77 lines
2.3 KiB
Go
77 lines
2.3 KiB
Go
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// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package font
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/*
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#cgo darwin LDFLAGS: -framework CoreFoundation -framework CoreText
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#include <CoreFoundation/CFArray.h>
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#include <CoreFoundation/CFBase.h>
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#include <CoreFoundation/CFData.h>
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#include <CoreText/CTFont.h>
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*/
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import "C"
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import "unsafe"
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func buildFont(f C.CTFontRef) []byte {
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ctags := C.CTFontCopyAvailableTables(f, C.kCTFontTableOptionExcludeSynthetic)
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tagsCount := C.CFArrayGetCount(ctags)
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var tags []uint32
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var dataRefs []C.CFDataRef
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var dataLens []uint32
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for i := C.CFIndex(0); i < tagsCount; i++ {
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tag := (C.CTFontTableTag)((uintptr)(C.CFArrayGetValueAtIndex(ctags, i)))
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dataRef := C.CTFontCopyTable(f, tag, 0) // retained
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tags = append(tags, uint32(tag))
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dataRefs = append(dataRefs, dataRef)
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dataLens = append(dataLens, uint32(C.CFDataGetLength(dataRef)))
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}
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totalLen := 0
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for _, l := range dataLens {
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totalLen += int(l)
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}
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// Big-endian output.
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buf := make([]byte, 0, 12+16*len(tags)+totalLen)
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write16 := func(x uint16) { buf = append(buf, byte(x>>8), byte(x)) }
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write32 := func(x uint32) { buf = append(buf, byte(x>>24), byte(x>>16), byte(x>>8), byte(x)) }
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// File format description: http://www.microsoft.com/typography/otspec/otff.htm
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write32(0x00010000) // version 1.0
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write16(uint16(len(tags))) // numTables
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write16(0) // searchRange
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write16(0) // entrySelector
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write16(0) // rangeShift
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// Table tags, includes offsets into following data segments.
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offset := uint32(12 + 16*len(tags)) // offset starts after table tags
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for i, tag := range tags {
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write32(tag)
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write32(0)
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write32(offset)
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write32(dataLens[i])
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offset += dataLens[i]
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}
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// Data segments.
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for i, dataRef := range dataRefs {
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data := (*[1<<31 - 2]byte)((unsafe.Pointer)(C.CFDataGetBytePtr(dataRef)))[:dataLens[i]]
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buf = append(buf, data...)
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C.CFRelease(C.CFTypeRef(dataRef))
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}
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return buf
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}
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func buildDefault() ([]byte, error) {
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return buildFont(C.CTFontCreateUIFontForLanguage(C.kCTFontSystemFontType, 0, nil)), nil
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}
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func buildMonospace() ([]byte, error) {
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return buildFont(C.CTFontCreateUIFontForLanguage(C.kCTFontUserFixedPitchFontType, 0, nil)), nil
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}
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