[feat] Option to change page gap in continuous mode (#5705)

Fixes #5656.

frontend/apps/reader/modules/readerview.lua

@@ -48,13 +48,8 @@ local ReaderView = OverlapGroup:extend{
     page_scroll = nil,
     page_bgcolor = Blitbuffer.gray(DBACKGROUND_COLOR/15),
     page_states = {},
-    scroll_mode = "vertical",
     -- properties of the gap drawn between each page in scroll mode:
     page_gap = {
-        -- width in pixels (when scrolling horizontally)
-        width = Screen:scaleBySize(G_reader_settings:readSetting("page_gap_width") or 8),
-        -- height in pixels (when scrolling vertically)
-        height = Screen:scaleBySize(G_reader_settings:readSetting("page_gap_height") or 8),
         -- color (0 = white, 8 = gray, 15 = black)
         color = Blitbuffer.gray((G_reader_settings:readSetting("page_gap_color") or 8)/15),
     },
@@ -387,11 +382,7 @@ function ReaderView:getScrollPageRect(page, rect_p)
 end
 
 function ReaderView:drawPageGap(bb, x, y)
-    if self.scroll_mode == "vertical" then
-        bb:paintRect(x, y, self.dimen.w, self.page_gap.height, self.page_gap.color)
-    elseif self.scroll_mode == "horizontal" then
-        bb:paintRect(x, y, self.page_gap.width, self.dimen.h, self.page_gap.color)
-    end
+    bb:paintRect(x, y, self.dimen.w, self.page_gap.height, self.page_gap.color)
 end
 
 function ReaderView:drawSinglePage(bb, x, y)
@@ -780,6 +771,8 @@ function ReaderView:onReadSettings(config)
     self.page_scroll = page_scroll == 1 and true or false
     self.highlight.saved = config:readSetting("highlight") or {}
     self.page_overlap_style = config:readSetting("page_overlap_style") or G_reader_settings:readSetting("page_overlap_style") or "dim"
+    self.page_gap.height = Screen:scaleBySize(config:readSetting("kopt_page_gap_height") or
+        G_reader_settings:readSetting("kopt_page_gap_height") or 8)
 end
 
 function ReaderView:onPageUpdate(new_page_no)
@@ -843,6 +836,14 @@ function ReaderView:onSetViewMode(new_mode)
     return true
 end
 
+--Refresh after changing a variable done by koptoptions.lua since all of them
+--requires full screen refresh. If this handler used for changing page gap from
+--another source (eg. coptions.lua) triggering a redraw is needed.
+function ReaderView:onPageGapUpdate(page_gap)
+    self.page_gap.height = page_gap
+    return true
+end
+
 function ReaderView:onSaveSettings()
     self.ui.doc_settings:saveSetting("render_mode", self.render_mode)
     self.ui.doc_settings:saveSetting("screen_mode", self.screen_mode)

frontend/ui/data/koptoptions.lua

@@ -83,6 +83,19 @@ local KoptOptions = {
                 advanced = true,
                 name_text_hold_callback = optionsutil.showValues,
             },
+            {
+                name = "page_gap_height",
+                name_text = S.PAGE_GAP,
+                toggle = {S.NONE, S.SMALL, S.MEDIUM, S.LARGE},
+                values = {0, 8, 16, 32},
+                default_value = 8,
+                args = {0, 8, 16, 32},
+                event = "PageGapUpdate",
+                enabled_func = function (configurable)
+                    return optionsutil.enableIfEquals(configurable, "page_scroll", 1)
+                end,
+                name_text_hold_callback = optionsutil.showValues,
+            },
             {
                 name = "max_columns",
                 name_text = S.COLUMNS,

frontend/ui/data/strings.lua

@@ -46,6 +46,7 @@ S.HW_DITHERING = _("Dithering")
 S.INVERSE_READING_ORDER = _("Inverse Order")
 S.IMAGE_SCALING = _("Image Scaling")
 S.NIGHTMODE_IMAGES = _("Invert Images")
+S.PAGE_GAP = _("Page Gap")
 
 S.ON = _("on")
 S.OFF = _("off")