[feat] Comics: zoom to panel (#6511)

This pull requests aims to provide convenient way to zoom in comics. The idea is when user holds/double taps (not decided yet) on a manga/comic panel, it gets cut out from the rest of the image and zoomed. More details in koreader/koreader-base#1148. Depends on koreader/koreader-base#1159

frontend/apps/reader/modules/readerhighlight.lua

@@ -98,6 +98,12 @@ function ReaderHighlight:addToMainMenu(menu_items)
         text = _("Highlighting"),
         sub_item_table = self:genHighlightDrawerMenu(),
     }
+    if self.document.info.has_pages then
+        menu_items.panel_zoom_options = {
+            text = _("Panel zoom (manga/comic)"),
+            sub_item_table = self:genPanelZoomMenu(),
+        }
+    end
     menu_items.translation_settings = Translator:genSettingsMenu()
 end
 
@@ -107,6 +113,41 @@ local highlight_style = {
     invert = _("Invert"),
 }
 
+local function getPanelZoomSupportedExt()
+    local default_supported_ext = {
+        cbz = true,
+        cbt = true,
+    }
+    return G_reader_settings:readSetting("panel_zoom_ext") or default_supported_ext
+end
+
+local function isPanelZoomSupported(file)
+    local filetype = util.getFileNameSuffix(file)
+    local supported_filetypes = getPanelZoomSupportedExt()
+    return supported_filetypes[filetype]
+end
+
+function ReaderHighlight:genPanelZoomMenu()
+    return {
+        {
+            text = _("Allow panel zoom"),
+            checked_func = function()
+                return self.panel_zoom_enabled
+            end,
+            callback = function()
+                self:onTogglePanelZoomSetting()
+            end,
+            hold_callback = function()
+                local ext = util.getFileNameSuffix(self.ui.document.file)
+                local supported_ext = getPanelZoomSupportedExt()
+                supported_ext[ext] = not supported_ext[ext]
+                G_reader_settings:saveSetting("panel_zoom_ext", supported_ext)
+            end,
+            separator = true,
+        },
+    }
+end
+
 function ReaderHighlight:genHighlightDrawerMenu()
     local get_highlight_style = function(style)
         return {
@@ -576,7 +617,36 @@ function ReaderHighlight:_resetHoldTimer(clear)
     end
 end
 
+function ReaderHighlight:onTogglePanelZoomSetting(arg, ges)
+    if not self.document.info.has_pages then return end
+    self.panel_zoom_enabled = not self.panel_zoom_enabled
+end
+
+function ReaderHighlight:onPanelZoom(arg, ges)
+    self:clear()
+    local hold_pos = self.view:screenToPageTransform(ges.pos)
+    if not hold_pos then return false end -- outside page boundary
+    local rect = self.ui.document:getPanelFromPage(hold_pos.page, hold_pos)
+    if not rect then return false end -- panel not found, return
+    local image = self.ui.document:getPagePart(hold_pos.page, rect, 0)
+
+    if image then
+        local ImageViewer = require("ui/widget/imageviewer")
+        local imgviewer = ImageViewer:new{
+            image = image,
+            with_title_bar = false,
+            fullscreen = true,
+        }
+        UIManager:show(imgviewer)
+    end
+    return true
+end
+
 function ReaderHighlight:onHold(arg, ges)
+    if self.document.info.has_pages and self.panel_zoom_enabled then
+        return self:onPanelZoom(arg, ges)
+    end
+
     -- disable hold gesture if highlighting is disabled
     if self.view.highlight.disabled then return false end
     self:clear() -- clear previous highlight (delayed clear may not have done it yet)
@@ -1298,6 +1368,14 @@ function ReaderHighlight:onReadSettings(config)
         disable_highlight = G_reader_settings:readSetting("highlight_disabled") or false
     end
     self.view.highlight.disabled = disable_highlight
+
+    -- panel zoom settings isn't supported in EPUB
+    if self.document.info.has_pages then
+        self.panel_zoom_enabled = config:readSetting("panel_zoom_enabled")
+        if self.panel_zoom_enabled == nil then
+            self.panel_zoom_enabled = isPanelZoomSupported(self.ui.document.file)
+        end
+    end
 end
 
 function ReaderHighlight:onUpdateHoldPanRate()
@@ -1307,6 +1385,7 @@ end
 function ReaderHighlight:onSaveSettings()
     self.ui.doc_settings:saveSetting("highlight_drawer", self.view.highlight.saved_drawer)
     self.ui.doc_settings:saveSetting("highlight_disabled", self.view.highlight.disabled)
+    self.ui.doc_settings:saveSetting("panel_zoom_enabled", self.panel_zoom_enabled)
 end
 
