DevTools: Front-end for platform font inspection

Source/devtools/front_end/PlatformFontsSidebarPane.js

Index: Source/devtools/front_end/PlatformFontsSidebarPane.js
diff --git a/Source/devtools/front_end/PlatformFontsSidebarPane.js b/Source/devtools/front_end/PlatformFontsSidebarPane.js
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+++ b/Source/devtools/front_end/PlatformFontsSidebarPane.js
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+/*
+ * Copyright (C) 2013 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/**
+ * @constructor
+ * @extends {WebInspector.SidebarPane}
+ */
+WebInspector.PlatformFontsSidebarPane = function()
+{
+    WebInspector.SidebarPane.call(this, "Fonts");
+    this.element.addStyleClass("platform-fonts");
+    WebInspector.domAgent.addEventListener(WebInspector.DOMAgent.Events.AttrModified, this._onNodeChange.bind(this));
+    WebInspector.domAgent.addEventListener(WebInspector.DOMAgent.Events.AttrRemoved, this._onNodeChange.bind(this));
+    WebInspector.domAgent.addEventListener(WebInspector.DOMAgent.Events.CharacterDataModified, this._onNodeChange.bind(this));
+}
+
+WebInspector.PlatformFontsSidebarPane.MaxElementsInTextMap = 100;
+
+WebInspector.PlatformFontsSidebarPane.prototype = {
+    _onNodeChange: function()
+    {
+        if (this._innerUpdateTimeout)
+            clearTimeout(this._innerUpdateTimeout);
+        this._innerUpdateTimeout = setTimeout(this._innerUpdate.bind(this), 100);

[aandrey, 2013/08/22 18:10:16]

If _onNodeChanged is fired every 100ms for some period of time, you'll never
have a chance to update the UI. Is this OK?

+    },
+
+    /**
+     * @param {WebInspector.DOMNode=} node
+     */
+    update: function(node)
+    {
+        if (!node) {
+            this.element.removeChildren();
+            delete this._node;
+            delete this._platformFonts;
+            delete this._computedStyles;
+            return;
+        }
+        this._node = node;
+        this._innerUpdate();
+    },
+
+    _innerUpdate: function()
+    {
+        if (this._innerUpdateTimeout) {
+            clearTimeout(this._innerUpdateTimeout);
+            delete this._innerUpdateTimeout;
+        }
+        if (!this._node)
+            return;
+        var callbackBarrier = new CallbackBarrier();
+        var platformFontsCallback = callbackBarrier.createCallback(this._platformFontsCallback.bind(this, this._node));
+        var computedStyleCallback = callbackBarrier.createCallback(this._computedStyleCallback.bind(this, this._node));
+        callbackBarrier.callWhenDone(this._render.bind(this, this._node));
+        WebInspector.cssModel.getPlatformFontsForNode(this._node.id, platformFontsCallback);

[pfeldman, 2013/08/22 16:39:51]

Serve font family as a part of this request.

+        WebInspector.cssModel.getComputedStyleAsync(this._node.id, computedStyleCallback);

[pfeldman, 2013/08/22 16:39:51]

This operation is extremely expensive (up to 1 second)

[aandrey, 2013/08/22 18:30:47]

Yeah, you should not call it again until you get the callback for the old node,
otherwise there can be an unlimited backlog queue. You should have a flag like
this._rebuildUpdateInProgress in WebInspector.StylesSidebarPane, or
this._pendingReplayTraceLogEvent in WebInspector.CanvasProfileView. 

nit: we usually make callbacks like _platformFontsCallback and
_computedStyleCallback local functions, so that you no longer bind this._node.

+    },
+
+    /**
+     * @param {WebInspector.DOMNode} node
+     * @param {?Array.<CSSAgent.PlatformFontUsage>} platformFonts
+     */
+    _platformFontsCallback: function(node, platformFonts)
+    {
+        if (this._node !== node)
+            return;
+        if (!platformFonts || !platformFonts.length) {
+            delete this._platformFonts;
+            return;
+        }
+
+        this._platformFonts = platformFonts;
+    },
+
+    /**
+     * @param {WebInspector.DOMNode} node
+     * @param {?WebInspector.CSSStyleDeclaration} computedStyles
+     */
+    _computedStyleCallback: function(node, computedStyles)
+    {
+        if (this._node !== node)
+            return;
+        this._computedStyles = computedStyles;
+    },
+
+    /**
+     * @param {WebInspector.DOMNode} node
+     */
+    _render: function(node)
+    {
+        if (this._node !== node)
+            return;
+        this.element.removeChildren();
+        if (!this._platformFonts || !this._computedStyles)
+            return;
+
+        this._platformFonts.sort(function (a, b) {
+            return b.glyphCount - a.glyphCount;
+        });
+
+        var cssFontSection = this.element.createChild("div", "stats-section monospace");
+        var cssFontPrefix = cssFontSection.createChild("span", "webkit-css-property");
+        cssFontPrefix.textContent = "font-family";

[pfeldman, 2013/08/22 16:39:51]

You don't have to re-create this part.

+        cssFontSection.createTextChild(":");
+        var cssFontValue = cssFontSection.createChild("span", "css-font-value");
+        cssFontValue.textContent = this._computedStyles.getLiveProperty("font-family").value + ";";
+
+        var fontStatsSection = document.createElement("div");
+        fontStatsSection.className = "stats-section";
+        for (var i = 0; i < this._platformFonts.length; ++i) {
+            var fontStatElement = fontStatsSection.createChild("div", "font-stats-item");
+
+            var fontNameElement = fontStatElement.createChild("span", "font-name");
+            fontNameElement.textContent = this._platformFonts[i].familyName;
+
+            var fontDelimeterElement = fontStatElement.createChild("span", "delimeter");
+            fontDelimeterElement.textContent = "—";
+
+            var fontUsageElement = fontStatElement.createChild("span", "font-usage");
+            var usage = this._platformFonts[i].glyphCount;
+            fontUsageElement.textContent = usage + " glyph" + (usage === 1 ? "" : "s");
+        }
+        this.element.appendChild(fontStatsSection);
+    },
+
+    __proto__: WebInspector.SidebarPane.prototype
+}