Modify Canvas drawText to run bidi and shape.

Adds drawTextRun as internal API on Canvas and GraphicsOperations.
Adds implementation to implementors of GraphicsOperations.

Adds state and API on Paint to control the bidi algorithm when used
by Canvas.  This API is currently hidden.

The drawText changes are incomplete since shaping is not yet available
in the native code.

Change-Id: I4368048aef9545df0953a349381771603e04b619

2 files changed, 210 insertions, 22 deletions

diff --git a/graphics/java/android/graphics/Canvas.java b/graphics/java/android/graphics/Canvas.java
index 345f810..064fab6 100644
--- a/graphics/java/android/graphics/Canvas.java
+++ b/graphics/java/android/graphics/Canvas.java
@@ -16,11 +16,10 @@
 
 package android.graphics;
 
-import android.text.TextUtils;
-import android.text.SpannedString;
-import android.text.SpannableString;
 import android.text.GraphicsOperations;
-import android.util.DisplayMetrics;
+import android.text.SpannableString;
+import android.text.SpannedString;
+import android.text.TextUtils;
 
 import javax.microedition.khronos.opengles.GL;
 
@@ -59,6 +58,18 @@ public class Canvas {
     private int         mSurfaceFormat;
 
     /**
+     * Flag for drawTextRun indicating left-to-right run direction.
+     * @hide
+     */
+    public static final int DIRECTION_LTR = 0;
+    
+    /**
+     * Flag for drawTextRun indicating right-to-left run direction.
+     * @hide
+     */
+    public static final int DIRECTION_RTL = 1;
+    
+    /**
      * Construct an empty raster canvas. Use setBitmap() to specify a bitmap to
      * draw into.  The initial target density is {@link Bitmap#DENSITY_NONE};
      * this will typically be replaced when a target bitmap is set for the
@@ -1246,8 +1257,8 @@ public class Canvas {
             (text.length - index - count)) < 0) {
             throw new IndexOutOfBoundsException();
         }
-        native_drawText(mNativeCanvas, text, index, count, x, y,
-                        paint.mNativePaint);
+        native_drawText(mNativeCanvas, text, index, count, x, y, paint.mBidiFlags,
+                paint.mNativePaint);
     }
 
     /**
@@ -1259,7 +1270,10 @@ public class Canvas {
      * @param y     The y-coordinate of the origin of the text being drawn
      * @param paint The paint used for the text (e.g. color, size, style)
      */
-    public native void drawText(String text, float x, float y, Paint paint);
+    public void drawText(String text, float x, float y, Paint paint) {
+        native_drawText(mNativeCanvas, text, 0, text.length(), x, y, paint.mBidiFlags,
+                paint.mNativePaint);
+    }
 
     /**
      * Draw the text, with origin at (x,y), using the specified paint.
@@ -1277,8 +1291,8 @@ public class Canvas {
         if ((start | end | (end - start) | (text.length() - end)) < 0) {
             throw new IndexOutOfBoundsException();
         }
-        native_drawText(mNativeCanvas, text, start, end, x, y,
-                        paint.mNativePaint);
+        native_drawText(mNativeCanvas, text, start, end, x, y, paint.mBidiFlags,
+                paint.mNativePaint);
     }
 
