Gen2CssInjector.java

/*
 * Copyright 2008 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.gen2.widgetbase.client;

import com.google.gwt.core.client.GWT;
import com.google.gwt.dom.client.StyleInjector;
import com.google.gwt.libideas.resources.client.CssResource;
import com.google.gwt.libideas.resources.client.ImmutableResourceBundle;

/**
 * Helper class to allow developers to easily inject css for their widgets.
 */
public class Gen2CssInjector {
  /**
   * CSS resources for all gen2 widgets.
   */
  static interface DefaultBundle extends ImmutableResourceBundle {
    @Resource("com/google/gwt/gen2/widgetbase/public/CollapsiblePanel_base.css")
    CssResource collapsiblePanelBase();

    @Resource("com/google/gwt/gen2/widgetbase/public/CollapsiblePanel_ltr.css")
    CssResource collapsiblePanelLtr();

    @Resource("com/google/gwt/gen2/widgetbase/public/DropDownDatePicker.css")
    CssResource dropDownDatePicker();

    @Resource("com/google/gwt/gen2/widgetbase/public/DropDownListBox.css")
    CssResource dropDownListBox();

    @Resource("com/google/gwt/gen2/widgetbase/public/FastTree_base.css")
    CssResource fastTreeBase();

    @Resource("com/google/gwt/gen2/widgetbase/public/FastTree_ltr.css")
    CssResource fastTreeLtr();

    @Resource("com/google/gwt/gen2/widgetbase/public/LogHandlers.css")
    CssResource logHandlers();

    @Resource("com/google/gwt/gen2/widgetbase/public/Picker.css")
    CssResource picker();

    @Resource("com/google/gwt/gen2/widgetbase/public/SliderBar.css")
    CssResource sliderBar();
  }

  static class DisabledMode extends Mode {
    @Override
    public DefaultBundle createDefaultBundle() {
      return null;
    }

    @Override
    public void inject(CssResource res) {
    }

    @Override
    protected boolean shouldInject() {
      return false;
    }
  }

  static class Mode {
    public DefaultBundle createDefaultBundle() {
      return GWT.create(DefaultBundle.class);
    }

    public void inject(CssResource res) {
      StyleInjector.injectStylesheet(res.getText());
    }

    protected boolean shouldInject() {
      return true;
    }
  }

  private static Mode m = GWT.create(Mode.class);

  private static DefaultBundle DEFAULT_CSS_FILES = m.createDefaultBundle();

  /**
   * If css dependency injection is enabled, adds the ToggleButton.css file
   * included under public/widget.
   */
  public static void addCollapsiblePanelDefault() {
    if (Gen2CssInjector.isInjectionEnabled()) {
      inject(DEFAULT_CSS_FILES.collapsiblePanelBase(),
          DEFAULT_CSS_FILES.collapsiblePanelLtr());
    }
  }

  /**
   * If css dependency injection is enabled, adds the default dependencies for
   * DropDownDatePicker.
   */
  public static void addDropDownDatePickerDefault() {
    if (Gen2CssInjector.isInjectionEnabled()) {
      inject(DEFAULT_CSS_FILES.dropDownDatePicker());
      inject(DEFAULT_CSS_FILES.dropDownListBox());
    }
  }

  /**
   * If css dependency injection is enabled, adds the DropDownListBox
   * dependencies.
   */
  public static void addDropDownListBoxDefault() {
    if (Gen2CssInjector.isInjectionEnabled()) {
      inject(DEFAULT_CSS_FILES.dropDownListBox());
    }
  }

  /**
   * If css dependency injection is enabled, adds the FastTree CSS files
   * included under public/widget.
   */
  public static void addFastTreeDefault() {
    if (Gen2CssInjector.isInjectionEnabled()) {
      inject(DEFAULT_CSS_FILES.fastTreeBase(), DEFAULT_CSS_FILES.fastTreeLtr());
    }
  }

  /**
   * Injects the default css used for the log handlers defined in this package.
   */
  public static void addLogHandlerDefault() {
    if (Gen2CssInjector.isInjectionEnabled()) {
      inject(DEFAULT_CSS_FILES.dropDownListBox());
      inject(DEFAULT_CSS_FILES.logHandlers());
    }
  }

  /**
   * If css dependency injection is enabled, adds the Picker.css file
   * included under public/widget.
   */
  public static void addPickerDefault() {
    if (Gen2CssInjector.isInjectionEnabled()) {
      inject(DEFAULT_CSS_FILES.picker());
    }
  }

  /**
   * If css dependency injection is enabled, adds the SliderBar.css file.
   */
  public static void addSliderBarDefault() {
    if (Gen2CssInjector.isInjectionEnabled()) {
      inject(DEFAULT_CSS_FILES.sliderBar());
    }
  }

  /**
   * Injects the given css resource into the program when DebugCss is not
   * included.
   */
  public static <CssType extends CssResource> CssType inject(CssType b) {
    m.inject(b);
    return b;
  }

  /**
   * Can any css resources be injected?
   */
  public static boolean isInjectionEnabled() {
    return m.shouldInject();
  }

  // Inject multiple style sheets
  private static void inject(CssResource car, CssResource... cdr) {
    inject(car);
    for (CssResource resource : cdr) {
      inject(resource);
    }
  }
}