeEvent(KeyEvent event) {
//int cursorLine = txtInput.getCaretPosition();
if (event.isControlDown() == true && event.getCode() == KeyCode.ENTER) {
//select line of text where integer equals cursorLine
//txtInput.selectBackward();
//txtInput.selectForward();
}
}
Just search the text for the relevant delimiting character (e.g. a newline character), and select the relevant portion. The only thing you have to be careful of here is if the user selects the last line, in which case there will be subsequent newline character:
int caretPos = txtInput.getCaretPosition();
int previousNewline = txtInput.getText().lastIndexOf('\n', caretPos);
int nextNewline = txtInput.getText().indexOf('\n', caretPos);
if (nextNewline == -1) nextNewline = txtInput.getText().length();
txtInput.selectRange(previousNewLine + 1, nextNewLine);
I need to get the selected value in a combobox as of a data type char. I know how to get the selected item it's the conversion which I've got stuck on. Any suggestions?
This is the combobox and it content:
idCharCombo = new ComboBox<>();
idCharCombo.getItems().addAll("A","B","G","H","L","M","P","Z");
Now i will be using this data in a method which passes an int and a char (bellow is the use of the method where the second element is still an object rather than a char):
if (checkStaffMemberById(Integer.parseInt(idNoTxtFld.getText()), idCharCombo.getValue()) == true){
AlertBox.display("ID Validation", "ERROR! ID Already Exists.");
hope i arranged adequately
Since your combo box appears to only hold single-character strings, and you want to treat them as chars, the most obvious thing to do is to use a ComboBox<Character> instead of a ComboBox<String>. I.e. replace your declaration, which presumably looks like
ComboBox<String> idCharCombo ;
with
ComboBox<Character> idCharCombo ;
and then you can do
idCharCombo.getItems().addAll('A','B','G','H','L','M','P','Z');
Then
idCharCombo.getValue()
will return a Character which will be autounboxed to a char as needed, so your method call
checkStaffMemberById(Integer.parseInt(idNoTxtFld.getText()), idCharCombo.getValue())
should work as-is.
In IPython Notebook / Jupyter, arrow up/down keystrokes within a cell are handled by CodeMirror (as far as I can tell). I use these actions a lot (re-bound to control-p / control-n) to move between cells; but at the end of every cell, the cursor moves to end of line first before jumping to the next cell. This is counter-intuitive and, to me, rather distracting.
Is there any way to configure CodeMirror to make this move down to be just that - a move down?
Thanks!
The moving-to-next-cell behavior is defined by IPython wrapper code, which probably checks whether the cursor is at the end of the current cell, and overrides the default CodeMirror behavior in that case. You'll have to find that handler and somehow replace it with one that checks whether the cursor is on the last line. (I don't know much about IPython, only about CodeMirror, so I can't point you at the proper way to find and override the relevant code. They might have bound the Down key, or they might have overridden the goLineDown command.)
Knowing that I wasn't alone in wanting to skip the "going to end of line" behavior when going down from the last line of a code cell, I investigated that behavior and found out that:
it's CodeMirror that goes to the end of line when you type down in the last line of a code cell (file: codemirror.js ; "methods": findPosV and moveV)
and it's IPython that decides what to do with the "down" event after it has been handled by CodeMirror (file: cell.js ; class: Cell ; method: handle_codemirror_keyevent) ; looking at the code, I saw that IPython ignores the event when not at the last character of the last line.
This essentially confirms Marijin's answer.
The primary goal being to jump to the next cell, I think there's no need to prevent CodeMirror from going to the end of that line. The point is to force IPython to handle the event anyway.
My solution was to change the code from Cell.prototype.handle_codemirror_keyevent to this:
Cell.prototype.handle_codemirror_keyevent = function (editor, event) {
var shortcuts = this.keyboard_manager.edit_shortcuts;
var cur = editor.getCursor();
if((cur.line !== 0) && event.keyCode === 38){
// going up, but not from the first line
// don't do anything more with the event
event._ipkmIgnore = true;
}
var nLastLine = editor.lastLine();
if ((event.keyCode === 40) &&
((cur.line !== nLastLine))
) {
// going down, but not from the last line
// don't do anything more with the event
event._ipkmIgnore = true;
}
// if this is an edit_shortcuts shortcut, the global keyboard/shortcut
// manager will handle it
if (shortcuts.handles(event)) {
return true;
}
return false;
};
This code provides the desired behavior for the "down-arrow" key (almost: the cursor still goes to the end of the line, except that we don't see it, as we're already in another cell at that point), and also handles the "up-arrow" key similarly.
