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/*
* Copyright (C) 2008 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.
*/
package android.text.method;
import android.text.Layout;
import android.text.Layout.Alignment;
import android.text.NoCopySpan;
import android.text.Spannable;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.ViewConfiguration;
import android.widget.TextView;
public class Touch {
private Touch() { }
/**
* 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.
*/
public static void scrollTo(TextView widget, Layout layout, int x, int y) {
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);
}
/**
* Handles touch events for dragging. You may want to do other actions
* like moving the cursor on touch as well.
*/
public static boolean onTouchEvent(TextView widget, Spannable buffer,
MotionEvent event) {
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) {
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 (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;
float dx;
float dy;
if (cap) {
// 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();
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;
}
/**
* @param widget The text view.
* @param buffer The text buffer.
*/
public static int getInitialScrollX(TextView widget, Spannable buffer) {
DragState[] ds = buffer.getSpans(0, buffer.length(), DragState.class);
return ds.length > 0 ? ds[0].mScrollX : -1;
}
/**
* @param widget The text view.
* @param buffer The text buffer.
*/
public static int getInitialScrollY(TextView widget, Spannable buffer) {
DragState[] ds = buffer.getSpans(0, buffer.length(), DragState.class);
return ds.length > 0 ? ds[0].mScrollY : -1;
}
private static class DragState implements NoCopySpan {
public float mX;
public float mY;
public int mScrollX;
public int mScrollY;
public boolean mFarEnough;
public boolean mUsed;
public DragState(float x, float y, int scrollX, int scrollY) {
mX = x;
mY = y;
mScrollX = scrollX;
mScrollY = scrollY;
}
}
}
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