org.crsh.text.ui.Layout Maven / Gradle / Ivy
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/*
* Copyright (C) 2012 eXo Platform SAS.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.crsh.text.ui;
import java.util.Arrays;
/**
* The layout computes the lengths of a list of contiguous cells.
*/
public abstract class Layout {
public static Layout flow() {
return RTL;
}
public static Layout weighted(int... weights) throws NullPointerException, IllegalArgumentException {
return new Weighted(weights);
}
/**
* Computes the list of lengths for the specifid list of cells with the following constraints:
*
*
* - the sum of the returned array elements must be equals to the
totalLength argument
* - a cell length should never be lesser than the provided minimum length
*
*
* The returned array is the list of lengths from left to right, the array size may be less than the
* number of cells (i.e the size of the actualLengths and minLengths arguments). Missing
* cells are just be discarded and not part of the resulting layout. Array should contain only positive values,
* any zero length cell should be discarded. When cells must be discarded it must begin with the tail of the
* list, i.e it is not allowed to discard a cell that does not have a successor.
*
*
* @param spaced true if the cells are separated by one char
* @param totalLength the total length of the line
* @param actualLengths the actual length : an estimation of what cell's desired length
* @param minLengths the minmum length : the length under which a cell cannot be rendered
* @return the list of length.
*/
abstract int[] compute(boolean spaced, int totalLength, int[] actualLengths, int[] minLengths);
public static class Weighted extends Layout {
/** The weights. */
private final int[] weights;
/**
* Create a new weighted layout.
*
* @param weights the weights
* @throws NullPointerException if the weights argument is null
* @throws IllegalArgumentException if any weight is negative
*/
private Weighted(int... weights) throws NullPointerException, IllegalArgumentException {
if (weights == null) {
throw new NullPointerException("No null weights accepted");
}
for (int weight : weights) {
if (weight < 0) {
throw new IllegalArgumentException("No negative weight accepted");
}
}
this.weights = weights.clone();
}
public int[] getWeights() {
return weights.clone();
}
@Override
int[] compute(boolean spaced, int length, int[] actualLengths, int[] minLengths) {
//
int count = Math.min(actualLengths.length, weights.length);
//
for (int i = count;i > 0;i--) {
//
int totalLength = length;
int totalWeight = 0;
for (int j = 0;j < i;j++) {
totalWeight += weights[j];
if (spaced) {
if (j > 0) {
totalLength--;
}
}
}
// Compute the length of each cell
int[] ret = new int[i];
for (int j = 0;j < i;j++) {
int w = totalLength * weights[j];
if (w < minLengths[j] * totalWeight) {
ret = null;
break;
} else {
ret[j] = w;
}
}
//
if (ret != null) {
// Error based scaling inspired from Brensenham algorithm:
// => sum of the weights == length
// => minimize error
// for instance with "foo","bar" scaled to 11 chars
// using floor + division gives "foobar_____"
// this methods gives "foo_bar____"
int err = 0;
for (int j = 0;j < ret.length;j++) {
// Compute base value
int value = ret[j] / totalWeight;
// Lower value
int lower = value * totalWeight;
int errLower = err + ret[j] - lower;
// Upper value
int upper = lower + totalWeight;
int errUpper = err + ret[j] - upper;
// We choose between lower/upper according to the accumulated error
// and we propagate the error
if (Math.abs(errLower) < Math.abs(errUpper)) {
ret[j] = value;
err = errLower;
} else {
ret[j] = value + 1;
err = errUpper;
}
}
return ret;
}
}
//
return null;
}
}
private static final Layout RTL = new Layout() {
@Override
int[] compute(boolean spaced, int length, int[] actualLengths, int[] minLengths) {
//
int[] ret = actualLengths.clone();
//
int totalLength = 0;
for (int i = 0;i < actualLengths.length;i++) {
totalLength += actualLengths[i];
if (spaced && i > 0) {
totalLength++;
}
}
//
int index = minLengths.length - 1;
while (totalLength > length && index >= 0) {
int delta = totalLength - length;
int bar = actualLengths[index] - minLengths[index];
if (delta <= bar) {
// We are done
totalLength = length;
ret[index] -= delta;
} else {
int foo = actualLengths[index];
if (spaced) {
if (index > 0) {
foo++;
}
}
totalLength -= foo;
ret[index] = 0;
index--;
}
}
//
if (totalLength > 0) {
if (index == minLengths.length - 1) {
return ret;
} else {
return Arrays.copyOf(ret, index + 1);
}
} else {
return null;
}
}
};
/*
public static final ColumnLayout DISTRIBUTED = new ColumnLayout() {
@Override
public int[] compute(Border border, int width, int[] widths, int[] minWidths) {
int index = 0;
while (true) {
// Compute now the number of chars
boolean done = false;
int total = 0;
for (int i = 0;i < widths.length;i++) {
if (widths[i] >= minWidths[i]) {
total += widths[i];
if (border != null) {
if (done) {
total++;
}
else {
total += 2;
done = true;
}
}
}
}
// It's not valid
if (total == 0) {
return null;
}
//
int delta = width - total;
//
if (delta == 0) {
break;
} else if (delta > 0) {
switch (widths[index]) {
case 0:
break;
default:
widths[index]++;
break;
}
index = (index + 1) % widths.length;
} else {
// First try to remove from a column above min size
int found = -1;
for (int i = widths.length - 1;i >= 0;i--) {
int p = (index + i) % widths.length;
if (widths[p] > minWidths[p]) {
found = p;
if (--index < 0) {
index += widths.length;
}
break;
}
}
// If we haven't found a victim then we consider removing a column
if (found == -1) {
for (int i = widths.length - 1;i >= 0;i--) {
if (widths[i] > 0) {
found = i;
break;
}
}
}
// We couldn't find any solution we give up
if (found == -1) {
break;
} else {
widths[found]--;
}
}
}
//
return widths;
}
};
*/
}
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