rename BitmapTextBlob and move it to its own file

src/gpu/GrAtlasTextBlob.h

+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrAtlasTextBlob_DEFINED
+#define GrAtlasTextBlob_DEFINED
+
+#include "GrBatchAtlas.h"
+#include "GrBatchFontCache.h"
+#include "SkDescriptor.h"
+#include "SkMaskFilter.h"
+#include "GrMemoryPool.h"
+#include "SkTInternalLList.h"
+
+/*
+ * A GrAtlasTextBlob contains a fully processed SkTextBlob, suitable for nearly immediate drawing
+ * on the GPU.  These are initially created with valid positions and colors, but invalid
+ * texture coordinates.  The GrAtlasTextBlob itself has a few Blob-wide properties, and also
+ * consists of a number of runs.  Runs inside a blob are flushed individually so they can be
+ * reordered.
+ *
+ * The only thing(aside from a memcopy) required to flush a GrAtlasTextBlob is to ensure that
+ * the GrAtlas will not evict anything the Blob needs.
+ *
+ * Note: This struct should really be named GrCachedAtasTextBlob, but that is too verbose.
+ */
+struct GrAtlasTextBlob : public SkRefCnt {
+    SK_DECLARE_INTERNAL_LLIST_INTERFACE(GrAtlasTextBlob);
+
+    /*
+     * Each Run inside of the blob can have its texture coordinates regenerated if required.
+     * To determine if regeneration is necessary, fAtlasGeneration is used.  If there have been
+     * any evictions inside of the atlas, then we will simply regenerate Runs.  We could track
+     * this at a more fine grained level, but its not clear if this is worth it, as evictions
+     * should be fairly rare.
+     *
+     * One additional point, each run can contain glyphs with any of the three mask formats.
+     * We call these SubRuns.  Because a subrun must be a contiguous range, we have to create
+     * a new subrun each time the mask format changes in a run.  In theory, a run can have as
+     * many SubRuns as it has glyphs, ie if a run alternates between color emoji and A8.  In
+     * practice, the vast majority of runs have only a single subrun.
+     *
+     * Finally, for runs where the entire thing is too large for the GrAtlasTextContext to
+     * handle, we have a bit to mark the run as flusahable via rendering as paths.  It is worth
+     * pointing. It would be a bit expensive to figure out ahead of time whether or not a run
+     * can flush in this manner, so we always allocate vertices for the run, regardless of
+     * whether or not it is too large.  The benefit of this strategy is that we can always reuse
+     * a blob allocation regardless of viewmatrix changes.  We could store positions for these
+     * glyphs.  However, its not clear if this is a win because we'd still have to either go the
+     * glyph cache to get the path at flush time, or hold onto the path in the cache, which
+     * would greatly increase the memory of these cached items.
+     */
+    struct Run {
+        Run()
+            : fColor(GrColor_ILLEGAL)
+            , fInitialized(false)
+            , fDrawAsPaths(false) {
+            fVertexBounds.setLargestInverted();
+            // To ensure we always have one subrun, we push back a fresh run here
+            fSubRunInfo.push_back();
+        }
+        struct SubRunInfo {
+            SubRunInfo()
+                : fAtlasGeneration(GrBatchAtlas::kInvalidAtlasGeneration)
+                , fVertexStartIndex(0)
+                , fVertexEndIndex(0)
+                , fGlyphStartIndex(0)
+                , fGlyphEndIndex(0)
+                , fDrawAsDistanceFields(false) {}
+            // Distance field text cannot draw coloremoji, and so has to fall back.  However,
+            // though the distance field text and the coloremoji may share the same run, they
+            // will have different descriptors.  If fOverrideDescriptor is non-NULL, then it
+            // will be used in place of the run's descriptor to regen texture coords
+            // TODO we could have a descriptor cache, it would reduce the size of these blobs
+            // significantly, and then the subrun could just have a refed pointer to the
+            // correct descriptor.