 function ReaderHighlight:onClose()

frontend/dispatcher.lua

@@ -112,10 +112,11 @@ local settingsList = {
     toggle_bookmark = { category="none", event="ToggleBookmark", title=_("Toggle bookmark"), rolling=true, paging=true,},
     toggle_inverse_reading_order = { category="none", event="ToggleReadingOrder", title=_("Toggle page turn direction"), rolling=true, paging=true,},
     cycle_highlight_action = { category="none", event="CycleHighlightAction", title=_("Cycle highlight action"), rolling=true, paging=true,},
-    cycle_highlight_style = { category="none", event="CycleHighlightStyle", title=_("Cycle highlight style"), rolling=true, paging=true, separator=true,},
+    cycle_highlight_style = { category="none", event="CycleHighlightStyle", title=_("Cycle highlight style"), rolling=true, paging=true,},
     kosync_push_progress = { category="none", event="KOSyncPushProgress", title=_("Push progress from this device"), rolling=true, paging=true,},
     kosync_pull_progress = { category="none", event="KOSyncPullProgress", title=_("Pull progress from other devices"), rolling=true, paging=true, separator=true,},
     page_jmp = { category="absolutenumber", event="GotoViewRel", min=-100, max=100, title=_("Go %1 pages"), rolling=true, paging=true,},
+    panel_zoom_toggle = { category="none", event="TogglePanelZoomSetting", title=_("Toggle panel zoom"), paging=true, separator=true,},
 
     -- rolling reader settings
     increase_font = { category="incrementalnumber", event="IncreaseFontSize", min=1, max=255, title=_("Increase font size by %1"), rolling=true,},
@@ -260,6 +261,7 @@ local dispatcher_menu_order = {
     "zoom",
     "cycle_highlight_action",
     "cycle_highlight_style",
+    "panel_zoom_toggle",
 
     "kosync_push_progress",
     "kosync_pull_progress",

frontend/document/djvudocument.lua

@@ -72,6 +72,10 @@ function DjvuDocument:getPageTextBoxes(pageno)
     return self._document:getPageText(pageno)
 end
 
+function DjvuDocument:getPanelFromPage(pageno, pos)
+    return self.koptinterface:getPanelFromPage(self, pageno, pos)
+end
+
 function DjvuDocument:getWordFromPosition(spos)
     return self.koptinterface:getWordFromPosition(self, spos)
 end

frontend/document/document.lua

@@ -413,6 +413,13 @@ function Document:getDrawnImagesStatistics()
     return self._drawn_images_count, self._drawn_images_surface_ratio
 end
 
+function Document:getPagePart(pageno, rect, rotation)
+    local tile = self:renderPage(pageno, rect, 1, rotation, 1, 0)
+    local target = Blitbuffer.new(rect.w, rect.h, self.render_color and self.color_bb_type or nil)
+    target:blitFrom(tile.bb, 0, 0, rect.x, rect.y, rect.w, rect.h)
+    return target
+end
+
 function Document:getPageText(pageno)
     -- is this worth caching? not done yet.
     local page = self._document:openPage(pageno)

frontend/document/koptinterface.lua

@@ -539,6 +539,23 @@ function KoptInterface:getReflowedTextBoxesFromScratch(doc, pageno)
     end
 end
 
+function KoptInterface:getPanelFromPage(doc, pageno, ges)
+    local page_size = Document.getNativePageDimensions(doc, pageno)
+    local bbox = {
+        x0 = 0, y0 = 0,
+        x1 = page_size.w,
+        y1 = page_size.h,
+    }
+    local kc = self:createContext(doc, pageno, bbox)
+    kc:setZoom(1.0)
+    local page = doc._document:openPage(pageno)
+    page:getPagePix(kc)
+    local panel = kc:getPanelFromPage(ges)
+    page:close()
+    kc:free()
+    return panel
+end
+
 --[[--
 Get text boxes in native page via optical method.
 

frontend/document/pdfdocument.lua

@@ -105,6 +105,10 @@ function PdfDocument:getPageTextBoxes(pageno)
     return text
 end
 
+function PdfDocument:getPanelFromPage(pageno, pos)
+    return self.koptinterface:getPanelFromPage(self, pageno, pos)
+end
+
 function PdfDocument:getWordFromPosition(spos)
     return self.koptinterface:getWordFromPosition(self, spos)
 end

frontend/ui/elements/reader_menu_order.lua

@@ -37,6 +37,7 @@ local order = {
         "speed_reading_module_perception_expander",
         "----------------------------",
         "highlight_options",
+        "panel_zoom_options"
     },
     setting = {
         -- common settings