fix: ASCII backend generates PDF binary content instead of text output #222
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…put docs - Replace %???? binary characters with %[binary] placeholder in scale_examples.md - Add BACKLOG.md to track current work on ASCII backend PDF output issue - Addresses issue where ASCII backend incorrectly generates PDF binary data fixes #220
Fixes issue #220 where .txt files generated PDF binary data instead of ASCII text. Root cause: The switch_backend_if_needed() function was hardcoding current_backend='ascii' instead of detecting the actual backend type. When a figure switched from ASCII->PDF->ASCII, the backend remained PDF but the switching logic incorrectly assumed it was ASCII, skipping the necessary switch back to ASCII backend. Solution: Use polymorphic type checking (select type) to properly detect the current backend type by examining the allocated backend object. Changes: - Replace hardcoded backend assumption with runtime type detection - Add proper imports for all backend context types - Maintain existing PNG backend workaround for segfault prevention Testing: - Verified with scale_examples.f90: .txt files now contain ASCII text - File type detection confirms files are "ASCII text" not "PDF document" - Sequential backend switching (ASCII->PDF->ASCII) works correctly 🤖 Generated with [Claude Code](https://claude.ai/code) Co-Authored-By: Claude <noreply@anthropic.com>
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Summary
Test plan
Details
The bug occurred when a figure switched backends multiple times (e.g., ASCII -> PDF -> ASCII). The
switch_backend_if_needed()function was hardcodingcurrent_backend = 'ascii'instead of checking what backend was actually allocated. This caused the function to skip backend switching when it should have switched from PDF back to ASCII for .txt files.The fix uses
select typeto examine the polymorphic backend object and correctly identify whether it's anascii_context,pdf_context,png_context, etc.🤖 Generated with Claude Code