Decrease fonts memory use (#10618)

Instead of opening the same font multiple times for each different
size (multiple face instances), share one face instance and create
multiple size instances.

base

@@ -1 +1 @@
-Subproject commit b4cfe83c1fb268f1a8213de3f3a3b4756f1348e8
+Subproject commit 9b5cf240bf8f60e4fa8328243f06ddaacb69342b

frontend/fontlist.lua

@@ -109,15 +109,15 @@ local function collectFaceInfo(path)
         return
     end
     for i=0, n-1 do
-        local ok, face = pcall(FT.newFace, path, nil, i)
+        local ok, ftsize = pcall(FT.newFaceSize, path, nil, i)
         if not ok then
             return nil
         end
 
         -- If family_name is missing, it's probably too broken to be useful
-        if face.family_name ~= nil then
-            local fres = face:getInfo()
-            local hbface = HB.hb_ft_face_create_referenced(face)
+        if ftsize.face.family_name ~= nil then
+            local fres = ftsize:getInfo()
+            local hbface = HB.hb_ft_face_create_referenced(ftsize.face)
             fres.names = hbface:getNames()
             fres.scripts, fres.langs = hbface:getCoverage()
             fres.path = path
@@ -125,7 +125,7 @@ local function collectFaceInfo(path)
             table.insert(res, fres)
             hbface:destroy()
         end
-        face:done()
+        ftsize:done()
     end
     return res
 end

frontend/ui/font.lua

@@ -195,7 +195,7 @@ local bold_strength_factor = 3/8 -- as crengine, lighter
 local _completeFaceProperties = function(face_obj)
     if not face_obj.embolden_half_strength then
         -- Cache this value in case we use bold, to avoid recomputation
-        face_obj.embolden_half_strength = face_obj.ftface:getEmboldenHalfStrength(bold_strength_factor)
+        face_obj.embolden_half_strength = face_obj.ftsize:getEmboldenHalfStrength(bold_strength_factor)
     end
 end
 
@@ -302,9 +302,9 @@ function Font:getFace(font, size, faceindex)
             face_obj.orig_size = orig_size
         end
     else
-        -- Build face if not found
+        -- Build face size if not found
         local builtin_font_location = FontList.fontdir.."/"..realname
-        local ok, face = pcall(Freetype.newFace, builtin_font_location, size, faceindex)
+        local ok, ftsize = pcall(Freetype.newFaceSize, builtin_font_location, size, faceindex)
 
         -- Not all fonts are bundled on all platforms because they come with the system.
         -- In that case, search through all font folders for the requested font.
@@ -315,14 +315,14 @@ function Font:getFace(font, size, faceindex)
             for _k, _v in ipairs(fonts) do
                 if _v:find(escaped_realname) then
                     logger.dbg("Found font:", realname, "in", _v)
-                    ok, face = pcall(Freetype.newFace, _v, size, faceindex)
+                    ok, ftsize = pcall(Freetype.newFaceSize, _v, size, faceindex)
 
                     if ok then break end
                 end
             end
         end
         if not ok then
-            logger.err("#! Font ", font, " (", realname, ") not supported: ", face)
+            logger.err("#! Font ", font, " (", realname, ") not supported: ", ftsize)
             return nil
         end
         --- Freetype font face wrapper object
@@ -330,14 +330,14 @@ function Font:getFace(font, size, faceindex)
         -- @field orig_font font name requested
         -- @field size size of the font face (after scaled by screen size)
         -- @field orig_size raw size of the font face (before scale)
-        -- @field ftface font face object from freetype
+        -- @field ftsize font size object from freetype
         -- @field hash hash key for this font face
         face_obj = {
             orig_font = font,
             realname = realname,
             size = size,
             orig_size = orig_size,
-            ftface = face,
+            ftsize = ftsize,
             hash = hash,
             is_real_bold = is_real_bold,
         }
@@ -433,7 +433,7 @@ function Font:getAdjustedFace(face, bold)
         -- We can keep the same FT object and the same hash in this face_obj
         -- (which is only used to identify cached glyphs, that we don't need
         -- to distinguish as "bold" is appended when synthetized as bold)
-        ftface = face.ftface,
+        ftsize = face.ftsize,
         hash = face.hash,
         hb_features = face.hb_features,
         is_real_bold = nil,

