matplotlib · QuLogic · Jul 30, 2026 · Aug 1, 2026
diff --git a/.github/workflows/wasm.yml b/.github/workflows/wasm.yml
@@ -53,7 +53,6 @@ jobs:
         uses: pypa/cibuildwheel@294735312765b09d24a2fbec22660ce817587d55  # v4.1.0
         env:
           CIBW_PLATFORM: "pyodide"
-          CIBW_TEST_COMMAND: "true"
 
       - uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a  # v7.0.1
         with:

diff --git a/lib/matplotlib/backends/backend_agg.py b/lib/matplotlib/backends/backend_agg.py
@@ -178,7 +178,16 @@ def _draw_text_glyphs_and_boxes(self, gc, x, y, angle, glyphs, boxes):
         sin = math.sin(math.radians(angle))
         load_flags = get_hinting_flag()
         for font, size, glyph_index, slant, extend, dx, dy in glyphs:  # dy is upwards.
+            print(f'Rendering {font.fname}@{size}/{self.dpi}:',
+                  glyph_index, slant, extend, dx, dy)
             font.set_size(size, self.dpi)
+            print(
+                f'set_transform {sin=} {cos=}',
+                (0x10000 * np.array([[cos, -sin], [sin, cos]])
+                 @ [[extend, extend * slant], [0, 1]]).round().astype(int),
+                [round(0x40 * (x + dx * cos - dy * sin)),
+                 # FreeType's y is upwards.
+                 round(0x40 * (self.height - y + dx * sin + dy * cos))])
             font._set_transform(
                 (0x10000 * np.array([[cos, -sin], [sin, cos]])
                  @ [[extend, extend * slant], [0, 1]]).round().astype(int),
@@ -193,6 +202,9 @@ def _draw_text_glyphs_and_boxes(self, gc, x, y, angle, glyphs, boxes):
             if not gc.get_antialiased():
                 buffer *= 0xff
             # draw_text_image's y is downwards & the bitmap bottom side.
+            print(f'draw_text_image at {bitmap.left=} {self.height=} {bitmap.top=} '
+                  f'{buffer.shape[0]=} {int(self.height)=} '
+                  f'{int(self.height) - bitmap.top + buffer.shape[0]=}')
             self._renderer.draw_text_image(
                 buffer,
                 bitmap.left, int(self.height) - bitmap.top + buffer.shape[0],
@@ -205,6 +217,7 @@ def _draw_text_glyphs_and_boxes(self, gc, x, y, angle, glyphs, boxes):
         gc1.set_linewidth(0)
         gc1.set_snap(gc.get_snap())
         for dx, dy, w, h in boxes:  # dy is upwards.
+            print(f'Draw rect {dx=} {dy=} {w=} {h=}')
             if gc1.get_snap() in [None, True]:
                 # Prevent thin bars from disappearing by growing symmetrically.
                 if w < 1:

diff --git a/pyproject.toml b/pyproject.toml
@@ -461,16 +461,20 @@ test-command = [
     """\
     pytest -p no:cacheprovider --pyargs \
         matplotlib mpl_toolkits.axes_grid1 mpl_toolkits.axisartist mpl_toolkits.mplot3d \
-	-k 'not test_complex_shaping'""",
+	-k 'test_mathtext or last_resort' || true""",
+    "cp -a result_images {project}",
 ]
+test-environment = { FT2_DEBUG="any:7 -v" }
+[tool.cibuildwheel.pyodide.config-settings]
+setup-args = ["-Dbuildtype=debug"]
 [tool.cibuildwheel.pyodide.environment]
 # Exception handling is needed for pybind11:
 # https://github.com/pybind/pybind11/pull/5298
 # And the pyemscripten_2025_0 platform and above uses -fwasm-exceptions for this.
 # https://pyodide.org/en/stable/development/abi/313.html
-CFLAGS = "-fwasm-exceptions"
-CXXFLAGS = "-fwasm-exceptions"
-LDFLAGS = "-fwasm-exceptions"
+CFLAGS = "-fwasm-exceptions -g"
+CXXFLAGS = "-fwasm-exceptions -g"
+LDFLAGS = "-fwasm-exceptions -g"
 
 [tool.cibuildwheel.windows]
 before-build = [

diff --git a/subprojects/freetype2.wrap b/subprojects/freetype2.wrap
@@ -10,7 +10,9 @@ source_hash = 36bc4f1cc413335368ee656c42afca65c5a3987e8768cc28cf11ba775e785a5f
 
 # First patch allows using our bundled HarfBuzz.
 # Second patch fixes symbol problems on wasm.
-diff_files = freetype-2.14.1-static-harfbuzz.patch, freetype-2.14.1-wasm-visibility.patch
+# Third and fourth fix debug logging https://gitlab.freedesktop.org/freetype/freetype/-/merge_requests/438
+# Fifth enables debug logging.
+diff_files = freetype-2.14.1-static-harfbuzz.patch, freetype-2.14.1-wasm-visibility.patch, 0003-Add-missing-dlg-logging-library-to-meson-build.patch, 0004-Fix-debug-logging-when-NDEBUG-is-set.patch, 0005-Enable-debug-logging.patch
 
