Add functions for measuring cursor positioning

New functions for computing the correspondence between cursor
position and advance, respecting grapheme boundaries.

Change-Id: I620378d5f64cd74300cd43db522adeb555825dff

2 files changed, 36 insertions, 1 deletions

diff --git a/include/minikin/Layout.h b/include/minikin/Layout.h
index 543f553..930407a 100644
--- a/include/minikin/Layout.h
+++ b/include/minikin/Layout.h
@@ -106,9 +106,13 @@ public:
     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).
+    // buffer must match the length of the string (count arg to doLayout).
     void getAdvances(float* advances);
 
+    // The i parameter is an offset within the buf relative to start, it is < count, where
+    // start and count are the parameters to doLayout
+    float getCharAdvance(size_t i) const { return mAdvances[i]; }
+
     void getBounds(MinikinRect* rect);
 
     // Purge all caches, useful in low memory conditions
diff --git a/include/minikin/Measurement.h b/include/minikin/Measurement.h
new file mode 100644
index 0000000..fc47fa3
--- /dev/null
+++ b/include/minikin/Measurement.h
@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef MINIKIN_MEASUREMENT_H
+#define MINIKIN_MEASUREMENT_H
+
+#include <minikin/Layout.h>
+
+namespace android {
+
+float getRunAdvance(Layout& layout, const uint16_t* buf, size_t start, size_t count, size_t offset);
+
+size_t getOffsetForAdvance(Layout& layout, const uint16_t* buf, size_t start, size_t count,
+        float advance);
+
+}
+
+#endif  // MINIKIN_MEASUREMENT_H