Fix cairo for Windows

mathicsscript/__init__.py

@@ -4,11 +4,15 @@
 
 Copyright 2020-2021 The Mathics Team
 """
+from ctypes.util import find_library
+
+from mathicsscript.fixcairo import fix_cairo
 from mathicsscript.version import __version__
 
 
 def load_default_settings_files(definitions):
     import os.path as osp
+
     from mathics.core.definitions import autoload_files
 
     root_dir = osp.realpath(osp.dirname(__file__))
@@ -17,3 +21,6 @@ def load_default_settings_files(definitions):
 
 
 __all__ = ["__version__", "load_default_settings_files"]
+
+if not find_library("libcairo-2"):
+    fix_cairo()

mathicsscript/fixcairo.py

@@ -0,0 +1,147 @@
+# -*- coding: utf-8 -*-
+"""
+Fix cairo for Windows
+"""
+
+import os
+import platform
+import subprocess
+from ctypes.util import find_library
+from importlib.util import find_spec
+
+import requests
+from tqdm import tqdm
+
+mathicsscript_path = find_spec("mathicsscript").submodule_search_locations[0]
+
+if platform.architecture()[0] == "64bit":
+    release_url = "https://api.github.com/repos/tschoonj/GTK-for-Windows-Runtime-Environment-Installer/releases/latest"
+else:
+    release_url = "https://api.github.com/repos/miegir/GTK-for-Windows-Runtime-Environment-Installer-32/releases/latest"
+
+fix_cairo_long_intro = f"""
+We noticed that you are using mathicsscript on Windows. Due to a well known bug in the dependency
+package cairocffi for mathicsscript on Windows, mathicsscript is not working properly right now.
+We will now try to fix it, or you can visit https://github.com/Mathics3/mathicsscript/issues/76
+to fix it yourself.
+
+Specifically, cairocffi needs libcairo-2.dll and some other dll files to work properly on Windows.
+To get these libraries, we will download the latest GTK+ for Windows Runtime Environment Installer
+from {release_url}
+and install it for you. After installation, whenever you run mathicsscript, the GTK+ for Windows 
+dll libraries will be automatically loaded to make mathicsscript run properly.
+
+IMPORTANT: Remember to check the "Set up PATH environment variable to include GTK+" option!
+
+Please note that now the GTK+ for Windows dll libraries will only be loaded when mathicsscript is
+imported. If you want to load them when importing cairocffi, see 
+https://github.com/Mathics3/mathicsscript/issues/76.
+
+Do you want us to install GTK+ for Windows Runtime Environment for you? [Y/n] (default: Y)
+"""
+
+
+def download_file(url, dest, name=None):
+    response = requests.get(url, stream=True, timeout=5)
+    total_size = int(response.headers.get("content-length", 0))
+    if response.status_code == 200:
+        with open(dest, "wb") as file:
+            with tqdm(
+                total=total_size,
+                unit="B",
+                unit_scale=True,
+                unit_divisor=1024,
+                desc=f"Downloading {name}",
+            ) as pbar:
+                for chunk in response.iter_content(chunk_size=1024):
+                    if chunk:
+                        file.write(chunk)
+                        file.flush()
+                        pbar.update(len(chunk))
+                        pbar.refresh()
+    else:
+        print(f"Failed to download: {url}")
+
+
+def download_GTK_installer():
+    response = requests.get(release_url, timeout=5)
+    if response.status_code == 200:
+        name = response.json()["assets"][0]["name"]
+        file_url = response.json()["assets"][0]["browser_download_url"]
+        file_path = os.path.join(mathicsscript_path, name)
+        download_file(file_url, file_path, name)
+        print("Done.")
+        return file_path
+    else:
+        print("Failed to retrieve directory contents.")
+
+
+def set_dll_search_path():
+    """
+    Python 3.8+ no longer searches for DLLs in PATH, so we have to add
+    everything in PATH manually. Note that unlike PATH add_dll_directory
+    has no defined order, so if there are two cairo DLLs in PATH we
+    might get a random one.
+    """
+    if not hasattr(os, "add_dll_directory"):
+        return
+    for path in os.environ.get("PATH", "").split(os.pathsep):
+        try:
+            os.add_dll_directory(path)
+        except OSError:
+            pass
+
+
+def search_folders(root_path, folder_name):
+    found_folders = []
+    with os.scandir(root_path) as entries:
+        for entry in entries:
+            if entry.is_dir() and folder_name in entry.name:
+                found_folders.append(entry.path)
+    return found_folders
+
+
+def search_file_in_folders(folders, file_name):
+    found_paths = []
+    for folder_path in folders:
+        file_paths = search_file_recursive(folder_path, file_name)
+        found_paths.extend(file_paths)
+    return found_paths
+
+
+def search_file_recursive(folder_path, file_name):
+    found_paths = []
+    for dirpath, _, filenames in os.walk(folder_path):
+        for filename in filenames:
+            if filename == file_name:
+                found_paths.append(dirpath)
+    return found_paths
+
+
+def fix_cairo():
+    set_dll_search_path()
+    if find_library("libcairo-2"):
+        return
+    else:
+        choice = input(fix_cairo_long_intro).lower()
+        if choice == "y" or choice == "":
+            GTK_installer = download_GTK_installer()
+            GTK_install_cmd = os.path.join(mathicsscript_path, "install_GTK.cmd")
+            with open(os.path.join(mathicsscript_path, "install_GTK.cmd"), "w") as file:
+                file.write(f'"{GTK_installer}"')
+            subprocess.run(
+                GTK_install_cmd
+            )  # Allow users to run installer as administrators. Tried to run it directly with subprocess.run(['runas', '/user:Administrator', ...]) and failed :(
+            os.remove(GTK_install_cmd)
+            set_dll_search_path()
+            # Manually add GTK+ for Windows dll libraries to os.environ["PATH"]
+            GTK_folders = search_folders("C:\\Program Files", "GTK")
+            GTK_dll_paths = search_file_in_folders(GTK_folders, "libcairo-2.dll")
+            if GTK_dll_paths:
+                os.environ["PATH"] += os.pathsep + GTK_dll_paths[0]
+            if find_library("libcairo-2"):
+                print("Successfully fixed cairocffi for mathicsscript.")
+            else:
+                print(
+                    "Please restart the current terminal to make the changes take effect."
+                )

setup.py

@@ -86,6 +86,7 @@ def read(*rnames):
         # "mathics_pygments @ https://github.com/Mathics3/mathics-pygments/archive/master.zip#egg=mathics_pygments",
         "mathics_pygments>=1.0.2",
         "term-background >= 1.0.1",
+        'tqdm',
     ],
     entry_points={
         "console_scripts": [