fix(highlight): make intra-line bg visible under line backgrounds

README.md

@@ -128,5 +128,5 @@ See the documentation for more information.
 - [@phanen](https://github.com/phanen) - diff header highlighting, unknown
   filetype fix, shebang/modeline detection, treesitter injection support,
   decoration provider highlighting architecture, gitsigns blame popup
-  highlighting
+  highlighting, intra-line bg visibility fix
 - [@tris203](https://github.com/tris203) - support for transparent backgrounds

doc/diffs.nvim.txt

@@ -956,15 +956,14 @@ Fugitive unified diff highlights: ~
 
                                                               *DiffsAddText*
     DiffsAddText        Character-level background for changed characters
-                        within `+` lines. Derived by blending `diffAdded`
-                        foreground with `Normal` background at 60% alpha.
-                        Only sets `bg`, so treesitter foreground colors show
-                        through.
+                        within `+` lines. Uses the raw `DiffAdd` background
+                        color. Only sets `bg`, so treesitter foreground
+                        colors show through.
 
                                                            *DiffsDeleteText*
     DiffsDeleteText     Character-level background for changed characters
-                        within `-` lines. Derived by blending `diffRemoved`
-                        foreground with `Normal` background at 60% alpha.
+                        within `-` lines. Uses the raw `DiffDelete`
+                        background color.
 
 Conflict highlights: ~
                                                         *DiffsConflictOurs*

lua/diffs/highlight.lua

@@ -636,11 +636,20 @@ function M.highlight_hunk(bufnr, ns, hunk, opts)
       end
 
       if opts.highlights.background and is_diff_line then
+        local bg_end_col = raw_len or (line_len + qw)
         pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_line, 0, {
-          line_hl_group = line_hl,
-          number_hl_group = opts.highlights.gutter and number_hl or nil,
+          end_row = buf_line,
+          end_col = bg_end_col,
+          hl_group = line_hl,
+          hl_eol = true,
           priority = p.line_bg,
         })
+        if opts.highlights.gutter then
+          pcall(vim.api.nvim_buf_set_extmark, bufnr, ns, buf_line, 0, {
+            number_hl_group = number_hl,
+            priority = p.line_bg,
+          })
+        end
       end
 
       if is_marker and line_len > pw then

lua/diffs/init.lua

@@ -543,11 +543,10 @@ local function compute_highlight_groups(is_default)
   local normal_fg = normal.fg or (dark and 0xcccccc or 0x333333)
 
   local alpha = config.highlights.blend_alpha or 0.6
-  local text_alpha = math.min(alpha + 0.3, 1.0)
   local blended_add = blend_color(add_bg, bg, alpha)
   local blended_del = blend_color(del_bg, bg, alpha)
-  local blended_add_text = blend_color(add_bg, bg, text_alpha)
-  local blended_del_text = blend_color(del_bg, bg, text_alpha)
+  local blended_add_text = add_bg
+  local blended_del_text = del_bg
 
   local clear_hl = { default = dflt, fg = normal_fg }
   if not transparent then

spec/email_quote_spec.lua

@@ -465,7 +465,7 @@ describe('email-quoted diffs', function()
       local line_bg_count = 0
       for _, mark in ipairs(extmarks) do
         local d = mark[4]
-        if d and d.line_hl_group == 'DiffsAdd' then
+        if d and d.hl_group == 'DiffsAdd' then
           line_bg_count = line_bg_count + 1
         end
       end

spec/highlight_spec.lua

@@ -287,7 +287,7 @@ describe('highlight', function()
       local extmarks = get_extmarks(bufnr)
       local has_diff_add = false
       for _, mark in ipairs(extmarks) do
-        if mark[4] and mark[4].line_hl_group == 'DiffsAdd' then
+        if mark[4] and mark[4].hl_group == 'DiffsAdd' then
           has_diff_add = true
           break
         end
@@ -320,7 +320,7 @@ describe('highlight', function()
       local extmarks = get_extmarks(bufnr)
       local has_diff_delete = false
       for _, mark in ipairs(extmarks) do
-        if mark[4] and mark[4].line_hl_group == 'DiffsDelete' then
+        if mark[4] and mark[4].hl_group == 'DiffsDelete' then
           has_diff_delete = true
           break
         end
@@ -362,7 +362,7 @@ describe('highlight', function()
       delete_buffer(bufnr)
     end)
 
