From 85fe21d290aa46b67470341ae76b11665762f802 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Hubert=20G=C5=82uchowski?= <fishhh@fishhh.dev>
Date: Fri, 5 Jun 2026 17:58:21 +0200
Subject: [PATCH] sub/sd_sbr: fix zooming

Previously both the padding and clip rect calculations didn't take into
account zoom (negative margins) which resulted in more or less broken
behavior depending on if `sub-use-margins` was set or not.

This fixes those to properly handle negative margins which:
- Makes us calculate a tighter clip rect if `!sub-use-margins`.
- Unbreaks layout zoomed in and `sub-use-margins`.
---
 sub/sd_sbr.c | 32 +++++++++++++++++++++++---------
 1 file changed, 23 insertions(+), 9 deletions(-)

diff --git a/sub/sd_sbr.c b/sub/sd_sbr.c
index 1cb12a6cce..6ac0d0c11f 100644
--- a/sub/sd_sbr.c
+++ b/sub/sd_sbr.c
@@ -191,14 +191,24 @@ static struct sub_bitmaps *get_bitmaps(struct sd *sd, struct mp_osd_res dim,
         .max_x = dim.w, .max_y = dim.h
     };
 
+    // Translate our clip rect by the zoom (negative) margin to get the
+    // part we're actually interested in.
+    clip_rect.min_x -= MPMIN(0, dim.ml);
+    clip_rect.min_y -= MPMIN(0, dim.mt);
+    clip_rect.max_x -= MPMIN(0, dim.ml);
+    clip_rect.max_y -= MPMIN(0, dim.mt);
+
     if (opts->sub_use_margins) {
-        context.padding_top = (int32_t)dim.mt << 6;
-        context.padding_bottom = (int32_t)dim.mb << 6;
-        context.padding_left = (int32_t)dim.ml << 6;
-        context.padding_right = (int32_t)dim.mr << 6;
+        context.padding_left = (int32_t)MPMAX(0, dim.ml) << 6;
+        context.padding_right = (int32_t)MPMAX(0, dim.mr) << 6;
+        context.padding_top = (int32_t)MPMAX(0, dim.mt) << 6;
+        context.padding_bottom = (int32_t)MPMAX(0, dim.mb) << 6;
     } else {
-        clip_rect.max_x -= dim.ml + dim.mr;
-        clip_rect.max_y -= dim.mt + dim.mb;
+        // Remove normal (positive) margins from our clip rect as
+        // those are already included in `dim.{w,h}` but we specifically
+        // don't want them here.
+        clip_rect.max_x -= MPMAX(0, dim.ml) + MPMAX(0, dim.mr);
+        clip_rect.max_y -= MPMAX(0, dim.mt) + MPMAX(0, dim.mb);
     }
 
     unsigned t = lrint(pts * 1000);
@@ -223,12 +233,16 @@ static struct sub_bitmaps *get_bitmaps(struct sd *sd, struct mp_osd_res dim,
         mp_sub_packer_pack_sbr(ctx->packer, pass, &res);
         sbr_instanced_raster_pass_finish(pass);
 
-        if (!opts->sub_use_margins)
-            for (int i = 0; i < res.num_parts; ++i) {
-                struct sub_bitmap *part = &res.parts[i];
+        for (int i = 0; i < res.num_parts; ++i) {
+            struct sub_bitmap *part = &res.parts[i];
+            if (opts->sub_use_margins) {
+                part->x += MPMIN(0, dim.ml);
+                part->y += MPMIN(0, dim.mt);
+            } else {
                 part->x += dim.ml;
                 part->y += dim.mt;
             }
+        }
     } else
         res = *cached;