add regional zoom mode in pdf/djvu page

In regional zoom mode double tap will zoom to the tapped
region(paragraph or column, etc., detected optically via libk2pdfopt).
As the first demo, this feature is only turned on in flipping mode by
tapping the top-left corner of the screen. Eventually we may incorporate
this feature in "free" zoom mode.

frontend/document/djvudocument.lua

@@ -80,6 +80,10 @@ function DjvuDocument:getOCRText(pageno, tboxes)
 	return self.koptinterface:getOCRText(self, pageno, tboxes)
 end
 
+function DjvuDocument:getPageRegions(pageno)
+	return self.koptinterface:getPageRegions(self, pageno)
+end
+
 function DjvuDocument:getUsedBBox(pageno)
 	-- djvu does not support usedbbox, so fake it.
 	local used = {}

frontend/document/koptinterface.lua

@@ -447,6 +447,35 @@ function KoptInterface:getNativeTextBoxesFromScratch(doc, pageno)
 	end
 end
 
+--[[
+get page regions in native page via optical method, 
+--]]
+function KoptInterface:getPageRegions(doc, pageno)
+	local bbox = doc:getPageBBox(pageno)
+	local context_hash = self:getContextHash(doc, pageno, bbox)
+	local hash = "pageregions|"..context_hash
+	local cached = Cache:check(hash)
+	if not cached then
+		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 regions = kc:getPageRegions()
+		Cache:insert(hash, CacheItem:new{ pageregions = regions })
+		page:close()
+		kc:free()
+		return regions
+	else
+		return cached.pageregions
+	end
+end
+
 --[[
 get word from OCR providing selected word box
 --]]

frontend/document/pdfdocument.lua

@@ -70,6 +70,10 @@ function PdfDocument:getOCRText(pageno, tboxes)
 	return self.koptinterface:getOCRText(self, pageno, tboxes)
 end
 
+function PdfDocument:getPageRegions(pageno)
+	return self.koptinterface:getPageRegions(self, pageno)
+end
+
 function PdfDocument:getUsedBBox(pageno)
 	local hash = "pgubbox|"..self.file.."|"..pageno
 	local cached = Cache:check(hash)

frontend/ui/geometry.lua

@@ -274,6 +274,35 @@ function Geom:offsetWithin(rect_b, dx, dy)
 	end
 end
 
+--[[
+center the current rectangle at position x and y of a given rectangle
+]]--
+function Geom:centerWithin(rect_b, x, y)
+	-- check size constraints and shrink us when we're too big
+	if self.w > rect_b.w then
+		self.w = rect_b.w
+	end
+	if self.h > rect_b.h then
+		self.h = rect_b.h
+	end
+	-- place to center
+	self.x = x - self.w/2
+	self.y = y - self.h/2
+	-- check boundary
+	if self.x < rect_b.x then
+		self.x = rect_b.x
+	end
+	if self.y < rect_b.y then
+		self.y = rect_b.y
+	end
+	if self.x + self.w > rect_b.x + rect_b.w then
+		self.x = rect_b.x + rect_b.w - self.w
+	end
+	if self.y + self.h > rect_b.y + rect_b.h then
+		self.y = rect_b.y + rect_b.h - self.h
+	end
+end
+
 function Geom:shrinkInside(rect_b, dx, dy)
 	self:offsetBy(dx, dy)
 	return self:intersect(rect_b)

frontend/ui/reader/readerpaging.lua

@@ -209,16 +209,26 @@ function ReaderPaging:enterFlippingMode()
 	self.orig_reflow_mode = self.view.document.configurable.text_wrap
 	self.orig_footer_mode = self.view.footer_visible
 	self.orig_scroll_mode = self.view.page_scroll
+	self.orig_zoom_mode = self.view.zoom_mode
+	DEBUG("store zoom mode", self.orig_zoom_mode)
+	self.DGESDETECT_DISABLE_DOUBLE_TAP = DGESDETECT_DISABLE_DOUBLE_TAP
 	
