As per below code snippet shared in coliru link, Each time the user clicks the i’th button, the m_clicks[i] and m_total_clicks should both get incremented. To achieve this, the class MyFrame will register a "on_click-handler" callback with each button. Trying to register button_clicked as the callback doesn’t work.
m_pushbuttons[i].on_click_handler(MyFrame::button_clicked);// Doesn't give expected result
Below is the coliru link for source code.
https://coliru.stacked-crooked.com/a/c15865d59b41341f
Here is the expected output based on below test cases for both f1 and f2 objects with print_stats method.
//MyFrame f1(2)
//f1.m_buttons[0].click();
//f1.m_buttons[0].click();
//f1.m_buttons[0].click();
//f1.m_buttons[1].click();
//f1.m_buttons[1].click();
//f1.print_stats();
//MyFrame f2(3);
//f2.m_buttons[2].click();
//f2.m_buttons[2].click();
//f2.m_buttons[2].click();
//f2.m_buttons[1].click();
//f2.print_stats();
// Should print:
// Total Clicks: 4
// Button[0] clicks: 0
// Button[1] clicks: 1
// Button[2] clicks: 3
So basically I need to write a client class so that when instantiated, will create N such buttons (where N is a constructor time parameter).
The client class wishes to register a callback to keep track of button clicks but in current implementation, There are couple of issues.
(1) std::vector MyFrame :: m_clicks (2) is initialized
statically and initialize value should be same as MyFrame initialized object value instead of static value .
(2) Without declaring static m_total_clicks and m_clicks , Is there any other way to achieve the same.
(3) on line no. 20 ,m_ftr pointer needs to be properly initialized.
Could you suggest any proper design/implementation for this callback implementation.
Related
I have this sprite: spr_meteoriteLv3, which has two sub-images with index image_index 0 and 1 respectively.
I have these objects: obj_meteoriteLv3, obj_tempMeteoriteLv3, and obj_score. Object obj_meteoriteLv3 spawns from above with random position, random amount, and random sub-image. Object obj_tempMeteoriteLv3 makes obj_meteoriteLv3s spawn. When player clicks on a meteorite, the program checks the value of image_index for that object.
obj_meteoriteLv3 has these events:
Create Event: change sprite_index into spr_meteoriteLv3, and start moving downwards.
Left-pressed Mouse Event: destroy the self instance, and check image_index: if image_index == 0 then score += 5; else score -= 5).
obj_tempMeteoriteLv3 has these events:
Create Event: set Alarm 0 to 3600, set variable exist to 1, and set variable add to 1.
Alarm 0: set variable add to 0, and destroy the obj_meteoriteLv3 instance.
Alarm 1: set variable exist to 1.
Step Event: if (exist == 1) then, if (add == 1) then create instance of obj_meteoriteLv3, set variable exist to 0, and set Alarm 1 to 10.
obj_score has these events:
Create Event: set score to 0.
Draw Event: draw the value of score.
The problem is, no matter which sub-image the meteorite image_index has when clicked, the score will always be incremented by 5 points. It's like the else condition isn't working. How can I fix this? Please explain your answer. Thanks.
I add some images for better understanding. Link 1. Link 2
In obj_meteoriteLv3 it's being destroyed before it can execute the rest of the code blocks. Move "Destroy Instance" to the bottom.
In obj_tempMeteoriteLv3 both variables "add" and "exist" are not necessary, instead have-
Create Event-
alarm[0] = 3600
alarm[1] = 10
Alarm[0] Event-
destroy_instance
Alarm[1] Event
Create_instance of obj_meteoriteLv3
alarm[1] = 10
Potentially, when you click, every single meteorite is triggered.
On the left click event of the meteorite, you did not check if the cursor was on the sprite. You have to use the position_meeting function, to which you pass the mouse position and the instance to click.
it would look like :
if (position_meeting(mouse_x, mouse_y, id))
{
//your destroy code
}
Moreover, when the instance_destroy(); line is read, the following code is ignored and the program jumps to the destroy_event. William explained it well and suggested to change the order of the lines of code, but you can also change the score in the destroy event directly.
I would like to add that checking for clicks in every instance of the meteorites is not optimal for performances.
My recommendation would be to use a single object to check for clicks (your player or your meteorite spawner, for example), in which you would check for clicks, and if a meteorite is touched, you would trigger it's destroy event. And in this event, you would increment the score and check the sprite.
