Add SkTypeface::makeClone.

This adds an method to typeface to allow users to create a copy of the
typeface with different arguments for its parameters. This is far more
efficient when animating a variation font.

BUG=skia:7121

Change-Id: I34e7557a08c7005f8149ea44f0c28de9c59d15a7
Reviewed-on: https://skia-review.googlesource.com/132480
Commit-Queue: Ben Wagner <bungeman@google.com>
Reviewed-by: Mike Reed <reed@google.com>

2 files changed, 18 insertions, 0 deletions

diff --git a/include/core/SkTypeface.h b/include/core/SkTypeface.h
index 665491c3db..4118152dea 100644
--- a/include/core/SkTypeface.h
+++ b/include/core/SkTypeface.h
@@ -117,6 +117,14 @@ public:
     */
     static sk_sp<SkTypeface> MakeFromFontData(std::unique_ptr<SkFontData>);
 
+    /** Return a new typeface based on this typeface but parameterized as specified in the
+        SkFontArguments. If the SkFontArguments does not supply an argument for a parameter
+        in the font then the value from this typeface will be used as the value for that
+        argument. If the cloned typeface would be exaclty the same as this typeface then
+        this typeface may be ref'ed and returned. May return nullptr on failure.
+    */
+    sk_sp<SkTypeface> makeClone(const SkFontArguments&) const;
+
     /** Write a unique signature to a stream, sufficient to reconstruct a
         typeface referencing the same font when Deserialize is called.
      */
@@ -301,6 +309,8 @@ protected:
     SkTypeface(const SkFontStyle& style, bool isFixedPitch = false);
     virtual ~SkTypeface();
 
+    virtual sk_sp<SkTypeface> onMakeClone(const SkFontArguments&) const;
+
     /** Sets the fixedPitch bit. If used, must be called in the constructor. */
     void setIsFixedPitch(bool isFixedPitch) { fIsFixedPitch = isFixedPitch; }
     /** Sets the font style. If used, must be called in the constructor. */
diff --git a/src/core/SkTypeface.cpp b/src/core/SkTypeface.cpp
index 92c8c09e33..a59075b908 100644
--- a/src/core/SkTypeface.cpp
+++ b/src/core/SkTypeface.cpp
@@ -161,6 +161,10 @@ sk_sp<SkTypeface> SkTypeface::MakeFromFile(const char path[], int index) {
     return fm->makeFromFile(path, index);
 }
 
+sk_sp<SkTypeface> SkTypeface::makeClone(const SkFontArguments& args) const {
+    return this->onMakeClone(args);
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 void SkTypeface::serialize(SkWStream* wstream) const {
@@ -321,6 +325,10 @@ bool SkTypeface::onGetKerningPairAdjustments(const uint16_t glyphs[], int count,
     return false;
 }
 
+sk_sp<SkTypeface> SkTypeface::onMakeClone(const SkFontArguments& args) const {
+    return sk_ref_sp(this);
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 
 #include "SkDescriptor.h"