Pythonista & Working Copy Drag & Drop Experiments

drag_provider.py

import ui
from objc_util import ObjCClass, ObjCInstance, ns, create_objc_class, on_main_thread, ObjCBlock
from ctypes import c_void_p, CFUNCTYPE, Structure, cast, c_int, c_ulong, c_char_p, POINTER
import editor
import os
import zipfile

ASYNC = True
DRAG_PATH = editor.get_path()  # Drag itself, ie. drag_provider.py
# DRAG_PATH = os.path.expanduser('~/Documents/Examples')  # Drag ZIPpped folder

_TMP_DIR = os.environ.get('TMPDIR', os.environ.get('TMP'))

NSItemProvider = ObjCClass('NSItemProvider')
UIDragItem = ObjCClass('UIDragItem')
UIDragInteraction = ObjCClass('UIDragInteraction')
NSData = ObjCClass('NSData')
NSItemProviderRepresentationVisibilityAll = 0
NSError = ObjCClass('NSError')


def _type_identifier(path):
    if os.path.isdir(path):
        return 'public.folder'
    elif os.path.isfile(path):
        return 'public.data'
    return None


def _suggested_name(path):
    name = os.path.basename(path)

    if os.path.isdir(path):
        name += '.zip'

    return name


def _provide_file_data(path):
    data = NSData.dataWithContentsOfFile_(path)
    if not data:
        print('Failed to read file: {}'.format(path))
        return None

    return data


def _provide_folder_data(path):
    #
    # Let's say path is ~/Documents/Playground, ZIP content is:
    #
    # - Playground/
    # - Playground/some.py
    # - Playground/folder/another.py
    #
    # .git folders are not included.
    #
    saved_dir = os.getcwd()
    os.chdir(os.path.dirname(path))
    folder_name = os.path.basename(path)

    zip_file_path = os.path.join(_TMP_DIR, '{}.zip'.format(folder_name))

    if os.path.exists(zip_file_path):
        os.remove(zip_file_path)

    ignore_folders = ['.git']
    ignore_files = ['.DS_Store']

    with zipfile.ZipFile(zip_file_path, 'w') as zip:
        for root, subdirs, files in os.walk(folder_name, topdown=True):
            if ignore_folders:
                subdirs[:] = [d for d in subdirs if d not in ignore_folders]
            for file in files:
                if file not in ignore_files:
                    zip.write(os.path.join(root, file))

    os.chdir(saved_dir)

    return _provide_file_data(zip_file_path)


def _provide_data(path):
    if os.path.isfile(path):
        return _provide_file_data(path)
    elif os.path.isdir(path):
        return _provide_folder_data(path)

    return None


# - (void)registerDataRepresentationForTypeIdentifier:(NSString *)typeIdentifier
#    visibility:(NSItemProviderRepresentationVisibility)visibility
#    loadHandler:(NSProgress * _Nullable (^)(void (^completionHandler)(NSData *data, NSError *error)))loadHandler;

# https://clang.llvm.org/docs/Block-ABI-Apple.html

class BlockDescriptor (Structure):
    _fields_ = [('reserved', c_ulong),
                ('size', c_ulong),
                ('copy_helper', c_void_p),
                ('dispose_helper', c_void_p),
                ('signature', c_char_p)]


class Block(Structure):
    _fields_ = [('isa', c_void_p),
                ('flags', c_int),
                ('reserved', c_int),
                ('invoke', c_void_p),
                ('descriptor', BlockDescriptor)]


def block_signature(block):
    copy_dispose_flag = 1 << 25
    signature_flag = 1 << 30

    if not block.contents.flags & signature_flag:
        return None

    if block.contents.flags & copy_dispose_flag:
        return block.contents.descriptor.signature
    else:
        return block.contents.descriptor.copy_helper


def _load_data_imp(_cmd, _block_ptr):
    print('Load data requested...')

    block = cast(_block_ptr, POINTER(Block))

    IMPTYPE = CFUNCTYPE(None, c_void_p, c_void_p, c_void_p)
    completion_handler = IMPTYPE(block.contents.invoke)

    data = _provide_data(DRAG_PATH)

    if not data:
        print('Failed to load data')
        error = NSError.errorWithDomain_code_userInfo_('dragprovider', 1, None)
        completion_handler(_block_ptr, None, error)
    else:
        completion_handler(_block_ptr, data, None)


load_data = ObjCBlock(_load_data_imp, restype=c_void_p, argtypes=[c_void_p, c_void_p])


def dragInteraction_itemsForBeginningSession_(_self, _cmd, interaction, session):
    type_identifier = _type_identifier(DRAG_PATH)
    if not type_identifier:
        print('Failed to provide data, file does not exists?')
        return ns([]).ptr

    suggested_name = _suggested_name(DRAG_PATH)

    if ASYNC:
        print('Async dragging {} ({}) ...'.format(suggested_name, type_identifier))
        item_provider = NSItemProvider.alloc().init()
        item_provider.registerDataRepresentationForTypeIdentifier_visibility_loadHandler_(type_identifier, NSItemProviderRepresentationVisibilityAll, load_data)
    else:
        data = _provide_data(DRAG_PATH)
        if not data:
            print('Unable to load data: {}'.format(DRAG_PATH))

        print('Dragging {} ({}) file size: {} bytes'.format(suggested_name, type_identifier, data.length()))
        item_provider = NSItemProvider.alloc().initWithItem_typeIdentifier_(data, type_identifier)

    if not item_provider:
        print('Failed to create item provider.')
        return ns([]).ptr

    if suggested_name:
        item_provider.setSuggestedName(suggested_name)

    item = UIDragItem.alloc().initWithItemProvider_(item_provider)
    if not item:
        print('Failed to create drag item.')
        return ns([]).ptr

    return ns([item]).ptr


class DragView(ui.View):
    def __init__(self):
        self.width = 540
        self.height = 540

        self.label = ui.Label()
        self.label.text = 'Drag Me'
        self.label.alignment = ui.ALIGN_CENTER
        self.label.frame = self.bounds

        self.add_subview(self.label)

        methods = [dragInteraction_itemsForBeginningSession_]
        protocols = ['UIDragInteractionDelegate']
        DragProviderDelegate = create_objc_class('DragProviderDelegate', methods=methods, protocols=protocols)

        self.delegate = DragProviderDelegate.alloc().init()
        interaction = UIDragInteraction.alloc().initWithDelegate_(self.delegate)

        label_objc = ObjCInstance(self.label._objc_ptr)
        label_objc.addInteraction(interaction)
        label_objc.setUserInteractionEnabled(True)


@on_main_thread
def main():
    v = DragView()
    v.present('sheet')
    v.wait_modal()


if __name__ == '__main__':
    main()