From acbf4b7a8c60326220ec52c3edf93ea7ead4ba2a Mon Sep 17 00:00:00 2001
From: NiLuJe <ninuje@gmail.com>
Date: Thu, 2 Sep 2021 23:50:10 +0200
Subject: [PATCH] Document: Round dimensions properly in getPageDimensions
 (#8170)
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* Geom:transformByScale:
  * Apply the right scaling factor to the y axis
  * Round in a more sensible fashion (àla fz_round_rect, since we pretty much exclusively use it in a similar fashion).
* Bump base (https://github.com/koreader/koreader-base/pull/1407)
---
 base                           |  2 +-
 frontend/document/document.lua |  4 +++-
 frontend/ui/geometry.lua       | 14 ++++++++------
 spec/unit/readerlink_spec.lua  |  4 ++--
 spec/unit/readerview_spec.lua  |  4 ++--
 5 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/base b/base
index 2a526000d..ac9a8757d 160000
--- a/base
+++ b/base
@@ -1 +1 @@
-Subproject commit 2a526000d9c0a92e4951caef9202d0f12e8b343b
+Subproject commit ac9a8757de78769150c3ac084170cb6744183435
diff --git a/frontend/document/document.lua b/frontend/document/document.lua
index 2d673eb97..44a8c0d1f 100644
--- a/frontend/document/document.lua
+++ b/frontend/document/document.lua
@@ -256,7 +256,8 @@ function Document:getPageDimensions(pageno, zoom, rotation)
         -- switch orientation
         native_dimen.w, native_dimen.h = native_dimen.h, native_dimen.w
     end
-    native_dimen:scaleBy(zoom)
+    -- Apply the zoom factor, and round to integer in a sensible manner
+    native_dimen:transformByScale(zoom)
     return native_dimen
 end
 
@@ -305,6 +306,7 @@ function Document:getUsedBBoxDimensions(pageno, zoom, rotation)
             w = bbox.x1 - bbox.x0,
             h = bbox.y1 - bbox.y0,
         }
+        --- @note: Should we round this regardless of zoom?
         if zoom ~= 1 then
             ubbox_dimen:transformByScale(zoom)
         end
diff --git a/frontend/ui/geometry.lua b/frontend/ui/geometry.lua
index 5037b9303..d6e929c26 100644
--- a/frontend/ui/geometry.lua
+++ b/frontend/ui/geometry.lua
@@ -81,7 +81,7 @@ function Geom:offsetTo(x, y)
 end
 
 --[[--
-Scales rectangle (grow to bottom and to the right) or dimension
+Scales rectangle (top-left corner is rounded down, bottom-right corner is rounded up) or dimension
 
 If a single factor is given, it is applied to both width and height
 
@@ -89,20 +89,22 @@ If a single factor is given, it is applied to both width and height
 @int zy scale for y axis
 ]]
 function Geom:scaleBy(zx, zy)
-    self.w = Math.round(self.w * zx)
-    self.h = Math.round(self.h * (zy or zx))
+    self.w = math.ceil(self.w * zx - 0.001)
+    self.h = math.ceil(self.h * (zy or zx) - 0.001)
     return self
 end
 
 --[[--
-This method also takes care of x and y on top of @{Geom:scaleBy}
+This method also takes care of x and y on top of @{Geom:scaleBy},
+c.f., fz_round_rect in MµPDF,
+      <https://github.com/ArtifexSoftware/mupdf/blob/d00de0e96a4a5ec90ffc30837d40cd624a6a89e0/source/fitz/geometry.c#L400-L416>
 
 @int zx scale for x axis
 @int zy scale for y axis
 ]]
 function Geom:transformByScale(zx, zy)
-    self.x = Math.round(self.x * zx)
-    self.y = Math.round(self.y * (zx or zy))
+    self.x = math.floor(self.x * zx + 0.001)
+    self.y = math.floor(self.y * (zy or zx) + 0.001)
     self:scaleBy(zx, zy)
 end
 
diff --git a/spec/unit/readerlink_spec.lua b/spec/unit/readerlink_spec.lua
index 98786961d..e94e0fca8 100644
--- a/spec/unit/readerlink_spec.lua
+++ b/spec/unit/readerlink_spec.lua
@@ -130,7 +130,7 @@ describe("ReaderLink module", function()
                   x = 0, y = 694,
                   h = 106, w = 566,
                 },
-                zoom = 0.9501187648456056456,
+                zoom = 0.95032191328269044472,
            },
            {
                 gamma = 1,
@@ -145,7 +145,7 @@ describe("ReaderLink module", function()
                   h = 686, w = 566,
                   x = 0, y = 0,
                 },
-                zoom = 0.9501187648456056456,
+                zoom = 0.95032191328269044472,
             },
         }
         -- disable footer
diff --git a/spec/unit/readerview_spec.lua b/spec/unit/readerview_spec.lua
index bc06153a8..52aca89c1 100644
--- a/spec/unit/readerview_spec.lua
+++ b/spec/unit/readerview_spec.lua
@@ -90,7 +90,7 @@ describe("Readerview module", function()
             },
         }
         assert.are.same(saved_ctx, ctx)
-        assert.is.near(0.95011876484561, zoom, 0.0001)
+        assert.is.near(0.95024316487116200491, zoom, 0.0001)
 
         assert.is.same(view.state.page, 1)
         assert.is.same(view.visible_area.x, 0)
@@ -144,7 +144,7 @@ describe("Readerview module", function()
         }
 
         assert.are.same(saved_ctx, ctx)
-        assert.is.near(0.95011876484561, zoom, 0.0001)
+        assert.is.near(0.95024316487116200491, zoom, 0.0001)
 
         assert.is.same(view.state.page, 1)
         assert.is.same(view.visible_area.x, 0)