Java tutorial
/* * Copyright (C) 2006 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.annotation.UnsupportedAppUsage; import android.os.Build; import android.text.Layout; import android.text.NoCopySpan; import android.text.Selection; import android.text.Spannable; import android.text.style.ClickableSpan; import android.view.KeyEvent; import android.view.MotionEvent; import android.view.View; import android.view.textclassifier.TextLinks.TextLinkSpan; import android.widget.TextView; /** * A movement method that traverses links in the text buffer and scrolls if necessary. * Supports clicking on links with DPad Center or Enter. */ public class LinkMovementMethod extends ScrollingMovementMethod { private static final int CLICK = 1; private static final int UP = 2; private static final int DOWN = 3; private static final int HIDE_FLOATING_TOOLBAR_DELAY_MS = 200; @Override public boolean canSelectArbitrarily() { return true; } @Override protected boolean handleMovementKey(TextView widget, Spannable buffer, int keyCode, int movementMetaState, KeyEvent event) { switch (keyCode) { case KeyEvent.KEYCODE_DPAD_CENTER: case KeyEvent.KEYCODE_ENTER: if (KeyEvent.metaStateHasNoModifiers(movementMetaState)) { if (event.getAction() == KeyEvent.ACTION_DOWN && event.getRepeatCount() == 0 && action(CLICK, widget, buffer)) { return true; } } break; } return super.handleMovementKey(widget, buffer, keyCode, movementMetaState, event); } @Override protected boolean up(TextView widget, Spannable buffer) { if (action(UP, widget, buffer)) { return true; } return super.up(widget, buffer); } @Override protected boolean down(TextView widget, Spannable buffer) { if (action(DOWN, widget, buffer)) { return true; } return super.down(widget, buffer); } @Override protected boolean left(TextView widget, Spannable buffer) { if (action(UP, widget, buffer)) { return true; } return super.left(widget, buffer); } @Override protected boolean right(TextView widget, Spannable buffer) { if (action(DOWN, widget, buffer)) { return true; } return super.right(widget, buffer); } private boolean action(int what, TextView widget, Spannable buffer) { Layout layout = widget.getLayout(); int padding = widget.getTotalPaddingTop() + widget.getTotalPaddingBottom(); int areaTop = widget.getScrollY(); int areaBot = areaTop + widget.getHeight() - padding; int lineTop = layout.getLineForVertical(areaTop); int lineBot = layout.getLineForVertical(areaBot); int first = layout.getLineStart(lineTop); int last = layout.getLineEnd(lineBot); ClickableSpan[] candidates = buffer.getSpans(first, last, ClickableSpan.class); int a = Selection.getSelectionStart(buffer); int b = Selection.getSelectionEnd(buffer); int selStart = Math.min(a, b); int selEnd = Math.max(a, b); if (selStart < 0) { if (buffer.getSpanStart(FROM_BELOW) >= 0) { selStart = selEnd = buffer.length(); } } if (selStart > last) selStart = selEnd = Integer.MAX_VALUE; if (selEnd < first) selStart = selEnd = -1; switch (what) { case CLICK: if (selStart == selEnd) { return false; } ClickableSpan[] links = buffer.getSpans(selStart, selEnd, ClickableSpan.class); if (links.length != 1) { return false; } ClickableSpan link = links[0]; if (link instanceof TextLinkSpan) { ((TextLinkSpan) link).onClick(widget, TextLinkSpan.INVOCATION_METHOD_KEYBOARD); } else { link.onClick(widget); } break; case UP: int bestStart, bestEnd; bestStart = -1; bestEnd = -1; for (int i = 0; i < candidates.length; i++) { int end = buffer.getSpanEnd(candidates[i]); if (end < selEnd || selStart == selEnd) { if (end > bestEnd) { bestStart = buffer.getSpanStart(candidates[i]); bestEnd = end; } } } if (bestStart >= 0) { Selection.setSelection(buffer, bestEnd, bestStart); return true; } break; case DOWN: bestStart = Integer.MAX_VALUE; bestEnd = Integer.MAX_VALUE; for (int i = 0; i < candidates.length; i++) { int start = buffer.getSpanStart(candidates[i]); if (start > selStart || selStart == selEnd) { if (start < bestStart) { bestStart = start; bestEnd = buffer.getSpanEnd(candidates[i]); } } } if (bestEnd < Integer.MAX_VALUE) { Selection.setSelection(buffer, bestStart, bestEnd); return true; } break; } return false; } @Override public boolean onTouchEvent(TextView widget, Spannable buffer, MotionEvent event) { int action = event.getAction(); if (action == MotionEvent.ACTION_UP || action == MotionEvent.ACTION_DOWN) { int x = (int) event.getX(); int y = (int) event.getY(); x -= widget.getTotalPaddingLeft(); y -= widget.getTotalPaddingTop(); x += widget.getScrollX(); y += widget.getScrollY(); Layout layout = widget.getLayout(); int line = layout.getLineForVertical(y); int off = layout.getOffsetForHorizontal(line, x); ClickableSpan[] links = buffer.getSpans(off, off, ClickableSpan.class); if (links.length != 0) { ClickableSpan link = links[0]; if (action == MotionEvent.ACTION_UP) { if (link instanceof TextLinkSpan) { ((TextLinkSpan) link).onClick(widget, TextLinkSpan.INVOCATION_METHOD_TOUCH); } else { link.onClick(widget); } } else if (action == MotionEvent.ACTION_DOWN) { if (widget.getContext().getApplicationInfo().targetSdkVersion >= Build.VERSION_CODES.P) { // Selection change will reposition the toolbar. Hide it for a few ms for a // smoother transition. widget.hideFloatingToolbar(HIDE_FLOATING_TOOLBAR_DELAY_MS); } Selection.setSelection(buffer, buffer.getSpanStart(link), buffer.getSpanEnd(link)); } return true; } else { Selection.removeSelection(buffer); } } return super.onTouchEvent(widget, buffer, event); } @Override public void initialize(TextView widget, Spannable text) { Selection.removeSelection(text); text.removeSpan(FROM_BELOW); } @Override public void onTakeFocus(TextView view, Spannable text, int dir) { Selection.removeSelection(text); if ((dir & View.FOCUS_BACKWARD) != 0) { text.setSpan(FROM_BELOW, 0, 0, Spannable.SPAN_POINT_POINT); } else { text.removeSpan(FROM_BELOW); } } public static MovementMethod getInstance() { if (sInstance == null) sInstance = new LinkMovementMethod(); return sInstance; } @UnsupportedAppUsage private static LinkMovementMethod sInstance; private static Object FROM_BELOW = new NoCopySpan.Concrete(); }