# Saving images with a key press

**URL:** https://discourse.vtk.org/t/saving-images-with-a-key-press/1839
**Category:** Development
**Created:** [September 28, 2019, 9:13am UTC](https://discourse.vtk.org/t/saving-images-with-a-key-press/1839 "2019-09-28T09:13:38Z")
**Posts on this page:** 14
**Page:** 1

<div class="post-metadata">

### Author: ![1111](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/1/71e660/32.png) [@1111](https://discourse.vtk.org/u/1111)
#### Post date: [September 28, 2019, 9:13am UTC](https://discourse.vtk.org/t/saving-images-with-a-key-press/1839/1 "2019-09-28T09:13:38Z")

</div>

Hi,  
I am creating a program to save raw data of slice plane by pressing “c” based on KeypressEvents.

I was able to create a part that saves the raw data by pressing a key, but I don’t know how to adapt the cutout plane in the callback(vtkIPWCallback).

How can I connect the updated plane in the vtkImplicitPlaneWidget2 to the key press operation?

Could you give me a hint if possible?

Below is the callback and key press code.

```
  virtual void Execute(vtkObject *caller, unsigned long, void*)
 {
   vtkImplicitPlaneWidget2 *planeWidget = reinterpret_cast<vtkImplicitPlaneWidget2*>(caller);
vtkImplicitPlaneRepresentation *rep =reinterpret_cast<vtkImplicitPlaneRepresentation*>(planeWidget->GetRepresentation());
 rep->GetPlane(this->Plane);

double normal[3];
Plane->GetNormal(normal);
double Origin[3];
Plane->GetOrigin(Origin);

// Set the slice orientation
vtkSmartPointer<vtkMatrix4x4> resliceMatrix =
vtkSmartPointer<vtkMatrix4x4>::New();

(Compute of the 4x4 matrix)
}
vtkIPWCallback():Plane(0) {}
vtkPlane *Plane;
vtkImageReslice *Reslice;
};

```

Part of keypress

```
 class KeyPressInteractorStyle : public vtkInteractorStyleTrackballCamera
{
public:
static KeyPressInteractorStyle* New();
vtkTypeMacro(KeyPressInteractorStyle, vtkInteractorStyleTrackballCamera);

virtual void OnKeyPress() override
{
  // Get the keypress
vtkRenderWindowInteractor *rwi = this->Interactor;
std::string key = rwi->GetKeySym();
 
vtkImageReslice *reslice = this->ImageReslice;

// Output the key that was pressed
std::cout << "Pressed " << key << std::endl;

// Handle a "normal" key
if(key == "c")
{
  std::cout << "The a key was pressed." << std::endl;
  // adapt path !
  std::string filePathRaw = "slice_512x512.raw";

  vtkSmartPointer<vtkImageCast> castFilter = 
   vtkSmartPointer<vtkImageCast>::New();
  castFilter->SetOutputScalarTypeToUnsignedChar();
  castFilter->SetInputConnection(reslice->GetOutputPort());
  castFilter->Update();

  vtkSmartPointer<vtkImageWriter> writer =
   vtkSmartPointer<vtkImageWriter>::New();
  writer->SetInputConnection(castFilter->GetOutputPort());
  writer->SetFileName(filePathRaw.c_str());
  writer->Write();
  }

// Forward events
vtkInteractorStyleTrackballCamera::OnKeyPress();
}

// Pointer to vtkImageReslice
 vtkImageReslice *ImageReslice;
};
vtkStandardNewMacro(KeyPressInteractorStyle);

```

@dgobbi

---

<div class="post-metadata">

### Author: ![dgobbi](https://discourse.vtk.org/user_avatar/discourse.vtk.org/dgobbi/32/18_2.png) [@dgobbi](https://discourse.vtk.org/u/dgobbi)
#### Post date: [September 30, 2019, 9:53pm UTC](https://discourse.vtk.org/t/saving-images-with-a-key-press/1839/2 "2019-09-30T21:53:56Z")

</div>

> [@1111](#):
>
> How can I connect the updated plane in the vtkImplicitPlaneWidget2 to the key press operation?

That is not necessary. Just make sure that `Reslice` in your callback and `ImageReslice` in your KeyPressInteractorStyle are the same object.

---

<div class="post-metadata">

### Author: ![1111](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/1/71e660/32.png) [@1111](https://discourse.vtk.org/u/1111)
#### Post date: [October 3, 2019, 9:16am UTC](https://discourse.vtk.org/t/saving-images-with-a-key-press/1839/3 "2019-10-03T09:16:08Z")

</div>

Thank you for your reply.

