René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[Bug]: savefig() breaks FancyArrowPatch position on saved PNG when using custom DPI","articleBody":"### Bug summary\n\nHeyho,\n\nI encountered an error with patches (FancyArrowPatch).\nWhen i draw FancyArrowPatches into a figure and save the figures with savefig(), the patches shift around to different positions depending on my set `dpi=`parameter as shown by the following screenshots, produced by code underneath.\n\n\n### Code for reproduction\n\n```Python\nimport os\nfrom os.path import dirname\n\nimport copy\n\nimport matplotlib.pyplot as plt\nimport matplotlib.patches as patches\n\n\n\nos.chdir(dirname(__file__))\nprint(f\"Changed WD to PyFile-root \\\"{os.getcwd()}\\\"\")\n\n\nColor1 = \"#1776D4\"\nColor2 = \"#E27A12\"\n\nfig, axL = plt.subplots(nrows=1, ncols=1)\naxR = axL.twinx()\n\nplt.show(block=False)\n\n\narrowUpBG = patches.FancyArrowPatch(\n    posA=(0.500, 0.535),        # Startpoint Arrow  (0..1)\n    posB=(0.560, 0.560),        # Endpoint Base     (0..1)\n    transform=fig.transFigure,  # Coordinate system of figure\n    arrowstyle='fancy',\n    color=Color1,\n    linewidth=10,\n    mutation_scale=30\n)\n\n# NOTE: Copies have to be made before first draw! Otherwise figure gets cloned too!\narrowUpFG = copy.deepcopy(arrowUpBG)\narrowUpFG.set_color(Color2)\narrowUpFG.set_linewidth(1)\n\narrowDownBG = copy.deepcopy(arrowUpBG)\narrowDownFG = copy.deepcopy(arrowUpFG)\narrowDownBG.set_positions(posA=(0.590, 0.745),   # Startpoint Arrow  (0..1)\n                          posB=(0.535, 0.690),   # Endpoint Base     (0..1)\n                          )\narrowDownFG.set_positions(posA=(0.590, 0.745),\n                          posB=(0.535, 0.690),\n                          )\n\n# NOTE: Draw is here (together, copies have to be made beforehand, as otherwise savefig gets cloned too!)\nfig.add_artist(arrowUpBG)\nfig.add_artist(arrowUpFG)\n\nfig.add_artist(arrowDownBG)\nfig.add_artist(arrowDownFG)\n\n\n\nfig.savefig(\"./FancyIssue - SVG.svg\")\nfig.savefig(\"./FancyIssue - Std dpi.png\")\nfig.savefig(\"./FancyIssue - 200 dpi.png\", dpi=200)\nfig.savefig(\"./FancyIssue - 300 dpi.png\", dpi=300)\nfig.savefig(\"./FancyIssue - 600 dpi.png\", dpi=600)\n\nprint(\"EOS\")\n```\n\n### Actual outcome\n\n| DPI | Standard | 200 | 300 | 600 | SVG (in Firefox) |\n|-----|-----------|------|-----|------|------------------|\n| Imgs |\u003cimg width=\"640\" height=\"480\" alt=\"Image\" src=\"https://github.com/user-attachments/assets/15f133ed-03a3-4a63-a627-415cb5e36a0a\" /\u003e | \u003cimg width=\"1280\" height=\"960\" alt=\"Image\" src=\"https://github.com/user-attachments/assets/113f024c-cb45-46bb-a86d-dd7664ad42d1\" /\u003e | \u003cimg width=\"1920\" height=\"1440\" alt=\"Image\" src=\"https://github.com/user-attachments/assets/01440e27-35a4-424a-81df-725333775812\" /\u003e| \u003cimg width=\"3840\" height=\"2880\" alt=\"Image\" src=\"https://github.com/user-attachments/assets/87a2a221-0c2e-45b8-a4bd-cc334d9cbbd1\" /\u003e | \u003cimg width=\"552\" height=\"435\" alt=\"Image\" src=\"https://github.com/user-attachments/assets/e7142f64-24ed-48a1-869f-84c4aa431379\" /\u003e  |\n\n### Expected outcome\n\nPatches stay in relative position to the figure size.\nNote: The patches are drawn correctly in the preview (plt.show()).\n\n### Additional information\n\n_No response_\n\n### Operating system\n\nWindows 11 (24H2)\n\n### Matplotlib Version\n\n 3.10.8\n\n### Matplotlib Backend\n\n tkagg\n\n### Python version\n\n3.14.3\n\n### Jupyter version\n\nN/A\n\n### Installation\n\npip\n\n\n\n\n\nBest regards,\nDeph","author":{"url":"https://github.com/Dephrilibrium","@type":"Person","name":"Dephrilibrium"},"datePublished":"2026-04-20T15:26:07.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":10},"url":"https://github.com/31536/matplotlib/issues/31536"}