A basket of features: itemization, bounds, refcount

This patch improves script run itemization and also exposes metrics
and bounds for layouts. In addition, there is a fair amount of internal
cleanup, including ref counting, and making the MinikinFont abstraction
strong enough to support both FreeType and Skia implementations. There
is also a sample implementation using Skia, in the sample directory.

As part of its functionality, his patch measures the bounds of the
layout and gives access through Layout::GetBounds().  The corresponding
method is not implemented in the FreeType-only implementation of
MinikinFont, so that will probably have to be fixed.

Change-Id: Ib1a3fe9d7c90519ac651fb4aa957848e4bb758ec

2 files changed, 50 insertions, 4 deletions

diff --git a/include/minikin/Layout.h b/include/minikin/Layout.h
index fd0ed75..896478b 100644
--- a/include/minikin/Layout.h
+++ b/include/minikin/Layout.h
@@ -57,32 +57,50 @@ struct LayoutGlyph {
 
 class Layout {
 public:
+
     void dump() const;
-    void setFontCollection(const FontCollection *collection);
+    void setFontCollection(const FontCollection* collection);
     void doLayout(const uint16_t* buf, size_t nchars);
     void draw(Bitmap*, int x0, int y0) const;
     void setProperties(const std::string css);
 
-    float getAdvance() const;
-
     // This must be called before any invocations.
 	// TODO: probably have a factory instead
     static void init();
+
+    // public accessors
+    size_t nGlyphs() const;
+    // Does not bump reference; ownership is still layout
+    MinikinFont *getFont(int i) const;
+    unsigned int getGlyphId(int i) const;
+    float getX(int i) const;
+    float getY(int i) const;
+
+    float getAdvance() const;
+
+    // Get advances, copying into caller-provided buffer. The size of this
+    // buffer must match the length of the string (nchars arg to doLayout).
+    void getAdvances(float* advances);
+
+    void getBounds(MinikinRect* rect);
+
 private:
     // Find a face in the mFaces vector, or create a new entry
     int findFace(MinikinFont* face, MinikinPaint* paint);
 
     CssProperties mProps;  // TODO: want spans
     std::vector<LayoutGlyph> mGlyphs;
+    std::vector<float> mAdvances;
 
     // In future, this will be some kind of mapping from the
     // identifier used to represent font-family to a font collection.
     // But for the time being, it should be ok to have just one
     // per layout.
-    const FontCollection *mCollection;
+    const FontCollection* mCollection;
     std::vector<MinikinFont *> mFaces;
     std::vector<hb_font_t *> mHbFonts;
     float mAdvance;
+    MinikinRect mBounds;
 };
 
 }  // namespace android
diff --git a/include/minikin/MinikinFont.h b/include/minikin/MinikinFont.h
index c08e4fe..e84f5df 100644
--- a/include/minikin/MinikinFont.h
+++ b/include/minikin/MinikinFont.h
@@ -31,6 +31,29 @@ struct MinikinPaint {
     // todo: skew, stretch, hinting
 };
 
+struct MinikinRect {
+    float mLeft, mTop, mRight, mBottom;
+    bool isEmpty() const {
+        return mLeft == mRight || mTop == mBottom;
+    }
+    void set(const MinikinRect& r) {
+        mLeft = r.mLeft;
+        mTop = r.mTop;
+        mRight = r.mRight;
+        mBottom = r.mBottom;
+    }
+    void offset(float dx, float dy) {
+        mLeft += dx;
+        mTop += dy;
+        mRight += dx;
+        mBottom += dy;
+    }
+    void setEmpty() {
+        mLeft = mTop = mRight = mBottom = 0;
+    }
+    void join(const MinikinRect& r);
+};
+
 class MinikinFontFreeType;
 
 class MinikinFont {
@@ -38,6 +61,8 @@ public:
     void Ref() { mRefcount_++; }
     void Unref() { if (--mRefcount_ == 0) { delete this; } }
 
+    MinikinFont() : mRefcount_(1) { }
+
     virtual ~MinikinFont() { };
 
     virtual bool GetGlyph(uint32_t codepoint, uint32_t *glyph) const = 0;
@@ -45,6 +70,9 @@ public:
     virtual float GetHorizontalAdvance(uint32_t glyph_id,
         const MinikinPaint &paint) const = 0;
 
+    virtual void GetBounds(MinikinRect* bounds, uint32_t glyph_id,
+        const MinikinPaint &paint) const = 0;
+
     // If buf is NULL, just update size
     virtual bool GetTable(uint32_t tag, uint8_t *buf, size_t *size) = 0;