user/src/com/google/gwt/dom/client/StyleInjector.java - gwt.git - Git at Google

 /*
  * 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.dom.client;

 import com.google.gwt.core.client.GWT;
 import com.google.gwt.core.client.JavaScriptObject;
 import com.google.gwt.core.client.JsArray;
 import com.google.gwt.core.client.JsArrayInteger;

 /**
  * Used to add stylesheets to the document.
  */
 public class StyleInjector {

   /**
    * The DOM-compatible way of adding stylesheets. This implementation requires
    * the host HTML page to have a head element defined.
    */
   public static class StyleInjectorImpl {
     private static final StyleInjectorImpl IMPL = GWT.create(StyleInjectorImpl.class);

     private HeadElement head;

     public StyleElement injectStyleSheet(String contents) {
       StyleElement style = createElement(contents);
       getHead().appendChild(style);
       return style;
     }

     public StyleElement injectStyleSheetAtEnd(String contents) {
       return injectStyleSheet(contents);
     }

     public StyleElement injectStyleSheetAtStart(String contents) {
       StyleElement style = createElement(contents);
       getHead().insertBefore(style, head.getFirstChild());
       return style;
     }

     public void setContents(StyleElement style, String contents) {
       style.setInnerText(contents);
     }

     private StyleElement createElement(String contents) {
       StyleElement style = Document.get().createStyleElement();
       style.setPropertyString("language", "text/css");
       setContents(style, contents);
       return style;
     }

     private HeadElement getHead() {
       if (head == null) {
         Element elt = Document.get().getElementsByTagName("head").getItem(0);
         assert elt != null : "The host HTML page does not have a <head> element"
             + " which is required by StyleInjector";
         head = HeadElement.as(elt);
       }
       return head;
     }
   }

   /**
    * IE doesn't allow manipulation of a style element through DOM methods. There
    * is also a hard-coded limit on the number of times that createStyleSheet can
    * be called before IE6 starts throwing exceptions.
    */
   public static class StyleInjectorImplIE extends StyleInjectorImpl {

     /*
      * TODO(bobv) : Talk to scottb about being able to read this out of the
      * module xml file as a configuration-property to handle cases where
      * multiple GWT modules are living in the same page.
      */
     private static final int MAX_STYLE_SHEETS = 30;
     private static final JsArray<StyleElement> STYLE_ELEMENTS = JavaScriptObject.createArray().cast();
     private static final JsArrayInteger STYLE_ELEMENT_LENGTHS = JavaScriptObject.createArray().cast();

     public native void appendContents(StyleElement style, String contents) /*-{
       style.cssText += contents;
     }-*/;

     @Override
     public StyleElement injectStyleSheet(String contents) {
       int idx = STYLE_ELEMENTS.length();
       if (getDocumentStyleCount() < MAX_STYLE_SHEETS) {
         // Just create a new style element and add it to the list
         StyleElement style = createElement();
         setContents(style, contents);
         STYLE_ELEMENTS.set(idx, style);
         STYLE_ELEMENT_LENGTHS.set(idx, contents.length());
         return style;
       } else {
         /*
          * Find shortest style element to minimize re-parse time in the general
          * case.
          */
         int shortestLen = Integer.MAX_VALUE;
         int shortestIdx = -1;
         for (int i = 0; i < idx; i++) {
           if (STYLE_ELEMENT_LENGTHS.get(i) < shortestLen) {
             shortestLen = STYLE_ELEMENT_LENGTHS.get(i);
             shortestIdx = i;
           }
         }

         /**
          * This assertion can fail if the max number of style elements exist
          * before this module can inject any style elements, so STYLE_ELEMENTS
          * will be empty. However, the fix would degrade performance for the
          * general case.
          * TODO(jlabanca): Can we handle this scenario efficiently?
          */
         assert shortestIdx != -1;

         StyleElement style = STYLE_ELEMENTS.get(shortestIdx);
         STYLE_ELEMENT_LENGTHS.set(shortestIdx, shortestLen + contents.length());
         appendContents(style, contents);
         return style;
       }
     }

     @Override
     public StyleElement injectStyleSheetAtEnd(String contents) {
       if (STYLE_ELEMENTS.length() == 0) {
         return injectStyleSheet(contents);
       }

       int idx = STYLE_ELEMENTS.length() - 1;
       StyleElement style = STYLE_ELEMENTS.get(idx);
       STYLE_ELEMENT_LENGTHS.set(idx, STYLE_ELEMENT_LENGTHS.get(idx)
           + contents.length());
       appendContents(style, contents);

       return style;
     }

     @Override
     public StyleElement injectStyleSheetAtStart(String contents) {
       if (STYLE_ELEMENTS.length() == 0) {
         return injectStyleSheet(contents);
       }

       StyleElement style = STYLE_ELEMENTS.get(0);
       STYLE_ELEMENT_LENGTHS.set(0, STYLE_ELEMENT_LENGTHS.get(0)
           + contents.length());
       prependContents(style, contents);

       return style;
     }

     public native void prependContents(StyleElement style, String contents) /*-{
       style.cssText = contents + style.cssText;
     }-*/;

