307 lines
13 KiB
Java
307 lines
13 KiB
Java
/*
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* Copyright (C) 2006 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package android.view;
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import android.graphics.Rect;
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/**
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* Standard constants and tools for placing an object within a potentially
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* larger container.
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*/
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public class Gravity
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{
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/** Constant indicating that no gravity has been set **/
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public static final int NO_GRAVITY = 0x0000;
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/** Raw bit indicating the gravity for an axis has been specified. */
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public static final int AXIS_SPECIFIED = 0x0001;
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/** Raw bit controlling how the left/top edge is placed. */
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public static final int AXIS_PULL_BEFORE = 0x0002;
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/** Raw bit controlling how the right/bottom edge is placed. */
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public static final int AXIS_PULL_AFTER = 0x0004;
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/** Raw bit controlling whether the right/bottom edge is clipped to its
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* container, based on the gravity direction being applied. */
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public static final int AXIS_CLIP = 0x0008;
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/** Bits defining the horizontal axis. */
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public static final int AXIS_X_SHIFT = 0;
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/** Bits defining the vertical axis. */
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public static final int AXIS_Y_SHIFT = 4;
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/** Push object to the top of its container, not changing its size. */
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public static final int TOP = (AXIS_PULL_BEFORE|AXIS_SPECIFIED)<<AXIS_Y_SHIFT;
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/** Push object to the bottom of its container, not changing its size. */
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public static final int BOTTOM = (AXIS_PULL_AFTER|AXIS_SPECIFIED)<<AXIS_Y_SHIFT;
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/** Push object to the left of its container, not changing its size. */
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public static final int LEFT = (AXIS_PULL_BEFORE|AXIS_SPECIFIED)<<AXIS_X_SHIFT;
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/** Push object to the right of its container, not changing its size. */
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public static final int RIGHT = (AXIS_PULL_AFTER|AXIS_SPECIFIED)<<AXIS_X_SHIFT;
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/** Place object in the vertical center of its container, not changing its
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* size. */
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public static final int CENTER_VERTICAL = AXIS_SPECIFIED<<AXIS_Y_SHIFT;
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/** Grow the vertical size of the object if needed so it completely fills
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* its container. */
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public static final int FILL_VERTICAL = TOP|BOTTOM;
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/** Place object in the horizontal center of its container, not changing its
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* size. */
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public static final int CENTER_HORIZONTAL = AXIS_SPECIFIED<<AXIS_X_SHIFT;
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/** Grow the horizontal size of the object if needed so it completely fills
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* its container. */
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public static final int FILL_HORIZONTAL = LEFT|RIGHT;
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/** Place the object in the center of its container in both the vertical
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* and horizontal axis, not changing its size. */
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public static final int CENTER = CENTER_VERTICAL|CENTER_HORIZONTAL;
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/** Grow the horizontal and vertical size of the object if needed so it
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* completely fills its container. */
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public static final int FILL = FILL_VERTICAL|FILL_HORIZONTAL;
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/** Flag to clip the edges of the object to its container along the
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* vertical axis. */
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public static final int CLIP_VERTICAL = AXIS_CLIP<<AXIS_Y_SHIFT;
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/** Flag to clip the edges of the object to its container along the
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* horizontal axis. */
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public static final int CLIP_HORIZONTAL = AXIS_CLIP<<AXIS_X_SHIFT;
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/**
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* Binary mask to get the horizontal gravity of a gravity.
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*/
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public static final int HORIZONTAL_GRAVITY_MASK = (AXIS_SPECIFIED |
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AXIS_PULL_BEFORE | AXIS_PULL_AFTER) << AXIS_X_SHIFT;
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/**
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* Binary mask to get the vertical gravity of a gravity.
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*/
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public static final int VERTICAL_GRAVITY_MASK = (AXIS_SPECIFIED |
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AXIS_PULL_BEFORE | AXIS_PULL_AFTER) << AXIS_Y_SHIFT;
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/** Special constant to enable clipping to an overall display along the
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* vertical dimension. This is not applied by default by
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* {@link #apply(int, int, int, Rect, int, int, Rect)}; you must do so
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* yourself by calling {@link #applyDisplay}.
