René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[ENH]: Add a QtPgfPng backend?","articleBody":"### Problem\r\n\r\nPer #28084 and a few other older similar issues, some users are confused because they cannot see pgf-generated plots (which can include xelatex/lualatex-specific latex constructs, in particular) interactively, as the interactive guis still use the \"standard\" latex support.\r\n\r\nAs it turns out it is relatively easy(?) to implement a minimal \"interactive\" backend that uses pgf and pdf-\u003epng to conversion to interactively display pgf-generated plots.  Obviously it has the *most terrible* performance ever (each draw involves a full tex compilation of the image), but (per the above) it could have some uses...\r\n\r\n### Proposed solution\r\n\r\nMinimum patch implementing the (minimally tested...) backend is below.  Test e.g. by setting MPLBACKEND to qtpgfpng and plotting.\r\n\r\n```patch\r\ndiff --git c/lib/matplotlib/backends/backend_qtpgfpng.py i/lib/matplotlib/backends/backend_qtpgfpng.py\r\nnew file mode 100644\r\nindex 0000000000..f44097dc0b\r\n--- /dev/null\r\n+++ i/lib/matplotlib/backends/backend_qtpgfpng.py\r\n@@ -0,0 +1,27 @@\r\n+from tempfile import TemporaryDirectory\r\n+\r\n+import numpy as np\r\n+import PIL.Image\r\n+\r\n+from .backend_pgf import FigureCanvasPgf\r\n+from .backend_qt import FigureCanvasQT\r\n+from .qt_compat import QtGui\r\n+\r\n+\r\n+class FigureCanvasQTPgfPng(FigureCanvasPgf, FigureCanvasQT):\r\n+    def paintEvent(self, event):\r\n+        with TemporaryDirectory() as tmpdir:\r\n+            self.print_png(f\"{tmpdir}/image.png\")\r\n+            img = np.asarray(PIL.Image.open(f\"{tmpdir}/image.png\"))\r\n+        qimage = QtGui.QImage(\r\n+            img, img.shape[1], img.shape[0],\r\n+            QtGui.QImage.Format.Format_RGBA8888)\r\n+        qimage.setDevicePixelRatio(self.device_pixel_ratio)\r\n+        painter = QtGui.QPainter(self)\r\n+        painter.eraseRect(event.rect())\r\n+        painter.drawImage(0, 0, qimage)\r\n+        self._draw_rect_callback(painter)\r\n+        painter.end()\r\n+\r\n+\r\n+FigureCanvas = FigureCanvasQTPgfPng\r\ndiff --git c/lib/matplotlib/backends/meson.build i/lib/matplotlib/backends/meson.build\r\nindex 1e3e47c0a9..967cab902b 100644\r\n--- c/lib/matplotlib/backends/meson.build\r\n+++ i/lib/matplotlib/backends/meson.build\r\n@@ -19,6 +19,7 @@ python_sources = [\r\n   'backend_qt.py',\r\n   'backend_qtagg.py',\r\n   'backend_qtcairo.py',\r\n+  'backend_qtpgfpng.py',\r\n   'backend_qt5.py',\r\n   'backend_qt5agg.py',\r\n   'backend_qt5cairo.py',\r\ndiff --git c/lib/matplotlib/backends/registry.py i/lib/matplotlib/backends/registry.py\r\nindex 484d6ed5f2..ac18cc28c9 100644\r\n--- c/lib/matplotlib/backends/registry.py\r\n+++ i/lib/matplotlib/backends/registry.py\r\n@@ -32,7 +32,7 @@ class BackendRegistry:\r\n         \"GTK3Agg\", \"GTK3Cairo\", \"GTK4Agg\", \"GTK4Cairo\",\r\n         \"MacOSX\",\r\n         \"nbAgg\",\r\n-        \"QtAgg\", \"QtCairo\", \"Qt5Agg\", \"Qt5Cairo\",\r\n+        \"QtAgg\", \"QtCairo\", \"QtPgfPng\", \"Qt5Agg\", \"Qt5Cairo\",\r\n         \"TkAgg\", \"TkCairo\",\r\n         \"WebAgg\",\r\n         \"WX\", \"WXAgg\", \"WXCairo\",\r\n```\r\n\r\n(https://github.com/matplotlib/matplotlib/pull/27913#issuecomment-1999230861 is also relevant)","author":{"url":"https://github.com/anntzer","@type":"Person","name":"anntzer"},"datePublished":"2024-04-16T16:25:35.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":9},"url":"https://github.com/28086/matplotlib/issues/28086"}