Just reporting back. Turns out I didn't RTFM, and I didn't see Actor.transform_stage_point(x,y). So for my final zoomable-scroll area, the code looks like this:
# Get relative position of event location (X,Y) = self.group.transform_stage_point(event.x, event.y) # Get the current scaled size of the group (oldscalesizex, oldscalesizey) = self.group.get_transformed_size() #Initiate the scale animation self.group.set_scale(scale, scale) # Get the new scaled size of the group (newscalesizex, newscalesizey) = self.group.get_transformed_size() # Get the pixel difference between the old scale and the new scale pdifx = newscalesizex - oldscalesizex pdify = newscalesizey - oldscalesizey # Get the current position and size of the group (posx, posy) = self.group.get_position() (sizex, sizey) = self.group.get_size() # Calculate the final offset for the position of group # multiply pixel difference in scale by the ratio of relative event position vs size offsetx = (pdifx * (X / sizex)) offsety = (pdify * (Y / sizey)) # apply offset posx -= offsetx posy -= offsety # Move position of group so the event position appears to be the zoom center self.group.set_position(posx, posy) Perhaps this code could be included as a method for Actor? set_scale_relative(scale_x, scale_y, center_x, center_y) or similar ? It's quite useful for times where you don't want the anchor to move, but still want scaling from a relative position. Anyway hope it helps someone in a similar position. On Wed, May 23, 2012 at 9:50 AM, Mark Boorer <markbo...@gmail.com> wrote: > Hi all, > > Not sure if this has been answered before, and I couldn't find anything in > my searches. > > I'm using python-clutter, and I'm implementing a zoomable-scroll area > using nested Group containers. > > Like this: > > viewArea = clutter.Group() > container = clutter.Group() > viewArea.add(container) > > I'm nesting them, so that the top level group doesn't move, and receives > all the mouse events, and it moves / scales the "container" inside. > > I've hit a slight problem though. When scaling the "container", I want the > user to have the area the mouse is under remain in the center of the zoom. > I can use set_scale_full() and calculate the center coordinates relative to > "viewArea" but these values don't work it the container is already scaled. > > Is there a way to get the relative position of an actor when it's already > scaled? > > Thanks, > Mark >
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