 	self.view.document.configurable.text_wrap = 0
 	self.view.page_scroll = false
 	self.view.footer_visible = true
+	Input.disable_double_tap = false
+	DGESDETECT_DISABLE_DOUBLE_TAP = false
+	self.ui:handleEvent(Event:new("SetZoomMode", "page"))
 end
 
 function ReaderPaging:exitFlippingMode()
 	self.view.document.configurable.text_wrap = self.orig_reflow_mode
 	self.view.page_scroll = self.orig_scroll_mode
 	self.view.footer_visible = self.orig_footer_mode
+	DGESDETECT_DISABLE_DOUBLE_TAP = self.DGESDETECT_DISABLE_DOUBLE_TAP
+	Input.disable_double_tap = DGESDETECT_DISABLE_DOUBLE_TAP
+	DEBUG("restore zoom mode", self.orig_zoom_mode)
+	self.ui:handleEvent(Event:new("SetZoomMode", self.orig_zoom_mode))
 end
 
 function ReaderPaging:updateOriginalPage(page)
@@ -268,7 +278,11 @@ end
 
 function ReaderPaging:onPan(arg, ges)
 	if self.flipping_mode then
-		self:flipping(self.flipping_page, ges)
+		if self.view.zoom_mode == "page" then
+			self:flipping(self.flipping_page, ges)
+		else
+			self.view:PanningStart(-ges.relative.x, -ges.relative.y)
+		end
 	elseif ges.direction == "north" or ges.direction == "south" then
 		self:onPanningRel(self.last_pan_relative_y - ges.relative.y)
 		self.last_pan_relative_y = ges.relative.y
@@ -278,7 +292,11 @@ end
 
 function ReaderPaging:onPanRelease(arg, ges)
 	if self.flipping_mode then
-		self:updateFlippingPage(self.current_page)
+		if self.view.zoom_mode == "page" then
+			self:updateFlippingPage(self.current_page)
+		else
+			self.view:PanningStop()
+		end
 	else
 		self.last_pan_relative_y = 0
 		UIManager.full_refresh = true
@@ -588,7 +606,9 @@ function ReaderPaging:onGotoPageRel(diff)
 	local new_va = self.visible_area:copy()
 	local x_pan_off, y_pan_off = 0, 0
 
-	if self.zoom_mode:find("width") then
+	if self.zoom_mode == "free" then
+		-- do nothing in free zoom mode
+	elseif self.zoom_mode:find("width") then
 		y_pan_off = self.visible_area.h * diff
 	elseif self.zoom_mode:find("height") then
 		x_pan_off = self.visible_area.w * diff

frontend/ui/reader/readerview.lua

@@ -439,6 +439,30 @@ function ReaderView:PanningUpdate(dx, dy)
 	return true
 end
 
+function ReaderView:PanningStart(x, y)
+	DEBUG("panning start", x, y)
+	if not self.panning_visible_area then
+		self.panning_visible_area = self.visible_area:copy()
+	end
+	self.visible_area = self.panning_visible_area:copy()
+	self.visible_area:offsetWithin(self.page_area, x, y)
+	self.ui:handleEvent(Event:new("ViewRecalculate", self.visible_area, self.page_area))
+	UIManager:setDirty(self.dialog)
+end
+
+function ReaderView:PanningStop()
+	self.panning_visible_area = nil
+end
+
+function ReaderView:SetZoomCenter(x, y)
+	local old = self.visible_area:copy()
+	self.visible_area:centerWithin(self.page_area, x, y)
+	if self.visible_area ~= old then
+		self.ui:handleEvent(Event:new("ViewRecalculate", self.visible_area, self.page_area))
+		UIManager:setDirty(self.dialog)
+	end
+end
+
 function ReaderView:onSetScreenMode(new_mode, rotation)
 	if new_mode == "landscape" or new_mode == "portrait" then
 		self.screen_mode = new_mode

frontend/ui/reader/readerzooming.lua

@@ -84,6 +84,16 @@ function ReaderZooming:init()
 					}
 				}
 			},
+			ToggleFreeZoom = {
+				GestureRange:new{
+					ges = "double_tap",
+					range = Geom:new{
+						x = 0, y = 0,
+						w = Screen:getWidth(),
+						h = Screen:getHeight(),
+					}
+				}
+			},
 		}
 	end
 	self.ui.menu:registerToMainMenu(self)
@@ -126,6 +136,24 @@ function ReaderZooming:onPinch(arg, ges)
 	return true
 end
 
