/*
* Copyright 2010 Google Inc.
*
* 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 com.google.gwt.cell.client;
import com.google.gwt.core.client.GWT;
import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.NativeEvent;
import com.google.gwt.i18n.client.LocaleInfo;
import com.google.gwt.resources.client.ImageResource;
import com.google.gwt.safecss.shared.SafeStyles;
import com.google.gwt.safecss.shared.SafeStylesBuilder;
import com.google.gwt.safecss.shared.SafeStylesUtils;
import com.google.gwt.safehtml.client.SafeHtmlTemplates;
import com.google.gwt.safehtml.shared.SafeHtml;
import com.google.gwt.safehtml.shared.SafeHtmlBuilder;
import com.google.gwt.safehtml.shared.SafeHtmlUtils;
import com.google.gwt.user.client.ui.AbstractImagePrototype;
import com.google.gwt.user.client.ui.HasVerticalAlignment;
import com.google.gwt.user.client.ui.HasVerticalAlignment.VerticalAlignmentConstant;
import java.util.Set;
/**
* A {@link Cell} decorator that adds an icon to another {@link Cell}.
*
* @param <C> the type that this Cell represents
*/
public class IconCellDecorator<C> implements Cell<C> {
interface Template extends SafeHtmlTemplates {
@Template("<div style=\"{0}position:relative;zoom:1;\">{1}<div>{2}</div></div>")
SafeHtml outerDiv(SafeStyles padding, SafeHtml icon, SafeHtml cellContents);
/**
* The wrapper around the image vertically aligned to the bottom.
*/
@Template("<div style=\"{0}position:absolute;bottom:0px;line-height:0px;\">{1}</div>")
SafeHtml imageWrapperBottom(SafeStyles styles, SafeHtml image);
/**
* The wrapper around the image vertically aligned to the middle.
*/
@Template("<div style=\"{0}position:absolute;top:50%;line-height:0px;\">{1}</div>")
SafeHtml imageWrapperMiddle(SafeStyles styles, SafeHtml image);
/**
* The wrapper around the image vertically aligned to the top.
*/
@Template("<div style=\"{0}position:absolute;top:0px;line-height:0px;\">{1}</div>")
SafeHtml imageWrapperTop(SafeStyles styles, SafeHtml image);
}
/**
* The default spacing between the icon and the text in pixels.
*/
private static final int DEFAULT_SPACING = 6;
private static Template template;
private final Cell<C> cell;
private final String direction = LocaleInfo.getCurrentLocale().isRTL()
? "right" : "left";
private final SafeHtml iconHtml;
private final int imageWidth;
private final SafeStyles outerDivPadding;
private final SafeHtml placeHolderHtml;
/**
* Construct a new {@link IconCellDecorator}. The icon and the content will be
* middle aligned by default.
*
* @param icon the icon to use
* @param cell the cell to decorate
*/
public IconCellDecorator(ImageResource icon, Cell<C> cell) {
this(icon, cell, HasVerticalAlignment.ALIGN_MIDDLE, DEFAULT_SPACING);
}
/**
* Construct a new {@link IconCellDecorator}.
*
* @param icon the icon to use
* @param cell the cell to decorate
* @param valign the vertical alignment attribute of the contents
* @param spacing the pixel space between the icon and the cell
*/
public IconCellDecorator(ImageResource icon, Cell<C> cell, VerticalAlignmentConstant valign,
int spacing) {
if (template == null) {
template = GWT.create(Template.class);
}
this.cell = cell;
this.iconHtml = getImageHtml(icon, valign, false);
this.imageWidth = icon.getWidth() + spacing;
this.placeHolderHtml = getImageHtml(icon, valign, true);
this.outerDivPadding =
SafeStylesUtils.fromTrustedString("padding-" + direction + ": " + imageWidth + "px;");
}
public boolean dependsOnSelection() {
return cell.dependsOnSelection();
}
public Set<String> getConsumedEvents() {
return cell.getConsumedEvents();
}
public boolean handlesSelection() {
return cell.handlesSelection();
}
public boolean isEditing(Context context, Element parent, C value) {
return cell.isEditing(context, getCellParent(parent), value);
}
public void onBrowserEvent(Context context, Element parent, C value,
NativeEvent event, ValueUpdater<C> valueUpdater) {
cell.onBrowserEvent(context, getCellParent(parent), value, event,
valueUpdater);
}
public void render(Context context, C value, SafeHtmlBuilder sb) {
SafeHtmlBuilder cellBuilder = new SafeHtmlBuilder();
cell.render(context, value, cellBuilder);
sb.append(template.outerDiv(outerDivPadding, isIconUsed(value) ? getIconHtml(value)
: placeHolderHtml, cellBuilder.toSafeHtml()));
}
public boolean resetFocus(Context context, Element parent, C value) {
return cell.resetFocus(context, getCellParent(parent), value);
}
public void setValue(Context context, Element parent, C value) {
cell.setValue(context, getCellParent(parent), value);
}
/**
* Get the safe HTML string that represents the icon. Override this method to
* change the icon based on the value.
*
* @param value the value being rendered
* @return the HTML string that represents the icon
*/
protected SafeHtml getIconHtml(C value) {
return iconHtml;
}
/**
* Check if the icon should be used for the value. If the icon should not be
* used, a placeholder of the same size will be used instead. The default
* implementations returns true.
*
* @param value the value being rendered
* @return true to use the icon, false to use a placeholder
*/
protected boolean isIconUsed(C value) {
return true;
}
/**
* Get the HTML representation of an image. Visible for testing.
*
* @param res the {@link ImageResource} to render as HTML
* @param valign the vertical alignment
* @param isPlaceholder if true, do not include the background image
* @return the rendered HTML
*/
SafeHtml getImageHtml(ImageResource res, VerticalAlignmentConstant valign, boolean isPlaceholder) {
// Get the HTML for the image.
SafeHtml image;
if (isPlaceholder) {
image = SafeHtmlUtils.fromSafeConstant("<div></div>");
} else {
AbstractImagePrototype proto = AbstractImagePrototype.create(res);
image = SafeHtmlUtils.fromTrustedString(proto.getHTML());
}
// Create the wrapper based on the vertical alignment.
SafeStylesBuilder cssStyles =
new SafeStylesBuilder().appendTrustedString(direction + ":0px;");
if (HasVerticalAlignment.ALIGN_TOP == valign) {
return template.imageWrapperTop(cssStyles.toSafeStyles(), image);
} else if (HasVerticalAlignment.ALIGN_BOTTOM == valign) {
return template.imageWrapperBottom(cssStyles.toSafeStyles(), image);
} else {
int halfHeight = (int) Math.round(res.getHeight() / 2.0);
cssStyles.appendTrustedString("margin-top:-" + halfHeight + "px;");
return template.imageWrapperMiddle(cssStyles.toSafeStyles(), image);
}
}
/**
* Get the parent element of the decorated cell.
*
* @param parent the parent of this cell
* @return the decorated cell's parent
*/
private Element getCellParent(Element parent) {
return parent.getFirstChildElement().getChild(1).cast();
}
}