     @Override
     public native void setContents(StyleElement style, String contents) /*-{
       style.cssText = contents;
     }-*/;

     private native StyleElement createElement() /*-{
       return $doc.createStyleSheet();
     }-*/;

     private native int getDocumentStyleCount() /*-{
       return $doc.styleSheets.length;
     }-*/;
   }

   /**
    * Add a stylesheet to the document. The StyleElement returned by this method
    * is not guaranteed to be unique.
    *
    * @param contents the CSS contents of the stylesheet
    * @return the StyleElement that contains the newly-injected CSS
    */
   public static StyleElement injectStylesheet(String contents) {
     return StyleInjectorImpl.IMPL.injectStyleSheet(contents);
   }

   /**
    * Add stylesheet data to the document as though it were declared after all
    * stylesheets previously created by {@link #injectStylesheet(String)}. The
    * StyleElement returned by this method is not guaranteed to be unique.
    *
    * @param contents the CSS contents of the stylesheet
    * @return the StyleElement that contains the newly-injected CSS
    */
   public static StyleElement injectStylesheetAtEnd(String contents) {
     return StyleInjectorImpl.IMPL.injectStyleSheetAtEnd(contents);
   }

   /**
    * Add stylesheet data to the document as though it were declared before any
    * stylesheet previously created by {@link #injectStylesheet(String)}. The
    * StyleElement returned by this method is not guaranteed to be unique.
    *
    * @param contents the CSS contents of the stylesheet
    * @return the StyleElement that contains the newly-injected CSS
    */
   public static StyleElement injectStylesheetAtStart(String contents) {
     return StyleInjectorImpl.IMPL.injectStyleSheetAtStart(contents);
   }

   /**
    * Replace the contents of a previously-injected stylesheet. Updating the
    * stylesheet in-place is typically more efficient than removing a
    * previously-created element and adding a new one. This method should be used
    * with some caution as StyleInjector may recycle StyleElements on certain
    * browsers.
    *
    * @param style a StyleElement previously-returned from
    *          {@link #injectStylesheet(String)}.
    * @param contents the new contents of the stylesheet.
    */
   public static void setContents(StyleElement style, String contents) {
     StyleInjectorImpl.IMPL.setContents(style, contents);
   }

   /**
    * Utility class.
    */
   private StyleInjector() {
   }
 }
	/*
	* 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.dom.client;

	import com.google.gwt.core.client.GWT;
	import com.google.gwt.core.client.JavaScriptObject;
	import com.google.gwt.core.client.JsArray;
	import com.google.gwt.core.client.JsArrayInteger;

	/**
	* Used to add stylesheets to the document.
	*/
	public class StyleInjector {

	/**
	* The DOM-compatible way of adding stylesheets. This implementation requires
	* the host HTML page to have a head element defined.
	*/
	public static class StyleInjectorImpl {
	private static final StyleInjectorImpl IMPL = GWT.create(StyleInjectorImpl.class);

	private HeadElement head;

	public StyleElement injectStyleSheet(String contents) {
	StyleElement style = createElement(contents);
	getHead().appendChild(style);
	return style;
	}

	public StyleElement injectStyleSheetAtEnd(String contents) {
	return injectStyleSheet(contents);
	}

	public StyleElement injectStyleSheetAtStart(String contents) {
	StyleElement style = createElement(contents);
	getHead().insertBefore(style, head.getFirstChild());
	return style;
	}

	public void setContents(StyleElement style, String contents) {
	style.setInnerText(contents);
	}

	private StyleElement createElement(String contents) {
	StyleElement style = Document.get().createStyleElement();
	style.setPropertyString("language", "text/css");
	setContents(style, contents);
	return style;
	}

	private HeadElement getHead() {
	if (head == null) {
	Element elt = Document.get().getElementsByTagName("head").getItem(0);
	assert elt != null : "The host HTML page does not have a <head> element"
	+ " which is required by StyleInjector";
	head = HeadElement.as(elt);
	}
	return head;
	}
	}

	/**
	* IE doesn't allow manipulation of a style element through DOM methods. There
	* is also a hard-coded limit on the number of times that createStyleSheet can
	* be called before IE6 starts throwing exceptions.
	*/
	public static class StyleInjectorImplIE extends StyleInjectorImpl {

	/*
	* TODO(bobv) : Talk to scottb about being able to read this out of the
	* module xml file as a configuration-property to handle cases where
	* multiple GWT modules are living in the same page.
	*/
	private static final int MAX_STYLE_SHEETS = 30;
	private static final JsArray<StyleElement> STYLE_ELEMENTS = JavaScriptObject.createArray().cast();
	private static final JsArrayInteger STYLE_ELEMENT_LENGTHS = JavaScriptObject.createArray().cast();

	public native void appendContents(StyleElement style, String contents) /*-{
	style.cssText += contents;
	}-*/;

