abf00aaaa0
subpixel text (it may be that the paint requested it, but the scaler ignored it) git-svn-id: http://skia.googlecode.com/svn/trunk@2946 2bbb7eff-a529-9590-31e7-b0007b416f81
342 lines
10 KiB
C++
342 lines
10 KiB
C++
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/*
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* Copyright 2006 The Android Open Source Project
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef SkScalerContext_DEFINED
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#define SkScalerContext_DEFINED
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#include "SkMask.h"
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#include "SkMatrix.h"
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#include "SkPaint.h"
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#include "SkPath.h"
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#include "SkPoint.h"
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class SkDescriptor;
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class SkMaskFilter;
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class SkPathEffect;
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class SkRasterizer;
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// needs to be != to any valid SkMask::Format
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#define MASK_FORMAT_UNKNOWN (0xFF)
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#define MASK_FORMAT_JUST_ADVANCE MASK_FORMAT_UNKNOWN
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#define kMaxGlyphWidth (1<<13)
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struct SkGlyph {
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void* fImage;
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SkPath* fPath;
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SkFixed fAdvanceX, fAdvanceY;
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uint32_t fID;
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uint16_t fWidth, fHeight;
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int16_t fTop, fLeft;
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uint8_t fMaskFormat;
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int8_t fRsbDelta, fLsbDelta; // used by auto-kerning
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void init(uint32_t id) {
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fID = id;
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fImage = NULL;
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fPath = NULL;
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fMaskFormat = MASK_FORMAT_UNKNOWN;
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}
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/**
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* Compute the rowbytes for the specified width and mask-format.
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*/
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static unsigned ComputeRowBytes(unsigned width, SkMask::Format format) {
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unsigned rb = width;
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if (SkMask::kBW_Format == format) {
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rb = (rb + 7) >> 3;
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} else if (SkMask::kARGB32_Format == format ||
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SkMask::kLCD32_Format == format)
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{
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rb <<= 2;
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} else if (SkMask::kLCD16_Format == format) {
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rb = SkAlign4(rb << 1);
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} else {
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rb = SkAlign4(rb);
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}
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return rb;
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}
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unsigned rowBytes() const {
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return ComputeRowBytes(fWidth, (SkMask::Format)fMaskFormat);
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}
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bool isJustAdvance() const {
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return MASK_FORMAT_JUST_ADVANCE == fMaskFormat;
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}
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bool isFullMetrics() const {
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return MASK_FORMAT_JUST_ADVANCE != fMaskFormat;
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}
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uint16_t getGlyphID() const {
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return ID2Code(fID);
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}
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unsigned getGlyphID(unsigned baseGlyphCount) const {
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unsigned code = ID2Code(fID);
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SkASSERT(code >= baseGlyphCount);
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return code - baseGlyphCount;
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}
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unsigned getSubX() const {
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return ID2SubX(fID);
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}
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SkFixed getSubXFixed() const {
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return SubToFixed(ID2SubX(fID));
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}
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SkFixed getSubYFixed() const {
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return SubToFixed(ID2SubY(fID));
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}
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size_t computeImageSize() const;
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/** Call this to set all of the metrics fields to 0 (e.g. if the scaler
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encounters an error measuring a glyph). Note: this does not alter the
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fImage, fPath, fID, fMaskFormat fields.
