feat: allow kitty to handle cropping in default mode for better perf

lua/image/backends/kitty/init.lua

@@ -14,6 +14,9 @@ end
 local backend = {
   ---@diagnostic disable-next-line: assign-type-mismatch
   state = nil,
+  features = {
+    crop = true,
+  },
 }
 
 -- TODO: check for kitty
@@ -24,6 +27,8 @@ backend.setup = function(state)
     return
   end
 
+  if state.options.kitty_method == "unicode-placeholders" then backend.features.crop = false end
+
   vim.api.nvim_create_autocmd("VimLeavePre", {
     pattern = "*",
     callback = function()
@@ -37,7 +42,7 @@ backend.render = function(image, x, y, width, height)
   local with_virtual_placeholders = backend.state.options.kitty_method == "unicode-placeholders"
 
   -- transmit image
-  if transmitted_images[image.id] ~= image.crop_hash then
+  local transmit = function()
     helpers.write_graphics({
       action = codes.control.action.transmit,
       image_id = image.internal_id,
@@ -47,7 +52,17 @@ backend.render = function(image, x, y, width, height)
       display_virtual_placeholder = with_virtual_placeholders and 1 or 0,
       quiet = 2,
     }, image.path)
-    transmitted_images[image.id] = true
+  end
+  if backend.features.crop then
+    if not transmitted_images[image.id] then
+      transmit()
+      transmitted_images[image.id] = true
+    end
+  else
+    if transmitted_images[image.id] ~= image.crop_hash then
+      transmit()
+      transmitted_images[image.id] = image.crop_hash
+    end
   end
 
   -- unicode placeholders
@@ -70,15 +85,43 @@ backend.render = function(image, x, y, width, height)
     return
   end
 
-  helpers.move_cursor(x + 1, y + 1, true, backend.state.options.kitty_tmux_write_delay)
-  helpers.write_graphics({
+  local display_payload = {
     action = codes.control.action.display,
     quiet = 2,
     image_id = image.internal_id,
     display_zindex = -1,
     display_cursor_policy = codes.control.display_cursor_policy.do_not_move,
     placement_id = image.internal_id,
-  })
+  }
+
+  -- crop
+  if backend.features.crop then
+    local term_size = utils.term.get_size()
+    local pixel_width = width * term_size.cell_width
+    local pixel_height = height * term_size.cell_height
+    local pixel_top = 0
+
+    -- crop top
+    if y < image.bounds.top then
+      local visible_rows = height - (image.bounds.top - y)
+      pixel_height = visible_rows * term_size.cell_height
+      pixel_top = (image.bounds.top - y) * term_size.cell_height
+      y = image.bounds.top
+    end
+
+    -- crop bottom
+    if y + height > image.bounds.bottom then pixel_height = (image.bounds.bottom - y + 1) * term_size.cell_height end
+
+    -- crop right
+    if x + width > image.bounds.right then pixel_width = (image.bounds.right - x) * term_size.cell_width end
+
+    display_payload.display_width = pixel_width
+    display_payload.display_height = pixel_height
+    display_payload.display_y = pixel_top
+  end
+
+  helpers.move_cursor(x + 1, y + 1, true, backend.state.options.kitty_tmux_write_delay)
+  helpers.write_graphics(display_payload)
   image.is_rendered = true
   backend.state.images[image.id] = image
   helpers.restore_cursor()
@@ -96,7 +139,10 @@ backend.clear = function(image_id, shallow)
       quiet = 2,
     })
     image.is_rendered = false
-    if not shallow then backend.state.images[image_id] = nil end
+    if not shallow then
+      backend.state.images[image_id] = nil
+      transmitted_images[image.id] = nil
+    end
     return
   end
 
