2 files changed, 38 insertions, 5 deletions
diff --git a/src/drivers/Android/Fl_Android_Graphics_Font.H b/src/drivers/Android/Fl_Android_Graphics_Font.H
index 7e8af7d52..788119045 100644
--- a/src/drivers/Android/Fl_Android_Graphics_Font.H
+++ b/src/drivers/Android/Fl_Android_Graphics_Font.H
@@ -21,6 +21,10 @@
 
 
 #include "Fl_Android_Graphics_Driver.H"
+
+// We violate FLTKs avoidance of STL because we live in a defined driver space
+#include <map>
+
 #include "stb_truetype.h"
 
 
@@ -35,7 +39,7 @@ public:
   ~Fl_Android_Bytemap();
 
 public:
-  int pWidth, pHeight, pStride, pXOffset, pYOffset;
+  int pWidth, pHeight, pStride, pXOffset, pYOffset, pAdvance;
   unsigned char *pBytes;
 };
 
@@ -69,9 +73,11 @@ class Fl_Android_Font_Descriptor : public Fl_Font_Descriptor
 private:
   Fl_Android_Font_Source *pFontSource;
   Fl_Font pFontIndex;
+  std::map<uint32_t, Fl_Android_Bytemap*> pBytemapTable;
 
 public:
   Fl_Android_Font_Descriptor(const char *fname, Fl_Android_Font_Source *fsrc, Fl_Font fnum, Fl_Fontsize size);
+  ~Fl_Android_Font_Descriptor();
   float get_advance(uint32_t c);
   Fl_Android_Bytemap *get_bytemap(uint32_t c);
   Fl_Android_Font_Source *get_font_source() { return pFontSource; }
diff --git a/src/drivers/Android/Fl_Android_Graphics_Font.cxx b/src/drivers/Android/Fl_Android_Graphics_Font.cxx
index 681d910bf..acbdf8406 100644
--- a/src/drivers/Android/Fl_Android_Graphics_Font.cxx
+++ b/src/drivers/Android/Fl_Android_Graphics_Font.cxx
@@ -163,6 +163,11 @@ Fl_Android_Bytemap *Fl_Android_Font_Source::get_bytemap(uint32_t c, int size)
                                              &byteMap->pXOffset, &byteMap->pYOffset);
   byteMap->pStride = byteMap->pWidth;
 
+  int advance, lsb;
+  stbtt_GetCodepointHMetrics(&pFont, c, &advance, &lsb);
+  float scale = stbtt_ScaleForPixelHeight(&pFont, size);
+  byteMap->pAdvance = (int)((scale * advance)+0.5f);
+
   return byteMap;
 }
 
@@ -213,6 +218,17 @@ Fl_Android_Font_Descriptor::Fl_Android_Font_Descriptor(const char *fname, Fl_And
   //  unsigned int listbase; // base of display list, 0 = none
 }
 
+/**
+ * Release resources, including all cached unicode character shapes.
+ */
+Fl_Android_Font_Descriptor::~Fl_Android_Font_Descriptor()
+{
+  // Life is easy in C++11.
+  for (auto &i: pBytemapTable) {
+    delete i.second;
+  }
+}
+
 /*
  * Get the width of the character in pixels.
  * @param c unicode character
@@ -220,18 +236,30 @@ Fl_Android_Font_Descriptor::Fl_Android_Font_Descriptor(const char *fname, Fl_And
  */
 float Fl_Android_Font_Descriptor::get_advance(uint32_t c)
 {
+  // TODO: should we cache the advance value inside the bytemap?
   return pFontSource->get_advance(c, size);
 }
 
 /**
  * Get the pixels for a given Unicode character.
+ *
+ * Calculating a bitmap is relatively expensive. This class will cache every
+ * bitmap ever generated. Currently, this is pretty much brute force because
+ * none of the bitmaps are ever released.
+ *
  * @param c unicode character
  * @return a bytemap
  */
 Fl_Android_Bytemap *Fl_Android_Font_Descriptor::get_bytemap(uint32_t c)
 {
-  // TODO: cache bytemaps here for fast access
-  return pFontSource->get_bytemap(c, size);
+  Fl_Android_Bytemap *bm = 0;
+  try {
+    bm = pBytemapTable.at(c);
+  } catch(...) {
+    bm = pFontSource->get_bytemap(c, size);
+    pBytemapTable[c] = bm;
+  }
+  return bm;
 }
 
 
@@ -325,8 +353,7 @@ int Fl_Android_Graphics_Driver::render_letter(int xx, int yy, uint32_t c)
       d++;
     }
   }
-  delete bm;
-  return oxx + (int)(fd->get_advance(c)+0.5f);
+  return oxx + bm->pAdvance;
 }
 
 /**