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*/
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public static final int DISPLAY_CLIP_VERTICAL = 0x10000000;
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/** Special constant to enable clipping to an overall display along the
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* horizontal dimension. This is not applied by default by
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* {@link #apply(int, int, int, Rect, int, int, Rect)}; you must do so
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* yourself by calling {@link #applyDisplay}.
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*/
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public static final int DISPLAY_CLIP_HORIZONTAL = 0x01000000;
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/**
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* Apply a gravity constant to an object.
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*
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* @param gravity The desired placement of the object, as defined by the
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* constants in this class.
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* @param w The horizontal size of the object.
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* @param h The vertical size of the object.
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* @param container The frame of the containing space, in which the object
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* will be placed. Should be large enough to contain the
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* width and height of the object.
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* @param outRect Receives the computed frame of the object in its
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* container.
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*/
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public static void apply(int gravity, int w, int h, Rect container,
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Rect outRect) {
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apply(gravity, w, h, container, 0, 0, outRect);
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}
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/**
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* Apply a gravity constant to an object.
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*
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* @param gravity The desired placement of the object, as defined by the
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* constants in this class.
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* @param w The horizontal size of the object.
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* @param h The vertical size of the object.
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* @param container The frame of the containing space, in which the object
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* will be placed. Should be large enough to contain the
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* width and height of the object.
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* @param xAdj Offset to apply to the X axis. If gravity is LEFT this
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* pushes it to the right; if gravity is RIGHT it pushes it to
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* the left; if gravity is CENTER_HORIZONTAL it pushes it to the
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* right or left; otherwise it is ignored.
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* @param yAdj Offset to apply to the Y axis. If gravity is TOP this pushes
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* it down; if gravity is BOTTOM it pushes it up; if gravity is
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* CENTER_VERTICAL it pushes it down or up; otherwise it is
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* ignored.
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* @param outRect Receives the computed frame of the object in its
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* container.
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*/
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public static void apply(int gravity, int w, int h, Rect container,
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int xAdj, int yAdj, Rect outRect) {
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switch (gravity&((AXIS_PULL_BEFORE|AXIS_PULL_AFTER)<<AXIS_X_SHIFT)) {
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case 0:
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outRect.left = container.left
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+ ((container.right - container.left - w)/2) + xAdj;
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outRect.right = outRect.left + w;
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if ((gravity&(AXIS_CLIP<<AXIS_X_SHIFT))
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== (AXIS_CLIP<<AXIS_X_SHIFT)) {
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if (outRect.left < container.left) {
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outRect.left = container.left;
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}
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if (outRect.right > container.right) {
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outRect.right = container.right;
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}
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}
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break;
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case AXIS_PULL_BEFORE<<AXIS_X_SHIFT:
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outRect.left = container.left + xAdj;
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outRect.right = outRect.left + w;
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if ((gravity&(AXIS_CLIP<<AXIS_X_SHIFT))
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== (AXIS_CLIP<<AXIS_X_SHIFT)) {
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if (outRect.right > container.right) {
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outRect.right = container.right;
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}
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}
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break;
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case AXIS_PULL_AFTER<<AXIS_X_SHIFT:
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outRect.right = container.right - xAdj;
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outRect.left = outRect.right - w;
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if ((gravity&(AXIS_CLIP<<AXIS_X_SHIFT))
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== (AXIS_CLIP<<AXIS_X_SHIFT)) {
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if (outRect.left < container.left) {
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outRect.left = container.left;
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}
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}
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break;
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default:
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outRect.left = container.left + xAdj;
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outRect.right = container.right + xAdj;
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break;
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}
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switch (gravity&((AXIS_PULL_BEFORE|AXIS_PULL_AFTER)<<AXIS_Y_SHIFT)) {
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case 0:
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outRect.top = container.top
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+ ((container.bottom - container.top - h)/2) + yAdj;
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outRect.bottom = outRect.top + h;
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if ((gravity&(AXIS_CLIP<<AXIS_Y_SHIFT))
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== (AXIS_CLIP<<AXIS_Y_SHIFT)) {
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if (outRect.top < container.top) {
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outRect.top = container.top;
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}
