drm_rect_calc_hscale(9)

💅 drm_rect_calc_hscale — like, the horizontal scaling factor calculator

okay bestie, welcome to the Kernel API Manual ✨ this one's a tiny little function from the DRM rect squad, and honestly? it's giving "small but crucial" energy. let's get into it 🎀

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✨ NAME ✨

drm_rect_calc_hscale — calculate the horizontal scaling factor 🌸

like, it figures out how much your rectangle is being stretched sideways. that's the whole vibe. 💖

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🦋 SYNOPSIS 🦋

int drm_rect_calc_hscale (const struct drm_rect *src , const struct drm_rect *dst , int min_hscale , int max_hscale );

yep, that's the whole signature, no cap. four args, one int coming back at ya. 👑

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🍓 ARGUMENTS 🍓

• src — the source window rectangle 💜 this is the rectangle you're scaling from, the origin story if you will.
• dst — the destination window rectangle ✨ the rectangle you're scaling to. where the glow-up happens.
• min_hscale — minimum allowed horizontal scaling factor 🎀 the floor, the "bestie please don't shrink past this" line.
• max_hscale — maximum allowed horizontal scaling factor 🔥 the ceiling, the "okay that's enough stretching" limit.

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🌈 DESCRIPTION 🌈

so here's the tea ☕ this function calculates the horizontal scaling factor as (src width) / (dst width). literally just src width over dst width. simple. iconic. periodt. 💅

and then there's the rounding rules, which are lowkey the main character here:

• if the scale is below 1 << 16, it rounds down ⬇️
• if the scale is above 1 << 16, it rounds up ⬆️

the way that this works out means you get the scale calculated with the most pessimistic limit calculation 😭 and yes, pessimistic is the exact word — this thing is not out here being optimistic about your limits, it's assuming the worst-case and acting accordingly. respect, honestly. 🫶

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⭐ RETURN ⭐

the horizontal scaling factor 💖 or, if things go out of limits, the errno of out of limits 🙈 so like, check the return value, bestie. don't just assume it's a happy number.

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🔥 SEE ALSO 🔥

• Kernel file ./drivers/gpu/drm/drm_rect.c 📁 (this is where the magic lives)
• drm_rect_intersect(9)
• drm_rect_clip_scaled(9)
• drm_rect_calc_vscale(9) — the vertical sibling 👀
• drm_rect_debug_print(9)
• drm_rect_rotate(9)
• drm_rect_rotate_inv(9)

go read those too, the whole rect friend group is honestly so good 💜

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aaaand that's the page! 🌸 this lil masterpiece comes to you from ./drivers/gpu/drm, dated October 2026, living in the Kernel API Manual (version 9, because of course). mwah, go scale those rectangles horizontally bestie 💋🎀🦋