fr.mncc.gwttoolbox.ui.client.LightBox.java Source code

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Here is the source code for fr.mncc.gwttoolbox.ui.client.LightBox.java

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/**
 * Copyright (c) 2014 MNCC
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and
 * associated documentation files (the "Software"), to deal in the Software without restriction,
 * including without limitation the rights to use, copy, modify, merge, publish, distribute,
 * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in all copies or
 * substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT
 * NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 * 
 * @author http://www.mncc.fr
 */
package fr.mncc.gwttoolbox.ui.client;

import com.google.gwt.core.client.GWT;
import com.google.gwt.core.client.Scheduler;
import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.Style;
import com.google.gwt.uibinder.client.UiBinder;
import com.google.gwt.uibinder.client.UiConstructor;
import com.google.gwt.uibinder.client.UiField;
import com.google.gwt.user.client.ui.Composite;
import com.google.gwt.user.client.ui.HTMLPanel;
import com.google.gwt.user.client.ui.Widget;

/**
 * Implementation of an image gallery similar to the one from http://www.lightbox.com/.
 */
public final class LightBox extends Composite {

    private final static LightBoxUiBinder uiBinder_ = GWT.create(LightBoxUiBinder.class);
    private final int DELTA = 20;
    private final int columnsWidth_;
    private final int margin_;
    @UiField
    HTMLPanel lightBox;
    private int[] columnsHeight_;
    private int extraMargin_;

    @UiConstructor
    public LightBox(int columnsWidth, int margin) {
        columnsWidth_ = columnsWidth;
        margin_ = margin;
        initWidget(uiBinder_.createAndBindUi(this));
    }

    @Override
    protected void onLoad() {
        super.onLoad();
        Scheduler.get().scheduleDeferred(new Scheduler.ScheduledCommand() {

            @Override
            public void execute() {
                int containerSize = getOffsetWidth() - 2 * (DELTA + margin_);
                int nbColumns = (int) Math.floor(containerSize / (columnsWidth_ + margin_));
                extraMargin_ = (getOffsetWidth() - containerSize
                        + (containerSize - nbColumns * (columnsWidth_ + margin_))) / 2;
                createColumns(nbColumns);
            }
        });
    }

    @Override
    protected void onUnload() {
        columnsHeight_ = null;
        super.onUnload();
    }

    private void createColumns(int n) {
        columnsHeight_ = new int[n];
        for (int i = 0; i < n; ++i) {
            columnsHeight_[i] = margin_;
        }
    }

    private int getMaxHeight() {
        int maxHeight = Integer.MIN_VALUE;
        for (int i = 0; i < columnsHeight_.length; ++i) {
            if (columnsHeight_[i] > maxHeight) {
                maxHeight = columnsHeight_[i];
            }
        }
        return maxHeight;
    }

    private int getMinColumn() {
        int minHeight = Integer.MAX_VALUE;
        int minIndex = -1;
        for (int i = 0; i < columnsHeight_.length; ++i) {
            if (columnsHeight_[i] < minHeight) {
                minHeight = columnsHeight_[i];
                minIndex = i;
            }
        }
        return minIndex;
    }

    private ImageSize fitWidth(int imageWidth, int imageHeight, int rowspan) {
        int imageWidthNew = columnsWidth_ * rowspan;
        if (rowspan > 1) {
            imageWidthNew += margin_;
        }

        int imageHeightNew = (imageHeight * imageWidthNew) / imageWidth;
        return new ImageSize(imageWidthNew, imageHeightNew);
    }

    private void addColumnElem(int i, Element elem, int elemWidth, int elemHeight, int rowspan) {
        ImageSize newSize = fitWidth(elemWidth, elemHeight, 1 + Math.abs(rowspan));
        newSize.height_ -= (columnsHeight_[i] + newSize.height_ + margin_) % DELTA;

        Style elemStyle = elem.getStyle();
        elemStyle.setMarginLeft(extraMargin_ + margin_ + (columnsWidth_ + margin_) * (i + (rowspan == -1 ? -1 : 0)),
                Style.Unit.PX);
        elemStyle.setMarginTop(columnsHeight_[i], Style.Unit.PX);
        elemStyle.setWidth(newSize.width_, Style.Unit.PX);
        elemStyle.setHeight(newSize.height_, Style.Unit.PX);

        int nextHeight = columnsHeight_[i] + newSize.height_ + margin_;
        columnsHeight_[i + rowspan] = columnsHeight_[i] = nextHeight;
    }

    /**
     * Add a new image to the gallery.
     * 
     * @param image to be added
     */
    public void addImage(LightBoxImage image) {
        int column = getMinColumn();
        int rowspan = 0;
        if (Math.random() > 0.5) {
            if (column - 1 > 0 && columnsHeight_[column - 1] <= columnsHeight_[column]) {
                rowspan = -1;
            } else if (column + 1 < columnsHeight_.length && columnsHeight_[column + 1] <= columnsHeight_[column]) {
                rowspan = 1;
            }
        }
        Element elem = image.getImage();
        elem.addClassName("img");
        addColumnElem(column, elem, image.getTrueImageWidth(), image.getTrueImageHeight(), rowspan);
        lightBox.setHeight(getMaxHeight() + "px");
        lightBox.add(image);
    }

    interface LightBoxUiBinder extends UiBinder<Widget, LightBox> {
    }

    public static abstract class LightBoxImage extends Composite {

        public abstract Element getImage();

        public abstract int getTrueImageWidth();

        public abstract int getTrueImageHeight();
    }

    class ImageSize {

        public int width_;
        public int height_;

        public ImageSize(int width, int height) {
            width_ = width;
            height_ = height;
        }
    }
}