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*/
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void zeroMetrics();
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enum {
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kSubBits = 2,
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kSubMask = ((1 << kSubBits) - 1),
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kSubShift = 24, // must be large enough for glyphs and unichars
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kCodeMask = ((1 << kSubShift) - 1),
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// relative offsets for X and Y subpixel bits
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kSubShiftX = kSubBits,
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kSubShiftY = 0
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};
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static unsigned ID2Code(uint32_t id) {
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return id & kCodeMask;
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}
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static unsigned ID2SubX(uint32_t id) {
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return id >> (kSubShift + kSubShiftX);
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}
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static unsigned ID2SubY(uint32_t id) {
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return (id >> (kSubShift + kSubShiftY)) & kSubMask;
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}
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static unsigned FixedToSub(SkFixed n) {
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return (n >> (16 - kSubBits)) & kSubMask;
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}
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static SkFixed SubToFixed(unsigned sub) {
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SkASSERT(sub <= kSubMask);
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return sub << (16 - kSubBits);
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}
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static uint32_t MakeID(unsigned code) {
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return code;
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}
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static uint32_t MakeID(unsigned code, SkFixed x, SkFixed y) {
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SkASSERT(code <= kCodeMask);
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x = FixedToSub(x);
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y = FixedToSub(y);
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return (x << (kSubShift + kSubShiftX)) |
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(y << (kSubShift + kSubShiftY)) |
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code;
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}
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void toMask(SkMask* mask) const;
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};
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class SkScalerContext {
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public:
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enum Flags {
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kFrameAndFill_Flag = 0x0001,
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kDevKernText_Flag = 0x0002,
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kEmbeddedBitmapText_Flag = 0x0004,
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kEmbolden_Flag = 0x0008,
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kSubpixelPositioning_Flag = 0x0010,
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kAutohinting_Flag = 0x0020,
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kVertical_Flag = 0x0040,
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// together, these two flags resulting in a two bit value which matches
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// up with the SkPaint::Hinting enum.
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kHinting_Shift = 7, // to shift into the other flags above
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kHintingBit1_Flag = 0x0080,
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kHintingBit2_Flag = 0x0100,
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// these should only ever be set if fMaskFormat is LCD16 or LCD32
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kLCD_Vertical_Flag = 0x0200, // else Horizontal
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kLCD_BGROrder_Flag = 0x0400, // else RGB order
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// luminance : 0 for black text, kLuminance_Max for white text
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kLuminance_Shift = 11, // to shift into the other flags above
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kLuminance_Bits = 3, // ensure Flags doesn't exceed 16bits
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};
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// computed values
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enum {
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kHinting_Mask = kHintingBit1_Flag | kHintingBit2_Flag,
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kLuminance_Max = (1 << kLuminance_Bits) - 1,
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kLuminance_Mask = kLuminance_Max << kLuminance_Shift,
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};
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struct Rec {
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uint32_t fOrigFontID;
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uint32_t fFontID;
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SkScalar fTextSize, fPreScaleX, fPreSkewX;
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SkScalar fPost2x2[2][2];
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SkScalar fFrameWidth, fMiterLimit;
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uint8_t fMaskFormat;
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uint8_t fStrokeJoin;
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uint16_t fFlags;
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// Warning: when adding members note that the size of this structure
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// must be a multiple of 4. SkDescriptor requires that its arguments be
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// multiples of four and this structure is put in an SkDescriptor in
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// SkPaint::MakeRec.
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void getMatrixFrom2x2(SkMatrix*) const;
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void getLocalMatrix(SkMatrix*) const;
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void getSingleMatrix(SkMatrix*) const;
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SkPaint::Hinting getHinting() const {
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unsigned hint = (fFlags & kHinting_Mask) >> kHinting_Shift;
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return static_cast<SkPaint::Hinting>(hint);
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}
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void setHinting(SkPaint::Hinting hinting) {
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fFlags = (fFlags & ~kHinting_Mask) | (hinting << kHinting_Shift);
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}
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unsigned getLuminanceBits() const {
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return (fFlags & kLuminance_Mask) >> kLuminance_Shift;
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}
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void setLuminanceBits(unsigned lum) {
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SkASSERT(lum <= kLuminance_Max);
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fFlags = (fFlags & ~kLuminance_Mask) | (lum << kLuminance_Shift);
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}
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U8CPU getLuminanceByte() const {
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SkASSERT(3 == kLuminance_Bits);
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unsigned lum = this->getLuminanceBits();
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lum |= (lum << kLuminance_Bits);
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lum |= (lum << kLuminance_Bits*2);
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return lum >> (4*kLuminance_Bits - 8);
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}
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SkMask::Format getFormat() const {
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return static_cast<SkMask::Format>(fMaskFormat);
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}
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};
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SkScalerContext(const SkDescriptor* desc);
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virtual ~SkScalerContext();
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SkMask::Format getMaskFormat() const {
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return (SkMask::Format)fRec.fMaskFormat;
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}
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bool isSubpixel() const {
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return SkToBool(fRec.fFlags & kSubpixelPositioning_Flag);
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}
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// remember our glyph offset/base
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void setBaseGlyphCount(unsigned baseGlyphCount) {
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fBaseGlyphCount = baseGlyphCount;
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}
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/** Return the corresponding glyph for the specified unichar. Since contexts
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may be chained (under the hood), the glyphID that is returned may in
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fact correspond to a different font/context. In that case, we use the
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base-glyph-count to know how to translate back into local glyph space.