-    it('line bg uses line_hl_group not hl_group with end_row', function()
+    it('line bg uses hl_group with hl_eol not line_hl_group', function()
       local bufnr = create_buffer({
         '@@ -1,1 +1,2 @@',
         ' local x = 1',
@@ -384,11 +384,16 @@ describe('highlight', function()
       )
 
       local extmarks = get_extmarks(bufnr)
+      local found = false
       for _, mark in ipairs(extmarks) do
         local d = mark[4]
-        assert.is_not_equal('DiffsAdd', d and d.hl_group)
-        assert.is_not_equal('DiffsDelete', d and d.hl_group)
+        if d and d.hl_group == 'DiffsAdd' then
+          assert.is_true(d.hl_eol)
+          assert.is_nil(d.line_hl_group)
+          found = true
+        end
       end
+      assert.is_true(found)
       delete_buffer(bufnr)
     end)
 
@@ -427,7 +432,7 @@ describe('highlight', function()
       )
       local has_line_bg = false
       for _, mark in ipairs(marks) do
-        if mark[4] and mark[4].line_hl_group == 'DiffsAdd' then
+        if mark[4] and mark[4].hl_group == 'DiffsAdd' then
           has_line_bg = true
         end
       end
@@ -502,7 +507,7 @@ describe('highlight', function()
       local extmarks = get_extmarks(bufnr)
       local has_diff_add = false
       for _, mark in ipairs(extmarks) do
-        if mark[4] and mark[4].line_hl_group == 'DiffsAdd' then
+        if mark[4] and mark[4].hl_group == 'DiffsAdd' then
           has_diff_add = true
           break
         end
@@ -693,7 +698,7 @@ describe('highlight', function()
       local extmarks = get_extmarks(bufnr)
       local has_diff_add = false
       for _, mark in ipairs(extmarks) do
-        if mark[4] and mark[4].line_hl_group == 'DiffsAdd' then
+        if mark[4] and mark[4].hl_group == 'DiffsAdd' then
           has_diff_add = true
           break
         end
@@ -778,7 +783,7 @@ describe('highlight', function()
       local found = false
       for _, mark in ipairs(extmarks) do
         local d = mark[4]
-        if d and (d.line_hl_group == 'DiffsAdd' or d.line_hl_group == 'DiffsDelete') then
+        if d and (d.hl_group == 'DiffsAdd' or d.hl_group == 'DiffsDelete') then
           found = true
         end
       end
@@ -934,7 +939,7 @@ describe('highlight', function()
         if d then
           if d.hl_group == 'DiffsClear' then
             table.insert(priorities.clear, d.priority)
-          elseif d.line_hl_group == 'DiffsAdd' or d.line_hl_group == 'DiffsDelete' then
+          elseif d.hl_group == 'DiffsAdd' or d.hl_group == 'DiffsDelete' then
             table.insert(priorities.line_bg, d.priority)
           elseif d.hl_group == 'DiffsAddText' or d.hl_group == 'DiffsDeleteText' then
             table.insert(priorities.char_bg, d.priority)
@@ -1035,8 +1040,8 @@ describe('highlight', function()
       local line_bgs = {}
       for _, mark in ipairs(extmarks) do
         local d = mark[4]
-        if d and (d.line_hl_group == 'DiffsAdd' or d.line_hl_group == 'DiffsDelete') then
-          line_bgs[mark[2]] = d.line_hl_group
+        if d and (d.hl_group == 'DiffsAdd' or d.hl_group == 'DiffsDelete') then
+          line_bgs[mark[2]] = d.hl_group
         end
       end
       assert.is_nil(line_bgs[1])
@@ -1232,8 +1237,8 @@ describe('highlight', function()
       local marker_text = {}
       for _, mark in ipairs(extmarks) do
         local d = mark[4]
-        if d and (d.line_hl_group == 'DiffsAdd' or d.line_hl_group == 'DiffsDelete') then
-          line_bgs[mark[2]] = d.line_hl_group
+        if d and (d.hl_group == 'DiffsAdd' or d.hl_group == 'DiffsDelete') then
+          line_bgs[mark[2]] = d.hl_group
         end
         if d and d.number_hl_group then
           gutter_hls[mark[2]] = d.number_hl_group
@@ -1376,7 +1381,7 @@ describe('highlight', function()
         for _, mark in ipairs(extmarks) do
           if mark[2] == row then
             local d = mark[4]
-            if d.line_hl_group then
+            if d.hl_group and d.hl_eol then
               line_hl_count = line_hl_count + 1
             end
             if d.number_hl_group then
@@ -1387,7 +1392,7 @@ describe('highlight', function()
             end
           end
         end
-        assert.are.equal(1, line_hl_count, 'row ' .. row .. ' has duplicate line_hl_group')
+        assert.are.equal(1, line_hl_count, 'row ' .. row .. ' has duplicate line bg')
         assert.are.equal(1, number_hl_count, 'row ' .. row .. ' has duplicate number_hl_group')
         assert.is_true(intra_count <= 1, 'row ' .. row .. ' has duplicate intra extmarks')
       end
@@ -1429,18 +1434,18 @@ describe('highlight', function()
 