 [provide]
 freetype2 = freetype_dep

diff --git a/subprojects/packagefiles/0003-Add-missing-dlg-logging-library-to-meson-build.patch b/subprojects/packagefiles/0003-Add-missing-dlg-logging-library-to-meson-build.patch
@@ -0,0 +1,28 @@
+From a4279b16570434a2d46f073d221a1d3a5034f9e7 Mon Sep 17 00:00:00 2001
+From: Elliott Sales de Andrade <quantum.analyst@gmail.com>
+Date: Fri, 31 Jul 2026 23:09:34 -0400
+Subject: [PATCH 3/5] Add missing dlg logging library to meson build
+
+Without this source file, the final library fails to link if you set
+`FT_DEBUG_LOGGING` for the build.
+
+Signed-off-by: Elliott Sales de Andrade <quantum.analyst@gmail.com>
+---
+ meson.build | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/meson.build b/meson.build
+index 046163ecd..c731ed938 100644
+--- a/meson.build
++++ b/meson.build
+@@ -236,6 +236,7 @@ endif
+ # might make these platform-specific files much smaller, and could be moved
+ # into `ftsystem.c` as well.
+
++ft2_sources += 'src/dlg/dlgwrap.c'
+ if host_machine.system() == 'windows'
+   winmod = import('windows')
+   ft2_sources += [
+-- 
+2.55.0
+
diff --git a/subprojects/packagefiles/0004-Fix-debug-logging-when-NDEBUG-is-set.patch b/subprojects/packagefiles/0004-Fix-debug-logging-when-NDEBUG-is-set.patch
@@ -0,0 +1,36 @@
+From 36633fe4a2bc417ce575f6aa74e9f3a6da20b7e7 Mon Sep 17 00:00:00 2001
+From: Elliott Sales de Andrade <quantum.analyst@gmail.com>
+Date: Fri, 31 Jul 2026 23:12:47 -0400
+Subject: [PATCH 4/5] Fix debug logging when `NDEBUG` is set
+
+In Meson, the default for `b_ndebug` is `is-release`, which will enable
+it when in release mode. Additionally, in `dlg`, the default log level
+is `warn` if `NDEBUG` is set or `trace` otherwise. Because `FT_LOG` uses
+the `trace` level always, all debug logging will be disabled if
+`b_ndebug` is set (or in release mode).
+
+Using `NDEBUG` is not documented anywhere to toggle debug logging, so
+define `DLG_LOG_LEVEL` so that `trace` level is always output by `dlg`.
+FreeType's other (runtime or otherwise) configuration remains as it is
+to toggle logging per-component.
+
+Signed-off-by: Elliott Sales de Andrade <quantum.analyst@gmail.com>
+---
+ include/freetype/internal/ftdebug.h | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/include/freetype/internal/ftdebug.h b/include/freetype/internal/ftdebug.h
+index 62b9ec2f7..f2339aff4 100644
+--- a/include/freetype/internal/ftdebug.h
++++ b/include/freetype/internal/ftdebug.h
+@@ -33,6 +33,7 @@
+
+ #ifdef FT_DEBUG_LOGGING
+ #define DLG_STATIC
++#define DLG_LOG_LEVEL dlg_level_trace
+ #include <dlg/output.h>
+ #include <dlg/dlg.h>
+
+-- 
+2.55.0
+
diff --git a/subprojects/packagefiles/0005-Enable-debug-logging.patch b/subprojects/packagefiles/0005-Enable-debug-logging.patch
@@ -0,0 +1,26 @@
+From dc723711549e7710e074b210f48391c6b07c013e Mon Sep 17 00:00:00 2001
+From: Elliott Sales de Andrade <quantum.analyst@gmail.com>
+Date: Sat, 1 Aug 2026 01:46:51 -0400
+Subject: [PATCH 5/5] Enable debug logging
+
+Signed-off-by: Elliott Sales de Andrade <quantum.analyst@gmail.com>
+---
+ include/freetype/config/ftoption.h | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/include/freetype/config/ftoption.h b/include/freetype/config/ftoption.h
+index b857e0ebb..bef9e6853 100644
+--- a/include/freetype/config/ftoption.h
++++ b/include/freetype/config/ftoption.h
+@@ -473,7 +473,7 @@ FT_BEGIN_HEADER
+    *
+    *   This option needs a C99 compiler.
+    */
+-/* #define FT_DEBUG_LOGGING */
++#define FT_DEBUG_LOGGING
+
+
+   /**************************************************************************
+-- 
+2.55.0
+