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*/
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uint16_t charToGlyphID(SkUnichar uni);
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/** Map the glyphID to its glyph index, and then to its char code. Unmapped
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glyphs return zero.
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*/
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SkUnichar glyphIDToChar(uint16_t glyphID);
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unsigned getGlyphCount() { return this->generateGlyphCount(); }
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void getAdvance(SkGlyph*);
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void getMetrics(SkGlyph*);
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void getImage(const SkGlyph&);
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void getPath(const SkGlyph&, SkPath*);
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void getFontMetrics(SkPaint::FontMetrics* mX,
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SkPaint::FontMetrics* mY);
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static inline void MakeRec(const SkPaint&, const SkMatrix*, Rec* rec);
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static SkScalerContext* Create(const SkDescriptor*);
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protected:
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Rec fRec;
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unsigned fBaseGlyphCount;
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virtual unsigned generateGlyphCount() = 0;
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virtual uint16_t generateCharToGlyph(SkUnichar) = 0;
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virtual void generateAdvance(SkGlyph*) = 0;
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virtual void generateMetrics(SkGlyph*) = 0;
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virtual void generateImage(const SkGlyph&) = 0;
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virtual void generatePath(const SkGlyph&, SkPath*) = 0;
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virtual void generateFontMetrics(SkPaint::FontMetrics* mX,
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SkPaint::FontMetrics* mY) = 0;
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// default impl returns 0, indicating failure.
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virtual SkUnichar generateGlyphToChar(uint16_t);
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void forceGenerateImageFromPath() { fGenerateImageFromPath = true; }
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private:
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SkPathEffect* fPathEffect;
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SkMaskFilter* fMaskFilter;
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SkRasterizer* fRasterizer;
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SkScalar fDevFrameWidth;
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// if this is set, we draw the image from a path, rather than
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// calling generateImage.
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bool fGenerateImageFromPath;
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void internalGetPath(const SkGlyph& glyph, SkPath* fillPath,
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SkPath* devPath, SkMatrix* fillToDevMatrix);
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// return the next context, treating fNextContext as a cache of the answer
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SkScalerContext* getNextContext();
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// returns the right context from our link-list for this glyph. If no match
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// is found, just returns the original context (this)
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SkScalerContext* getGlyphContext(const SkGlyph& glyph);
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// link-list of context, to handle missing chars. null-terminated.
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SkScalerContext* fNextContext;
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};
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#define kRec_SkDescriptorTag SkSetFourByteTag('s', 'r', 'e', 'c')
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#define kPathEffect_SkDescriptorTag SkSetFourByteTag('p', 't', 'h', 'e')
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#define kMaskFilter_SkDescriptorTag SkSetFourByteTag('m', 's', 'k', 'f')
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#define kRasterizer_SkDescriptorTag SkSetFourByteTag('r', 'a', 's', 't')
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///////////////////////////////////////////////////////////////////////////////
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enum SkAxisAlignment {
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kNone_SkAxisAlignment,
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kX_SkAxisAlignment,
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kY_SkAxisAlignment
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};
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/**
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* Return the axis (if any) that the baseline for horizontal text will land on
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* after running through the specified matrix.
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*
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* As an example, the identity matrix will return kX_SkAxisAlignment
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*/
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SkAxisAlignment SkComputeAxisAlignmentForHText(const SkMatrix& matrix);
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#endif
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