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Commit 8f502656 authored by Fabrice Di Meglio's avatar Fabrice Di Meglio
Browse files

Add charCount heuristic to TextView textDirection 

- threshold set to 60% (using a constant)
- fix also one issue during layout direction resolution (parent could be null so delay resolution
up to when parent is no more null)

Change-Id: I65f24a297aac6bc0d5d482ee31b55db0b201e5bf
parent 22268868

api/current.txt

+1 −0
Original line number Diff line number Diff line
@@ -22069,6 +22069,7 @@ package android.view { 
    method public boolean willNotDraw();

    field public static android.util.Property ALPHA;

    field protected static int DEFAULT_TEXT_DIRECTION;

    field protected static float DEFAULT_TEXT_DIRECTION_CHAR_COUNT_THRESHOLD;

    field public static final int DRAWING_CACHE_QUALITY_AUTO = 0; // 0x0

    field public static final int DRAWING_CACHE_QUALITY_HIGH = 1048576; // 0x100000

    field public static final int DRAWING_CACHE_QUALITY_LOW = 524288; // 0x80000

core/java/android/view/View.java

+19 −3
Original line number Diff line number Diff line
@@ -2522,25 +2522,38 @@ public class View implements Drawable.Callback2, KeyEvent.Callback, Accessibilit 
     */

    public static final int TEXT_DIRECTION_ANY_RTL = 2;



    /**

     * Text direction is the same as the one held by a 60% majority of the characters. If there is

     * no majority then the paragraph direction is the resolved layout direction of the View.

     *

     * @hide

     */

    public static final int TEXT_DIRECTION_CHAR_COUNT = 3;



    /**

     * Text direction is forced to LTR.

     *

     * @hide

     */

    public static final int TEXT_DIRECTION_LTR = 3;

    public static final int TEXT_DIRECTION_LTR = 4;



    /**

     * Text direction is forced to RTL.

     *

     * @hide

     */

    public static final int TEXT_DIRECTION_RTL = 4;

    public static final int TEXT_DIRECTION_RTL = 5;



    /**

     * Default text direction is inherited

     */

    protected static int DEFAULT_TEXT_DIRECTION = TEXT_DIRECTION_INHERIT;



    /**

     * Default threshold for "char count" heuristic.

     */

    protected static float DEFAULT_TEXT_DIRECTION_CHAR_COUNT_THRESHOLD = 0.6f;



    /**

     * The text direction that has been defined by {@link #setTextDirection(int)}.

     *
@@ -2551,6 +2564,7 @@ public class View implements Drawable.Callback2, KeyEvent.Callback, Accessibilit 
            @ViewDebug.IntToString(from = TEXT_DIRECTION_INHERIT, to = "INHERIT"),

            @ViewDebug.IntToString(from = TEXT_DIRECTION_FIRST_STRONG, to = "FIRST_STRONG"),

            @ViewDebug.IntToString(from = TEXT_DIRECTION_ANY_RTL, to = "ANY_RTL"),

            @ViewDebug.IntToString(from = TEXT_DIRECTION_CHAR_COUNT, to = "CHAR_COUNT"),

            @ViewDebug.IntToString(from = TEXT_DIRECTION_LTR, to = "LTR"),

            @ViewDebug.IntToString(from = TEXT_DIRECTION_RTL, to = "RTL")

    })
@@ -11963,7 +11977,7 @@ public class View implements Drawable.Callback2, KeyEvent.Callback, Accessibilit 
        mPrivateFlags |= FORCE_LAYOUT;

        mPrivateFlags |= INVALIDATED;



        if (mLayoutParams != null) {

        if (mLayoutParams != null && mParent != null) {

            mLayoutParams.resolveWithDirection(getResolvedLayoutDirection());

        }
@@ -12990,6 +13004,7 @@ public class View implements Drawable.Callback2, KeyEvent.Callback, Accessibilit 
     * {@link #TEXT_DIRECTION_INHERIT},

     * {@link #TEXT_DIRECTION_FIRST_STRONG}

     * {@link #TEXT_DIRECTION_ANY_RTL},

     * {@link #TEXT_DIRECTION_CHAR_COUNT},

     * {@link #TEXT_DIRECTION_LTR},

     * {@link #TEXT_DIRECTION_RTL},

     *
@@ -13007,6 +13022,7 @@ public class View implements Drawable.Callback2, KeyEvent.Callback, Accessibilit 
     * {@link #TEXT_DIRECTION_INHERIT},

