2 * This file is part of the internal font implementation.
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23 // This file provides additional functionality to the Mac FontPlatformData class
24 // defined in WebCore/platform/cocoa/FontPlatformDataCocoa.mm .
25 // Because we want to support loading fonts between processes in the face of
26 // font loading being blocked by the sandbox, we need a mechnasim to both
27 // do the loading of in-memory fonts and keep track of them.
30 #import "platform/fonts/mac/MemoryActivatedFont.h"
32 #import <AppKit/NSFont.h>
33 #import "platform/LinkHash.h"
34 #import "platform/fonts/FontPlatformData.h"
35 #import "public/platform/mac/WebSandboxSupport.h"
36 #import "public/platform/Platform.h"
37 #import "wtf/HashMap.h"
43 typedef HashMap<uint32, MemoryActivatedFont*> FontContainerRefMemoryFontHash;
44 typedef HashMap<WTF::String, MemoryActivatedFont*> FontNameMemoryFontHash;
48 // Requesting a font from the browser process is expensive and so is
49 // "activating" said font. Caching of loaded fonts is complicated by the fact
50 // that it's impossible to get a unique identifier for the on-disk font file
51 // from inside the sandboxed renderer process.
52 // This means that when loading a font we need to round-trip through the browser
53 // process in order to get the unique font file identifer which we might already
54 // have activated and cached.
56 // In order to save as much work as we can, we maintain 2 levels of caching
58 // 1. A dumb cache keyed by the font name/style (information we can determine
59 // from inside the sandbox).
60 // 2. A smarter cache keyed by the real "unique font id".
62 // In order to perform a lookup in #2 we need to consult with the browser to get
63 // us the lookup key. While this doesn't save us the font load, it does save
64 // us font activation.
66 // It's important to remember that existing FontPlatformData objects are already
67 // cached, so a cache miss in the code in this file isn't necessarily so bad.
69 FontContainerRefMemoryFontHash& fontCacheByFontID()
71 DEFINE_STATIC_LOCAL(FontContainerRefMemoryFontHash, srcFontIDCache, ());
72 return srcFontIDCache;
76 FontNameMemoryFontHash& fontCacheByFontName()
78 DEFINE_STATIC_LOCAL(FontNameMemoryFontHash, srcFontNameCache, ());
79 return srcFontNameCache;
82 // Given a font specified by |srcFont|, use the information we can query in
83 // the sandbox to construct a key which we hope will be as unique as possible
84 // to the containing font file.
85 WTF::String hashKeyFromNSFont(NSFont* srcFont)
87 NSFontDescriptor* desc = [srcFont fontDescriptor];
88 NSFontSymbolicTraits traits = [desc symbolicTraits];
89 return WTF::String::format("%s %x", [[srcFont fontName] UTF8String], traits);
92 // The only way we can tell that an in-process font has failed to load
93 // is if CTFontCopyGraphicsFont() returns the LastResort font.
94 bool isLastResortFont(CGFontRef cgFont)
96 NSString* fontName = (NSString*)CGFontCopyPostScriptName(cgFont);
97 return [fontName isEqualToString:@"LastResort"];
100 // Given an in-process font which has failed to load, return a
101 // MemoryActivatedFont* corresponding to an in-memory representation of the
102 // same font loaded from the browser process.
103 // On failure this function returns a PassRefPtr pointing to 0.
104 PassRefPtr<MemoryActivatedFont> loadFontFromBrowserProcess(NSFont* nsFont)
106 // First try to lookup in our cache with the limited information we have.
107 WTF::String hashKey = hashKeyFromNSFont(nsFont);
108 RefPtr<MemoryActivatedFont> font(fontCacheByFontName().get(hashKey));
114 // Send cross-process request to load font.
115 blink::WebSandboxSupport* sandboxSupport = blink::Platform::current()->sandboxSupport();
116 if (!sandboxSupport) {
117 // This function should only be called in response to an error loading a
118 // font due to being blocked by the sandbox.
119 // This by definition shouldn't happen if there is no sandbox support.
120 ASSERT_NOT_REACHED();
123 if (!sandboxSupport->loadFont(nsFont, &tmpCGFont, &fontID))
126 RetainPtr<CGFontRef> cgFont(tmpCGFont);
127 // Now that we have the fontID from the browser process, we can consult
129 font = fontCacheByFontID().get(fontID);
131 // FIXME: WebSandboxSupport::loadFont() should consult the id cache
132 // before activating the font.
135 return MemoryActivatedFont::create(fontID, nsFont, cgFont.get());
140 PassRefPtr<MemoryActivatedFont> MemoryActivatedFont::create(uint32_t fontID, NSFont* nsFont, CGFontRef cgFont)
142 return adoptRef(new MemoryActivatedFont(fontID, nsFont, cgFont));
145 MemoryActivatedFont::MemoryActivatedFont(uint32_t fontID, NSFont* nsFont, CGFontRef cgFont)
148 , m_inSandboxHashKey(hashKeyFromNSFont(nsFont))
150 // Add ourselves to caches.
151 fontCacheByFontID().add(fontID, this);
152 fontCacheByFontName().add(m_inSandboxHashKey, this);
155 // Destructor - Unload font container from memory and remove ourselves
157 MemoryActivatedFont::~MemoryActivatedFont()
159 // First remove ourselves from the caches.
160 ASSERT(fontCacheByFontID().contains(m_fontID));
161 ASSERT(fontCacheByFontName().contains(m_inSandboxHashKey));
163 fontCacheByFontID().remove(m_fontID);
164 fontCacheByFontName().remove(m_inSandboxHashKey);
167 // Given an NSFont, try to load a representation of that font into the cgFont
168 // parameter. If loading is blocked by the sandbox, the font may be loaded
170 // If sandbox loading also fails, a fallback font is loaded.
173 // * cgFont must be CFRelease()ed by the caller when done.
176 // * nsFont - The font we wish to load.
177 // * fontSize - point size of the font we wish to load.
178 // * outNSFont - The font that was actually loaded or null if loading failed.
179 // * cgFont - on output this contains the CGFontRef corresponding to the NSFont
180 // that was picked in the end. The caller is responsible for calling
181 // CFRelease() on this parameter when done with it.
182 // * fontID - on output, the ID corresponding to nsFont.
183 void FontPlatformData::loadFont(NSFont* nsFont, float fontSize, NSFont*& outNSFont, CGFontRef& cgFont)
186 cgFont = CTFontCopyGraphicsFont(toCTFontRef(outNSFont), 0);
187 if (outNSFont && cgFont && isLastResortFont(cgFont)) {
188 // Release old CGFontRef since it points at the LastResort font which we don't want.
192 // Font loading was blocked by the Sandbox.
193 m_inMemoryFont = loadFontFromBrowserProcess(outNSFont);
194 if (m_inMemoryFont) {
195 cgFont = m_inMemoryFont->cgFont();
197 // Need to add an extra retain so output semantics of this function
201 // If we still can't load the font, set |outNSFont| to null so that FontPlatformData won't be used.