       local extmarks = get_extmarks(bufnr)
       local has_ts = false
-      local line_hl_count = 0
+      local line_bg_count = 0
       for _, mark in ipairs(extmarks) do
         local d = mark[4]
         if d and d.hl_group and d.hl_group:match('^@.*%.lua$') then
           has_ts = true
         end
-        if d and d.line_hl_group then
-          line_hl_count = line_hl_count + 1
+        if d and d.hl_group and d.hl_eol then
+          line_bg_count = line_bg_count + 1
         end
       end
       assert.is_true(has_ts)
-      assert.are.equal(1, line_hl_count)
+      assert.are.equal(1, line_bg_count)
       delete_buffer(bufnr)
     end)
   end)

spec/integration_spec.lua

@@ -249,7 +249,7 @@ describe('integration', function()
       local extmarks = get_extmarks(bufnr, ns)
       local has_diff_add = false
       for _, mark in ipairs(extmarks) do
-        if mark[4] and mark[4].line_hl_group == 'DiffsAdd' then
+        if mark[4] and mark[4].hl_group == 'DiffsAdd' then
           has_diff_add = true
           break
         end
@@ -275,7 +275,7 @@ describe('integration', function()
       local extmarks = get_extmarks(bufnr, ns)
       local has_diff_delete = false
       for _, mark in ipairs(extmarks) do
-        if mark[4] and mark[4].line_hl_group == 'DiffsDelete' then
+        if mark[4] and mark[4].hl_group == 'DiffsDelete' then
           has_diff_delete = true
           break
         end
@@ -302,10 +302,10 @@ describe('integration', function()
       local has_add = false
       local has_delete = false
       for _, mark in ipairs(extmarks) do
-        if mark[4] and mark[4].line_hl_group == 'DiffsAdd' then
+        if mark[4] and mark[4].hl_group == 'DiffsAdd' then
           has_add = true
         end
-        if mark[4] and mark[4].line_hl_group == 'DiffsDelete' then
+        if mark[4] and mark[4].hl_group == 'DiffsDelete' then
           has_delete = true
         end
       end
@@ -334,8 +334,8 @@ describe('integration', function()
       local line_bgs = {}
       for _, mark in ipairs(extmarks) do
         local d = mark[4]
-        if d and (d.line_hl_group == 'DiffsAdd' or d.line_hl_group == 'DiffsDelete') then
-          line_bgs[mark[2]] = d.line_hl_group
+        if d and (d.hl_group == 'DiffsAdd' or d.hl_group == 'DiffsDelete') then
+          line_bgs[mark[2]] = d.hl_group
         end
       end
       assert.is_nil(line_bgs[1])
@@ -417,10 +417,10 @@ describe('integration', function()
       local del_lines = {}
       for _, mark in ipairs(extmarks) do
         local d = mark[4]
-        if d and d.line_hl_group == 'DiffsAdd' then
+        if d and d.hl_group == 'DiffsAdd' then
           add_lines[mark[2]] = true
         end
-        if d and d.line_hl_group == 'DiffsDelete' then
+        if d and d.hl_group == 'DiffsDelete' then
           del_lines[mark[2]] = true
         end
       end