I understood that there is no need to connect.  
Currently, the vtkImplicitPlaneWidget2 window automatically disappears when the “c” key is pressed.

Is this because of the incorrect code in the writer part?  
Can you tell me where to improve if possible?

@dgobbi

---

<div class="post-metadata">

### Author: ![dgobbi](https://discourse.vtk.org/user_avatar/discourse.vtk.org/dgobbi/32/18_2.png) [@dgobbi](https://discourse.vtk.org/u/dgobbi)
#### Post date: [October 3, 2019, 10:39pm UTC](https://discourse.vtk.org/t/saving-images-with-a-key-press/1839/4 "2019-10-03T22:39:14Z")

</div>

The code for the writer looks fine. If you run your program in a debugger, it might be able to tell you why the window disappears. It isn’t a question that I can answer for you.

---

<div class="post-metadata">

### Author: ![1111](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/1/71e660/32.png) [@1111](https://discourse.vtk.org/u/1111)
#### Post date: [October 4, 2019, 10:01am UTC](https://discourse.vtk.org/t/saving-images-with-a-key-press/1839/5 "2019-10-04T10:01:53Z")

</div>

Thank you for your reply.

“Just make sure that `Reslice` in your callback and `ImageReslice` in your KeyPressInteractorStyle are the same object.”

I would like to confirm one,  
Does this mean that the updated plane of the callback is adapted to the KeyPressInteractorStyle’s ImageReslice?

@dgobbi

---

<div class="post-metadata">

### Author: ![dgobbi](https://discourse.vtk.org/user_avatar/discourse.vtk.org/dgobbi/32/18_2.png) [@dgobbi](https://discourse.vtk.org/u/dgobbi)
#### Post date: [October 4, 2019, 2:56pm UTC](https://discourse.vtk.org/t/saving-images-with-a-key-press/1839/6 "2019-10-04T14:56:26Z")

</div>

No, I meant `interactorstyle->ImageReslice == callback->Reslice`. They are the same object.

---

<div class="post-metadata">

### Author: ![1111](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/1/71e660/32.png) [@1111](https://discourse.vtk.org/u/1111)
#### Post date: [October 5, 2019, 12:51pm UTC](https://discourse.vtk.org/t/saving-images-with-a-key-press/1839/7 "2019-10-05T12:51:01Z")

</div>

I can understand that they are the same object.

The callback and key press parts are divided as follows:

```
  class vtkIPWCallback : public vtkCommand
 {
 public:
 static vtkIPWCallback *New()
{ return new vtkIPWCallback; }

virtual void Execute(vtkObject *caller, unsigned long, void*)
{
vtkImplicitPlaneWidget2 *planeWidget = reinterpret_cast<vtkImplicitPlaneWidget2*>(caller);
vtkImplicitPlaneRepresentation *rep =reinterpret_cast<vtkImplicitPlaneRepresentation*>(planeWidget->GetRepresentation());
rep->GetPlane(this->Plane);
(Compute of the 4x4 matrix)
vtkImageReslice *reslice = this->Reslice;
reslice->SetResliceAxes(resliceMatrix);
reslice->Update();
}
vtkIPWCallback():Plane(0),Reslice(0){};
vtkPlane *Plane;
vtkImageReslice *Reslice;
 };

 class KeyPressInteractorStyle : public vtkInteractorStyleTrackballCamera
{
public:
static KeyPressInteractorStyle* New();
vtkTypeMacro(KeyPressInteractorStyle, vtkInteractorStyleTrackballCamera);
virtual void OnKeyPress() override
{
  // Get the keypress
vtkRenderWindowInteractor *rwi = this->Interactor;
std::string key = rwi->GetKeySym();

vtkImageReslice *reslice = this->ImageReslice;

 // Output the key that was pressed
 std::cout << "Pressed " << key << std::endl;

// Handle a "normal" key
if(key == "c")
{
std::cout << "The a key was pressed." << std::endl;
// adapt path !
std::string filePathRaw = "slice_512x512.raw";

vtkSmartPointer<vtkImageCast> castFilter = 
vtkSmartPointer<vtkImageCast>::New();
castFilter->SetOutputScalarTypeToUnsignedChar();
castFilter->SetInputConnection(reslice->GetOutputPort());
castFilter->Update();

vtkSmartPointer<vtkImageWriter> writer =
vtkSmartPointer<vtkImageWriter>::New();
writer->SetInputConnection(castFilter->GetOutputPort());
writer->SetFileName(filePathRaw.c_str());
writer->Write();
}

// Forward events
vtkInteractorStyleTrackballCamera::OnKeyPress();
}

// Pointer to vtkImageReslice
vtkImageReslice *ImageReslice;
};
vtkStandardNewMacro(KeyPressInteractorStyle);

```

Callback and key press are separated.  
Using the same object, I tried to adapt the “reslice” updated in the callback with the “writer” that presses the key.

