android.text.Layout#DIR_LEFT_TO_RIGHT源码实例Demo

private static String getTextDirection(Spanned text, int start, int end) {
        // FIXME not supported
        int paraDir = Layout.DIR_LEFT_TO_RIGHT;
//        final int len = end - start;
//        final byte[] levels = ArrayUtils.newUnpaddedByteArray(len);
//        final char[] buffer = TextUtils.obtain(len);
//        TextUtils.getChars(text, start, end, buffer, 0);
//        int paraDir = AndroidBidi.bidi(Layout.DIR_REQUEST_DEFAULT_LTR, buffer, levels, len,
//                false /* no info */);
        switch (paraDir) {
            case Layout.DIR_RIGHT_TO_LEFT:
                return " dir=\"rtl\"";
            case Layout.DIR_LEFT_TO_RIGHT:
            default:
                return " dir=\"ltr\"";
        }
    }
 

/**
 * If the direction of the URL has changed, update mUrlDirection and notify the
 * UrlDirectionListeners.
 */
private void updateUrlDirection() {
    Layout layout = getLayout();
    if (layout == null) return;

    int urlDirection;
    if (length() == 0) {
        urlDirection = LAYOUT_DIRECTION_LOCALE;
    } else if (layout.getParagraphDirection(0) == Layout.DIR_LEFT_TO_RIGHT) {
        urlDirection = LAYOUT_DIRECTION_LTR;
    } else {
        urlDirection = LAYOUT_DIRECTION_RTL;
    }

    if (urlDirection != mUrlDirection) {
        mUrlDirection = urlDirection;
        if (mUrlDirectionListener != null) {
            mUrlDirectionListener.onUrlDirectionChanged(urlDirection);
        }
    }
}
 

private static String getTextDirection(Spanned text, int start, int end) {
    /*final int len = end - start;
    final byte[] levels = ArrayUtils.newUnpaddedByteArray(len);
    final char[] buffer = TextUtils.obtain(len);
    TextUtils.getChars(text, start, end, buffer, 0);
    int paraDir = AndroidBidi.bidi(Layout.DIR_REQUEST_DEFAULT_LTR, buffer, levels, len,
            false *//* no info *//*);*/
    int paraDir = Layout.DIR_LEFT_TO_RIGHT;
    switch (paraDir) {
        case Layout.DIR_RIGHT_TO_LEFT:
            return " dir=\"rtl\"";
        case Layout.DIR_LEFT_TO_RIGHT:
        default:
            return " dir=\"ltr\"";
    }
}
 

/**
 * If the direction of the URL has changed, update mUrlDirection and notify the
 * UrlDirectionListeners.
 */
private void updateUrlDirection() {
    Layout layout = getLayout();
    if (layout == null) return;

    int urlDirection;
    if (length() == 0) {
        urlDirection = LAYOUT_DIRECTION_LOCALE;
    } else if (layout.getParagraphDirection(0) == Layout.DIR_LEFT_TO_RIGHT) {
        urlDirection = LAYOUT_DIRECTION_LTR;
    } else {
        urlDirection = LAYOUT_DIRECTION_RTL;
    }

    if (urlDirection != mUrlDirection) {
        mUrlDirection = urlDirection;
        if (mUrlDirectionListener != null) {
            mUrlDirectionListener.onUrlDirectionChanged(urlDirection);
        }
    }
}
 

/**
 * If the direction of the URL has changed, update mUrlDirection and notify the
 * UrlDirectionListeners.
 */
private void updateUrlDirection() {
    Layout layout = getLayout();
    if (layout == null) return;

    int urlDirection;
    if (length() == 0) {
        urlDirection = LAYOUT_DIRECTION_LOCALE;
    } else if (layout.getParagraphDirection(0) == Layout.DIR_LEFT_TO_RIGHT) {
        urlDirection = LAYOUT_DIRECTION_LTR;
    } else {
        urlDirection = LAYOUT_DIRECTION_RTL;
    }

    if (urlDirection != mUrlDirection) {
        mUrlDirection = urlDirection;
        if (mUrlDirectionListener != null) {
            mUrlDirectionListener.onUrlDirectionChanged(urlDirection);
        }
    }
}
 

/**
 * Draws this frame onto the given <code>canvas</code> using the given <code>renderer</code>.
 *
 * @param renderer The renderer to use for drawing this frame.
 * @param canvas The canvas onto which to draw this frame.
 * @param x The x- position at which to draw this frame.
 * @param y The y- position at which to draw this frame.
 */
public void draw(@NonNull Renderer renderer, @NonNull Canvas canvas, float x, float y) {
    canvas.translate(x, y);

    drawBackground(canvas);

    int lineCount = lineList.size();
    for (int i = 0; i < lineCount; i++) {
        ComposedLine composedLine = lineList.get(i);
        Object[] lineSpans = composedLine.getSpans();

        int lineLeft = 0;
        int lineRight = (int) (mWidth + 0.5f);

        // Draw leading margins of this line.
        for (Object style : lineSpans) {
            if (style instanceof LeadingMarginSpan) {
                LeadingMarginSpan span = (LeadingMarginSpan) style;

                byte paragraphLevel = composedLine.getParagraphLevel();
                boolean isLTR = (paragraphLevel & 1) == 0;

                Paint paint = lazyPaint();
                int margin = (isLTR ? lineLeft : lineRight);
                int direction = (isLTR ? Layout.DIR_LEFT_TO_RIGHT : Layout.DIR_RIGHT_TO_LEFT);
                int lineTop = (int) (composedLine.getTop() + 0.5f);
                int lineBaseline = (int) (composedLine.getOriginY() + 0.5f);
                int lineBottom = (int) (composedLine.getTop() + composedLine.getHeight() + 0.5f);
                Spanned sourceText = (Spanned) source;
                int lineStart = composedLine.getCharStart();
                int lineEnd = composedLine.getCharEnd();
                boolean isFirst = composedLine.isFirst();

                span.drawLeadingMargin(canvas, paint, margin, direction,
                                       lineTop, lineBaseline, lineBottom,
                                       sourceText, lineStart, lineEnd, isFirst, null);

                if (isLTR) {
                    lineLeft += span.getLeadingMargin(isFirst);
                } else {
                    lineRight -= span.getLeadingMargin(isFirst);
                }
            }
        }

        composedLine.draw(renderer, canvas, composedLine.getOriginX(), composedLine.getOriginY());
    }

    canvas.translate(-x, -y);
}