From 23ecaf897fad6e786d8e833695baecae148c739c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tor=20Arne=20Vestb=C3=B8?= <tor.arne.vestbo@qt.io>
Date: Tue, 9 Aug 2022 13:11:28 +0200
Subject: [PATCH] Don't assume that QtFontFamily::ensurePopulated() will
 populate

The WASM platform populates a family asynchronously, so we can't
assume that a family will be populated straight after calling
ensurePopulated().

By adding a bool return to the function we can teach all the call
sites to behave as if the font family does not exist yet if the
font was not populated.

The WASM platform will then invalidate the font database when the
populated font's data comes in asynchronously, and then be ready
for another call to ensurePopulated, which this time will succeed
to populate the family.

Change-Id: I4e0e6211c10e5c1123beebd77aca28ac82ba7186
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>
Reviewed-by: Aleksandr Reviakin <aleksandr.reviakin@qt.io>
---
 src/gui/text/qfontdatabase.cpp | 29 +++++++++++++++++------------
 src/gui/text/qfontdatabase_p.h |  2 +-
 2 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/src/gui/text/qfontdatabase.cpp b/src/gui/text/qfontdatabase.cpp
index 5ffda4eb880..f2d2a2401dc 100644
--- a/src/gui/text/qfontdatabase.cpp
+++ b/src/gui/text/qfontdatabase.cpp
@@ -254,13 +254,13 @@ bool QtFontFamily::matchesFamilyName(const QString &familyName) const
     return equalsCaseInsensitive(name, familyName) || aliases.contains(familyName, Qt::CaseInsensitive);
 }
 
-void QtFontFamily::ensurePopulated()
+bool QtFontFamily::ensurePopulated()
 {
     if (populated)
-        return;
+        return true;
 
     QGuiApplicationPrivate::platformIntegration()->fontDatabase()->populateFamily(name);
-    Q_ASSERT_X(populated, Q_FUNC_INFO, qPrintable(name));
+    return populated;
 }
 
 void QFontDatabasePrivate::clearFamilies()
@@ -329,8 +329,10 @@ QtFontFamily *QFontDatabasePrivate::family(const QString &f, FamilyRequestFlags
         fam = families[pos];
     }
 
-    if (fam && (flags & EnsurePopulated))
-        fam->ensurePopulated();
+    if (fam && (flags & EnsurePopulated)) {
+        if (!fam->ensurePopulated())
+            return nullptr;
+    }
 
     return fam;
 }
@@ -1047,7 +1049,8 @@ int QFontDatabasePrivate::match(int script, const QFontDef &request, const QStri
 
         if (!matchFamilyName(family_name, test.family))
             continue;
-        test.family->ensurePopulated();
+        if (!test.family->ensurePopulated())
+            continue;
 
         // Check if family is supported in the script we want
         if (writingSystem != QFontDatabase::Any && !familySupportsWritingSystem(test.family, writingSystem))
@@ -1351,7 +1354,8 @@ QList<QFontDatabase::WritingSystem> QFontDatabase::writingSystems()
 
     for (int i = 0; i < d->count; ++i) {
         QtFontFamily *family = d->families[i];
-        family->ensurePopulated();
+        if (!family->ensurePopulated())
+            continue;
 
         if (family->count == 0)
             continue;
@@ -1423,7 +1427,8 @@ QStringList QFontDatabase::families(WritingSystem writingSystem)
         if (f->populated && f->count == 0)
             continue;
         if (writingSystem != Any) {
-            f->ensurePopulated();
+            if (!f->ensurePopulated())
+                continue;
             if (f->writingSystems[writingSystem] != QtFontFamily::Supported)
                 continue;
         }
@@ -1571,8 +1576,8 @@ bool QFontDatabase::isSmoothlyScalable(const QString &family, const QString &sty
         for (int i = 0; i < d->count; i++) {
             if (d->families[i]->matchesFamilyName(familyName)) {
                 f = d->families[i];
-                f->ensurePopulated();
-                break;
+                if (f->ensurePopulated())
+                    break;
             }
         }
     }
@@ -2592,8 +2597,8 @@ Q_GUI_EXPORT QStringList qt_sort_families_by_writing_system(QChar::Script script
         for (int x = 0; x < db->count; ++x) {
             if (Q_UNLIKELY(matchFamilyName(family, db->families[x]))) {
                 testFamily = db->families[x];
-                testFamily->ensurePopulated();
-                break;
+                if (testFamily->ensurePopulated())
+                    break;
             }
         }
 
diff --git a/src/gui/text/qfontdatabase_p.h b/src/gui/text/qfontdatabase_p.h
index 5428e18071f..a0796d25c0a 100644
--- a/src/gui/text/qfontdatabase_p.h
+++ b/src/gui/text/qfontdatabase_p.h
@@ -174,7 +174,7 @@ struct Q_GUI_EXPORT QtFontFamily
     bool matchesFamilyName(const QString &familyName) const;
     QtFontFoundry *foundry(const QString &f, bool = false);
 
-    void ensurePopulated();
+    bool ensurePopulated();
 };
 
 class Q_GUI_EXPORT QFontDatabasePrivate