To modify the handle_codemirror_keyevent prototype, you have two possibilities:
You edit the cell.js file and change the code of the prototype to the code I gave above. The file is in <python>/Lib/site-packages/IPython/html/static/notebook/js or something similar depending on you distro
Much better, after the page is loaded, you change that prototype dynamically by doing this:
IPython.Cell.prototype.handle_codemirror_keyevent = function (editor, event) {
<same code as above>
};
You can do that in your custom.js for example, or create an extension to do it (that's what I did).
EDIT: Forgot to mention that my programming language is C++, and my IDE is Qt Creator.
I don't understand why I am having trouble adding elements to a referenced vector of a map (i.e. sometimes it works and sometimes it fails).
For example:
class C_html4_tags {
public:
C_html4_tags();
//.......
typedef std::vector<S_html_attr_value> TYPE_attr_values;
//.....
};
//...
C_html4_tags::C_html4_tags() {
//........
map<S_browser, TYPE_attr_values> attr_supported_attr_values_map;
S_browser dummy_browser; //a fake browser key for referencing a fully Html 4.01-compliant supported attr values list
dummy_browser.name = "Dummy";
//.....
TYPE_attr_values& attr_supported_attr_values = attr_supported_attr_values_map[dummy_browser];
//......
**attr_supported_attr_values = attr_supported_attr_values_map[dummy_browser];**
//...
**attr_supported_attr_values.clear();
attr_supported_attr_values_map.clear();**
//......
**attr_supported_attr_values = attr_supported_attr_values_map[dummy_browser];**
//...
**attr_supported_attr_values.clear();
attr_supported_attr_values_map.clear();**
}
I do the bolded lines multiple times with a bunch of different attributes, with very little difference between them, without a problem until reaching this one attribute (a_tabindex_attr), in which the IDE doesn't report anything wrong when running it normally (except "The program has unexpectedly finished." However, when debugging it, it now reports:
Signal received
The inferior stopped because it received a signal from the Operating
System.
Signal name : SIGSEGV Signal meaning : Segmentation fault
And the backtrace points to the attribute I mentioned above, on the line of code which does this:
attr_supported_attr_values.clear();
Now, after adding some debugging cout lines to the code, I learned that what's happening is, for some reason, even after doing:
attr_supported_attr_values.push_back(attr_value);
the vector object which is the returned mapped value of:
attr_supported_attr_values = attr_supported_attr_values_map[dummy_browser];
is not actually being changed when I push_back an S_html_attr_value object to the referenced vector. Now, I don't why that is, since I do pretty much the exact same thing in a bunch of other attributes' code before this one, without any problem, but for some reason now, on this one, it ain't adding the object to attr_supported_attr_values (which is a reference to the returned mapped value of 'dummy_browser'). And I know this for a fact, because I outputted the size of the internal mapped value object of the map (using an iterator for the map), and it was 0 after the call to push_back(). However, what is even more odd is, I ALSO outputted attr_supported_attr_values.size() after the call to push_back(), and that was 1! Now how could that be since they're both supposed to be the same object??
Note:
The full code of what I'm talking about is below (or at least the attribute code, minus the debugging statements...):
//a_tabindex_attr:
attr_desc = "Specifies the position of an <a> element in the\n"
"tabbing order for the current document.\n"
"The tabbing order defines the order in which\n"
"elements will receive focus when navigated by\n"
"the user via the keyboard. The tabbing order\n"
"may include elements nested within other elements.\n"
"Elements that may receive focus based on tabindex\n"
"adhere to the following rules:\n\n"
"1. Those elements that support this attribute and\n"
"assign a positive value to it are navigated first.\n"
"Navigation proceeds from the element with the\n"
"lowest tabindex value to the element with the\n"
"highest value. Values need not be sequential\n"
"nor must they begin with any particular value.\n"
"Elements that have identical tabindex values\n"
"should be navigated in the order they appear\n"
"in the character stream.\n"
"2. Those elements that do not support this\n"
"attribute or support it and assign it a value\n"
"of \"0\" are navigated next. These elements are\n"
"navigated in the order they appear in the\n"
"character stream.\n"
"3. Elements that are disabled do not participate\n"
"in the tabbing order.";
attr_supported_attr_values = attr_supported_attr_values_map[dummy_browser];
attr_value_desc = "A number you specify for the tab index/order.\n"
"It must be a value between 0 and 32767.";
attr_value_content = "<i>number</i>";
attr_value = C_html4_attributes_obj.getAttrValue(attr_value_desc, attr_value_content,
attr_value_supported_browsers,
attr_value_required, attr_value_deprecated,
attr_value_notes, attr_value_tips);
attr_value.is_relative = true;
attr_supported_attr_values.push_back(attr_value);
try {
N_init_class_members::initAttr(C_html4_attributes::attr_tabindex, a_tabindex_attr, attr_desc,
attr_supported_browsers, attr_supported_attr_values_map, attr_required,
attr_deprecated, attr_notes, attr_tips);
}
catch (const char* exc) {
string exc_str = "Error! Call to N_init_class_members::initAttr() from\n"
"constructor of C_html4_tags class. That function\n"
"reported the following exception:\n\n";
exc_str += exc;
throw (exc_str.c_str()); //re-throw exception
}
a_tabindex_attr.is_standard_attr = true;
a_tabindex_attr.is_optional_attr = true;
//cleanup from attribute operations so we can begin working on the next attribute:
C_html4_attributes_obj.clear(); //wipes the slate clean for all the supported attributes' properties except content
attr_desc.clear();
attr_supported_attr_values.clear();
attr_supported_attr_values_map.clear();
attr_value_desc.clear();
attr_value_content.clear();
N.B. Keep in mind the difference between key code and character code. For example, the number 1 (one) and the character ! (bang) both have the same key code but different character codes. Likewise, the number 7 from the row of numbers and the number 7 from the numpad have different key codes but the same character codes.
