From 31753adebe0f19b90f332e81e1a9b063b40f982d Mon Sep 17 00:00:00 2001
From: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>
Date: Tue, 30 Jul 2019 08:59:15 +0200
Subject: Revert "Fontconfig font database: Short-circuit matching by filename"

This reverts commit eea99e1e8f3eb67fda35dd3a656fe9b5a9be84f2.

The call to FcFreeTypeQuery() takes over 300 ms for
NotoSansCJK-Regular.ttc and friends, so in the current state,
this change cannot be used. I am not sure why these file
in particular takes so long, but it might be because it is
large (around 19MB) or because it is a font collection.

The original fix was intended to be a smaller performance
optimization, but it has added over 2 seconds startup time to
simple applications showing Chinese text, so we revert it
for now and it can be resubmitted later when the problems
have been ironed out.

Task-number: QTBUG-77108
Change-Id: Ibb2ef799573d7effd1595d788939fe33d82cc923
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
---
 .../fontconfig/qfontconfigdatabase.cpp             | 72 +++++++---------------
 1 file changed, 22 insertions(+), 50 deletions(-)

(limited to 'src/platformsupport/fontdatabases/fontconfig/qfontconfigdatabase.cpp')

diff --git a/src/platformsupport/fontdatabases/fontconfig/qfontconfigdatabase.cpp b/src/platformsupport/fontdatabases/fontconfig/qfontconfigdatabase.cpp
index e28b40c240..7abf295782 100644
--- a/src/platformsupport/fontdatabases/fontconfig/qfontconfigdatabase.cpp
+++ b/src/platformsupport/fontdatabases/fontconfig/qfontconfigdatabase.cpp
@@ -927,66 +927,38 @@ void QFontconfigDatabase::setupFontEngine(QFontEngineFT *engine, const QFontDef
             antialias = antialiasingEnabled - 1;
     }
 
-    // try to find a match for fid
-    const QFontEngine::FaceId fid = engine->faceId();
+    QFontEngine::GlyphFormat format;
+    // try and get the pattern
     FcPattern *pattern = FcPatternCreate();
-    FcPattern *match = nullptr;
-
-    // try a trivial match by filename - FC_FILE is highest priority, so if it matches, FcFontMatch
-    // will just find the file (fine) and spend a millisecond or so doing unnecessary work (bad).
-    if (!fid.filename.isEmpty() && QFile::exists(QString::fromUtf8(fid.filename))) {
-        FcBlanks *blanks = FcConfigGetBlanks(nullptr);
-        int count = 0;
-        FcPattern *fileMatch = FcFreeTypeQuery((const FcChar8 *)fid.filename.data(), fid.index,
-                                               blanks, &count);
-        if (fileMatch) {
-            // Apply Fontconfig configuration - FcFreeTypeQuery only returns information stored in
-            // the font file, we also want to respect system and user settings.
-            FcConfigSubstitute(0, pattern, FcMatchPattern);
-            FcDefaultSubstitute(pattern);
-            match = FcFontRenderPrepare(0, pattern, fileMatch);
-            FcPatternDestroy(fileMatch);
-        }
-    }
 
-    if (!match) {
-        FcValue value;
+    FcValue value;
+    value.type = FcTypeString;
+    QByteArray cs = fontDef.family.toUtf8();
+    value.u.s = (const FcChar8 *)cs.data();
+    FcPatternAdd(pattern,FC_FAMILY,value,true);
 
-        // Fontconfig rules might process this information for arbitrary purposes, so add it,
-        // even though we already know that it doesn't match an existing file.
-        if (!fid.filename.isEmpty()) {
-            value.type = FcTypeString;
-            value.u.s = (const FcChar8 *)fid.filename.data();
-            FcPatternAdd(pattern, FC_FILE, value, true);
+    QFontEngine::FaceId fid = engine->faceId();
 
-            value.type = FcTypeInteger;
-            value.u.i = fid.index;
-            FcPatternAdd(pattern, FC_INDEX, value, true);
-        }
+    if (!fid.filename.isEmpty()) {
+        value.u.s = (const FcChar8 *)fid.filename.data();
+        FcPatternAdd(pattern,FC_FILE,value,true);
 
-        const QByteArray cs = fontDef.family.toUtf8();
-        value.type = FcTypeString;
-        value.u.s = (const FcChar8 *)cs.data();
-        FcPatternAdd(pattern, FC_FAMILY, value, true);
-
-        if (fontDef.pixelSize > 0.1) {
-            value.type = FcTypeDouble;
-            value.u.d = fontDef.pixelSize;
-            FcPatternAdd(pattern, FC_PIXEL_SIZE, value, true);
-        }
+        value.type = FcTypeInteger;
+        value.u.i = fid.index;
+        FcPatternAdd(pattern,FC_INDEX,value,true);
+    }
 
-        FcResult result;
+    if (fontDef.pixelSize > 0.1)
+        FcPatternAddDouble(pattern, FC_PIXEL_SIZE, fontDef.pixelSize);
 
-        FcConfigSubstitute(0, pattern, FcMatchPattern);
-        FcDefaultSubstitute(pattern);
+    FcResult result;
 
-        match = FcFontMatch(0, pattern, &result);
-    }
+    FcConfigSubstitute(0, pattern, FcMatchPattern);
+    FcDefaultSubstitute(pattern);
 
-    QFontEngine::GlyphFormat format;
+    FcPattern *match = FcFontMatch(0, pattern, &result);
     if (match) {
-        engine->setDefaultHintStyle(defaultHintStyleFromMatch(
-            (QFont::HintingPreference)fontDef.hintingPreference, match, useXftConf));
+        engine->setDefaultHintStyle(defaultHintStyleFromMatch((QFont::HintingPreference)fontDef.hintingPreference, match, useXftConf));
 
         FcBool fc_autohint;
         if (FcPatternGetBool(match, FC_AUTOHINT,0, &fc_autohint) == FcResultMatch)
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