frontend/ui/rendertext.lua

@@ -87,15 +87,15 @@ function RenderText:getGlyph(face, charcode, bold)
         -- cache hit
         return glyph
     end
-    local rendered_glyph = face.ftface:renderGlyph(charcode, bold)
-    if face.ftface:checkGlyph(charcode) == 0 then
+    local rendered_glyph = face.ftsize:renderGlyph(charcode, bold)
+    if not face.ftsize:hasGlyph(charcode) then
         for index, font in pairs(Font.fallbacks) do
             -- use original size before scaling by screen DPI
             local fb_face = Font:getFace(font, face.orig_size)
             if fb_face ~= nil then
             -- for some characters it cannot find in Fallbacks, it will crash here
-                if fb_face.ftface:checkGlyph(charcode) ~= 0 then
-                    rendered_glyph = fb_face.ftface:renderGlyph(charcode, orig_bold)
+                if fb_face.ftsize:hasGlyph(charcode) then
+                    rendered_glyph = fb_face.ftsize:renderGlyph(charcode, orig_bold)
                     break
                 end
             end
@@ -127,7 +127,7 @@ function RenderText:getSubTextByWidth(text, face, width, kerning, bold)
         if pen_x < width then
             local glyph = self:getGlyph(face, charcode, bold)
             if kerning and prevcharcode then
-                local kern = face.ftface:getKerning(prevcharcode, charcode)
+                local kern = face.ftsize:getKerning(prevcharcode, charcode)
                 pen_x = pen_x + kern
             end
             pen_x = pen_x + glyph.ax
@@ -170,7 +170,7 @@ function RenderText:sizeUtf8Text(x, width, face, text, kerning, bold)
         if not width or pen_x < (width - x) then
             local glyph = self:getGlyph(face, charcode, bold)
             if kerning and (prevcharcode ~= 0) then
-                pen_x = pen_x + (face.ftface):getKerning(prevcharcode, charcode)
+                pen_x = pen_x + (face.ftsize):getKerning(prevcharcode, charcode)
             end
             pen_x = pen_x + glyph.ax
             pen_y_top = math.max(pen_y_top, glyph.t)
@@ -225,7 +225,7 @@ function RenderText:renderUtf8Text(dest_bb, x, baseline, face, text, kerning, bo
         if pen_x < text_width then
             local glyph = self:getGlyph(face, charcode, bold)
             if kerning and (prevcharcode ~= 0) then
-                pen_x = pen_x + face.ftface:getKerning(prevcharcode, charcode)
+                pen_x = pen_x + face.ftsize:getKerning(prevcharcode, charcode)
             end
             dest_bb:colorblitFrom(
                 glyph.bb,
@@ -299,7 +299,7 @@ function RenderText:getGlyphByIndex(face, glyphindex, bold)
         -- cache hit
         return glyph
     end
-    local rendered_glyph = face.ftface:renderGlyphByIndex(glyphindex, bold and face.embolden_half_strength)
+    local rendered_glyph = face.ftsize:renderGlyphByIndex(glyphindex, bold and face.embolden_half_strength)
     if not rendered_glyph then
         logger.warn("error rendering glyph (glyphindex=", glyphindex, ") for face", face)
         return

frontend/ui/widget/textboxwidget.lua

@@ -125,7 +125,7 @@ function TextBoxWidget:init()
     self.line_height_px = Math.round( (1 + self.line_height) * self.face.size )
     -- Get accurate initial baseline and possible height overflow (so our bb
     -- is tall enough to draw glyphs with descender larger than line height)
-    local face_height, face_ascender = self.face.ftface:getHeightAndAscender()
+    local face_height, face_ascender = self.face.ftsize:getHeightAndAscender()
     local line_heights_diff = math.floor(self.line_height_px - face_height)
     if line_heights_diff >= 0 then
         -- Glyphs will fit in our line_height_px: adjust baseline.
@@ -1113,7 +1113,7 @@ function TextBoxWidget:getFontSizeToFitHeight(height_px, nb_lines, line_height_e
             local line_height_px = Math.round( (1 + line_height_em) * Screen:scaleBySize(font_size) )
             local face = Font:getFace(font_face, font_size)
             face = Font:getAdjustedFace(face, font_bold)
-            local face_height = face.ftface:getHeightAndAscender()
+            local face_height = face.ftsize:getHeightAndAscender()
             local line_heights_diff = math.floor(line_height_px - face_height)
             if line_heights_diff >= 0 then
                 break

frontend/ui/widget/textwidget.lua

@@ -81,7 +81,7 @@ function TextWidget:getFontSizeToFitHeight(font_name, height_px, padding)
             break
         end
         local face = Font:getFace(font_name, font_size)
-        local face_height = face.ftface:getHeightAndAscender()
+        local face_height = face.ftsize:getHeightAndAscender()
         face_height = math.ceil(face_height) + 2*padding
     until face_height <= height_px
     return font_size
@@ -109,7 +109,7 @@ function TextWidget:updateSize()
     -- But better compute baseline alignment from freetype font metrics
     -- to get better vertical centering of text in box
     -- (Freetype doc on this at https://www.freetype.org/freetype2/docs/tutorial/step2.html)
-    local face_height, face_ascender = self.face.ftface:getHeightAndAscender()
+    local face_height, face_ascender = self.face.ftsize:getHeightAndAscender()
     self._height = math.ceil(face_height) + 2*self.padding
     self._baseline_h = Math.round(face_ascender) + self.padding
     -- With our UI fonts, this usually gives 0.72 to 0.74, so text is aligned

spec/unit/font_spec.lua

@@ -7,10 +7,10 @@ describe("Font module", function()
     it("should get face", function()
         local f
         f = Font:getFace('cfont', 18)
-        assert.are_not.equals(f.ftface, nil)
+        assert.are_not.equals(f.ftsize, nil)
         f = Font:getFace('tfont', 16)
-        assert.are_not.equals(f.ftface, nil)
+        assert.are_not.equals(f.ftsize, nil)
         f = Font:getFace('hfont', 12)
-        assert.are_not.equals(f.ftface, nil)
+        assert.are_not.equals(f.ftsize, nil)
     end)
 end)