I am using Qt creator to make a simple drawing program in c++. I have a mouseevent, that should get the coordinates to the nearest point (dot) allready existing from the point where mouse was clicked, and put them to line starting point coordinates. Thats done. But now the event should wait for a second mouse click to get the nearest dot coordninates again and put them to end point of line. But instead it does not wait for the second input and puts the same first point for the line endpoint also.
How can I make mouseevent take two click inputs, not do everything right away? Is it even possible? Thank you in advance.
You cannot make one event require two clicks (excluding, of course, the double click event). You can, however, establish a state within your application, where the first click starts the state and the second completes it. Pseudo-code to manage this:
// in your constructor:
StartingClickPoint = INVALID; // indicate that we have not entered our special state
// in your mouse event handler:
if (StartingClickPoint == INVALID) {
// we're only now starting this state; we don't have enough information to complete it
StartingClickPoint = CurrentClickPoint;
return;
}
else {
// complete the state handling and arm for the next pair of clicks
EndingClickPoint = CurrentClickPoint;
DoSomethingWithTheClickPoints();
StartingClickPoint = INVALID; // reset for the next pair of clicks
}
Related
I need to make an If/Else condition.
I make a form with Adobe Flash, at the first page, I need to make a login form. I want to make Input Text, but the input text must be filled. If the input text is empty, I want to make alert if the form must be filled. In my idea I have an input text called nama.text and in the bottom of the input text, I put a button called next.bt. Then, I put dynamic text "alert.text" in the bottom of the button.
My problem:
I want, if the button pressed by user with a filled input text, user will be direct to go to next frame. But, if the input text is empty, I want to make alert "Nama Must Be filled" and make user stay in this page and cannot go to next frame until the Nama.text is filled. I'm so sorry for my English, but I hope, everyone here understand with my questions.
"I want, if the button pressed by user with a filled input text, user
will be direct to go to next frame. But, if the input text is empty, i
want to make alert "Nama Must Be filled" and make user stay in this
page and cannot go to next frame until the Nama.text is filled"
(1) Don't ever use . (eg: fullstop) as part of a variable name. A fullstop means something else to the AS3 compiler. Generally it means "a property belonging to this variable". Maybe rename astxt_Nama?
(2) You can check the AS3 manual for Textfield options. One of them is a property called .length. This tells you how many chars exist inside your textfield.
So in your click function for handling Next button press:
if (txt_Nama.length <= 1) //if smaller or equal to 1
{
//if Smaller-than or Equal-to 1 then not enough chars typed
showTheAlert(); //tell AS3 to do this function
}
else
{
//if larger than 1 then something was typed
mc_Pages.gotoAndStop(2); //tells content MovieClip go to its frame 2
}
Then create a separate function to handle the display of alert (Don't put this function inside of another function)
function showTheAlert() :void
{
trace("No name was typed. Try again...");
//# Do something here like make some "warning" MClip visible
//maybe... mc_Alert.addChild;
//or... mc_Alert.visible = true;
}
(3) I suggest you create a MovieClip object to hold your content or pages. An MClip has its own timeline and go to its own frames like Stage. If you tell Stage to move to another frame then your code may not work
someMC.gotoAndStop(5); //# Correct... tells MovieClip to move frames. Code works because and MovieClip are on same Stage frame.
gotoAndStop(5); //# Wrong... tells Stage to move frames. Code only works on other frame where it is typed.
To handle text input I've set up a char-event callback with glfwSetCharCallback, and to handle non-text keypresses (arrow keys & hotkeys) I've set up a key-event callback with glfwSetKeyCallback.
What happens in this situation is that for a key press of a character key, I get two calls, one in the key-event callback, and then one in the char-event callback. This can cause unwanted effects - for example let's suppose the user configured the key "a" to enter "Append Mode" of a text editor - after it enters the mode it will also enter the character "a".. Is there a good way to handle this?
So far I've relied on both events arriving together before glfwPollEvents returns, and have merged them. But I get reports that this scheme doesn't work well on some Ubuntu systems..
