47 lines
1.0 KiB
Go
47 lines
1.0 KiB
Go
// 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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// +build linux darwin
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package font
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import (
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"bytes"
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"fmt"
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"testing"
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)
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func looksLikeATTF(b []byte) error {
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if len(b) < 256 {
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return fmt.Errorf("not a TTF: not enough data")
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}
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b = b[:256]
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// Look for the 4-byte magic header. See
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// http://www.microsoft.com/typography/otspec/otff.htm
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switch string(b[:4]) {
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case "\x00\x01\x00\x00", "ttcf":
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// No-op.
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default:
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return fmt.Errorf("not a TTF: missing magic header")
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}
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// Look for a glyf table.
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if i := bytes.Index(b, []byte("glyf")); i < 0 {
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return fmt.Errorf(`not a TTF: missing "glyf" table`)
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} else if i%0x10 != 0x0c {
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return fmt.Errorf(`not a TTF: invalid "glyf" offset 0x%02x`, i)
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}
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return nil
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}
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func TestLoadFonts(t *testing.T) {
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if err := looksLikeATTF(Default()); err != nil {
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t.Errorf("default font: %v", err)
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}
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if err := looksLikeATTF(Monospace()); err != nil {
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t.Errorf("monospace font: %v", err)
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}
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}
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