Support for fake bold and italics

This patch adds support for computing when fake bold and fake italics
are needed (because the styles are requested but not provided by the
matching FontFamily), and providing them as part of the layout result.

Part of the fix for bug 15436379 Fake bold doesn't fully work (Minikin)

Change-Id: I180c034b559837943673b5c272c8e890178dff0d

3 files changed, 40 insertions, 18 deletions

diff --git a/libs/minikin/FontCollection.cpp b/libs/minikin/FontCollection.cpp
index c13670e..6115ecc 100644
--- a/libs/minikin/FontCollection.cpp
+++ b/libs/minikin/FontCollection.cpp
@@ -52,7 +52,7 @@ FontCollection::FontCollection(const vector<FontFamily*>& typefaces) :
         FontInstance* instance = &mInstances.back();
         instance->mFamily = family;
         instance->mCoverage = new SparseBitSet;
-        MinikinFont* typeface = family->getClosestMatch(defaultStyle);
+        MinikinFont* typeface = family->getClosestMatch(defaultStyle).font;
         if (typeface == NULL) {
             ALOGE("FontCollection: closest match was null");
             // TODO: we shouldn't hit this, as there should be more robust
@@ -171,11 +171,9 @@ void FontCollection::itemize(const uint16_t *string, size_t string_size, FontSty
                 result->push_back(dummy);
                 run = &result->back();
                 if (instance == NULL) {
-                    run->font = NULL;  // maybe we should do something different here
+                    run->fakedFont.font = NULL;
                 } else {
-                    run->font = instance->mFamily->getClosestMatch(style);
-                    // TODO: simplify refcounting (FontCollection lifetime dominates)
-                    run->font->RefLocked();
+                    run->fakedFont = instance->mFamily->getClosestMatch(style);
                 }
                 lastInstance = instance;
                 run->start = i;
@@ -186,13 +184,16 @@ void FontCollection::itemize(const uint16_t *string, size_t string_size, FontSty
 }
 
 MinikinFont* FontCollection::baseFont(FontStyle style) {
+    return baseFontFaked(style).font;
+}
+
+FakedFont FontCollection::baseFontFaked(FontStyle style) {
     if (mInstances.empty()) {
-        return NULL;
+        return FakedFont();
     }
     return mInstances[0].mFamily->getClosestMatch(style);
 }
 
-
 uint32_t FontCollection::getId() const {
     return mId;
 }
diff --git a/libs/minikin/FontFamily.cpp b/libs/minikin/FontFamily.cpp
index 0fb98ae..9106f63 100644
--- a/libs/minikin/FontFamily.cpp
+++ b/libs/minikin/FontFamily.cpp
@@ -109,7 +109,7 @@ void FontFamily::addFontLocked(MinikinFont* typeface, FontStyle style) {    type
 }
 
 // Compute a matching metric between two styles - 0 is an exact match
-int computeMatch(FontStyle style1, FontStyle style2) {
+static int computeMatch(FontStyle style1, FontStyle style2) {
     if (style1 == style2) return 0;
     int score = abs(style1.getWeight() - style2.getWeight());
     if (style1.getItalic() != style2.getItalic()) {
@@ -118,7 +118,15 @@ int computeMatch(FontStyle style1, FontStyle style2) {
     return score;
 }
 
-MinikinFont* FontFamily::getClosestMatch(FontStyle style) const {
+static FontFakery computeFakery(FontStyle wanted, FontStyle actual) {
+    // If desired weight is 2 or more grades higher than actual
+    // (for example, medium 500 -> bold 700), then select fake bold.
+    bool isFakeBold = (wanted.getWeight() - actual.getWeight()) >= 2;
+    bool isFakeItalic = wanted.getItalic() && !actual.getItalic();
+    return FontFakery(isFakeBold, isFakeItalic);
+}
+
+FakedFont FontFamily::getClosestMatch(FontStyle style) const {
     const Font* bestFont = NULL;
     int bestMatch = 0;
     for (size_t i = 0; i < mFonts.size(); i++) {
@@ -129,7 +137,14 @@ MinikinFont* FontFamily::getClosestMatch(FontStyle style) const {
             bestMatch = match;
         }
     }
-    return bestFont == NULL ? NULL : bestFont->typeface;
+    FakedFont result;
+    if (bestFont == NULL) {
+        result.font = NULL;
+    } else {
+        result.font = bestFont->typeface;
+        result.fakery = computeFakery(style, bestFont->style);
+    }
+    return result;
 }
 