Your click event would look like :
with (instance_position(mouse_x, mouse_y, obj_meteoriteLv3))
{
instance_destroy();
}
and in the meteorite destroy event, you would check the image_index and change the score accordingly.
EDIT : why the score doesn't change
I believe you didn't declare the score as a global variable, but as an instance variable. So when you write "score = ..." in an other object, it creates a new score variable, unrelated to the precedent.
You have 2 options :
1 - Declare the score a global variable in the create event of obj_score:
globalvar score;
score = //your starting score
Be aware that a global variable can't be set on it's initialisation line.
2 - Change the score through the score object :
whenever the score has to change :
obj_score.score = ...
I made a function that sets .click for the number of buttons passed to it.
The function is called when another Jquery detects the number of buttons on the page
...
var n = $(".button").length + 1;
...
set_navig(n);
...
function set_navig(n){
for(i=1 ; i<n ; i++){
var btn = "#pb" + i;
$(document).ready(function(){
$(btn).click(function(){
alert('Working!');
});
});
}
}
I have tried removing or adding buttons on the page - correct (n) is passed to the function, but ALWAYS only the last one doesn't work at all.
ANY IDEAS?
Thnx to EVERYBODY for so much good stuff available here. You where the major source of Jquery knowledge when I started learning it.
Well, I originally thought you should use i<=n, but you pass length + 1 (that's unusual by the way). You could just pass the button array instead of the length. Then you can iterate through each one.
I don't see a specific error with the code other than style, so perhaps you are not getting as many .button objects as you think or perhaps you have a typo in the last ID. You should paste a sample of the html code or just debug it yourself using alert() to see what values are being passed.
For future reference, common loops in many languages are either: for(i=0;i<n;i++){} or for(i=1;i<=n;i++){} I would say passing length + 1 to your function is very poor practice.
I'm doing an asynchronous read from a USB printer. The read works correctly. My trouble is updating a NSTextField from within the callback.
-(IBAction)printTest:(id)sender
{
// Setup... then:
NSLog(#"starting async read: %#", _printerOutput);
NSLog(#"_printerOutput pointer = %p", _printerOutput);
result = (*interface)->ReadPipeAsyncTO(interface,
1,
readBuffer,
numBytesRead,
500,
1000,
USBDeviceReadCompletionCallback,
&(_printerOutput)
);
The callback is defined as:
void USBDeviceReadCompletionCallback(void *refCon, IOReturn result, void *messageArg)
{
NSTextField *printerOutput = (__bridge NSTextField *) messageArg;
NSLog(#"_printerOutput pointer = %p", printerOutput);
}
The pointer loses its value when inside of the callback.
starting async read: <NSTextField: 0x10221dc60>
_printerOutput pointer = 0x10221dc60
_printerOutput pointer = 0x0
I've looked in many places trying to mimic different ways to pass in the pointer. There can be only one correct way. :)
Another variation on the theme: (__bridge void *)(_printerOutput). This doesn't work, either.
I understand that the callback is of type IOAsyncCallback1.
Other URLs of note:
http://www.google.com/search?client=safari&rls=en&q=another+usb+notification+example&ie=UTF-8&oe=UTF-8 and updating UI from a C function in a thread
I presume _printerOutput is an NSTextField*?
First, is there a particular reason why are you passing an NSTextField** into the callback? (Note the ampersand in the last argument you're passing to ReadPipeAsyncTO.)
Second, I'd avoid ARC with sensitive code, just as a precaution.
Third, from what I see, last argument of ReadPipeAsyncTO is called refcon. Is it a coincidence that callback's first argument is called refCon? Note you're trying to get a text field from messageArg, not refCon.
To extend on my third point…
ReadPipeAsyncTO has an argument called refcon. This is the last argument.
Please pass _printerOutput there. Not a pointer to _printerOutput (do not pass &(_printerOutput)) -- _printerOutput is already a pointer.
Now finally. Look at the first argument of the callback. It's called refcon. In fact -- let's see what Apple docs say about this callback:
refcon
The refcon passed into the original I/O request
My conclusion is that your code should read:
void USBDeviceReadCompletionCallback(void *refCon, IOReturn result, void *messageArg)
{
NSTextField *printerOutput = (__bridge NSTextField *) refCon; // <=== the change is here
NSLog(#"_printerOutput pointer = %p", printerOutput);
}
Can you, please, try this out? I get a feeling that you didn't try this.
