grab from latest android

git-svn-id: http://skia.googlecode.com/svn/trunk@27 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 122 insertions, 0 deletions

diff --git a/include/core/SkFontHost.h b/include/core/SkFontHost.h
new file mode 100644
index 0000000000..ede40b7a31
--- /dev/null
+++ b/include/core/SkFontHost.h
@@ -0,0 +1,122 @@
+/*
+ * Copyright (C) 2006 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#ifndef SkFontHost_DEFINED
+#define SkFontHost_DEFINED
+
+#include "SkScalerContext.h"
+#include "SkTypeface.h"
+
+class SkDescriptor;
+class SkStream;
+class SkWStream;
+
+/** \class SkFontHost
+
+    This class is ported to each environment. It is responsible for bridging the gap
+    between SkTypeface and the resulting platform-specific instance of SkScalerContext.
+*/
+class SkFontHost {
+public:
+    /** Return the closest matching typeface given either an existing family
+        (specified by a typeface in that family) or by a familyName, and a
+        requested style.
+        1) If familyFace is null, use famillyName.
+        2) If famillyName is null, use familyFace.
+        3) If both are null, return the default font that best matches style
+
+        NOTE: this does not return a new typeface, nor does it affect the
+        owner count of an existing one, so the caller is free to ignore the
+        return result, or just compare it against null.
+     */
+    static SkTypeface* FindTypeface(const SkTypeface* familyFace,
+                                    const char famillyName[],
+                                    SkTypeface::Style style);
+
+    /** Return the typeface associated with the uniqueID, or null if that ID
+        does not match any faces.
+
+        NOTE: this does not return a new typeface, nor does it affect the
+        owner count of an existing one, so the caller is free to ignore the
+        return result, or just compare it against null.
+    */
+    static SkTypeface* ResolveTypeface(uint32_t uniqueID);
+    
+    /** Return a new stream to read the font data, or null if the uniqueID does
+        not match an existing typeface. The caller must call CloseStream() when
+        it is finished reading the stream.
+    */
+    static SkStream* OpenStream(uint32_t uniqueID);
+    
+    /** Call this when finished reading from the stream returned by OpenStream.
+        The caller should NOT try to delete the stream.
+     */
+    static void CloseStream(uint32_t uniqueID, SkStream*);
+
+    /** Return a new typeface given the data buffer (owned by the caller).
+        If the data does not represent a valid font, return null. The caller is
+        responsible for unref-ing the returned typeface (if it is not null).
+    */
+    static SkTypeface* CreateTypeface(SkStream*);
+
+    ///////////////////////////////////////////////////////////////////////////
+
+    /** Write a unique identifier to the stream, so that the same typeface can
+        be retrieved with Deserialize().
+    */
+    static void Serialize(const SkTypeface*, SkWStream*);
+
+    /** Given a stream created by Serialize(), return the corresponding typeface
+        or null if no match is found.
+
+        NOTE: this does not return a new typeface, nor does it affect the
+        owner count of an existing one, so the caller is free to ignore the
+        return result, or just compare it against null.
+     */
+    static SkTypeface* Deserialize(SkStream*);
+
+    ///////////////////////////////////////////////////////////////////////////
+    
+    /** Return a subclass of SkScalarContext
+    */
+    static SkScalerContext* CreateScalerContext(const SkDescriptor* desc);
+
+    /** Return a scalercontext using the "fallback" font. If there is no designated
+        fallback, return null.
+    */
+    static SkScalerContext* CreateFallbackScalerContext(const SkScalerContext::Rec&);
+
+    /** Return the number of bytes (approx) that should be purged from the font
+        cache. The input parameter is the cache's estimate of how much as been
+        allocated by the cache so far.
+        To purge (basically) everything, return the input parameter.
+        To purge nothing, return 0
+    */
+    static size_t ShouldPurgeFontCache(size_t sizeAllocatedSoFar);
+
+    /** Return SkScalerContext gamma flag, or 0, based on the paint that will be
+        used to draw something with antialiasing.
+    */
+    static int ComputeGammaFlag(const SkPaint& paint);
+
+    /** Return NULL or a pointer to 256 bytes for the black (table[0]) and
+        white (table[1]) gamma tables.
+    */
+    static void GetGammaTables(const uint8_t* tables[2]);
+};
+
+#endif
+