+function ReaderZooming:onToggleFreeZoom(arg, ges)
+	if self.zoom_mode ~= "free" then
+		self.orig_zoom = self.zoom
+		self.orig_zoom_mode = self.zoom_mode
+		local xpos, ypos
+		self.zoom, xpos, ypos = self:getRegionalZoomCenter(self.current_page, ges.pos)
+		DEBUG("zoom center", self.zoom, xpos, ypos)
+		self.ui:handleEvent(Event:new("SetZoomMode", "free"))
+		if xpos == nil or ypos == nil then
+			xpos = ges.pos.x * self.zoom / self.orig_zoom
+			ypos = ges.pos.y * self.zoom / self.orig_zoom
+		end
+		self.view:SetZoomCenter(xpos, ypos)
+	else
+		self.ui:handleEvent(Event:new("SetZoomMode", self.orig_zoom_mode or "page"))
+	end
+end
+
 function ReaderZooming:onSetDimensions(dimensions)
 	-- we were resized
 	self.dimen = dimensions
@@ -160,9 +188,9 @@ function ReaderZooming:onSetZoomMode(new_mode)
 	self.view.zoom_mode = new_mode
 	if self.zoom_mode ~= new_mode then
 		DEBUG("setting zoom mode to", new_mode)
+		self.ui:handleEvent(Event:new("ZoomModeUpdate", new_mode))
 		self.zoom_mode = new_mode
 		self:setZoom()
-		self.ui:handleEvent(Event:new("ZoomModeUpdate", new_mode))
 	end
 end
 
@@ -212,15 +240,34 @@ function ReaderZooming:getZoom(pageno)
 		zoom = zoom_w
 	elseif self.zoom_mode == "contentheight" or self.zoom_mode == "pageheight" then
 		zoom = zoom_h
+	elseif self.zoom_mode == "free" then
+		zoom = self.zoom
 	end
 	return zoom
 end
 
-function ReaderZooming:setZoom()
-	-- nothing to do in free zoom mode
-	if self.zoom_mode == "free" then
-		return
+function ReaderZooming:getRegionalZoomCenter(pageno, pos)
+	local p_pos = self.view:getSinglePagePosition(pos)
+	local page_size = self.ui.document:getNativePageDimensions(pageno)
+	local pos_x = p_pos.x / page_size.w / p_pos.zoom
+	local pos_y = p_pos.y / page_size.h / p_pos.zoom
+	local regions = self.ui.document:getPageRegions(pageno)
+	DEBUG("get page regions", regions)
+	local margin = self.ui.document.configurable.page_margin * Screen:getDPI()
+	for i = 1, #regions do
+		if regions[i].x0 <= pos_x and pos_x <= regions[i].x1
+			and regions[i].y0 <= pos_y and pos_y <= regions[i].y1 then
+			local zoom = 1/(regions[i].x1 - regions[i].x0)
+			zoom = zoom/(1 + 3*margin/zoom/page_size.w)
+			local xpos = (regions[i].x0 + regions[i].x1)/2 * zoom * page_size.w
+			local ypos = p_pos.y / p_pos.zoom * zoom
+			return zoom, xpos, ypos
+		end
 	end
+	return 2
+end
+
+function ReaderZooming:setZoom()
 	if not self.dimen then
 		self.dimen = self.ui.dimen
 	end

koreader-base

@@ -1 +1 @@
-Subproject commit 8b9989a5f91d1e708a285c3e660009232ad14a08
+Subproject commit bf3ef2a6c9002a665b8c224632eba744e6147fe0