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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"TypeError in `QwtSymbol.drawSymbol` method due to outdated `renderSymbols` call","articleBody":"## Description\n\n### Issue Description\nFixed a critical bug in the `QwtSymbol.drawSymbol` method that was causing a TypeError when attempting to draw a symbol into a rectangle. The error message was:\n```\nTypeError: QwtSymbol.renderSymbols() takes 3 positional arguments but 4 were given\n```\n\n### Root Cause Analysis\nThis bug had two distinct causes:\n\n1. **Outdated method call**: Following changeset 6a36ce7 \"QwtSymbol.drawSymbols/renderSymbols: removed numPoints argument\" (version 0.11), the call to `renderSymbols` in the `drawSymbol` method was not updated to match the new signature. The method was still being called with incorrect arguments, causing the TypeError.\n\n2. **Incorrect parameter type**: Even after fixing the parameter count, there was another issue: the second argument of `renderSymbols` expects a list of points (`points`, plural), but a single `QPointF` object was being passed directly. The method expects an iterable collection, not a single point.\n\n### Location\nFile: `qwt/symbol.py`\nMethod: `QwtSymbol.drawSymbol`\n\n### Fixed Code\nThe issue was fixed by:\n1. Updating the call to use the correct number of parameters\n2. Passing a list containing the single QPointF rather than the QPointF directly, as the method expects an iterable collection of points\n\nThe affected code section was in `drawSymbol` method:\n\n```python\n# Before:\nself.renderSymbols(painter, QPointF(), 1)  # Incorrect call with wrong arguments\n\n# After:\nself.renderSymbols(painter, [QPointF()])  # Fixed call with correct arguments\n```\n\n### Impact\nThis bug would prevent symbols from being properly rendered in certain contexts, particularly when using the `drawSymbol` method with a rectangle parameter, which is critical for displaying symbols in legends and other UI elements.\n\n### Additional Context\nThis bug appears to have been introduced during the transition to version 0.11 when the `numPoints` parameter was removed from the `renderSymbols` method but not all calls to this method were updated accordingly.\n","author":{"url":"https://github.com/PierreRaybaut","@type":"Person","name":"PierreRaybaut"},"datePublished":"2025-06-12T09:33:57.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/100/PythonQwt/issues/100"}