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A library jar that provides APIs for Applications written for the Google Android Platform.
/*
* 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.view;
import android.graphics.Rect;
/**
* Standard constants and tools for placing an object within a potentially
* larger container.
*/
public class Gravity
{
/** Constant indicating that no gravity has been set **/
public static final int NO_GRAVITY = 0x0000;
/** Raw bit indicating the gravity for an axis has been specified. */
public static final int AXIS_SPECIFIED = 0x0001;
/** Raw bit controlling how the left/top edge is placed. */
public static final int AXIS_PULL_BEFORE = 0x0002;
/** Raw bit controlling how the right/bottom edge is placed. */
public static final int AXIS_PULL_AFTER = 0x0004;
/** Raw bit controlling whether the right/bottom edge is clipped to its
* container, based on the gravity direction being applied. */
public static final int AXIS_CLIP = 0x0008;
/** Bits defining the horizontal axis. */
public static final int AXIS_X_SHIFT = 0;
/** Bits defining the vertical axis. */
public static final int AXIS_Y_SHIFT = 4;
/** Push object to the top of its container, not changing its size. */
public static final int TOP = (AXIS_PULL_BEFORE|AXIS_SPECIFIED)< container.right) {
outRect.right = container.right;
}
}
break;
case AXIS_PULL_BEFORE< container.right) {
outRect.right = container.right;
}
}
break;
case AXIS_PULL_AFTER< container.bottom) {
outRect.bottom = container.bottom;
}
}
break;
case AXIS_PULL_BEFORE< container.bottom) {
outRect.bottom = container.bottom;
}
}
break;
case AXIS_PULL_AFTER< display.bottom) inoutObj.bottom = display.bottom;
} else {
int off = 0;
if (inoutObj.top < display.top) off = display.top-inoutObj.top;
else if (inoutObj.bottom > display.bottom) off = display.bottom-inoutObj.bottom;
if (off != 0) {
if (inoutObj.height() > (display.bottom-display.top)) {
inoutObj.top = display.top;
inoutObj.bottom = display.bottom;
} else {
inoutObj.top += off;
inoutObj.bottom += off;
}
}
}
if ((gravity&DISPLAY_CLIP_HORIZONTAL) != 0) {
if (inoutObj.left < display.left) inoutObj.left = display.left;
if (inoutObj.right > display.right) inoutObj.right = display.right;
} else {
int off = 0;
if (inoutObj.left < display.left) off = display.left-inoutObj.left;
else if (inoutObj.right > display.right) off = display.right-inoutObj.right;
if (off != 0) {
if (inoutObj.width() > (display.right-display.left)) {
inoutObj.left = display.left;
inoutObj.right = display.right;
} else {
inoutObj.left += off;
inoutObj.right += off;
}
}
}
}
/**
* Apply additional gravity behavior based on the overall "display" that an
* object exists in. This can be used after
* {@link #apply(int, int, int, Rect, int, int, Rect)} to place the object
* within a visible display. By default this moves or clips the object
* to be visible in the display; the gravity flags
* {@link #DISPLAY_CLIP_HORIZONTAL} and {@link #DISPLAY_CLIP_VERTICAL}
* can be used to change this behavior.
*
* @param gravity Gravity constants to modify the placement within the
* display.
* @param display The rectangle of the display in which the object is
* being placed.
* @param inoutObj Supplies the current object position; returns with it
* modified if needed to fit in the display.
* @param layoutDirection The layout direction.
*
* @see View#LAYOUT_DIRECTION_LTR
* @see View#LAYOUT_DIRECTION_RTL
*/
public static void applyDisplay(int gravity, Rect display, Rect inoutObj, int layoutDirection) {
int absGravity = getAbsoluteGravity(gravity, layoutDirection);
applyDisplay(absGravity, display, inoutObj);
}
/**
* Indicate whether the supplied gravity has a vertical pull.
*
* @param gravity the gravity to check for vertical pull
* @return true if the supplied gravity has a vertical pull
*/
public static boolean isVertical(int gravity) {
return gravity > 0 && (gravity & VERTICAL_GRAVITY_MASK) != 0;
}
/**
* Indicate whether the supplied gravity has an horizontal pull.
*
* @param gravity the gravity to check for horizontal pull
* @return true if the supplied gravity has an horizontal pull
*/
public static boolean isHorizontal(int gravity) {
return gravity > 0 && (gravity & RELATIVE_HORIZONTAL_GRAVITY_MASK) != 0;
}
/**
* Convert script specific gravity to absolute horizontal value.
*
* if horizontal direction is LTR, then START will set LEFT and END will set RIGHT.
* if horizontal direction is RTL, then START will set RIGHT and END will set LEFT.
*
*
* @param gravity The gravity to convert to absolute (horizontal) values.
* @param layoutDirection The layout direction.
* @return gravity converted to absolute (horizontal) values.
*/
public static int getAbsoluteGravity(int gravity, int layoutDirection) {
int result = gravity;
// If layout is script specific and gravity is horizontal relative (START or END)
if ((result & RELATIVE_LAYOUT_DIRECTION) > 0) {
if ((result & Gravity.START) == Gravity.START) {
// Remove the START bit
result &= ~START;
if (layoutDirection == View.LAYOUT_DIRECTION_RTL) {
// Set the RIGHT bit
result |= RIGHT;
} else {
// Set the LEFT bit
result |= LEFT;
}
} else if ((result & Gravity.END) == Gravity.END) {
// Remove the END bit
result &= ~END;
if (layoutDirection == View.LAYOUT_DIRECTION_RTL) {
// Set the LEFT bit
result |= LEFT;
} else {
// Set the RIGHT bit
result |= RIGHT;
}
}
// Don't need the script specific bit any more, so remove it as we are converting to
// absolute values (LEFT or RIGHT)
result &= ~RELATIVE_LAYOUT_DIRECTION;
}
return result;
}
}