How to make the sequencer 'Preview' area fullscreen with python?

Question

How do I, with python, select the sequencer area which has a view type as preview, to make it active/context? (And not select the "strip" window)

EDIT: My overall goal is to add a windowless, fullscreen, correctly scaled video-preview function to the VSE view menu(shortcuts: alt+F10, alt+F11 and home). In the video-editing workspace, there are two areas which are sequencer areas. One is the view type: sequencer(with strips) and one is view type: preview. When adding the function to the menu with SEQUENCER_MT_view, it is added to both areas, but I only want to make the preview area full screen, not the strip area. So I need help to make sure that the full-screen functions only will make the preview area full screen. How do I do that?

Where I am now(after help from SNU) - But get the working code from Snu further down:

import bpy

class SEQUENCE_MT_true_fullscreen(bpy.types.Operator):
    """True fullscreen preview. Close in upper right corner"""
    bl_label = "True Fullscreen"
    bl_idname = "sequencer.true_fullscreen"
    bl_options = {'REGISTER', 'UNDO'}

    def execute(self, context):
        scene=bpy.context.scene

        if not bpy.context.scene.sequence_editor: #create sequence, if missing
            bpy.context.scene.sequence_editor_create()   

        context = bpy.context
        for area in bpy.context.screen.areas:
            if area.type == 'SEQUENCE_EDITOR':
                if area.spaces[0].view_type == 'PREVIEW':  
                   override = bpy.context.copy()
                   override['space_data'] = area.spaces.active
                   override['region'] = area.regions[-1]
                   override['area'] = area
                   override['screen'] = context.screen
                   bpy.ops.screen.screen_full_area(override, use_hide_panels=True)
                   bpy.ops.wm.window_fullscreen_toggle()
                   #bpy.ops.sequencer.view_all_preview() #uncomment this to crash
                   break    

        return {'FINISHED'}

def menu_append(self, context):
    self.layout.operator(SEQUENCE_MT_true_fullscreen.bl_idname)

def register():
    bpy.utils.register_class(SEQUENCE_MT_true_fullscreen)
    bpy.types.SEQUENCER_MT_view.append(menu_append) # add to "view" vse header menu

def unregister():
    bpy.utils.unregister_class(SEQUENCE_MT_true_fullscreen)
    bpy.types.SEQUENCER_MT_view.remove(menu_append)

if __name__ == "__main__":
    register() 

Answer 1

After realizing I wanted this feature as well, I have been giving this some thought. The script shouldn't be trying to figure out which preview to full-screen (there may be more than one preview), it should let the user decide that. This can be accomplished by moving the check for the space view_type into the menu_append function, and having the operator just use the passed in context.

I was also thinking about how to close this preview, and I think the best way to do so would be to just use a modal operator for the whole thing, and revert everything once it ends.

So, after some reworking, here's the code I came up with:

import bpy

class SEQUENCE_MT_true_fullscreen(bpy.types.Operator):
    """True fullscreen preview"""
    bl_label = "True Fullscreen"
    bl_idname = "sequencer.true_fullscreen"

    runs = 0
    original_area = None

    def invoke(self, context, event):
        self.original_area = context.area
        bpy.ops.wm.window_fullscreen_toggle()
        self.runs = 0
        context.window_manager.modal_handler_add(self)
        return {'RUNNING_MODAL'}

    def modal(self, context, event):
        if self.runs == 0:
            override = context.copy()
            bpy.ops.screen.screen_full_area(override, use_hide_panels=True) #This has to be delayed because if it is run in the invoke function, it crashes blender...
        if self.runs == 1:
            bpy.ops.sequencer.view_all_preview() #This has to be delayed because if it is run right after the screen_full_area, it crashes blender...
        self.runs = self.runs + 1
        if event.type in {'RIGHTMOUSE', 'ESC'}:
            bpy.ops.wm.window_fullscreen_toggle()
            bpy.ops.screen.header()
            bpy.ops.screen.back_to_previous()
            override = context.copy()
            area = self.original_area
            override['area'] = area
            override['space_data'] = area.spaces.active
            for region in area.regions:
                if region.type == 'PREVIEW':
                    break
            override['region'] = region
            bpy.ops.sequencer.view_all_preview(override)
            return {'FINISHED'}
        return {'PASS_THROUGH'}

def true_fullscreen_menu(self, context):
    if context.area.spaces[0].view_type == 'PREVIEW':
        self.layout.operator(SEQUENCE_MT_true_fullscreen.bl_idname)

def register():
    bpy.utils.register_class(SEQUENCE_MT_true_fullscreen)
    bpy.types.SEQUENCER_MT_view.append(true_fullscreen_menu) # add to "view" vse header menu

def unregister():
    bpy.utils.unregister_class(SEQUENCE_MT_true_fullscreen)
    bpy.types.SEQUENCER_MT_view.remove(true_fullscreen_menu)

if __name__ == "__main__":
    register()

Note that I had to use the modal operator to delay a couple operators, or blender crashed -_-

edit: fixed that last issue!

Answer 2

This is kinda two problems. The first: you need to find the area that needs to be full-screened, second: you need to be able to full screen an arbitrary area.

For the first, the easiest way is to iterate through all areas and find the one that matches your conditions:

for area in bpy.context.screen.areas:
    if area.type == 'SEQUENCE_EDITOR':

this will find all areas of the sequencer type, now you need to check if its in preview mode:

        if area.spaces[0].view_type == 'PREVIEW':

now, it should have found the preview area, but we need to make it full screen. For this there is an operator, but the operator has no idea what area to work with (the second problem). So, we need to override it's context, and pass in a dictionary telling it to use the area we just found:

            bpy.ops.screen.screen_full_area({'area': area}, use_hide_panels=True)
            bpy.ops.wm.window_fullscreen_toggle()
            break

...and that break is there to just ensure it doesnt try to fullscreen multiple previews if there is such a thing in the current layout.

only problem i have with the script, next it needs to call bpy.ops.sequencer.view_all_preview() (the 'home' key shortcut), and it should be good enough with the same context override, but nothing happens when that operator is run.