I've been having trouble with this one as well. After some rudimentary debugging I found that if you press, hold then release a 'typable' key (meaning a key which may fire both the glfwKeyCallback and glfwCharCallback), the output is as follows:
KeyCallback - pressed
CharCallback - typed
KeyCallback - repeated
CharCallback - typed
(3. and 4. repeat until key is released)
KeyCallback - released
With this, and judging from the fact that there is a 0ms delay between the two events firing, they're probably fired sequentially. The solution I came up with (is rather janky), and involves creating some sort of KeyEvent structure:
(examples are in C++)
enum KeyEventType
{
Pressed,
Repeated,
Released
}
struct KeyEvent
{
KeyEventType Type;
int Key;
unsigned char Codepoint;
bool IsTyped;
}
and store it along with an index variable, such as
[main/input class]
std::vector<KeyEvent> m_KeyEvents;
size_t m_LastKeyEventIndex;
in the main file.
Then, when the glfwKeyCallback fires, push a new KeyEvent into the vector:
[glfwKeyCallback]
KeyEventType type = (action == GLFW_PRESS ? KeyEventType::Pressed : (action == GLFW_REPEAT ? KeyEventType::Repeated : KeyEventType::Released));
KeyEvent event = KeyEvent(type, key);
m_KeyEvents.push_back(event);
m_LastKeyEventIndex = m_KeyEvents.size() - 1;
and if the glfwCharCallback fires, we know from the debugging that it should be (immediately) after the corresponding keyCallback event, so you can modify the last added entry in the vector to add the codepoint and mark it as a 'typed' event, after-the-fact. This also gives the added benefit of tying the actual key that was pressed to the generated codepoint, which could come in useful.
[glfwCharCallback]
m_KeyEvents.at(m_LastKeyEventIndex).Codepoint = codepoint;
m_KeyEvents.at(m_LastKeyEventIndex).IsTyped = true;
Finally, in the main loop when you go to call glfwPollEvents(), process all those pending KeyEvents and then clear the vector and reset the index.
I haven't fully tested this yet, but some very rudimentary debugging shows this as a promising solution, resulting in the following*:
*I'm using a custom Key enum in place of the int Key. You could probably use glfwGetKeyName() to get the printable key name, however this resulted in exceptions for me when pressing some keys.
When typing in a cell in wxGrid, the arrow keys function to go back and forward between the characters. However, depending on caret position I would like to move the cursor to the next cell when an arrow key is pressed. Currently, wxGrid is configured to capture Enter key, which makes the cursor to move downwards (to the cell below).
My question is how can I capture KeyEvent when editor is still shown.
My approach:
void Grid::OnGridCmdEditorShown( wxGridEvent& event )
{
m_IsEditorShown=true;
//Connect(wxEVT_KEY_DOWN,wxKeyEventHandler(Grid::OnKeyDown),NULL, this); //This approach did not help either
event.Skip();
}
void Grid::OnKeyDown(wxKeyEvent& event)
{
if(m_IsEditorShown) wxMessageBox("You are keying");
event.Skip();
}
When the editor is shown and say I type abc to the current cell, the MessageBox only appears when I press enter. How can catch the KeyEvents when the editor is still shown, for example, the user types a to the current cell and the MessageBox is shown.
You need to use a custom editor (probably just deriving from the standard wxGridCellTextEditor) and bind to the wxEVT_CHAR event of the editing control created in its Create().
Notice that if you want to handle the initial key press, which results in showing the editor in the first place, you need to override wxGridCellEditor::StartingKey() instead, as this key press happens before the editing control is shown.
One way that worked for me was to connect a handler to each grid editor after it had been created, by adding this to Grid constructor:
Bind(wxEVT_GRID_EDITOR_CREATED, [=](wxGridEditorCreatedEvent& event) {
event.GetControl()->Bind(wxEVT_KEY_DOWN, &Grid::OnKeyDown, this);
});
This will not handle the initial key press which results in showing the editor in the first place, but from what I understand that would not be necessary here.