 size_t FontFamily::getNumFonts() const {
diff --git a/libs/minikin/Layout.cpp b/libs/minikin/Layout.cpp
index 3cab673..709393d 100644
--- a/libs/minikin/Layout.cpp
+++ b/libs/minikin/Layout.cpp
@@ -328,10 +328,10 @@ void Layout::dump() const {
     }
 }
 
-int Layout::findFace(MinikinFont* face, LayoutContext* ctx) {
+int Layout::findFace(FakedFont face, LayoutContext* ctx) {
     unsigned int ix;
     for (ix = 0; ix < mFaces.size(); ix++) {
-        if (mFaces[ix] == face) {
+        if (mFaces[ix].font == face.font) {
             return ix;
         }
     }
@@ -339,7 +339,7 @@ int Layout::findFace(MinikinFont* face, LayoutContext* ctx) {
     // Note: ctx == NULL means we're copying from the cache, no need to create
     // corresponding hb_font object.
     if (ctx != NULL) {
-        hb_font_t* font = create_hb_font(face, &ctx->paint);
+        hb_font_t* font = create_hb_font(face.font, &ctx->paint);
         ctx->hbFonts.push_back(font);
     }
     return ix;
@@ -631,12 +631,13 @@ void Layout::doLayoutRun(const uint16_t* buf, size_t start, size_t count, size_t
     float y = 0;
     for (size_t run_ix = 0; run_ix < items.size(); run_ix++) {
         FontCollection::Run &run = items[run_ix];
-        if (run.font == NULL) {
+        if (run.fakedFont.font == NULL) {
             ALOGE("no font for run starting u+%04x length %d", buf[run.start], run.end - run.start);
             continue;
         }
-        int font_ix = findFace(run.font, ctx);
-        ctx->paint.font = mFaces[font_ix];
+        int font_ix = findFace(run.fakedFont, ctx);
+        ctx->paint.font = mFaces[font_ix].font;
+        ctx->paint.fakery = mFaces[font_ix].fakery;
         hb_font_t* hbFont = ctx->hbFonts[font_ix];
 #ifdef VERBOSE
         std::cout << "Run " << run_ix << ", font " << font_ix <<
@@ -729,7 +730,7 @@ void Layout::draw(Bitmap* surface, int x0, int y0, float size) const {
     */
     for (size_t i = 0; i < mGlyphs.size(); i++) {
         const LayoutGlyph& glyph = mGlyphs[i];
-        MinikinFont* mf = mFaces[glyph.font_ix];
+        MinikinFont* mf = mFaces[glyph.font_ix].font;
         MinikinFontFreeType* face = static_cast<MinikinFontFreeType*>(mf);
         GlyphBitmap glyphBitmap;
         MinikinPaint paint;
@@ -754,7 +755,12 @@ size_t Layout::nGlyphs() const {
 
 MinikinFont* Layout::getFont(int i) const {
     const LayoutGlyph& glyph = mGlyphs[i];
-    return mFaces[glyph.font_ix];
+    return mFaces[glyph.font_ix].font;
+}
+
+FontFakery Layout::getFakery(int i) const {
+    const LayoutGlyph& glyph = mGlyphs[i];
+    return mFaces[glyph.font_ix].fakery;
 }
 
 unsigned int Layout::getGlyphId(int i) const {