I am writing a c program to do some calculations.It would really help me if I was able to get responses by clicks of mouse.
How can i do this also If it is not possible then using which functions or libraries of C only would I be able to do that.
Ncurses has support for GPM (mouse library).
Excerpt from Ncurses interfacing with the mouse how-to:
Once a class of mouse events have been enabled, getch() class of functions return KEY_MOUSE every time some mouse event happens. Then the mouse event can be retrieved with getmouse().
The code approximately looks like this:
MEVENT event;
ch = getch();
if(ch == KEY_MOUSE)
if(getmouse(&event) == OK)
. /* Do some thing with the event */
.
.
getmouse() returns the event into the pointer given to it. It's a structure which contains
typedef struct
{
short id; /* ID to distinguish multiple devices */
int x, y, z; /* event coordinates */
mmask_t bstate; /* button state bits */
}
The bstate is the main variable we are interested in. It tells the button state of the mouse.
Then with a code snippet like the following, we can find out what happened.
if(event.bstate & BUTTON1_PRESSED)
printw("Left Button Pressed");
Related
I'm a beginner using Arduino with a Teensy 3.2 board and programming it as a usb keyboard.
I have two 4 button membrane switches. Their button contacts are on pins 1-8, and the 9th pin holds a soldered together wire of both membrane switches' "ground" line or whatever it's true name is; the line that completes the circuit.
Basically when you press the buttons they are supposed to simply type "a, b, c..." respectively. I've been told I need to use a matrix for this.
I'm looking for an example of how to code a keyboard matrix that effectively supports a one row/9 column line (or vice versa?) I've been unable to find that solution online.
All I have so far is this code which, when the button on the second pin is pressed, sends tons of "AAAAAAAAAAAAAAAA" keystrokes.
void setup() {
// make pin 2 an input and turn on the
// pullup resistor so it goes high unless
// connected to ground:
pinMode(2, INPUT_PULLUP);
Keyboard.begin();
}
void loop() {
//if the button is pressed
if(digitalRead(2)==LOW){
//Send an ASCII 'A',
Keyboard.write(65);
}
}
Would anyone be able to help?
First of all, a 1-row keypad is NOT a matrix. Or better, technically it can be considered a matrix but... A matrix keypad is something like this:
You see? In order to scan this you have to
Pull Row1 to ground, while leaving rows 2-4 floating
Read the values of Col1-4. These are the values of switches 1-4
Pull Row2 to ground, while leaving rows 1 and 3-4 floating
Read the values of Col1-4. These are the values of switches 5-8
And so on, for all the rows
As for the other problem, you are printing an A when the button is held low. What you want to achieve is to print A only on the falling edge of the pin (ideally once per pressure), so
char currValue = digitalRead(2);
if((currValue==LOW) && (oldValue==HIGH))
{
//Send an ASCII 'A',
Keyboard.write(65);
}
oldValue = currValue;
Of course you need to declare oldValue outside the loop function and initialize it to HIGH in the main.
With this code you won't receive tons of 'A's, but however you will see something like 5-10 'A's every time you press the button. Why? Because of the bouncing of the button. That's what debouncing techniques are for!
I suggest you to look at the class Bounce2 to get an easy to use class for your button. IF you prefer some code, I wrote this small code for another question:
#define CHECK_EVERY_MS 20
#define MIN_STABLE_VALS 5
unsigned long previousMillis;
char stableVals;
char buttonPressed;
...
void loop() {
if ((millis() - previousMillis) > CHECK_EVERY_MS)
{
previousMillis += CHECK_EVERY_MS;
if (digitalRead(2) != buttonPressed)
{
stableVals++;
if (stableVals >= MIN_STABLE_VALS)
{
buttonPressed = !buttonPressed;
stableVals = 0;
if (buttonPressed)
{
//Send an ASCII 'A',
Keyboard.write(65);
}
}
}
else
stableVals = 0;
}
}
In this case there is no need to check for the previous value, since the function already has a point reached only when the state changes.
If you have to use this for more buttons, however, you will have to duplicate the whole code (and also to use more stableVals variables). That's why I suggsted you to use the Bounce2 class (it does something like this but, since it is all wrapped inside a class, you won't need to bother about variables).
My Qt based application has a QMainWindow and another modal widget. This modal widget does not have a restore option. The user is allowed to drag this widget across displays when more than one monitor is available. However, when my widget is large, and the user drags it across to an extended monitor( usually a projector with a very low resolution) the widget is too large for the screen and gets cut.