     /**
@@ -1299,16 +1313,100 @@ public class Canvas {
         if (text instanceof String || text instanceof SpannedString ||
             text instanceof SpannableString) {
             native_drawText(mNativeCanvas, text.toString(), start, end, x, y,
-                            paint.mNativePaint);
-        }
-        else if (text instanceof GraphicsOperations) {
+                            paint.mBidiFlags, paint.mNativePaint);
+        } else if (text instanceof GraphicsOperations) {
             ((GraphicsOperations) text).drawText(this, start, end, x, y,
                                                      paint);
+        } else {
+            char[] buf = TemporaryBuffer.obtain(end - start);
+            TextUtils.getChars(text, start, end, buf, 0);
+            native_drawText(mNativeCanvas, buf, 0, end - start, x, y, 
+                    paint.mBidiFlags, paint.mNativePaint);
+            TemporaryBuffer.recycle(buf);
         }
-        else {
+    }
+
+    /**
+     * Render a run of all LTR or all RTL text, with shaping. This does not run
+     * bidi on the provided text, but renders it as a uniform right-to-left or
+     * left-to-right run, as indicated by dir. Alignment of the text is as
+     * determined by the Paint's TextAlign value.
+     * 
+     * @param text the text to render
+     * @param index the start of the text to render. Data before this position
+     *            can be used for shaping context.
+     * @param length the length of the text to render. Data at or after this
+     *            position (start + length) can be used for shaping context.
+     * @param x the x position at which to draw the text
+     * @param y the y position at which to draw the text
+     * @param dir the run direction, either {@link DIRECTION_LTR} or 
+     *            {@link DIRECTION_RTL}.
+     * @param paint the paint
+     * @hide
+     */
+    public void drawTextRun(char[] text, int index, int length, float x, float y, int dir,
+            Paint paint) {
+
+        if (text == null) {
+            throw new NullPointerException("text is null");
+        }
+        if (paint == null) {
+            throw new NullPointerException("paint is null");
+        }
+        if ((index | length | text.length - index - length) < 0) {
+            throw new IndexOutOfBoundsException();
+        }
+        if (dir != DIRECTION_LTR && dir != DIRECTION_RTL) {
+            throw new IllegalArgumentException("unknown dir: " + dir);
+        }
+
+        native_drawTextRun(mNativeCanvas, text, index, length, x, y, dir, paint.mNativePaint);
+    }
+
+    /**
+     * Render a run of all LTR or all RTL text, with shaping. This does not run
+     * bidi on the provided text, but renders it as a uniform right-to-left or
+     * left-to-right run, as indicated by dir. Alignment of the text is as
+     * determined by the Paint's TextAlign value.
+     * 
+     * @param text the text to render
+     * @param start the start of the text to render. Data before this position
+     *            can be used for shaping context.
+     * @param end the end of the text to render. Data at or after this
+     *            position can be used for shaping context.
+     * @param x the x position at which to draw the text
+     * @param y the y position at which to draw the text
+     * @param dir the run direction, either 0 for LTR or 1 for RTL.
+     * @param paint the paint
+     * @hide
+     */
+    public void drawTextRun(CharSequence text, int start, int end, float x, 
+            float y, int dir, Paint paint) {
+
+        if (text == null) {
+            throw new NullPointerException("text is null");
+        }
+        if (paint == null) {
+            throw new NullPointerException("paint is null");
+        }
+        if ((start | end | end - start | text.length() - end) < 0) {
+            throw new IndexOutOfBoundsException();
+        }
+
+        int flags = dir == 0 ? 0 : 1;
+
+        if (text instanceof String || text instanceof SpannedString ||
+                text instanceof SpannableString) {
+            native_drawTextRun(mNativeCanvas, text.toString(), start, end, x, y,
+                    flags, paint.mNativePaint);
+        } else if (text instanceof GraphicsOperations) {
+            ((GraphicsOperations) text).drawTextRun(this, start, end, x, y, flags,
+                                                         paint);
+        } else {
             char[] buf = TemporaryBuffer.obtain(end - start);
             TextUtils.getChars(text, start, end, buf, 0);
-            drawText(buf, 0, end - start, x, y, paint);
+            native_drawTextRun(mNativeCanvas, buf, 0, end - start, x, y, 
+                        flags, paint.mNativePaint);
             TemporaryBuffer.recycle(buf);
         }
     }
@@ -1555,10 +1653,17 @@ public class Canvas {
     
     private static native void native_drawText(int nativeCanvas, char[] text,
                                                int index, int count, float x,
-                                               float y, int paint);
+                                               float y, int flags, int paint);
     private static native void native_drawText(int nativeCanvas, String text,
                                                int start, int end, float x,
-                                               float y, int paint);
+                                               float y, int flags, int paint);
+
+    private static native void native_drawTextRun(int nativeCanvas, String
+            text, int start, int end, float x, float y, int flags, int paint);
+
+    private static native void native_drawTextRun(int nativeCanvas, char[]
+            text, int start, int len, float x, float y, int flags, int paint);
+
     private static native void native_drawPosText(int nativeCanvas,
                                                   char[] text, int index,
                                                   int count, float[] pos,
diff --git a/graphics/java/android/graphics/Paint.java b/graphics/java/android/graphics/Paint.java
index 183c896..b564929 100644
--- a/graphics/java/android/graphics/Paint.java
+++ b/graphics/java/android/graphics/Paint.java
@@ -16,10 +16,10 @@
 
 package android.graphics;
 
-import android.text.TextUtils;
+import android.text.GraphicsOperations;
 import android.text.SpannableString;
 import android.text.SpannedString;
-import android.text.GraphicsOperations;
+import android.text.TextUtils;
 