I'm working on a c++ project for school, and my implementation at this moment requires mouse input for controlling a ship (It's supposed to be a remake of Tyrian). Everything is working fine, except for the first time I move the mouse, it has an offset depending on where the mouse was when I started the game. I guess this is because I'm using SDL_GetRelativeMouse but how can I prevent it?
You may wish to initialize the mouse to a good known position when the application begins, possibly right before events callbacks are initialized.
Making sure the mouse is within the bounds of the window may also be appropriate. It isn't really relevant to the application outside of its boundaries anyway.
This is what I do to toggle mousegrab in a FPS-type application:
if(event.key.keysym.sym == SDLK_z)
{
if( mouse_grabbed )
{
SDL_WM_GrabInput(SDL_GRAB_OFF);
SDL_WarpMouse( display->w/2, display->h/2 );
SDL_ShowCursor(1);
}
else
{
SDL_ShowCursor(0);
SDL_WM_GrabInput(SDL_GRAB_ON);
int tx,ty;
SDL_GetRelativeMouseState(&tx, &ty);
}
mouse_grabbed = !mouse_grabbed;
}
Consuming a mouse update via the dummy SDL_GetRelativeMouseState() call was the important part.
For the moment I'll just suppress the first time mouse movement is detected. This seems to work, but it seems a rather unprofessional approach.
I use this:
Sdl.SDL_ShowCursor(Sdl.SDL_DISABLE);
Sdl.SDL_WM_GrabInput(Sdl.SDL_GRAB_ON);
e=new Sdl.SDL_Event();
pollOne();
.
.
.
private void pollOne(){
while(Sdl.SDL_PollEvent(out e)==1){
switch(e.type){
case Sdl.SDL_MOUSEMOTION:
float throwAway=((float)e.motion.xrel*headSens);
break;
}
}
}
Basically, when initializing the mouse (grabbing it and making it invisible) call pollOne to throw the first event away. Every event captured hereafter in the main event processing function called by the main loop is with mouse at center screen.
I hope that I can explain my problem well enough for someone to help.
Basically, I have a horizontal scrollbar (ranged 0 to 1000) and an edit control that represents the position of the scrollbar divided by 1000, so that the user can use either the scrollbar to select a range of numbers between 0 and 1 up to a 3 decimal precision (.001, .002, ..., .987, etc.), or enter their own number in the edit box. As they scroll the scrollbar, the number in the edit control changes to reflect the new scroll position. When a new number is entered, the scrollbar sets itself to a new position reflecting the number entered. Meanwhile I also perform some calculations with this number as it changes (through either the scrollbar or the edit control) and display the results in another dialog.
Here is my problem: I'm having trouble deciding which event handlers to use to produce the proper behavior when a user enters a number into the edit control.
I'm using a double value variable called fuelMargin to handle my edit control and a CScrollBar control variable called fuelScroll to handle the scrollbar.
In my HSCROLL event I set the edit control to the scroll position / 1000. No problems there; when the user scrolls the scrollbar the edit box is correctly updated.
As for the edit box, my first attempt was an ONCHANGE event:
void MarginDlg::OnEnChangeFueledit()
{
CEdit* editBox;
editBox = (CEdit*)GetDlgItem(IDC_FUELEDIT);
CString editString;
editBox->GetWindowText(editString);
if (editString.Compare(".") != 0 && editString.Compare("0.") != 0
&& editString.Compare(".0") != 0 && editString.Compare("0.0") != 0
&& editString.Compare(".00") != 0 && editString.Compare("0.00") != 0)
{
UpdateData();
UpdateData(FALSE);
if (fuelMargin > 1)
{
UpdateData();
fuelMargin = 1;
UpdateData(FALSE);
}
if (fuelMargin < 0)
{
UpdateData();
fuelMargin = 0;
UpdateData(FALSE);
}
fuelScroll.SetScrollPos(int(fuelMargin*1000));
}
}
I needed that first if statement in there to keep from doing an UpdateData() when the user is trying to type a number like .5 or .05 or .005. It does produce a few wonky behaviors, though; when the user tries to type something like .56, after the .5 an UpdateData() is performed, the number becomes 0.5, and the cursor is moved to the far left, so if they tried to type .56 they would accidentally end up typing 60.5 -- which goes to 1, since I won't let them enter numbers lower than 0 or higher than 1. If they enter 0.56, however, this behavior is avoided.