I want to be able to detect when the user has moved to different screen so that I can resize the widget( and the content within) to fit the new screen's dimension and resolution. Is there any signal that Qt emits for this purpose?
This is probably the function call you are looking for:
http://qt-project.org/doc/qt-5/qdesktopwidget.html#screenNumber
int QDesktopWidget::screenNumber(const QWidget * widget = 0) const
Returns the index of the screen that contains the largest part of
widget, or -1 if the widget not on a screen.
To use this as part of a signal, you should subclass moveEvent and resizeEvent of a QWidget and put your logic for deciding how to place/resize your widget there. If you want to resize like a browser tab that gets dragged onto a new monitor, you may want to just use the point of the mouse instead of the widget to decide which monitor to react to.
So your end code could look something like this:
void Widget::moveEvent(QMoveEvent * e)
{
m_newScreenSize = qApp->desktop()->screenGeometry(this);
}
void Widget::mouseReleaseEvent(QMouseEvent * e)
{
this->resize(m_newScreenSize);
}
Other Links and References
QMoveEvent
QResizeEvent
QDesktopWidget
http://qt-project.org/doc/qt-5/qdesktopwidget.html#details
http://qt-project.org/doc/qt-5/qapplication.html#desktop
http://qt-project.org/doc/qt-5/qmoveevent.html#details
http://qt-project.org/doc/qt-5/qwidget.html#moveEvent
http://qt-project.org/doc/qt-5/qwidget.html#resizeEvent
http://qt-project.org/doc/qt-5/qrect.html#intersects
http://qt-project.org/doc/qt-5/qdesktopwidget.html#availableGeometry-2
const QRect QDesktopWidget::availableGeometry(const QWidget * widget) const
I'm trying to show a window in xcb, inside the main window, but actually without luck.
The idea is that when the user press a button (in that case the X button) a small white window is shown (just for test).
But actually i'm stuck on that step. I watched the example code here:
http://en.wikibooks.org/wiki/X_Window_Programming/XCB
And tried to do the same in my application.
[EDIT 28/10/2013] Now with that code i can show a window, but if i try to add other variable like int i=0, or whatever, the window doesn't appear, and no expose events were raised (all events that were raised are or 0 or 2 (even if i add the variables inside other events). Any idea?
This is the XCB_KEY_PRESS event handler code:
Edit (with the new code)
case XCB_KEY_PRESS:{
xcb_key_press_event_t *kp = (xcb_key_press_event_t *)ev;
if(kp->detail==53){
printf("X pressed\n");
uint32_t vals[2];
mask = XCB_CW_BACK_PIXEL | XCB_CW_EVENT_MASK;
vals[0]=screen->white_pixel;
vals[1]=XCB_EVENT_MASK_EXPOSURE | XCB_EVENT_MASK_KEY_PRESS;
win = xcb_generate_id(connection);
xcb_create_window(
connection,
XCB_COPY_FROM_PARENT,
win,
root,
80,80,
150,150,
10,
XCB_WINDOW_CLASS_INPUT_OUTPUT,
screen->root_visual,
mask, values);
mask = XCB_GC_FOREGROUND | XCB_GC_GRAPHICS_EXPOSURES;
vals[0]=screen->white_pixel;
vals[1]=0;
background=xcb_generate_id(connection);
xcb_create_gc(connection, background, win, mask, vals);
xcb_map_window(connection,win);
xcb_flush(connection);
printf("finished\n");
}
printf("KEY_PRESS - Pressed: %d\n", kp->detail);
}
root is the root window obtained from xcb_screen_t variable.
The definition of background and win are the following:
xcb_window_t win;
xcb_gcontext_t background;
And i added even a XCB_EXPOSE event handler:
case XCB_EXPOSE:{
printf("EXPOSE NEW WINDOW CREATED\n");
xcb_poly_fill_rectangle(connection, win, background,1,&rectangle);
xcb_flush(connection);
}
What is wrong with that code? What am i missing? (I'm trying to develop a very basic window manager, just for fun)
(My idea for that program is that when x is pressed an input box is shown, do you have any suggestion on how to do that?)
