The settings for the wxt terminal include an option to adjust the outline hinting parameter within a range of 0 to 100. However, in the pngcairo terminal and cairolatex (with PNG output), which rely on the same Cairo rendering routines, the hinting parameter is hardcoded at 100. This patch retains the default behavior but introduces an option to adjust the hinting parameter as needed, allowing users to set it anywhere between 0 and 100.
Outline hinting in raster image terminals enhances clarity by aligning outlines to pixel coordinates. This is primarily intended to improve the visibility of axis borderlines and reduce blurring. However, when line segments align with the axes, forced pixel alignment can cause distortion in the figure's shape. By setting the new hinting parameter to 0, anti-aliasing functions as usual, eliminating shape distortion—though at the cost of potentially blurred axis borderlines. By making this previously hardcoded parameter adjustable, users can choose their preferred balance between clarity and accuracy. To ensure continuity for existing users, the default settings remain unchanged.
Note that for vector formats such as pdfcairo, the hinting setting has no effect and should remain at its default value.
Patch file: cairotrm_hinting.patch
Test script: test_hinting.gp
