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Touch.javaAPI DocAndroid 5.1 API9422Thu Mar 12 22:22:10 GMT 2015android.text.method

Touch

public class Touch extends Object

Fields Summary
Constructors Summary
private Touch()
Methods Summary
public static intgetInitialScrollX(android.widget.TextView widget, android.text.Spannable buffer)

param
widget The text view.
param
buffer The text buffer.

        DragState[] ds = buffer.getSpans(0, buffer.length(), DragState.class);
        return ds.length > 0 ? ds[0].mScrollX : -1;
public static intgetInitialScrollY(android.widget.TextView widget, android.text.Spannable buffer)

param
widget The text view.
param
buffer The text buffer.

        DragState[] ds = buffer.getSpans(0, buffer.length(), DragState.class);
        return ds.length > 0 ? ds[0].mScrollY : -1;
static booleanisActivelySelecting(android.text.Spannable buffer)
Checks if selection is still active. This is useful for extending Selection span on buffer.

param
buffer The text buffer.
return
true if buffer has been marked for selection.
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        DragState[] ds;
        ds = buffer.getSpans(0, buffer.length(), DragState.class);

        return ds.length > 0 && ds[0].mIsActivelySelecting;
static booleanisSelectionStarted(android.text.Spannable buffer)
Checks if selection has begun (are we out of slop?). Note: DragState.mIsSelectionStarted goes back to false with the very next event. This is useful for starting Selection span on buffer.

param
buffer The text buffer.
return
true if selection has started on the buffer.
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        DragState[] ds;
        ds = buffer.getSpans(0, buffer.length(), DragState.class);

        return ds.length > 0 && ds[0].mIsSelectionStarted;
public static booleanonTouchEvent(android.widget.TextView widget, android.text.Spannable buffer, android.view.MotionEvent event)
Handles touch events for dragging. You may want to do other actions like moving the cursor on touch as well.

        DragState[] ds;

        switch (event.getActionMasked()) {
        case MotionEvent.ACTION_DOWN:
            ds = buffer.getSpans(0, buffer.length(), DragState.class);

            for (int i = 0; i < ds.length; i++) {
                buffer.removeSpan(ds[i]);
            }

            buffer.setSpan(new DragState(event.getX(), event.getY(),
                            widget.getScrollX(), widget.getScrollY()),
                    0, 0, Spannable.SPAN_MARK_MARK);
            return true;

        case MotionEvent.ACTION_UP:
            ds = buffer.getSpans(0, buffer.length(), DragState.class);

            for (int i = 0; i < ds.length; i++) {
                buffer.removeSpan(ds[i]);
            }

            if (ds.length > 0 && ds[0].mUsed) {
                return true;
            } else {
                return false;
            }

        case MotionEvent.ACTION_MOVE:
            ds = buffer.getSpans(0, buffer.length(), DragState.class);

            if (ds.length > 0) {
                ds[0].mIsSelectionStarted = false;

                if (ds[0].mFarEnough == false) {
                    int slop = ViewConfiguration.get(widget.getContext()).getScaledTouchSlop();

                    if (Math.abs(event.getX() - ds[0].mX) >= slop ||
                        Math.abs(event.getY() - ds[0].mY) >= slop) {
                        ds[0].mFarEnough = true;
                        if (event.isButtonPressed(MotionEvent.BUTTON_PRIMARY)) {
                            ds[0].mIsActivelySelecting = true;
                            ds[0].mIsSelectionStarted = true;
                        }
                    }
                }

                if (ds[0].mFarEnough) {
                    ds[0].mUsed = true;
                    boolean cap = (event.getMetaState() & KeyEvent.META_SHIFT_ON) != 0
                            || MetaKeyKeyListener.getMetaState(buffer,
                                    MetaKeyKeyListener.META_SHIFT_ON) == 1
                            || MetaKeyKeyListener.getMetaState(buffer,
                                    MetaKeyKeyListener.META_SELECTING) != 0;

                    if (!event.isButtonPressed(MotionEvent.BUTTON_PRIMARY)) {
                        ds[0].mIsActivelySelecting = false;
                    }

                    float dx;
                    float dy;
                    if (cap && event.isButtonPressed(MotionEvent.BUTTON_PRIMARY)) {
                        // if we're selecting, we want the scroll to go in
                        // the direction of the drag
                        dx = event.getX() - ds[0].mX;
                        dy = event.getY() - ds[0].mY;
                    } else {
                        dx = ds[0].mX - event.getX();
                        dy = ds[0].mY - event.getY();
                    }
                    ds[0].mX = event.getX();
                    ds[0].mY = event.getY();

                    int nx = widget.getScrollX() + (int) dx;
                    int ny = widget.getScrollY() + (int) dy;

                    int padding = widget.getTotalPaddingTop() + widget.getTotalPaddingBottom();
                    Layout layout = widget.getLayout();

                    ny = Math.min(ny, layout.getHeight() - (widget.getHeight() - padding));
                    ny = Math.max(ny, 0);

                    int oldX = widget.getScrollX();
                    int oldY = widget.getScrollY();

                    if (!event.isButtonPressed(MotionEvent.BUTTON_PRIMARY)) {
                        scrollTo(widget, layout, nx, ny);
                    }

                    // If we actually scrolled, then cancel the up action.
                    if (oldX != widget.getScrollX() || oldY != widget.getScrollY()) {
                        widget.cancelLongPress();
                    }

                    return true;
                }
            }
        }

        return false;
public static voidscrollTo(android.widget.TextView widget, android.text.Layout layout, int x, int y)
Scrolls the specified widget to the specified coordinates, except constrains the X scrolling position to the horizontal regions of the text that will be visible after scrolling to the specified Y position.

        final int horizontalPadding = widget.getTotalPaddingLeft() + widget.getTotalPaddingRight();
        final int availableWidth = widget.getWidth() - horizontalPadding;

        final int top = layout.getLineForVertical(y);
        Alignment a = layout.getParagraphAlignment(top);
        boolean ltr = layout.getParagraphDirection(top) > 0;

        int left, right;
        if (widget.getHorizontallyScrolling()) {
            final int verticalPadding = widget.getTotalPaddingTop() + widget.getTotalPaddingBottom();
            final int bottom = layout.getLineForVertical(y + widget.getHeight() - verticalPadding);

            left = Integer.MAX_VALUE;
            right = 0;

            for (int i = top; i <= bottom; i++) {
                left = (int) Math.min(left, layout.getLineLeft(i));
                right = (int) Math.max(right, layout.getLineRight(i));
            }
        } else {
            left = 0;
            right = availableWidth;
        }

        final int actualWidth = right - left;

        if (actualWidth < availableWidth) {
            if (a == Alignment.ALIGN_CENTER) {
                x = left - ((availableWidth - actualWidth) / 2);
            } else if ((ltr && (a == Alignment.ALIGN_OPPOSITE)) ||
                       (!ltr && (a == Alignment.ALIGN_NORMAL)) ||
                       (a == Alignment.ALIGN_RIGHT)) {
                // align_opposite does NOT mean align_right, we need the paragraph
                // direction to resolve it to left or right
                x = left - (availableWidth - actualWidth);
            } else {
                x = left;
            }
        } else {
            x = Math.min(x, right - availableWidth);
            x = Math.max(x, left);
        }

        widget.scrollTo(x, y);