+            GrBatchAtlas::BulkUseTokenUpdater fBulkUseToken;
+            uint64_t fAtlasGeneration;
+            size_t fVertexStartIndex;
+            size_t fVertexEndIndex;
+            uint32_t fGlyphStartIndex;
+            uint32_t fGlyphEndIndex;
+            SkScalar fTextRatio; // df property
+            GrMaskFormat fMaskFormat;
+            bool fDrawAsDistanceFields; // df property
+            bool fUseLCDText; // df property
+        };
+
+        SubRunInfo& push_back() {
+            // Forward glyph / vertex information to seed the new sub run
+            SubRunInfo& prevSubRun = fSubRunInfo.back();
+            SubRunInfo& newSubRun = fSubRunInfo.push_back();
+            newSubRun.fGlyphStartIndex = prevSubRun.fGlyphEndIndex;
+            newSubRun.fGlyphEndIndex = prevSubRun.fGlyphEndIndex;
+
+            newSubRun.fVertexStartIndex = prevSubRun.fVertexEndIndex;
+            newSubRun.fVertexEndIndex = prevSubRun.fVertexEndIndex;
+            return newSubRun;
+        }
+        static const int kMinSubRuns = 1;
+        SkAutoTUnref<GrBatchTextStrike> fStrike;
+        SkAutoTUnref<SkTypeface> fTypeface;
+        SkRect fVertexBounds;
+        SkSTArray<kMinSubRuns, SubRunInfo> fSubRunInfo;
+        SkAutoDescriptor fDescriptor;
+        SkAutoTDelete<SkAutoDescriptor> fOverrideDescriptor; // df properties
+        GrColor fColor;
+        bool fInitialized;
+        bool fDrawAsPaths;
+    };
+
+    struct BigGlyph {
+        BigGlyph(const SkPath& path, SkScalar vx, SkScalar vy)
+            : fPath(path)
+            , fVx(vx)
+            , fVy(vy) {}
+        SkPath fPath;
+        SkScalar fVx;
+        SkScalar fVy;
+    };
+
+    struct Key {
+        Key() {
+            sk_bzero(this, sizeof(Key));
+        }
+        uint32_t fUniqueID;
+        // Color may affect the gamma of the mask we generate, but in a fairly limited way.
+        // Each color is assigned to on of a fixed number of buckets based on its
+        // luminance. For each luminance bucket there is a "canonical color" that
+        // represents the bucket.  This functionality is currently only supported for A8
+        SkColor fCanonicalColor;
+        SkPaint::Style fStyle;
+        SkPixelGeometry fPixelGeometry;
+        bool fHasBlur;
+
+        bool operator==(const Key& other) const {
+            return 0 == memcmp(this, &other, sizeof(Key));
+        }
+    };
+
+    struct StrokeInfo {
+        SkScalar fFrameWidth;
+        SkScalar fMiterLimit;
+        SkPaint::Join fJoin;
+    };
+
+    enum TextType {
+        kHasDistanceField_TextType = 0x1,
+        kHasBitmap_TextType = 0x2,
+    };
+
+    // all glyph / vertex offsets are into these pools.
+    unsigned char* fVertices;
+    GrGlyph** fGlyphs;
+    Run* fRuns;
+    GrMemoryPool* fPool;
+    SkMaskFilter::BlurRec fBlurRec;
+    StrokeInfo fStrokeInfo;
+    SkTArray<BigGlyph> fBigGlyphs;
+    Key fKey;
+    SkMatrix fViewMatrix;
+    SkColor fPaintColor;
+    SkScalar fX;
+    SkScalar fY;
+
+    // We can reuse distance field text, but only if the new viewmatrix would not result in
+    // a mip change.  Because there can be multiple runs in a blob, we track the overall
+    // maximum minimum scale, and minimum maximum scale, we can support before we need to regen
+    SkScalar fMaxMinScale;
+    SkScalar fMinMaxScale;
+    int fRunCount;
+    uint8_t fTextType;
+
+    GrAtlasTextBlob()
+        : fMaxMinScale(-SK_ScalarMax)
+        , fMinMaxScale(SK_ScalarMax)
+        , fTextType(0) {}
+
+    ~GrAtlasTextBlob() override {
+        for (int i = 0; i < fRunCount; i++) {
+            fRuns[i].~Run();
+        }
+    }
+
+    static const Key& GetKey(const GrAtlasTextBlob& blob) {
+        return blob.fKey;
+    }
+
+    static uint32_t Hash(const Key& key) {
+        return SkChecksum::Murmur3(&key, sizeof(Key));
+    }
+
+    void operator delete(void* p) {
+        GrAtlasTextBlob* blob = reinterpret_cast<GrAtlasTextBlob*>(p);
+        blob->fPool->release(p);
+    }
+    void* operator new(size_t) {
+        SkFAIL("All blobs are created by placement new.");
+        return sk_malloc_throw(0);
+    }
+
+    void* operator new(size_t, void* p) { return p; }
+    void operator delete(void* target, void* placement) {
+        ::operator delete(target, placement);
+    }
+
+    bool hasDistanceField() const { return SkToBool(fTextType & kHasDistanceField_TextType); }
+    bool hasBitmap() const { return SkToBool(fTextType & kHasBitmap_TextType); }
+    void setHasDistanceField() { fTextType |= kHasDistanceField_TextType; }
+    void setHasBitmap() { fTextType |= kHasBitmap_TextType; }
+};
+
+#endif