From b6a49b6623ae623f33ec2a16256c06ef62f09640 Mon Sep 17 00:00:00 2001
From: wolfbeast <mcwerewolf@gmail.com>
Date: Tue, 27 Mar 2018 21:20:57 +0200
Subject: Allow bitmap fonts to force scaling and bypass tolerance check in
 gfxFcPlatformFontList.

---
 gfx/thebes/gfxFcPlatformFontList.cpp | 23 ++++++++++++++++++++---
 gfx/thebes/gfxFcPlatformFontList.h   |  4 +++-
 2 files changed, 23 insertions(+), 4 deletions(-)

(limited to 'gfx')

diff --git a/gfx/thebes/gfxFcPlatformFontList.cpp b/gfx/thebes/gfxFcPlatformFontList.cpp
index 3d183798f..75e8fb76a 100644
--- a/gfx/thebes/gfxFcPlatformFontList.cpp
+++ b/gfx/thebes/gfxFcPlatformFontList.cpp
@@ -811,6 +811,15 @@ ChooseFontSize(gfxFontconfigFontEntry* aEntry,
             bestSize = size;
         }
     }
+    // If the font has bitmaps but wants to be scaled, then let it scale.
+    if (bestSize >= 0.0) {
+        FcBool scalable;
+        if (FcPatternGetBool(aEntry->GetPattern(),
+                             FC_SCALABLE, 0, &scalable) == FcResultMatch &&
+            scalable) {
+            return requestedSize;
+        }
+    }
     return bestSize;
 }
 
@@ -950,6 +959,12 @@ gfxFontconfigFontFamily::AddFontPattern(FcPattern* aFontPattern)
     if (FcPatternGetBool(aFontPattern, FC_OUTLINE, 0, &outline) != FcResultMatch ||
         !outline) {
         mHasNonScalableFaces = true;
+
+        FcBool scalable;
+        if (FcPatternGetBool(aFontPattern, FC_SCALABLE, 0, &scalable) == FcResultMatch &&
+            scalable) {
+            mForceScalable = true;
+        }
     }
 
     nsCountedRef<FcPattern> pattern(aFontPattern);
@@ -961,7 +976,9 @@ static const double kRejectDistance = 10000.0;
 // Calculate a distance score representing the size disparity between the
 // requested style's size and the font entry's size.
 static double
-SizeDistance(gfxFontconfigFontEntry* aEntry, const gfxFontStyle& aStyle)
+SizeDistance(gfxFontconfigFontEntry* aEntry,
+             const gfxFontStyle& aStyle,
+             bool aForceScalable)
 {
     double requestedSize = SizeForStyle(aEntry, aStyle);
     double bestDist = -1.0;
@@ -978,7 +995,7 @@ SizeDistance(gfxFontconfigFontEntry* aEntry, const gfxFontStyle& aStyle)
     if (bestDist < 0.0) {
         // No size means scalable
         return -1.0;
-    } else if (5.0 * bestDist < requestedSize) {
+    } else if (aForceScalable || 5.0 * bestDist < requestedSize) {
         // fontconfig prefers a matching family or lang to pixelsize of bitmap
         // fonts. CSS suggests a tolerance of 20% on pixelsize.
         return bestDist;
@@ -1012,7 +1029,7 @@ gfxFontconfigFontFamily::FindAllFontsForStyle(const gfxFontStyle& aFontStyle,
     for (size_t i = 0; i < aFontEntryList.Length(); i++) {
         gfxFontconfigFontEntry* entry =
             static_cast<gfxFontconfigFontEntry*>(aFontEntryList[i]);
-        double dist = SizeDistance(entry, aFontStyle);
+        double dist = SizeDistance(entry, aFontStyle, mForceScalable);
         // If the entry is scalable or has a style that does not match
         // the group of unscalable fonts, then start a new group.
         if (dist < 0.0 ||
diff --git a/gfx/thebes/gfxFcPlatformFontList.h b/gfx/thebes/gfxFcPlatformFontList.h
index 1bc35021e..aa8f614a9 100644
--- a/gfx/thebes/gfxFcPlatformFontList.h
+++ b/gfx/thebes/gfxFcPlatformFontList.h
@@ -175,7 +175,8 @@ public:
     explicit gfxFontconfigFontFamily(const nsAString& aName) :
         gfxFontFamily(aName),
         mContainsAppFonts(false),
-        mHasNonScalableFaces(false)
+        mHasNonScalableFaces(false),
+        mForceScalable(false)
     { }
 
     void FindStyleVariations(FontInfoData *aFontInfoData = nullptr) override;
@@ -201,6 +202,7 @@ protected:
 
     bool      mContainsAppFonts;
     bool      mHasNonScalableFaces;
+    bool      mForceScalable;
 };
 
 class gfxFontconfigFont : public gfxFontconfigFontBase {
-- 
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