I'm programming a music rhythm game in Adobe Flex and would like to bind keyboard keys. This isn't a problem, but I certainly would have a problem, say, setting the default keys to A, S, D, and F and telling the user that this is the case.
If you take a look at the documentation for flash.ui.Keyboard, you'll see that there are constants for keyboard keys to key codes. However, these are only available in Adobe AIR and not the browser. This makes sense since not all operating systems and keyboards are alike (or present!), so key codes can vary.
So, how can I assign default keys that have meaning instead of picking key codes and praying?
My only sane thought is to store the character codes for the key bindings and then provide an character code to String mapping so I can tell the user what to press. However, my gut tells me that this will break in subtle or not-so-subtle ways. Like CAPSLOCK.
Thanks.
Update: I am currently using radekg's answer, but I still think that this will break easily. I would feel more comfortable with some persuasion that this is correct.
according to Flash 8 documentation you can simply rely on ASCII codes. Take a look at these topics of the Flash 8 documentation:
http://livedocs.adobe.com/flash/mx2004/main_7_2/wwhelp/wwhimpl/common/html/wwhelp.htm?context=Flash_MX_2004&file=00001113.html
http://livedocs.adobe.com/flash/mx2004/main_7_2/wwhelp/wwhimpl/common/html/wwhelp.htm?context=Flash_MX_2004&file=00001115.html#71579
http://livedocs.adobe.com/flash/mx2004/main_7_2/wwhelp/wwhimpl/common/html/wwhelp.htm?context=Flash_MX_2004&file=00001116.html#71709
http://livedocs.adobe.com/flash/mx2004/main_7_2/wwhelp/wwhimpl/common/html/wwhelp.htm?context=Flash_MX_2004&file=00001114.html#71525
As far as I'm aware of all modern operating systems use standard ASCII. These codes have not changed since Flash 5 era. To compare letters if you don't want to rely on ASCII codes:
private function compareChar(code:Number):void {
if ( "a" == String.fromCharCode( code ).toLowerCase() ) {
trace("A pressed");
} else {
trace("You pressed " + String.fromCharCode(code));
}
}
...
compareChar(65); // 65 is A
compareChar(96); // 96 is numpad 0
However I think you can rely on ASCII codes.
Hope this helps.
Radekg is mostly correct.
Flash has a built in Class flash.ui.KeyLocation with four static properties: LEFT, RIGHT, NUM_PAD, STANDARD. This means that you can have a definitive idea which key has been pressed, even if the keyboard has been remapped. If you this in combination with String.fromCharCode, you should be able to solve this problem rather neatly.
Your final code might look like:
import flash.ui.KeyLocation;
import flash.events.KeyboardEvent;
function handleKeyboardEvent( event:KeyboardEvent )
{
// This will work for a majority of the keys.
var key:String = String.fromCharCode( event.charCode ).toLowerCase();
// Use strict comparison
if( event.keyLocation !== KeyLocation.STANDARD )
{
// The key is a number, then it needs to be re-identified.
if( event.keyLocation == KeyLocation.RIGHT ) key = "r" + key;
if( event.keyLocation == KeyLocation.LEFT ) key = "l" + key;
if( event.keyLocation == KeyLocation.NUM_PAD) key = "n" + key;
}
switch( key )
{
case "r1":
// Do something with the one which is not on the keypad.
break;
case "n.":
// Do something with the number pad's period.
break;
case "n":
// Do something with the letter N.
break;
}
}
I will admit, I am not certain what will happen with String.fromCharCode and control keys (F1, Alt, Ctrl, etc), but the KeyboardEvent does support event.shiftKey, event.ctrlKey, event.altKey