Should the key press part be included in the callback?  
I would be grateful if you could give me advice.

@dgobbi

---

<div class="post-metadata">

### Author: ![1111](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/1/71e660/32.png) [@1111](https://discourse.vtk.org/u/1111)
#### Post date: [October 7, 2019, 2:12am UTC](https://discourse.vtk.org/t/saving-images-with-a-key-press/1839/8 "2019-10-07T02:12:52Z")

</div>

I’m sorry many times.

I want to know if using this same object is right or wrong in my code.

I don’t know if it’s correct, I tried to adapt the “reslice” updated in the callback with the “castFilter” that presses the key.

I would be grateful if you could advise me if possible.

@dgobbi

---

<div class="post-metadata">

### Author: ![dgobbi](https://discourse.vtk.org/user_avatar/discourse.vtk.org/dgobbi/32/18_2.png) [@dgobbi](https://discourse.vtk.org/u/dgobbi)
#### Post date: [October 7, 2019, 5:17am UTC](https://discourse.vtk.org/t/saving-images-with-a-key-press/1839/9 "2019-10-07T05:17:07Z")

</div>

If you post the whole code, not just parts of it, then I can look at it sometime this week.

---

<div class="post-metadata">

### Author: ![1111](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/1/71e660/32.png) [@1111](https://discourse.vtk.org/u/1111)
#### Post date: [October 7, 2019, 7:46am UTC](https://discourse.vtk.org/t/saving-images-with-a-key-press/1839/10 "2019-10-07T07:46:17Z")

</div>

Thank you for your support.  
Forgive me for stealing your time.

Attach the code file below.  
[ImplictWidget2.cxx](https://discourse.vtk.org/uploads/short-url/55PJ6sLtvxcqjXBNpu6w8WL8xnf.cxx) (11.8 KB)

I would be grateful if you could give me advice.

@dgobbi

---

<div class="post-metadata">

### Author: ![dgobbi](https://discourse.vtk.org/user_avatar/discourse.vtk.org/dgobbi/32/18_2.png) [@dgobbi](https://discourse.vtk.org/u/dgobbi)
#### Post date: [October 8, 2019, 9:59pm UTC](https://discourse.vtk.org/t/saving-images-with-a-key-press/1839/11 "2019-10-08T21:59:19Z")

</div>

There are two problems that I can see with the interator style.

First is that the “Reslice” of the interactor style is never set. You need code like this:

```
style->Reslice = reslice;

```

In order for the “style” and the “callback” to have the same reslice object, you must do `myCallback->Reslice = reslice` and `style->Reslice = reslice`.

Second, only one interactor style object is allowed, but you have two (the KeyPressInteractorStyle and the vtkInteractorStyleImage). To fix this problem, you should make your KeyPressInteractorStyle a subclass of vtkInteractorStyleImage.

---

<div class="post-metadata">

### Author: ![1111](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/1/71e660/32.png) [@1111](https://discourse.vtk.org/u/1111)
#### Post date: [October 10, 2019, 2:06pm UTC](https://discourse.vtk.org/t/saving-images-with-a-key-press/1839/12 "2019-10-10T14:06:46Z")

</div>

Thank you for your help, I know you have a busy schedule.

I was able to understand how to adapt reslice to the interactor style.

I understood the need for subclassing.  
But I don’t know what code to use for the subclass.  
Can you tell me if possible?

@dgobbi

---

<div class="post-metadata">

### Author: ![dgobbi](https://discourse.vtk.org/user_avatar/discourse.vtk.org/dgobbi/32/18_2.png) [@dgobbi](https://discourse.vtk.org/u/dgobbi)
#### Post date: [October 10, 2019, 2:41pm UTC](https://discourse.vtk.org/t/saving-images-with-a-key-press/1839/13 "2019-10-10T14:41:25Z")

</div>

Instead of this:

```
class KeyPressInteractorStyle : public vtkInteractorStyleTrackballCamera

```

Do this:

```
class KeyPressInteractorStyle : public vtkInteractorStyleImage
```

---

<div class="post-metadata">

### Author: ![1111](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/1/71e660/32.png) [@1111](https://discourse.vtk.org/u/1111)
#### Post date: [October 14, 2019, 3:22am UTC](https://discourse.vtk.org/t/saving-images-with-a-key-press/1839/14 "2019-10-14T03:22:05Z")

</div>

Sorry for my late reply.

Actual operation is now possible.  
Thank you very much for your support.

Thank you in the future.