Implement onMakeClone(const SkFontArguments& args) in class SkTypeface_AndroidSystem.

Add FontMgrAndroidSystemVariableTypeface test to test the above
function.

Change-Id: I36a2f65550784a86feecc6ef69a870a33e973804
Reviewed-on: https://skia-review.googlesource.com/136248
Commit-Queue: Bruce Wang <brucewang@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>

src/ports/SkFontMgr_android.cpp

@@ -98,6 +98,22 @@ public:
         return skstd::make_unique<SkFontData>(this->makeStream(), fIndex,
                                               fAxes.begin(), fAxes.count());
     }
+    sk_sp<SkTypeface> onMakeClone(const SkFontArguments& args) const override {
+        std::unique_ptr<SkFontData> data = this->cloneFontData(args);
+        if (!data) {
+            return nullptr;
+        }
+        return sk_make_sp<SkTypeface_AndroidSystem>(fPathName,
+                                                    fFile,
+                                                    fIndex,
+                                                    data->getAxis(),
+                                                    data->getAxisCount(),
+                                                    this->fontStyle(),
+                                                    this->isFixedPitch(),
+                                                    fFamilyName,
+                                                    fLang,
+                                                    fVariantStyle);
+    }
 
     const SkString fPathName;
     int fIndex;

tests/FontMgrAndroidParserTest.cpp

@@ -6,6 +6,7 @@
  */
 
 #include "Resources.h"
+#include "SkCanvas.h"
 #include "SkCommandLineFlags.h"
 #include "SkFixed.h"
 #include "SkFontMgr_android.h"
@@ -245,3 +246,98 @@ DEF_TEST(FontMgrAndroidLegacyMakeTypeface, reporter) {
     sk_sp<SkTypeface> t(fm->legacyMakeTypeface("non-existent-font", SkFontStyle()));
     REPORTER_ASSERT(reporter, nullptr == t);
 }
+
+static bool bitmap_compare(const SkBitmap& ref, const SkBitmap& test) {
+    for (int y = 0; y < test.height(); ++y) {
+        for (int x = 0; x < test.width(); ++x) {
+            SkColor testColor = test.getColor(x, y);
+            SkColor refColor = ref.getColor(x, y);
+            if (refColor != testColor) {
+                return false;
+            }
+        }
+    }
+    return true;
+}
+
+DEF_TEST(FontMgrAndroidSystemVariableTypeface, reporter) {
+    constexpr char fontsXmlFilename[] = "fonts/fonts.xml";
+    SkString basePath = GetResourcePath("fonts/");
+    SkString fontsXml = GetResourcePath(fontsXmlFilename);
+
+    if (!sk_exists(fontsXml.c_str())) {
+        ERRORF(reporter, "file missing: %s\n", fontsXmlFilename);
+        return;
+    }
+
+    SkFontMgr_Android_CustomFonts custom;
+    custom.fSystemFontUse = SkFontMgr_Android_CustomFonts::kOnlyCustom;
+    custom.fBasePath = basePath.c_str();
+    custom.fFontsXml = fontsXml.c_str();
+    custom.fFallbackFontsXml = nullptr;
+    custom.fIsolated = false;
+
+    sk_sp<SkFontMgr> fontMgr(SkFontMgr_New_Android(&custom));
+    // "sans-serif" in "fonts/fonts.xml" is "fonts/Distortable.ttf"
+    sk_sp<SkTypeface> typeface(fontMgr->legacyMakeTypeface("sans-serif", SkFontStyle()));
+
+    SkBitmap bitmapStream;
+    bitmapStream.allocN32Pixels(64, 64);
+    SkCanvas canvasStream(bitmapStream);
+    canvasStream.drawColor(SK_ColorWHITE);
+
+    SkBitmap bitmapClone;
+    bitmapClone.allocN32Pixels(64, 64);
+    SkCanvas canvasClone(bitmapClone);
+    canvasStream.drawColor(SK_ColorWHITE);
+
+    SkPaint paintStream;
+    paintStream.setColor(SK_ColorGRAY);
+    paintStream.setTextSize(SkIntToScalar(20));
+    paintStream.setAntiAlias(true);
+    paintStream.setLCDRenderText(true);
+
+    SkPaint paintClone;
+    paintClone.setColor(SK_ColorGRAY);
+    paintClone.setTextSize(SkIntToScalar(20));
+    paintClone.setAntiAlias(true);
+    paintClone.setLCDRenderText(true);
+
+    std::unique_ptr<SkStreamAsset> distortableStream(
+        GetResourceAsStream("fonts/Distortable.ttf"));
+    if (!distortableStream) {
+        return;
+    }
+
+    const char* text = "abc";
+    const size_t textLen = strlen(text);
+    SkPoint point = SkPoint::Make(20.0f, 20.0f);
+    SkFourByteTag tag = SkSetFourByteTag('w', 'g', 'h', 't');
+
+    for (int i = 0; i < 10; ++i) {
+        SkScalar styleValue =
+            SkDoubleToScalar(0.5 + i * ((2.0 - 0.5) / 10));
+        SkFontArguments::VariationPosition::Coordinate
+            coordinates[] = {{tag, styleValue}};
+        SkFontArguments::VariationPosition
+            position = {coordinates, SK_ARRAY_COUNT(coordinates)};
+
+        paintStream.setTypeface(sk_sp<SkTypeface>(
+            fontMgr->makeFromStream(distortableStream->duplicate(),
+                                    SkFontArguments().setVariationDesignPosition(position))));
+
+        paintClone.setTypeface(sk_sp<SkTypeface>(
+            typeface->makeClone(SkFontArguments().setVariationDesignPosition(position))));
+
+        canvasStream.drawColor(SK_ColorWHITE);
+        canvasStream.drawText(text, textLen, point.fX, point.fY, paintStream);
+
+        canvasClone.drawColor(SK_ColorWHITE);
+        canvasClone.drawText(text, textLen, point.fX, point.fY, paintClone);
+
+        bool success = bitmap_compare(bitmapStream, bitmapClone);
+        REPORTER_ASSERT(reporter, success);
+    }
+}
+
+