Add-On Dev: Popup Panel Position

Question

Is there any way to control the starting position of a popup panel / window?

I'm not familiar with the number of floating panel types in Blender, but I'm creating mine with an operator class, using bpy.context.window_manager.invoke_props_dialog(self,width=600) in invoke().

The default starting popup location seems to be related to the mouse cursor or activator button location. The problem occurs when the button to open the popup is near the bottom of the screen. The popup opens into the bottom right corner. I don't need to specify the exact location. But if possible, I would like to have it open somewhere near the vertical center of my standard side panel.

Answer 1

Hello from the future,

If we have us some properties on our operator, like so:

from bpy.types import Operator;
from bpy.props import IntProperty;

class MYADDON_OT_my_operator(Operator):

    bl_idname = "myaddon.myoperator";
    bl_label = "Pop!";
    bl_description = "Spawns a pop-up";

    # using annotations for 2.8+
    # change to equal signs on previous versions
    first_mouse_x : IntProperty(default = 0);
    first_mouse_y : IntProperty(default = 0);

    target_mouse_x : IntProperty(default = 0);
    target_mouse_y : IntProperty(default = 0);

    mouse_snap : BoolProperty(default = False);

Then we can save the original position of the mouse during invoke.

    def invoke(self, context, event):

        # assign position of the cursor at the time the operator is called
        self.first_mouse_x = event.mouse_x;
        self.first_mouse_y = event.mouse_y;

        # probably redundant but i can't recall if props actually reset to default
        self.mouse_snap = False;

        # now warp the mouse to some xy coords
        # here i center on the window and adjust y to approx. the height of my popup
        context.window.cursor_warp(context.window.width/2, (context.window.height/2) + 60);

        # now invoke
        wm = context.window_manager; 
        return wm.invoke_props_dialog(self, width = 600);

Next thing on the list is resetting the cursor to the original coordinates. I do this on the first run of draw and haven't really noticed any jumpy motion on the cursor.

    def draw(self, context):

        if not self.mouse_snap:
            self.mouse_snap = True;
            context.window.cursor_warp(self.first_mouse_x, self.first_mouse_y);

That gets you back where you started.

But wait, there's more! As a bonus, you can also pass the xy coords to the operator from your panel's draw.

    def draw(self, context):

        layout = self.layout;
        row = layout.row();

        # this gets you a handle to the operator properties
        props = row.operator("myaddon.myoperator");

        # now just assign them values as you would
        props.target_mouse_x = some_x_coord;
        props.target_mouse_y = some_y_coord;

It's a barebones example, but hopefully a good starting point for anyone else that google-wanders in here like I did. ;)