	@Override
	public StyleElement injectStyleSheet(String contents) {
	int idx = STYLE_ELEMENTS.length();
	if (getDocumentStyleCount() < MAX_STYLE_SHEETS) {
	// Just create a new style element and add it to the list
	StyleElement style = createElement();
	setContents(style, contents);
	STYLE_ELEMENTS.set(idx, style);
	STYLE_ELEMENT_LENGTHS.set(idx, contents.length());
	return style;
	} else {
	/*
	* Find shortest style element to minimize re-parse time in the general
	* case.
	*/
	int shortestLen = Integer.MAX_VALUE;
	int shortestIdx = -1;
	for (int i = 0; i < idx; i++) {
	if (STYLE_ELEMENT_LENGTHS.get(i) < shortestLen) {
	shortestLen = STYLE_ELEMENT_LENGTHS.get(i);
	shortestIdx = i;
	}
	}

	/**
	* This assertion can fail if the max number of style elements exist
	* before this module can inject any style elements, so STYLE_ELEMENTS
	* will be empty. However, the fix would degrade performance for the
	* general case.
	* TODO(jlabanca): Can we handle this scenario efficiently?
	*/
	assert shortestIdx != -1;

	StyleElement style = STYLE_ELEMENTS.get(shortestIdx);
	STYLE_ELEMENT_LENGTHS.set(shortestIdx, shortestLen + contents.length());
	appendContents(style, contents);
	return style;
	}
	}

	@Override
	public StyleElement injectStyleSheetAtEnd(String contents) {
	if (STYLE_ELEMENTS.length() == 0) {
	return injectStyleSheet(contents);
	}

	int idx = STYLE_ELEMENTS.length() - 1;
	StyleElement style = STYLE_ELEMENTS.get(idx);
	STYLE_ELEMENT_LENGTHS.set(idx, STYLE_ELEMENT_LENGTHS.get(idx)
	+ contents.length());
	appendContents(style, contents);

	return style;
	}

	@Override
	public StyleElement injectStyleSheetAtStart(String contents) {
	if (STYLE_ELEMENTS.length() == 0) {
	return injectStyleSheet(contents);
	}

	StyleElement style = STYLE_ELEMENTS.get(0);
	STYLE_ELEMENT_LENGTHS.set(0, STYLE_ELEMENT_LENGTHS.get(0)
	+ contents.length());
	prependContents(style, contents);

	return style;
	}

	public native void prependContents(StyleElement style, String contents) /*-{
	style.cssText = contents + style.cssText;
	}-*/;

	@Override
	public native void setContents(StyleElement style, String contents) /*-{
	style.cssText = contents;
	}-*/;

	private native StyleElement createElement() /*-{
	return $doc.createStyleSheet();
	}-*/;

	private native int getDocumentStyleCount() /*-{
	return $doc.styleSheets.length;
	}-*/;
	}

	/**
	* Add a stylesheet to the document. The StyleElement returned by this method
	* is not guaranteed to be unique.
	*
	* @param contents the CSS contents of the stylesheet
	* @return the StyleElement that contains the newly-injected CSS
	*/
	public static StyleElement injectStylesheet(String contents) {
	return StyleInjectorImpl.IMPL.injectStyleSheet(contents);
	}

	/**
	* Add stylesheet data to the document as though it were declared after all
	* stylesheets previously created by {@link #injectStylesheet(String)}. The
	* StyleElement returned by this method is not guaranteed to be unique.
	*
	* @param contents the CSS contents of the stylesheet
	* @return the StyleElement that contains the newly-injected CSS
	*/
	public static StyleElement injectStylesheetAtEnd(String contents) {
	return StyleInjectorImpl.IMPL.injectStyleSheetAtEnd(contents);
	}

	/**
	* Add stylesheet data to the document as though it were declared before any
	* stylesheet previously created by {@link #injectStylesheet(String)}. The
	* StyleElement returned by this method is not guaranteed to be unique.
	*
	* @param contents the CSS contents of the stylesheet
	* @return the StyleElement that contains the newly-injected CSS
	*/
	public static StyleElement injectStylesheetAtStart(String contents) {
	return StyleInjectorImpl.IMPL.injectStyleSheetAtStart(contents);
	}

	/**
	* Replace the contents of a previously-injected stylesheet. Updating the
	* stylesheet in-place is typically more efficient than removing a
	* previously-created element and adding a new one. This method should be used
	* with some caution as StyleInjector may recycle StyleElements on certain
	* browsers.
	*
	* @param style a StyleElement previously-returned from
	* {@link #injectStylesheet(String)}.
	* @param contents the new contents of the stylesheet.
	*/
	public static void setContents(StyleElement style, String contents) {
	StyleInjectorImpl.IMPL.setContents(style, contents);
	}

	/**
	* Utility class.
	*/
	private StyleInjector() {
	}
	}