Small but possibly important digression: Were it some other object, and if you didn't use ARC, I'd suggest retaining the _printerOutput variable when passing it into ReadPipeAsyncTO, and releasing it in the callback.
But, since the text field should, presumably, have the lifetime of the application, there is probably no need to do so.
ARC probably loses track of the need for the object behind the pointer to exist once it's passed into C code, but it doesn't matter, since the pointer is still stored in the printerOutput property. Besides, once a pointer is in C code, nothing can just "follow it around" and "reset it".
Confusion when it comes to understanding and explaining the concepts is precisely why I said "avoid ARC with sensitive code". :-)
I'm using Actionscript 2.0 for a mobile phone and can't get my head around Events.
I'm creating a class object with all my code and using a group of functions (all as direct 1st level children of the class). There's one function that creates a Movieclip with a square on it and sets the onPress event to another function called hit:
public function draw1Sqr(sName:String,pTL:Object,sSide:Number,rgb:Number){
// create a movie clip for the Sqr
var Sqr:MovieClip=this.canvas_mc.createEmptyMovieClip(sName,this.canvas_mc.getNextHighestDepth());
// draw square
Sqr.beginFill(rgb);
//etc ...more lines
//setup properties (these are accessible in the event)
Sqr.sSide=sSide;
Sqr.sName=sName;
//setup event
Sqr.onPress = hit; // this syntax seems to lead to 'this' within
// the handler function to be Sqr (movieclip)
//Sqr.onPress = Delegate.create(this, hit);
//I've read a lot about Delegate but it seems to make things harder for me.
}
Then in my event handler, I just cannot get the scope right...
public function hit(){
for (var x in this){
trace(x + " == " + this[x]);
}
//output results
//onPress == [type Function]
//sName == bSqr_7_4
//sSide == 20
trace(eval(this["._parent"])); //undefined
trace(eval(this["._x"])); //undefined
}
For some reason, although the scope is set to the calling object (Sqr, a Movieclip) and I can access properties I defined, I can't use the 'native' properties of a Movieclip object.
Any suggestions on how I can access the _x, _y and other properties of the Movieclip object that is pressed.
Use the array accessor or the dot accessor, but not both. For example:
trace(this._parent); // OR
trace(this["_parent"]);
As for the results of your iteration, I recall AS2 being screwy on this front. IIRC only dynamic properties are returned when looping with for ... in. This prevents Objects (which often serve as hash maps) from including their native properties when all you want are the key/value pairs you set yourself.
Also - the eval() function can be easily overused. Unless you absolutely must execute a String of AS2 that you don't have at compile-time I would recommend avoiding it. Happy coding!
I have a WxWidget Panel with two TextControls for user input. One TextControl input changes the value of the other input field. I used an EVT_COMMAND_TEXT_UPDATE event and bound it to a function like "OnValueChanged" ...
mTextCtrl1->Connect(wxEVT_COMMAND_TEXT_UPDATED, wxCommandEventHandler(MyClass::OnTextCtrlChanged1), NULL, this);
mTextCtrl2->Connect(wxEVT_COMMAND_TEXT_UPDATED, wxCommandEventHandler(MyClass::OnTextCtrlChanged2), NULL, this);
void MyClass::OnTextCtrlChanged1(wxCommandEvent &event) {
// ...
mTextCtrl2->SetValue(...); // Set a Hex value of entered Value in text ctrl 1
}
void MyClass::OnTextCtrlChanged2(wxCommandEvent &event) {
// ...
mTextCtrl1->SetValue(...); // Set a Integer value of entered Value in text ctrl 2
// at this point, MyClass::OnTextCtrl1 is handled,
// but should not, only if user himself enters something
}
Problem is, when Text in one TextControl is changed, it changes the value of the other correctly. But, as soon as text is changed in other input, it rises its own TEXT_UPDATE event and updates the current users inputs, resulting in funny curser jumping etc.
Is it possible to provide the execution of these events while changing the value of the other TextControl, so that it does not rise its TEXT_UPDATE event? If the user makes some input for himself to this text control, it should work as usual.
Maybe you can use wxTextCtrl::ChangeValue
virtual void ChangeValue(const wxString& value)
Sets the text value and marks the control as not-modified (which means that IsModified would return false immediately after the call to SetValue).
Note that this function will not generate the wxEVT_COMMAND_TEXT_UPDATED event. This is the only difference with SetValue. See this topic for more information.