For my second attempt, I commented out my ONCHANGE event and put in an ONKILLFOCUS event instead:
void MarginDlg::OnEnKillfocusFueledit()
{
UpdateData();
UpdateData(FALSE);
if (fuelMargin > 1)
{
UpdateData();
fuelMargin = 1;
UpdateData(FALSE);
}
if (fuelMargin < 0)
{
UpdateData();
fuelMargin = 0;
UpdateData(FALSE);
}
fuelScroll.SetScrollPos(int(fuelMargin*1000));
}
So now the user can finish typing their number and all is hunky dory--as long as they click out of the edit box. The scrollbar won't move and results won't be calculated until the box loses focus.
I want the results to be calculated as the numbers in the box are being typed; I want the scrollbar to move as the numbers are being typed. But I don't want typing to be disrupted, i.e. the actual numbers in the box changed or the cursor moved in any way.
Suggestions?
Thanks!
With the first approach, it looks like you're almost there: the only really significant problem is that the repeated calls to UpdateData() mess with the cursor position as the user is typing.
Given that you're trying to have a reasonably complex interaction between the controls, what I'd suggest is not to do validation in the OnChange() at all, so that as the user is typing he can type what he wants (which is how most numeric edit controls work anyway). When the user closes the dialog the controls are on (or clicks a button that uses the data in some way) then validation should be triggered, and a suitable error shown.
Once you're free from validating in OnChange(), you can fix the "cursor moves" problem by simply not calling UpdateData() in OnChange(). Instead, just parse the number from "editString" and, if it's in the valid range, update the scrollbar. That way, the scrollbar updates as the user types, and if they type in an invalid value the scrollbar stays put, and they'll get an error when they move to whatever the next stage is. Something like this (not tested):
void MarginDlg::OnEnChangeFueledit()
{
CString editString;
GetDlgItem(IDC_FUELEDIT)->GetWindowText(editString);
double editValue;
if ((sscanf(editString,"%lf",&editValue) == 1)
{
if (editValue >= 0.0) && (editValue <= 1.0))
fuelScroll.SetScrollPos(int(editValue*1000));
}
}
The only remaining important problem to note is that, if the user types some invalid value, or a number out of the valid range, then the edit control and the scrollbar will be out of sync. The simplest way to deal with that is to just decide that the edit control is the "master" value: that is, when we want to know what the user entered, we always look at the edit control, not the scrollbar, and validate data.
As for your second approach, one possible solution might be to implement a timer message handler: in the timer handler you could say the equivalent of "if the user hasn't typed anything for a second, I'll assume they're done, and parse the number and update the scrollbar". I'm not so keen on that as a solution, though.
I'd suggest watching for the Enter key, and performing UpdateData() then as well as OnKillFocus and OnChange. The more user-friendly the better.
Next, make sure your UpdateData() routine only works in the direction you need:
If ".5" is entered in the edit control, run your UpdateData() routine when the OnChange event is raised, but make sure to update your scrollbar only. Don't worry about updating the edit control to "0.5" until OnKillFocus is raised. Any updates in the reverse direction (to the edit control) will mess with your cursor. If your edit control is somehow bound to this double variable and auto updates when the var changes, consider leaving the double and your edit control seperate from each other until the OnKillFocus event is raised.
The same concept applies in the other direction as well. When the user scrolls, don't mess with the scrollbar. Just update the edit control and leave it at that.
I should add that XAML's data-binding features really help in situations like this, if you know how to use them properly. It's unfortunate for us native-type developers that it's so difficult to implement similar functionality using only event handlers.