     * {@link #TEXT_DIRECTION_FIRST_STRONG}

     * {@link #TEXT_DIRECTION_ANY_RTL},

     * {@link #TEXT_DIRECTION_CHAR_COUNT},

     * {@link #TEXT_DIRECTION_LTR},

     * {@link #TEXT_DIRECTION_RTL},

     *

core/java/android/view/ViewGroup.java

+1 −0
Original line number Diff line number Diff line
@@ -5039,6 +5039,7 @@ public abstract class ViewGroup extends View implements ViewParent, ViewManager 
            // Pass down the hierarchy the following text direction values

            case TEXT_DIRECTION_FIRST_STRONG:

            case TEXT_DIRECTION_ANY_RTL:

            case TEXT_DIRECTION_CHAR_COUNT:

            case TEXT_DIRECTION_LTR:

            case TEXT_DIRECTION_RTL:

                resolvedTextDirection = mTextDirection;

core/java/android/widget/TextView.java

+44 −0
Original line number Diff line number Diff line
@@ -10039,6 +10039,9 @@ public class TextView extends View implements ViewTreeObserver.OnPreDrawListener 
            case TEXT_DIRECTION_ANY_RTL:

                resolvedTextDirection = getTextDirectionFromAnyRtl(mText);

                break;

            case TEXT_DIRECTION_CHAR_COUNT:

                resolvedTextDirection = getTextDirectionFromCharCount(mText);

                break;

            case TEXT_DIRECTION_LTR:

                resolvedTextDirection = TEXT_DIRECTION_LTR;

                break;
@@ -10072,6 +10075,9 @@ public class TextView extends View implements ViewTreeObserver.OnPreDrawListener 
     */

    private static int getTextDirectionFromFirstStrong(final CharSequence cs) {

        final int length = cs.length();

        if (length == 0) {

            return TEXT_DIRECTION_UNDEFINED;

        }

        for(int i = 0; i < length; i++) {

            final char c = cs.charAt(i);

            final byte dir = Character.getDirectionality(c);
@@ -10094,6 +10100,9 @@ public class TextView extends View implements ViewTreeObserver.OnPreDrawListener 
     */

    private static int getTextDirectionFromAnyRtl(final CharSequence cs) {

        final int length = cs.length();

        if (length == 0) {

            return TEXT_DIRECTION_UNDEFINED;

        }

        boolean foundStrongLtr = false;

        boolean foundStrongRtl = false;

        for(int i = 0; i < length; i++) {
@@ -10114,6 +10123,41 @@ public class TextView extends View implements ViewTreeObserver.OnPreDrawListener 
        return TEXT_DIRECTION_UNDEFINED;

    }



    /**

     * Get text direction following the "char count" heuristic.

     *

     * @param cs the CharSequence used to get the text direction.

     *

     * @return {@link #TEXT_DIRECTION_RTL} if direction it RTL, {@link #TEXT_DIRECTION_LTR} if

     * direction it LTR or {@link #TEXT_DIRECTION_UNDEFINED} if direction cannot be found.

     */

    private int getTextDirectionFromCharCount(CharSequence cs) {

        final int length = cs.length();

        if (length == 0) {

            return TEXT_DIRECTION_UNDEFINED;

        }

        int countLtr = 0;

        int countRtl = 0;

        for(int i = 0; i < length; i++) {

            final char c = cs.charAt(i);

            final byte dir = Character.getDirectionality(c);

            if (isStrongLtrChar(dir)) {

                countLtr++;

            } else if (isStrongRtlChar(dir)) {

                countRtl++;

            }

        }

        final float percentLtr = ((float) countLtr) / (countLtr + countRtl);

        if (percentLtr > DEFAULT_TEXT_DIRECTION_CHAR_COUNT_THRESHOLD) {

            return TEXT_DIRECTION_LTR;

        }

        final float percentRtl = ((float) countRtl) / (countLtr + countRtl);

        if (percentRtl > DEFAULT_TEXT_DIRECTION_CHAR_COUNT_THRESHOLD) {

            return TEXT_DIRECTION_RTL;

        }

        return TEXT_DIRECTION_UNDEFINED;

    }



    /**

     * Return true if the char direction is corresponding to a "strong RTL char" following the

     * Unicode Bidirectional Algorithm (UBA).

core/res/res/values/attrs.xml

+8 −4
Original line number Diff line number Diff line
@@ -1985,10 +1985,14 @@ 
                 it is LTR if it contains any strong LTR characters.  If there are neither, the

                 paragraph direction is the view’s resolved layout direction. -->

            <enum name="anyRtl" value="2" />

            <!-- The text direction is left to right. -->

            <enum name="ltr" value="3" />

            <!-- The text direction is right to left. -->

            <enum name="rtl" value="4" />

            <!-- The paragraph direction is the same as the one held by a 60% majority of the

                 characters. If there is no majority then the paragraph direction is the resolved

                 layout direction of the View. -->

            <enum name="charCount" value="3" />

            <!-- The paragraph direction is left to right. -->

            <enum name="ltr" value="4" />

            <!-- The paragraph direction is right to left. -->

            <enum name="rtl" value="5" />

        </attr>

    </declare-styleable>