Create CLI wrapper

* Add README.md with Debian instructions

Code fixes

* Added `.encode()` to handle `str` to `byte` conversion
* Removed `is_supported_mysql_version_at_least()` check
* Fixed out-parameter handling for `cairo.cairo_text_extents()`
* Add missing argument to `cairo.cairo_set_dash()`

Author: leonyu

README.md

@@ -0,0 +1,32 @@
+# MySQL Visual Explain CLI
+
+[MySQL Workbench](https://github.com/mysql/mysql-workbench/) comes with a Visual Explain feature that is written in Python using [Cairo](https://www.cairographics.org/). This project is simply extracts that code and provides a minimal CLI for it.
+
+## Usages
+
+### Debian
+
+```sh
+sudo apt-get install python3-cairocffi
+
+python3 ./mysql_visual_explain_cli explain.json explain.png
+```
+
+### Poetry
+
+```sh
+poetry run python ./mysql_visual_explain_cli explain.json explain.png
+```
+
+## Notes
+
+The version of Python bundled with MySQL Workbench also seems to perform implicit `str` to `byte` conversion.
+
+The MySQL Workbench code does not use the common Pycairo library, but instead calls Cairo C directly via FFI. The following C functions appear to have been patched or used a different version compare to what is distrubted with modern Debian distributions.
+
+* `cairo.cairo_text_extents()`
+* `cairo.cairo_set_dash()`
+
+## License
+
+This project is a derivative work of MySQL Workbench which is GPLv2. Meaning unless I have money for a lawyer, it will forever be GPLv2 as well.

mysql_visual_explain_cli/__init__.py

@@ -0,0 +1,23 @@
+import argparse
+
+from query_analysis import explain_renderer
+
+
+def render(json_data, output_path):
+    ctx = explain_renderer.ExplainContext(explain_renderer.decode_json(json_data), None)
+    ctx.init_canvas(None, None, lambda x, y, w, h: None)
+    ctx.layout()
+    ctx.export_to_png(output_path)
+
+def main():
+    parser = argparse.ArgumentParser(description="CLI to convert MySQL JSON EXPLAIN to PNG file.")
+    parser.add_argument('infile', type=argparse.FileType('r'), help="Input file (must be JSON)")
+    parser.add_argument('outfile', help="Output file path (output is PNG)")
+    args = parser.parse_args()
+
+    with args.infile as f:
+        json_data = f.read().replace('\n','')
+        render(json_data, args.outfile)
+
+if __name__ == '__main__':
+    main()

mysql_visual_explain_cli/__main__.py

@@ -19,7 +19,9 @@
 # along with this program; if not, write to the Free Software Foundation, Inc.,
 # 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 
-import cairo
+import cairocffi
+from cairocffi import cairo
+
 from math import ceil, floor, fabs, atan, pi
 
 
@@ -31,7 +33,7 @@ def status(self):
         return cairo.cairo_surface_status(self.s)
 
     def write_to_png(self, file):
-        cairo.cairo_surface_write_to_png(self.s, file)
+        cairo.cairo_surface_write_to_png(self.s, file.encode())
 
 
 class ImageSurface(Surface):
@@ -125,10 +127,10 @@ def restore(self):
         cairo.cairo_restore(self.cr)
 
     def set_dash(self, dashes, offset):
-        cairo.cairo_set_dash(self.cr, dashes, offset)
+        cairo.cairo_set_dash(self.cr, dashes, 1, offset)
 
     def set_font(self, family, italic=False, bold=False):
-        cairo.cairo_select_font_face(self.cr, family, cairo.CAIRO_FONT_SLANT_ITALIC if italic else cairo.CAIRO_FONT_SLANT_NORMAL, cairo.CAIRO_FONT_WEIGHT_BOLD if bold else cairo.CAIRO_FONT_WEIGHT_NORMAL)
+        cairo.cairo_select_font_face(self.cr, family.encode(), cairo.CAIRO_FONT_SLANT_ITALIC if italic else cairo.CAIRO_FONT_SLANT_NORMAL, cairo.CAIRO_FONT_WEIGHT_BOLD if bold else cairo.CAIRO_FONT_WEIGHT_NORMAL)
 
     def set_font_size(self, size):
         cairo.cairo_set_font_size(self.cr, size)
@@ -155,7 +157,7 @@ def mask_surface(self, surface, x, y):
         cairo.cairo_mask_surface(self.cr, surface.s, x, y)
 
     def show_text(self, text):
-        cairo.cairo_show_text(self.cr, text)
+        cairo.cairo_show_text(self.cr, text.encode())
 
     def rounded_rect(self, x, y, w, h, r):
         self.move_to(x+r, y)
@@ -202,7 +204,9 @@ def stroke_preserve(self):
         cairo.cairo_stroke_preserve(self.cr)
 
     def text_extents(self, text):
-        return cairo.cairo_text_extents(self.cr, text)
+        extents = cairocffi.ffi.new('cairo_text_extents_t *')
+        cairo.cairo_text_extents(self.cr, text.encode(), extents)
+        return extents
 
 
 

mysql_visual_explain_cli/graphics/__init__.py

@@ -19,18 +19,18 @@
 # along with this program; if not, write to the Free Software Foundation, Inc.,
 # 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 
-import mforms
-
+import io
+import json
+import logging
 
-from workbench.log import log_error
+from cairocffi import cairo
 
+from graphics.canvas import VBoxFigure, Canvas, DiamondShapeFigure, RectangleShapeFigure, TextFigure, HFill, draw_varrow, draw_harrow
+from graphics.cairo_utils import ImageSurface, Context
 
-from workbench.graphics.canvas import VBoxFigure, Canvas, DiamondShapeFigure, RectangleShapeFigure, TextFigure, HFill, draw_varrow, draw_harrow
-from workbench.graphics.cairo_utils import ImageSurface, Context
-import cairo
 
-import io
-import json
+def log_error(error):
+    logging.exception(error)
 
 
 def decode_json(text):
@@ -425,9 +425,7 @@ def vconnect_pos_offset(self):
 
     @property
     def rows_count(self):
-        if self._context.server_version.is_supported_mysql_version_at_least(5, 7):
-            return self.child_below.rows_produced
-        return None
+        return self.child_below.rows_produced
 
 
     def get_read_eval_cost(self):

mysql_visual_explain_cli/graphics/cairo_utils.py

@@ -0,0 +1,17 @@
+[tool.poetry]
+name = "mysql-visual-explain-cli"
+version = "0.1.0"
+description = ""
+authors = ["Leon Yu <leon@leonyu.net>"]
+license = "GPL-2.0-only"
+readme = "README.md"
+packages = [{include = "mysql_visual_explain_cli"}]
+
+[tool.poetry.dependencies]
+python = "^3.11"
+cairocffi = "^1.6.1"
+
+
+[build-system]
+requires = ["poetry-core"]
+build-backend = "poetry.core.masonry.api"