| /* |
| * 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; |
| import com.google.gwt.core.client.JsArrayString; |
| import com.google.gwt.core.client.Scheduler; |
| import com.google.gwt.core.client.Scheduler.ScheduledCommand; |
| |
| /** |
| * Used to add stylesheets to the document. The one-argument versions of |
| * {@link #inject}, {@link #injectAtEnd}, and {@link #injectAtStart} use |
| * {@link Scheduler#scheduleFinally} to minimize the number of individual style |
| * elements created. |
| */ |
| 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; |
| }-*/; |
| } |
| |
| private static final JsArrayString toInject = JavaScriptObject.createArray().cast(); |
| private static final JsArrayString toInjectAtEnd = JavaScriptObject.createArray().cast(); |
| private static final JsArrayString toInjectAtStart = JavaScriptObject.createArray().cast(); |
| |
| private static ScheduledCommand flusher = new ScheduledCommand() { |
| public void execute() { |
| if (needsInjection) { |
| flush(null); |
| } |
| } |
| }; |
| |
| private static boolean needsInjection = false; |
| |
| /** |
| * Add a stylesheet to the document. |
| * |
| * @param css the CSS contents of the stylesheet |
| */ |
| public static void inject(String css) { |
| inject(css, false); |
| } |
| |
| /** |
| * Add a stylesheet to the document. |
| * |
| * @param css the CSS contents of the stylesheet |
| * @param immediate if <code>true</code> the DOM will be updated immediately |
| * instead of just before returning to the event loop. Using this |
| * option excessively will decrease performance, especially if used |
| * with an inject-css-on-init coding pattern |
| */ |
| public static void inject(String css, boolean immediate) { |
| toInject.push(css); |
| inject(immediate); |
| } |
| |
| /** |
| * Add stylesheet data to the document as though it were declared after all |
| * stylesheets previously created by {@link #inject(String)}. |
| * |
| * @param css the CSS contents of the stylesheet |
| */ |
| public static void injectAtEnd(String css) { |
| injectAtEnd(css, false); |
| } |
| |
| /** |
| * Add stylesheet data to the document as though it were declared after all |
| * stylesheets previously created by {@link #inject(String)}. |
| * |
| * @param css the CSS contents of the stylesheet |
| * @param immediate if <code>true</code> the DOM will be updated immediately |
| * instead of just before returning to the event loop. Using this |
| * option excessively will decrease performance, especially if used |
| * with an inject-css-on-init coding pattern |
| */ |
| public static void injectAtEnd(String css, boolean immediate) { |
| toInjectAtEnd.push(css); |
| inject(immediate); |
| } |
| |
| /** |
| * Add stylesheet data to the document as though it were declared before all |
| * stylesheets previously created by {@link #inject(String)}. |
| * |
| * @param css the CSS contents of the stylesheet |
| */ |
| public static void injectAtStart(String css) { |
| injectAtStart(css, false); |
| } |
| |
| /** |
| * Add stylesheet data to the document as though it were declared before all |
| * stylesheets previously created by {@link #inject(String)}. |
| * |
| * @param css the CSS contents of the stylesheet |
| * @param immediate if <code>true</code> the DOM will be updated immediately |
| * instead of just before returning to the event loop. Using this |
| * option excessively will decrease performance, especially if used |
| * with an inject-css-on-init coding pattern |
| */ |
| public static void injectAtStart(String css, boolean immediate) { |
| toInjectAtStart.unshift(css); |
| inject(immediate); |
| } |
| |
| /** |
| * 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 |
| * @deprecated The returned StyleElement cannot be implemented consistently |
| * across all browsers |
| */ |
| @Deprecated |
| public static StyleElement injectStylesheet(String contents) { |
| toInject.push(contents); |
| return flush(toInject); |
| } |
| |
| /** |
| * 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 |
| * @deprecated The returned StyleElement cannot be implemented consistently |
| * across all browsers |
| */ |
| @Deprecated |
| public static StyleElement injectStylesheetAtEnd(String contents) { |
| toInjectAtEnd.push(contents); |
| return flush(toInjectAtEnd); |
| } |
| |
| /** |
| * 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 |
| * @deprecated The returned StyleElement cannot be implemented consistently |
| * across all browsers |
| */ |
| @Deprecated |
| public static StyleElement injectStylesheetAtStart(String contents) { |
| toInjectAtStart.unshift(contents); |
| return flush(toInjectAtStart); |
| } |
| |
| /** |
| * 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. |
| * @deprecated The associated StyleElement cannot be implemented consistently |
| * across all browsers |
| */ |
| @Deprecated |
| public static void setContents(StyleElement style, String contents) { |
| StyleInjectorImpl.IMPL.setContents(style, contents); |
| } |
| |
| /** |
| * The <code>which</code> parameter is used to support the deprecated API. |
| */ |
| private static StyleElement flush(JavaScriptObject which) { |
| StyleElement toReturn = null; |
| StyleElement maybeReturn; |
| |
| if (toInjectAtStart.length() != 0) { |
| String css = toInjectAtStart.join(""); |
| maybeReturn = StyleInjectorImpl.IMPL.injectStyleSheetAtStart(css); |
| if (toInjectAtStart == which) { |
| toReturn = maybeReturn; |
| } |
| toInjectAtStart.setLength(0); |
| } |
| |
| if (toInject.length() != 0) { |
| String css = toInject.join(""); |
| maybeReturn = StyleInjectorImpl.IMPL.injectStyleSheet(css); |
| if (toInject == which) { |
| toReturn = maybeReturn; |
| } |
| toInject.setLength(0); |
| } |
| |
| if (toInjectAtEnd.length() != 0) { |
| String css = toInjectAtEnd.join(""); |
| maybeReturn = StyleInjectorImpl.IMPL.injectStyleSheetAtEnd(css); |
| if (toInjectAtEnd == which) { |
| toReturn = maybeReturn; |
| } |
| toInjectAtEnd.setLength(0); |
| } |
| |
| needsInjection = false; |
| return toReturn; |
| } |
| |
| private static void inject(boolean immediate) { |
| if (immediate) { |
| flush(null); |
| } else { |
| schedule(); |
| } |
| } |
| |
| private static void schedule() { |
| if (!needsInjection) { |
| needsInjection = true; |
| Scheduler.get().scheduleFinally(flusher); |
| } |
| } |
| |
| /** |
| * Utility class. |
| */ |
| private StyleInjector() { |
| } |
| } |