Text giving constantly feedback about current selection - python-2.7

Question

I am writing a script which has an UI in Maya. I have a text box that is supposed to constantly update based on the last item in the users selection list. How would I go about something that constantly keeps checken whithout having the user to push a button or something manually to call a function.
Thx
Edit: Cool that is what I was looking for. Thx. Your script works just fine. I tried implementing that into my big script which resulted in that every button in the UI had to be pushed twice in order to take effect. But I will deal with that later. However testing my own version in a seperate script as follows sometimes produces the following error: 'sl' must be passed a boolean argument
#________________________________________________________________________________________________________________________________________________
import maya.cmds as cmds
idManagerUI = cmds.window(title='Vray ID Manager', s = False, wh = (305,500))
cmds.columnLayout(adj = True)
cmds.text (l = '__________________________________________ \n your current selection has this ID: \n')
curSelTxt = cmds.text (l = '', backgroundColor = [0.2, 0.2, 0.2])
def update_label(*_):
upCurrentObjectSel = cmds.ls(sl=True)
upCurrentObjectSelShapes = cmds.listRelatives(upCurrentObjectSel)
upLastobj = upCurrentObjectSelShapes[-1]
print upLastobj
cmds.text(curSelTxt, e=True, label = upLastobj)
cmds.scriptJob(event=("SelectionChanged", update_label), p= curSelTxt)
cmds.showWindow(idManagerUI)
Also, making two of these ScriptJobs makes the script stop working properly entirely.
#________________________________________________________________________________________________________________________________________________
import maya.cmds as cmds
idManagerUI = cmds.window(title='Vray ID Manager', s = False, wh = (305,500))
cmds.columnLayout(adj = True)
cmds.text (l = '__________________________________________ \n your current selection has this ID: \n')
curSelObjTxt = cmds.text (l = '', backgroundColor = [0.2, 0.2, 0.2])
curSelShadTxt = cmds.text (l = '', backgroundColor = [0.2, 0.2, 0.2])
def update_obj_label(*_):
upCurrentObjectSel = cmds.ls(sl=True)
upCurrentObjectSelShapes = cmds.listRelatives(upCurrentObjectSel)
upLastobj = upCurrentObjectSelShapes[-1]
objID = cmds.getAttr(upLastobj + '.vrayObjectID')
print objID
cmds.text(curSelObjTxt, e=True, label = objID)
def update_shader_label(*_):
upCurrentShaderSel = cmds.ls(sl=True, type= shaderTypes)
upCurrentShaderSelLast = upCurrentShaderSel[-1]
shadID = cmds.getAttr(upCurrentShaderSelLast + '.vrayMaterialId')
cmds.text(curSelShadTxt, e=True, label = shadID)
print shadID
cmds.scriptJob(event=("SelectionChanged", update_obj_label), p= curSelObjTxt)
cmds.scriptJob(event=("SelectionChanged", update_shader_label), p= curSelShadTxt)
cmds.showWindow(idManagerUI)
Edit:
still your latest version of the script produces the error from time to time.
Also, I noticed in my own version of it, that it sometimes works lovely, then not at all, once I e.g. switched my active window to Firefox or so and then get back to Maya, and sometimes it does not work at all. That is with just one of the functions in my script. With both of them (s.below) it is totally unusable. Very unstable results.
import maya.cmds as cmds
def curSelTxtShower():
idManagerUI = cmds.window(title='Vray ID Manager', s = False, wh = (305,500))
cmds.columnLayout(adj = True)
cmds.text (l = '__________________________________________ \n your current selection has this ID: \n')
curSelObjTxt = cmds.text (l = '', backgroundColor = [0.2, 0.2, 0.2])
curSelShadTxt = cmds.text (l = '', backgroundColor = [0.2, 0.2, 0.2])
def update_obj_label(*_):
upCurrentObjectSelShapes = cmds.listRelatives(s=True) or ["nothing selected"]
upLastobj = upCurrentObjectSelShapes[-1]
if upLastobj is not "nothing selected":
if cmds.attributeQuery('vrayObjectID', node = upLastobj, ex = True) is True:
objID = cmds.getAttr(upLastobj + '.vrayObjectID')
cmds.text(curSelObjTxt, e=True, label = objID)
else:
cmds.text(curSelObjTxt, e=True, label = 'curSel has no ObjID assigned')
def update_shader_label(*_):
upCurrentShaderSel = cmds.ls(sl=True, type= shaderTypes)
upCurrentShaderSelLast = upCurrentShaderSel[-1]
if cmds.attributeQuery('vrayMaterialId', node = upCurrentShaderSelLast, ex = True) is True:
shadID = cmds.getAttr(upCurrentShaderSelLast + '.vrayMaterialId')
cmds.text(curSelShadTxt, e=True, label = shadID)
print shadID
else:
cmds.text(curSelShadTxt, e=True, label = 'curSel has no MatID assigned')
cmds.scriptJob(event=("SelectionChanged", lambda *x: update_obj_label()), p= curSelObjTxt)
cmds.scriptJob(event=("SelectionChanged", lambda *x: update_shader_label()), p= curSelShadTxt)
cmds.showWindow(idManagerUI)
curSelTxtShower()

Answer 1

You need to use a scriptJob to watch for selection change events and respond. You'll want to parent the scriptJob to a particular piece of UI so it deletes itself when the UI object goes away.
An absolutely minimal example looks like this:
import maya.cmds as cmds
wind = cmds.window()
col = cmds.columnLayout()
txt = cmds.text(label="", width = 240)
def update_label(*_):
cmds.text(txt, e=True, label = str(cmds.ls(sl=True)))
cmds.scriptJob(event=("SelectionChanged", update_label), p= txt)
cmds.showWindow(wind)
Edit
This version of OP's code helps avoid the false error message. the actual error was happening when due to an empty selection - but the scriptJob falsely reports it in the previous line:
def scoped():
idManagerUI = cmds.window(title='Vray ID Manager', s = False, wh = (305,500))
cmds.columnLayout(adj = True)
cmds.text (l = '__________________________________________ \n your current selection has this ID: \n')
curSelTxt = cmds.text (l = '', backgroundColor = [0.2, 0.2, 0.2])
def update_label(*_):
# listRelatives works off the current selection already
upCurrentObjectSelShapes = cmds.listRelatives(s=True) or ["nothing selected"]
upLastobj = upCurrentObjectSelShapes[-1]
cmds.text(curSelTxt, e=True, label = upLastobj)
cmds.showWindow(idManagerUI)
cmds.scriptJob(event=("SelectionChanged", update_label), p= idManagerUI)
scoped()