From e0f1a4ae33168ad1dd5d3c01fab0acadcb964943 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Ekl=C3=B6f?= <daniel@ekloef.se>
Date: Sun, 16 May 2021 10:57:43 +0200
Subject: [PATCH] =?UTF-8?q?sixel:=20don=E2=80=99t=20*ever*=20shrink=20imag?=
 =?UTF-8?q?e=20below=20its=20SRA=20size?=
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If the image was accompanied with a “Set Raster Attributes” (SRA)
command, make sure we *never* shrink the image below the size
specified in the SRA.

Images are normally shrunk when their bottom rows are fully
transparent. This enables sixels that aren’t a multiple of 6 to be
emitted, without also emitting an SRA command.

But if there *is* an SRA command, obey it.

Verified against XTerm-367
---
 CHANGELOG.md |  2 ++
 sixel.c      | 12 ++++++------
 2 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c225a576..34c12bf0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -101,6 +101,8 @@
 * Font underlines being positioned below the cell (and thus being
   invisible) for certain combinations of fonts and font sizes
   (https://codeberg.org/dnkl/foot/issues/503).
+* Sixels with transparent bottom border being resized below the size
+  specified in _”Set Raster Attributes”_.
 
 
 ### Security
diff --git a/sixel.c b/sixel.c
index 5840e887..eb34b646 100644
--- a/sixel.c
+++ b/sixel.c
@@ -816,7 +816,8 @@ sixel_unhook(struct terminal *term)
         xassert(image.rows <= term->grid->num_rows);
         xassert(image.pos.row + image.rows - 1 < term->grid->num_rows);
 
-        LOG_DBG("generating %dx%d pixman image at %d-%d",
+        LOG_DBG("generating %s %dx%d pixman image at %d-%d",
+                image.opaque ? "opaque" : "transparent",
                 image.width, image.height,
                 image.pos.row, image.pos.row + image.rows);
 
@@ -1195,11 +1196,10 @@ decgra(struct terminal *term, uint8_t c)
             ph <= term->sixel.max_height && pv <= term->sixel.max_width)
         {
             resize(term, ph, pv);
-            if (!term->sixel.transparent_bg) {
-                /* This ensures the sixel’s final image size is *at
-                 * least* this large */
-                term->sixel.max_non_empty_row_no = pv - 1;
-            }
+
+            /* This ensures the sixel’s final image size is *at least*
+             * this large */
+            term->sixel.max_non_empty_row_no = pv - 1;
         }
 
         term->sixel.state = SIXEL_DECSIXEL;