Keep a oval annotation as a circle by using dm-script

Question

If I manually change the size of the circle by using dm-script, is that possible to lock the center of the circle to center of FFT image, and also keep it as a circle, instead of ellipse

Answer 1

When you place a circle annotation (component) you of course determine its size and position yourself in the according commands:

Image img := RealImage( "Test", 4, 512, 512 )
img.ShowImage()
ImageDisplay disp = img.ImageGetImageDisplay(0)
Component testComp = NewOvalAnnotation(20,20,90,120)    // Specify coordinates
disp.ComponentAddChildAtEnd(testComp)

and

number kOvalType = 6
ImageDisplay disp = GetFrontImage().ImageGetImageDisplay(0)
Component anno = disp.ComponentGetNthChildOfType(kOvalType,0)
if (!anno.ComponentIsValid()) Throw("No oval annoation found")

number t,l,b,r,w,h, px, py
anno.ComponentGetRect(t,l,b,r)
w = abs(r-l)
h = abs(b-t)
px = (r+l)/2
py = (t+b)/2

// Place where you want it, f.e.:
px = 100
py = 100
w = 20
h = 20

anno.ComponentSetRect(py-h/2,px-w/2,py+h/2,px+w/2)

---

I assume, what you are asking here is, how one can have a script control how the annotation can and can not be altered by the user with the mouse. This can be done by adding event-listeners which jump into action, when the user changes the annotation by mouse. Here is an example script:

// EventListener example showing how to "restrict" annotation-interactions.
// Whenever the annotation changes, the event-listener restricts properties
// to allowed values and repositions the annoation accordingly.
// The listener-object stays in scope as long as it is registered to a valid
// imageDisplay. Therefore, it should not itself hold images or imageDisplays
// as member variables

Class CAnnoRestrictor
{
    number imgID
    number annoID
    number listenID     
    number cx,cy,rad,ar
    
    imageDisplay GetDisp(object self)
    {
        image img := FindImageByID(imgID)
        if ( !img.ImageIsValid() ) return NULL
        if ( 0 == img.ImageCountImageDisplays() ) return NULL       
        return img.ImageGetImageDisplay(0)      
    }
    
    component GetAnno(object self)
    {
        imageDisplay disp = self.GetDisp()
        if ( !disp.ImageDisplayIsValid() ) return NULL
        return disp.ComponentGetChildByID(annoID)
    }

    void DoRestrict(object self){
        // This now defines the restriction action.
        // here, we ensure that the centre of the annoation is always lying 
        // in a rect of +/- rad around the image centre 
        // and that the aspect ratio of the annotation matches that of the image
        component anno = self.GetAnno()
        number t,l,b,r, w, h, px, py
        anno.ComponentGetRect(t,l,b,r)
        w = abs(r-l)
        h = w/ar
        px = max( min( (r+l)/2, cx+rad ), cx-rad )
        py = max( min( (t+b)/2, cy+rad ), cy-rad )
        
        // Set the restrictet Annoation
        anno.ComponentSetRect(py-h/2,px-w/2,py+h/2,px+w/2)      
    }
    
    object AttachToAnno(object self, component anno){
        if ( !anno.ComponentIsValid() ) Throw( "Invalid annotation." )
        if ( 0 != imgID ) Throw( "Restrictor already initialized." )
        imageDisplay disp = anno.ComponentGetParentComponent()
        if ( !disp.ImageDisplayIsValid() ) Throw( "Annotation is not a child of an image display" )
        image img := disp.ImageDisplayGetImage()
        
        img.ImageGetDimensionSizes(cx,cy)
        ar = cx/cy
        cx/=2
        cy/=2
        rad = min(cx,cy)/2
        
        annoID = anno.ComponentGetID()      
        imgID = img.ImageGetID()
        
        self.DoRestrict()
        
        string messagemap = "component_property_changed:OnCompPropChanged" 
        listenID = ImageDisplayAddEventListener( self.GetDisp(), self, messagemap )                     
    }
    
    void OnCompPropChanged( object self, Number disp_flags, ImageDisplay disp, Number comp_flags1, Number comp_flags2, Component comp ){
        if ( comp.ComponentGetID() == annoID )
            self.DoRestrict()
    }
}

// Test Script
Image img := RealImage( "Test", 4, 512, 800 )
img.ShowImage()
ImageDisplay disp = img.ImageGetImageDisplay(0)
Component testComp = NewOvalAnnotation(20,20,90,120)
testComp.ComponentSetForeGroundColor(0.5,0.8,0.8)
testComp.ComponentSetBackGroundColor(1,0,0)
testComp.ComponentSetDrawingMode(1)
testComp.ComponentSetFillMode(1)
testComp.ComponentSetTransferrable(0)
disp.ComponentAddChildAtEnd(testComp)
If (TwoButtonDialog("Restrict Annotation?","Yes","No"))
    Alloc(CAnnoRestrictor).AttachToAnno( testComp )