Fix partial HW dithered refreshes sometimes appearing to shift refreshed content (#6267)

* Fix HW dithered partial refreshes sometimes behaving as if the refreshed
content had moved a few pixels to the side...

Probably a kernel issue with the alignment fixup in the EPDC?

* Get rid of the legacy coordinates fixup

It shouldn't be necessary anymore.
And I'd rather fix the root cause, anyway.

* Bump base

(https://github.com/koreader/koreader-base/pull/1116)

* Missed a few DIVs in #6224

base

@@ -1 +1 @@
-Subproject commit 3c3b7ca24bb7ac56a0b03d61a1e791edd377b088
+Subproject commit 21ac242ab2d536c9923dcb263830fd204b100960

frontend/apps/reader/modules/readercropping.lua

@@ -112,7 +112,7 @@ function ReaderCropping:onPageCrop(mode)
         self.ui:handleEvent(Event:new("SetZoomMode", "page", "cropping"))
     end
     self.ui:handleEvent(Event:new("SetDimensions",
-        Geom:new{w = Screen:getWidth(), h = Screen:getHeight()*11/12})
+        Geom:new{w = Screen:getWidth(), h = math.floor(Screen:getHeight()*11/12)})
     )
     self.bbox_widget = BBoxWidget:new{
         crop = self,

frontend/apps/reader/modules/readerfont.lua

@@ -154,7 +154,7 @@ function ReaderFont:onShowFontMenu()
         title = self.font_menu_title,
         item_table = self.face_table,
         width = Screen:getWidth() - 100,
-        height = Screen:getHeight() / 2,
+        height = math.floor(Screen:getHeight() * 0.5),
         single_line = true,
         perpage_custom = 8,
     }

frontend/apps/reader/modules/readerhighlight.lua

@@ -707,7 +707,7 @@ function ReaderHighlight:onHoldPan(_, ges)
                 -- Also, we are not able to move hold_pos.x out of screen,
                 -- so if we started on the right page, ignore top left corner,
                 -- and if we started on the left page, ignore bottom right corner.
-                local screen_half_width = math.floor(Screen:getWidth() * 1/2)
+                local screen_half_width = math.floor(Screen:getWidth() * 0.5)
                 if self.hold_pos.x >= screen_half_width and is_in_prev_page_corner then
                     return true
                 elseif self.hold_pos.x <= screen_half_width and is_in_next_page_corner then

frontend/apps/reader/modules/readerrolling.lua

@@ -634,7 +634,7 @@ function ReaderRolling:onGotoXPointer(xp, marker_xp)
                 if BD.mirroredUILayout() then
                     -- In the middle margin, on the right of text
                     -- Same trick as below, assuming page2_x is equal to page 1 right x
-                    screen_x = Screen:getWidth() / 2
+                    screen_x = math.floor(Screen:getWidth() * 0.5)
                     local page2_x = self.ui.document:getPageOffsetX(self.ui.document:getCurrentPage()+1)
                     marker_w = page2_x + marker_w - screen_x
                     screen_x = screen_x - marker_w
@@ -648,7 +648,7 @@ function ReaderRolling:onGotoXPointer(xp, marker_xp)
                     -- In the middle margin, on the left of text
                     -- This is a bit tricky with how the middle margin is sized
                     -- by crengine (see LVDocView::updateLayout() in lvdocview.cpp)
-                    screen_x = Screen:getWidth() / 2
+                    screen_x = math.floor(Screen:getWidth() * 0.5)
                     local page2_x = self.ui.document:getPageOffsetX(self.ui.document:getCurrentPage()+1)
                     marker_w = page2_x + marker_w - screen_x
                 end
@@ -1086,7 +1086,7 @@ function ReaderRolling:showEngineProgress(percent)
         -- so it does not override the footer or a bookmark dogear
         local x = 0
         local y = Size.margin.small
-        local w = Screen:getWidth() / 3
+        local w = math.floor(Screen:getWidth() / 3)
         local h = Size.line.progress
         if self.engine_progress_widget then
             self.engine_progress_widget:setPercentage(percent)

frontend/apps/reader/modules/readerstyletweak.lua

@@ -32,7 +32,7 @@ local TweakInfoWidget = InputContainer:new{
     is_global_default = nil,
     toggle_global_default_callback = function() end,
     modal = true,
-    width = Screen:getWidth()*3/4,
+    width = math.floor(Screen:getWidth() * 0.75),
 }
 
 function TweakInfoWidget:init()

frontend/apps/reader/modules/readertypography.lua

@@ -231,7 +231,7 @@ When the book's language tag is not among our presets, no specific features will
                 title = _("Language tags (and hyphenation dictionaries) used since start up"),
                 text = status_text,
                 text_face = Font:getFace("smallinfont"),
-                height = Screen:getHeight() * 4/5,
+                height = math.floor(Screen:getHeight() * 0.8),
             })
         end,
         keep_menu_open = true,

frontend/ui/translator.lua

@@ -499,7 +499,7 @@ function Translator:_showTranslation(text, target_lang, source_lang)
             -- Showing the translation target language in this title may make
             -- it quite long and wrapped, taking valuable vertical spacing
         text = table.concat(output, "\n"),
-        height = Screen:getHeight() * 4/5,
+        height = math.floor(Screen:getHeight() * 0.8),
         justified = G_reader_settings:nilOrTrue("dict_justify"),
     })
 end

frontend/ui/uimanager.lua

@@ -962,6 +962,21 @@ function UIManager:_refresh(mode, region, dither)
     table.insert(self._refresh_stack, {mode = mode, region = region, dither = dither})
 end
 