@@ -108,7 +154,10 @@ backend.clear = function(image_id, shallow)
   })
   for id, image in pairs(backend.state.images) do
     image.is_rendered = false
-    if not shallow then backend.state.images[id] = nil end
+    if not shallow then
+      backend.state.images[id] = nil
+      transmitted_images[image.id] = nil
+    end
   end
 end
 

lua/image/backends/ueberzug.lua

@@ -58,6 +58,9 @@ end
 local backend = {
   ---@diagnostic disable-next-line: assign-type-mismatch
   state = nil,
+  features = {
+    crop = false,
+  },
 }
 
 backend.setup = function(state)

lua/image/renderer.lua

@@ -252,49 +252,51 @@ local render = function(image, state)
   end
 
   -- crop
-  local pixel_width = width * term_size.cell_width
-  local pixel_height = height * term_size.cell_height
-  local crop_offset_top = 0
-  local needs_crop = false
-
-  -- crop top
-  if absolute_y < bounds.top then
-    local visible_rows = height - (bounds.top - absolute_y)
-    pixel_height = visible_rows * term_size.cell_height
-    crop_offset_top = (bounds.top - absolute_y) * term_size.cell_height
-    absolute_y = bounds.top
-    needs_crop = true
-  end
+  if not state.backend.features.crop then
+    local pixel_width = width * term_size.cell_width
+    local pixel_height = height * term_size.cell_height
+    local crop_offset_top = 0
+    local needs_crop = false
+
+    -- crop top
+    if absolute_y < bounds.top then
+      local visible_rows = height - (bounds.top - absolute_y)
+      pixel_height = visible_rows * term_size.cell_height
+      crop_offset_top = (bounds.top - absolute_y) * term_size.cell_height
+      absolute_y = bounds.top
+      needs_crop = true
+    end
 
-  -- crop bottom
-  if absolute_y + height > bounds.bottom then
-    pixel_height = (bounds.bottom - absolute_y + 1) * term_size.cell_height
-    needs_crop = true
-  end
+    -- crop bottom
+    if absolute_y + height > bounds.bottom then
+      pixel_height = (bounds.bottom - absolute_y + 1) * term_size.cell_height
+      needs_crop = true
+    end
 
-  -- crop right
-  if absolute_x + width > bounds.right then
-    pixel_width = (bounds.right - absolute_x) * term_size.cell_width
-    needs_crop = true
-  end
+    -- crop right
+    if absolute_x + width > bounds.right then
+      pixel_width = (bounds.right - absolute_x) * term_size.cell_width
+      needs_crop = true
+    end
 
-  -- perform crop
-  local crop_hash = needs_crop and ("%d-%d-%d-%d"):format(pixel_width, pixel_height, 0, crop_offset_top) or nil
-  if crop_hash or (image.crop_hash ~= crop_hash) then
-    local cropped_image = magick.load_image(image.original_path)
-    cropped_image:set_format("png")
-    cropped_image:crop(pixel_width, pixel_height, 0, crop_offset_top)
-    local tmp_path = state.tmp_dir .. "/" .. utils.random.id() .. ".png"
-    cropped_image:write(tmp_path)
-    cropped_image:destroy()
-    image.path = tmp_path
-    image.crop_hash = crop_hash
+    -- perform crop
+    local crop_hash = needs_crop and ("%d-%d-%d-%d"):format(pixel_width, pixel_height, 0, crop_offset_top) or nil
+    if crop_hash or (image.crop_hash ~= crop_hash) then
+      local cropped_image = magick.load_image(image.original_path)
+      cropped_image:set_format("png")
+      cropped_image:crop(pixel_width, pixel_height, 0, crop_offset_top)
+      local tmp_path = state.tmp_dir .. "/" .. utils.random.id() .. ".png"
+      cropped_image:write(tmp_path)
+      cropped_image:destroy()
+      image.path = tmp_path
+      image.crop_hash = crop_hash
+    end
   end
 
   -- utils.debug(("(5) x: %d, y: %d, width: %d, height: %d y_offset: %d"):format(x, y, width, height, y_offset))
+  image.bounds = bounds
   state.backend.render(image, absolute_x, absolute_y, width, height)
   image.rendered_geometry = rendered_geometry
-  image.bounds = bounds
 
   return true
 end

lua/types.lua

@@ -33,8 +33,12 @@
 ---@field kitty_method "normal"|"unicode-placeholders"
 ---@field kitty_tmux_write_delay? number
 
+---@class BackendFeatures
+---@field crop boolean
+
 ---@class Backend
 ---@field state State
+---@field features BackendFeatures
 ---@field setup fun(state: State)
 ---@field render fun(image: Image, x: number, y: number, width?: number, height?: number)
 ---@field clear fun(id?: string, shallow?: boolean)