 /**
  * The Paint class holds the style and color information about how to draw
@@ -39,6 +39,7 @@ public class Paint {
     private boolean     mHasCompatScaling;
     private float       mCompatScaling;
     private float       mInvCompatScaling;
+    /* package */ int   mBidiFlags = BIDI_DEFAULT_LTR;
     
     private static final Style[] sStyleArray = {
         Style.FILL, Style.STROKE, Style.FILL_AND_STROKE
@@ -76,8 +77,64 @@ public class Paint {
     private static final int DEFAULT_PAINT_FLAGS = DEV_KERN_TEXT_FLAG;
 
     /**
-     * The Style specifies if the primitive being drawn is filled,
-     * stroked, or both (in the same color). The default is FILL.
+     * Bidi flag to set LTR paragraph direction.
+     * 
+     * @hide
+     */
+    public static final int BIDI_LTR = 0x0;
+
+    /**
+     * Bidi flag to set RTL paragraph direction.
+     * 
+     * @hide
+     */
+    public static final int BIDI_RTL = 0x1;
+
+    /**
+     * Bidi flag to detect paragraph direction via heuristics, defaulting to
+     * LTR.
+     * 
+     * @hide
+     */
+    public static final int BIDI_DEFAULT_LTR = 0x2;
+
+    /**
+     * Bidi flag to detect paragraph direction via heuristics, defaulting to
+     * RTL.
+     * 
+     * @hide
+     */
+    public static final int BIDI_DEFAULT_RTL = 0x3;
+
+    /**
+     * Bidi flag to override direction to all LTR (ignore bidi).
+     * 
+     * @hide
+     */
+    public static final int BIDI_FORCE_LTR = 0x4;
+
+    /**
+     * Bidi flag to override direction to all RTL (ignore bidi).
+     * 
+     * @hide
+     */
+    public static final int BIDI_FORCE_RTL = 0x5;
+
+    /**
+     * Maximum Bidi flag value.
+     * @hide
+     */
+    private static final int BIDI_MAX_FLAG_VALUE = BIDI_FORCE_RTL;
+    
+    /**
+     * Mask for bidi flags.
+     * @hide
+     */
+    private static final int BIDI_FLAG_MASK = 0x7;
+    
+    /**
+     * The Style specifies if the primitive being drawn is filled, stroked, or
+     * both (in the same color). The default is FILL.
      */
     public enum Style {
         /**
@@ -210,6 +267,7 @@ public class Paint {
         mHasCompatScaling = paint.mHasCompatScaling;
         mCompatScaling = paint.mCompatScaling;
         mInvCompatScaling = paint.mInvCompatScaling;
+        mBidiFlags = paint.mBidiFlags;
     }
 
     /** Restores the paint to its default settings. */
@@ -218,6 +276,7 @@ public class Paint {
         setFlags(DEFAULT_PAINT_FLAGS);
         mHasCompatScaling = false;
         mCompatScaling = mInvCompatScaling = 1;
+        mBidiFlags = BIDI_DEFAULT_LTR;
     }
     
     /**
@@ -240,6 +299,7 @@ public class Paint {
             mHasCompatScaling = src.mHasCompatScaling;
             mCompatScaling    = src.mCompatScaling;
             mInvCompatScaling = src.mInvCompatScaling;
+            mBidiFlags      = src.mBidiFlags;
         }
     }
 
@@ -254,10 +314,33 @@ public class Paint {
             mInvCompatScaling = 1.0f/factor;
         }
     }
-    
+
+    /**
+     * Return the bidi flags on the paint.
+     * 
+     * @return the bidi flags on the paint
+     * @hide
+     */
+    public int getBidiFlags() {
+        return mBidiFlags;
+    }
+
+    /**
+     * Set the bidi flags on the paint.
+     * @hide
+     */
+    public void setBidiFlags(int flags) {
+        // only flag value is the 3-bit BIDI control setting
+        flags &= BIDI_FLAG_MASK;
+        if (flags > BIDI_MAX_FLAG_VALUE) {
+            throw new IllegalArgumentException("unknown bidi flag: " + flags);
+        }
+        mBidiFlags = flags;
+    }
+
     /**
      * Return the paint's flags. Use the Flag enum to test flag values.
-     *
+     * 
      * @return the paint's flags (see enums ending in _Flag for bit masks)
      */
     public native int getFlags();