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if (outRect.bottom > container.bottom) {
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outRect.bottom = container.bottom;
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}
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}
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break;
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case AXIS_PULL_BEFORE<<AXIS_Y_SHIFT:
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outRect.top = container.top + yAdj;
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outRect.bottom = outRect.top + h;
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if ((gravity&(AXIS_CLIP<<AXIS_Y_SHIFT))
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== (AXIS_CLIP<<AXIS_Y_SHIFT)) {
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if (outRect.bottom > container.bottom) {
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outRect.bottom = container.bottom;
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}
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}
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break;
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case AXIS_PULL_AFTER<<AXIS_Y_SHIFT:
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outRect.bottom = container.bottom - yAdj;
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outRect.top = outRect.bottom - h;
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if ((gravity&(AXIS_CLIP<<AXIS_Y_SHIFT))
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== (AXIS_CLIP<<AXIS_Y_SHIFT)) {
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if (outRect.top < container.top) {
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outRect.top = container.top;
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}
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}
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break;
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default:
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outRect.top = container.top + yAdj;
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outRect.bottom = container.bottom + yAdj;
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break;
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}
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}
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/**
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* Apply additional gravity behavior based on the overall "display" that an
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* object exists in. This can be used after
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* {@link #apply(int, int, int, Rect, int, int, Rect)} to place the object
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* within a visible display. By default this moves or clips the object
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* to be visible in the display; the gravity flags
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* {@link #DISPLAY_CLIP_HORIZONTAL} and {@link #DISPLAY_CLIP_VERTICAL}
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* can be used to change this behavior.
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*
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* @param gravity Gravity constants to modify the placement within the
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* display.
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* @param display The rectangle of the display in which the object is
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* being placed.
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* @param inoutObj Supplies the current object position; returns with it
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* modified if needed to fit in the display.
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*/
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public static void applyDisplay(int gravity, Rect display, Rect inoutObj) {
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if ((gravity&DISPLAY_CLIP_VERTICAL) != 0) {
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if (inoutObj.top < display.top) inoutObj.top = display.top;
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if (inoutObj.bottom > display.bottom) inoutObj.bottom = display.bottom;
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} else {
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int off = 0;
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if (inoutObj.top < display.top) off = display.top-inoutObj.top;
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else if (inoutObj.bottom > display.bottom) off = display.bottom-inoutObj.bottom;
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if (off != 0) {
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if (inoutObj.height() > (display.bottom-display.top)) {
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inoutObj.top = display.top;
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inoutObj.bottom = display.bottom;
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} else {
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inoutObj.top += off;
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inoutObj.bottom += off;
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}
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}
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}
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if ((gravity&DISPLAY_CLIP_HORIZONTAL) != 0) {
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if (inoutObj.left < display.left) inoutObj.left = display.left;
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if (inoutObj.right > display.right) inoutObj.right = display.right;
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} else {
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int off = 0;
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if (inoutObj.left < display.left) off = display.left-inoutObj.left;
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else if (inoutObj.right > display.right) off = display.right-inoutObj.right;
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if (off != 0) {
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if (inoutObj.width() > (display.right-display.left)) {
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inoutObj.left = display.left;
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inoutObj.right = display.right;
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} else {
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inoutObj.left += off;
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inoutObj.right += off;
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}
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}
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}
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}
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/**
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* <p>Indicate whether the supplied gravity has a vertical pull.</p>
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*
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* @param gravity the gravity to check for vertical pull
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* @return true if the supplied gravity has a vertical pull
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*/
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public static boolean isVertical(int gravity) {
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return gravity > 0 && (gravity & VERTICAL_GRAVITY_MASK) != 0;
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}
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/**
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* <p>Indicate whether the supplied gravity has an horizontal pull.</p>
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*
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* @param gravity the gravity to check for horizontal pull
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* @return true if the supplied gravity has an horizontal pull
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*/
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public static boolean isHorizontal(int gravity) {
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return gravity > 0 && (gravity & HORIZONTAL_GRAVITY_MASK) != 0;
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}
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}
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