I am trying to use an edit control along with a spin control using MFC visual studio .net 2003. I have carried out the basic settings for the spin control like setting the "AutoBuddy" property and "SetBuddyInteger" property to True so that the Spin control works in coordination with the edit control next to it. In my Spin control's event handler, I am facing a problem when I am trying to call my Invalidate() function. The float value in my edit control does not update and stays zero. If I remove the Invalidate(), then the value increments but my paint function is not updated obviously. A code of the following is given below:
void CMyDlg::OnSpinA(NMHDR *pNMHDR, LRESULT *pResult)
{
LPNMUPDOWN pNMUpDown = reinterpret_cast<LPNMUPDOWN>(pNMHDR);
// TODO: Add your control notification handler code here
UpdateData();
m_A = m_ASpinCtrl.GetPos(); // m_A is my edit control float value variable
Invalidate(); // Invalidate is to be called to update my paint function to redraw the drawing
UpdateData(false);
*pResult = 0;
}
I have carried out the tab order correctly as well for the two controls.
Any suggestions on where I am going wrong?
Thanks in advance.
If you just want to have a spinning integer, you don't have to override anything.
The spin control has to be right next to the edit control in the tab order. With AutoBuddy that's all you have to do.
m_A when getting the position back would do something weird and would not return you the correct value. Try using the pointer to get your position and value and then carry out the invalidate().
{
LPNMUPDOWN pNMUpDown = reinterpret_cast<LPNMUPDOWN>(pNMHDR);
// TODO: Add your control notification handler code here
UpdateData();
CString tempStr;
m_A += pNMUpDown->iDelta;
tempStr.Format("%f",m_A);
m_ACtrl.SetWindowText(tempStr); // Like a CEdit m_ACtrl to display your string
Invalidate();
UpdateData(false);
*pResult = 0;
}
This should work perfectly well. Let me know if you still get any problems.
I'm on a roll today with MFC! :D
I have a text box and a list view control.
When the user presses the VK_UP and VK_DOWN keys in the text box, I would like this to happen:
Do some stuff.
Have the list view control also process the message (to highlight the previous/next item).
I want the list view to wrap around the current selection, if the key press is the first in its sequence.
Do some more stuff.
I tried subclassing my edit box in my dialog:
class MyEditBox : public CWnd
{
bool allowWrap;
afx_msg void OnKeyUp(UINT, UINT, UINT) { this->allowWrap = true; }
afx_msg void OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags)
{
CListCtrl &listView = static_cast<CListView *>(
this->GetParent()->GetDlgItem(IDC_LIST_VIEW))->GetListCtrl();
if (nChar == VK_UP || nChar == VK_DOWN)
{
int iSelBefore = listView.GetNextItem(-1, LVNI_SELECTED);
this->GetParent()->GetDlgItem(IDC_LIST_VIEW)
->OnKeyDown(nChar, nRepCnt, nFlags); //Oops! Protected member :(
int iSelAfter = listView.GetNextItem(-1, LVNI_SELECTED);
if (iSelBefore == iSelAfter && // Did the selection reach an end?
this->allowWrap) // If so, can we wrap it around?
{
int i = a == 0 ? listView.GetItemCount() - 1 : 0;
listView.SetItemState(i, LVIS_SELECTED | LVIS_FOCUSED,
LVIS_SELECTED | LVIS_FOCUSED);
}
}
this->allowWrap = false;
}
}
but OnKeyDown() is a protected member, so I can't just call it on another control.
Is there a better way to solve this than manually sending the command with SendMessage? Should I change my design, e.g. subclass something else, etc.?
Your intention is to select previous or next item in list control, right? Then you should call the method to do that directly instaed of asking the CListCtrl to "process" your message.
You may call CListCtrl::SetSelectionMark and CListCtrl::SetItemState to select next or previous keystroke. Example:
cListCtrl.SetSelectionMark(nIndex);
cListCtrl.SetItemState(nIndex, LVIS_SELECTED | LVIS_FOCUSED, 0xFF);
You can handle Key Down, Key Up as well as Page Down, Page Up, End, Home or any any key from edit box. You need to do calculation, though.
Or you can just SendMessage. There is no need to call OnKeyDown directly. Let the framework call it for you when you send the message.
I am seeing also other ways to solve this:
Derive a class from CListCtrl called MyListCtrl and choose one of two things:
1.1 Declare MyEditBox as a friend and now you can call the protected methods on MyEditBox
1.2 Add public methods CallOnKeyDown(...) and CallOnKeyup(...) to it that only do what is needed.
And when creating the control, instance a MyListCtrl instead of a CListCtrl. Also replace the listView variable you have shown here to be a MyListCtrl and use the methods you have now available
Use PreTranslateMessage(...). I think this "hammer" solution is worse than sending a message.