B4J Question change the center of a ImageView

[BeneBarros]

Is there any way to change the center of a ImageView to rotate?
Without changing the size.

 

[Jeffrey Cameron]

Depending on the exact effect you are trying to achieve, you could probably use Informatix's Animation Plus library to rotate the image view:

https://www.b4x.com/android/forum/threads/lib-animationplus.21313/

 

[BeneBarros]

Depending on the exact effect you are trying to achieve, you could probably use Informatix's Animation Plus library to rotate the image view:

https://www.b4x.com/android/forum/threads/lib-animationplus.21313/

ok I'll check.

 

[moster67]

For animations you can also use ViewPropertyAnimator.
Add the JavaObject library to your project and use as follows:

Sub Animate(view As View, Degree As Float, Duration As Long)
    Dim jo As JavaObject = view
    jo.RunMethodJO("animate", Null).RunMethodJO("rotationY", Array(Degree)).RunMethodJO("setDuration", Array(Duration)).RunMethodJO("start", Null)
End Sub

Animate(yourview, 360.0F, 5000)

You can of course change the sub Animate adding other parameters.

To learn more, read about the APIs in the page linked above.

 

[Jeffrey Cameron]

In the past, when I explored this method I could only get the animation to work once, subsequent calls to the start method did not produce any animation (unless I changed orientation and forced a re-load of the activity, then it would animate again once). Is that normal behavior or was my test flawed?

 

[moster67]

I hadn't noticed that. You can resolve it by using the xBy form instead i.e. rotationYBy instead of rotationY.

In the first case, I guess it is related to start and end values and we are only indicating the "to end" value when we first run the animation. The second time we run it, the value is still 360 so no animation is shown. We would need to find a way to reset the start value....

 

[Daestrum]

Is there any way to change the center of a ImageView to rotate?

Do you mean allow it to rotate around a point that is not the default point which is the centre of the imageview ?
ie, rotate around the top left corner for example.

 

[BeneBarros]

Do you mean allow it to rotate around a point that is not the default point which is the centre of the imageview ?
ie, rotate around the top left corner for example.

Exactly.
I want to change the center of rotation to another point x, y.

I will try to use "javafx.scene.effect.PerspectiveTransform".
recalculate new position to the corners, and apply the effect.

 

[Daestrum]

This sample code does what you want

#if java
import javafx.scene.control.*;
import javafx.scene.image.*;
import javafx.scene.transform.Rotate;

private static Rotate rotation = new Rotate();

public static void setRotatePoint(ImageView n,Double angle,Double x,Double y){
    // clear transforms
    n.getTransforms().clear();
    //rotation
    rotation = new Rotate(angle,x,y);
    // add rotation to the imageview
    n.getTransforms().add(rotation);
}
#end if

Just call it like normal inline code
the params are :imageview, angle, xpos, ypos
so

??.RunMethod("setRotatePoint",Array(imgv,30.0,50.0,75.0))

will rotate the imageview 30 degrees clockwise around the point x 50, y 75

Hope this helps.

 

[BeneBarros]

This sample code does what you want

#if java
import javafx.scene.control.*;
import javafx.scene.image.*;
import javafx.scene.transform.Rotate;

private static Rotate rotation = new Rotate();

public static void setRotatePoint(ImageView n,Double angle,Double x,Double y){
    // clear transforms
    n.getTransforms().clear();
    //rotation
    rotation = new Rotate(angle,x,y);
    // add rotation to the imageview
    n.getTransforms().add(rotation);
}
#end if

Just call it like normal inline code
the params are :imageview, angle, xpos, ypos
so

??.RunMethod("setRotatePoint",Array(30.0,50.0,75.0))

will rotate the imageview 30 degrees clockwise around the point x 50, y 75

Hope this helps.

would it be this?

Dim imV as ImageView
imV.Initialize("imV")
MainForm.RootPane.AddNode(imV, 50, 50, -1, -1)
imV.SetImage(fx.LoadImage(File.DirAssets, "moto.png"))

asJavaObject(imV).RunMethod("setRotatePoint",Array(30.0,15.0,15.0))


Sub asJavaObject(j As JavaObject) As JavaObject
    Return j
End Sub

 

[Daestrum]

would it be this?

Yes that's how I call it.

 

[BeneBarros]

Yes that's how I call it.

This returning an error

Error occurred on line: 31 (Main)
java.lang.RuntimeException: Method: setRotatePoint not found in: javafx.scene.image.ImageView
at anywheresoftware.b4j.object.JavaObject$MethodCache.getMethod(JavaObject.java:366)
at anywheresoftware.b4j.object.JavaObject.RunMethod(JavaObject.java:119)
at b4j.example.main._bt_action(main.java:121)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:612)
at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:226)
at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:159)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:93)
at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:90)
at anywheresoftware.b4a.BA$2.run(BA.java:165)
at com.sun.javafx.application.PlatformImpl.lambda$null$173(PlatformImpl.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$174(PlatformImpl.java:294)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
at java.lang.Thread.run(Thread.java:745)

 

[Daestrum]

Sorry read what you posted again, not so tired now.
it should be

asJavaObject(Me).RunMethod("setRotatePoint",Array(imv,30.0,15.0,15.0))

 

[BeneBarros]

Sorry read what you posted again, not so tired now.
it should be

asJavaObject(Me).RunMethod("setRotatePoint",Array(imv,30.0,15.0,15.0))

Excellent .. now works perfectly
Thanks for your help

Its function working.



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