+
+-- A couple helper functions to compute aligned values...
+-- c.f., <linux/kernel.h> & ffi/framebuffer_linux.lua
+local function ALIGN_DOWN(x, a)
+    -- x & ~(a-1)
+    local mask = a - 1
+    return bit.band(x, bit.bnot(mask))
+end
+
+local function ALIGN_UP(x, a)
+    -- (x + (a-1)) & ~(a-1)
+    local mask = a - 1
+    return bit.band(x + mask, bit.bnot(mask))
+end
+
 --- Repaints dirty widgets.
 function UIManager:_repaint()
     -- flag in which we will record if we did any repaints at all
@@ -1031,12 +1046,34 @@ function UIManager:_repaint()
             refresh.dither = nil
         end
         dbg:v("triggering refresh", refresh)
-        -- NOTE: We overshoot by 1px to account for potential off-by-ones.
-        --       This may not strictly be needed anymore, and is blatantly unneeded for full-screen updates,
-        --       but checkBounds & getPhysicalRect will sanitize that in mxc_update @ ffi/framebuffer_mxcfb ;).
+        -- NOTE: If we're requesting hardware dithering on a partial update, make sure the rectangle is using
+        --       coordinates aligned to the previous multiple of 8, and dimensions aligned to the next multiple of 8.
+        --       Otherwise, some unlucky coordinates will play badly with the PxP's own alignment constraints,
+        --       leading to a refresh where content appears to have moved a few pixels to the side...
+        --       (Sidebar: this is probably a kernel issue, the EPDC driver is responsible for the alignment fixup,
+        --       c.f., epdc_process_update @ drivers/video/fbdev/mxc/mxc_epdc_v2_fb.c on a Kobo Mk. 7 kernel...).
+        if refresh.dither then
+            -- NOTE: Make sure the coordinates are positive, first! Otherwise, we'd gladly align further down below 0,
+            --       which would skew the rectangle's position/dimension after checkBounds...
+            local x_fixup = 0
+            if refresh.region.x > 0 then
+                local x_orig = refresh.region.x
+                refresh.region.x = ALIGN_DOWN(x_orig, 8)
+                x_fixup = x_orig - refresh.region.x
+            end
+            local y_fixup = 0
+            if refresh.region.y > 0 then
+                local y_orig = refresh.region.y
+                refresh.region.y = ALIGN_DOWN(y_orig, 8)
+                y_fixup = y_orig - refresh.region.y
+            end
+            -- And also make sure we won't be inadvertently cropping our rectangle in case of severe alignment fixups...
+            refresh.region.w = ALIGN_UP(refresh.region.w + (x_fixup * 2), 8)
+            refresh.region.h = ALIGN_UP(refresh.region.h + (y_fixup * 2), 8)
+        end
         Screen[refresh_methods[refresh.mode]](Screen,
-            refresh.region.x - 1, refresh.region.y - 1,
-            refresh.region.w + 2, refresh.region.h + 2,
+            refresh.region.x, refresh.region.y,
+            refresh.region.w, refresh.region.h,
             refresh.dither)
     end
     self._refresh_stack = {}

frontend/ui/widget/configdialog.lua

@@ -220,7 +220,7 @@ function ConfigOption:init()
     -- They will carry the left default_option_hpadding, but the in-between
     -- one (and the right one) will be carried by the option items.
     -- (Both these variables are between 0 and 1 and represent a % of screen width)
-    local default_name_align_right = (max_option_name_width + default_option_hpadding + 2*padding_small) / Screen:getWidth()
+    local default_name_align_right = math.floor((max_option_name_width + default_option_hpadding + 2*padding_small) / Screen:getWidth())
     default_name_align_right = math.max(default_name_align_right, 0.25)
     default_name_align_right = math.min(default_name_align_right, 0.5)
     local default_item_align_center = 1 - default_name_align_right

frontend/ui/widget/confirmbox.lua

@@ -76,7 +76,7 @@ function ConfirmBox:init()
     local text_widget = TextBoxWidget:new{
         text = self.text,
         face = self.face,
-        width = Screen:getWidth()*2/3,
+        width = math.floor(Screen:getWidth() * 2/3),
     }
     local content = HorizontalGroup:new{
         align = "center",

frontend/ui/widget/infomessage.lua

@@ -107,7 +107,7 @@ function InfoMessage:init()
 
     local text_width
     if self.width == nil then
-        text_width = Screen:getWidth() * 2 / 3
+        text_width = math.floor(Screen:getWidth() * 2/3)
     else
         text_width = self.width - image_widget:getSize().w
         if text_width < 0 then

frontend/ui/widget/multiconfirmbox.lua

@@ -87,7 +87,7 @@ function MultiConfirmBox:init()
         TextBoxWidget:new{
             text = self.text,
             face = self.face,
-            width = Screen:getWidth()*2/3,
+            width = math.floor(Screen:getWidth() * 2/3),
         }
     }
 

frontend/ui/widget/notification.lua

@@ -53,7 +53,7 @@ function Notification:init()
     self[1] = CenterContainer:new{
         dimen = Geom:new{
             w = Screen:getWidth(),
-            h = Screen:getHeight()/10,
+            h = math.floor(Screen:getHeight() / 10),
         },
         FrameContainer:new{
             background = Blitbuffer.COLOR_WHITE,

frontend/ui/widget/textboxwidget.lua

@@ -6,7 +6,7 @@ Example:
     local Foo = TextBoxWidget:new{
         face = Font:getFace("cfont", 25),
         text = 'We can show multiple lines.\nFoo.\nBar.',
-        -- width = Screen:getWidth()*2/3,
+        -- width = math.floor(Screen:getWidth() * 2/3),
     }
     UIManager:show(Foo)