~eliasnaur/gio

ref: ad4215a7ebb19bf5063e01bb8f3162fa95c63696 gio/ui/ops.go -rw-r--r-- 6.0 KiB
ad4215a7Elias Naur ui: use ints for unit conversions to pixels 2 years ago
                                                                                
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
package ui

import (
	"encoding/binary"
	"errors"
	"fmt"

	"gioui.org/ui/internal/ops"
)

// Ops holds a list of serialized Ops.
type Ops struct {
	// Stack of block start indices.
	stack []pc
	ops   opsData

	inAux  bool
	auxOff int
	auxLen int
}

type opsData struct {
	version int
	// Serialized ops.
	data []byte
	// Op references.
	refs []interface{}
}

// OpsReader parses an ops list. Internal use only.
type OpsReader struct {
	pc    pc
	stack []block
	ops   *opsData
}

// EncodedOp represents an encoded op returned by
// OpsReader. Internal use only.
type EncodedOp struct {
	Key  OpKey
	Data []byte
	Refs []interface{}
}

// OpKey is a unique key for a given op. Internal use only.
type OpKey struct {
	ops     *opsData
	pc      int
	version int
}

type block struct {
	ops   *opsData
	retPC pc
	endPC pc
}

type pc struct {
	data int
	refs int
}

type PushOp struct{}

type PopOp struct{}

type BlockOp struct {
	ops     *opsData
	version int
	pc      pc
}

type opBlockDef struct {
	endpc pc
}

type opAux struct {
	len int
}

func (p PushOp) Add(o *Ops) {
	o.Write([]byte{byte(ops.TypePush)})
}

func (p PopOp) Add(o *Ops) {
	o.Write([]byte{byte(ops.TypePop)})
}

// Begin a block of ops.
func (o *Ops) Begin() {
	o.stack = append(o.stack, o.ops.pc())
	// Make room for a block definition. Filled out in End.
	o.Write(make([]byte, ops.TypeBlockDefLen))
}

func (op *opAux) decode(data []byte) {
	if ops.OpType(data[0]) != ops.TypeAux {
		panic("invalid op")
	}
	bo := binary.LittleEndian
	*op = opAux{
		len: int(bo.Uint32(data[1:])),
	}
}

func (op *opBlockDef) decode(data []byte) {
	if ops.OpType(data[0]) != ops.TypeBlockDef {
		panic("invalid op")
	}
	bo := binary.LittleEndian
	dataIdx := int(bo.Uint32(data[1:]))
	refsIdx := int(bo.Uint32(data[5:]))
	*op = opBlockDef{
		endpc: pc{
			data: dataIdx,
			refs: refsIdx,
		},
	}
}

// End the most recent block and return
// an op for invoking the completed block.
func (o *Ops) End() BlockOp {
	if len(o.stack) == 0 {
		panic(errors.New("End with no matching Begin"))
	}
	start := o.stack[len(o.stack)-1]
	o.stack = o.stack[:len(o.stack)-1]
	pc := o.ops.pc()
	// Write the block header reserved in Begin.
	data := o.ops.data[start.data : start.data+ops.TypeBlockDefLen]
	data[0] = byte(ops.TypeBlockDef)
	bo := binary.LittleEndian
	bo.PutUint32(data[1:], uint32(pc.data))
	bo.PutUint32(data[5:], uint32(pc.refs))
	return BlockOp{ops: &o.ops, pc: start, version: o.ops.version}
}

// Reset the Ops, preparing it for re-use.
func (o *Ops) Reset() {
	o.inAux = false
	o.stack = o.stack[:0]
	o.ops.reset()
}

// Internal use only.
func (o *Ops) Aux() []byte {
	if !o.inAux {
		return nil
	}
	return o.ops.data[o.auxOff+ops.TypeAuxLen : o.auxOff+ops.TypeAuxLen+o.auxLen]
}

func (d *opsData) reset() {
	d.data = d.data[:0]
	d.refs = d.refs[:0]
	d.version++
}

func (d *opsData) write(op []byte, refs ...interface{}) {
	d.data = append(d.data, op...)
	d.refs = append(d.refs, refs...)
}

func (o *Ops) Write(op []byte, refs ...interface{}) {
	t := ops.OpType(op[0])
	if len(refs) != t.NumRefs() {
		panic("invalid ref count")
	}
	switch t {
	case ops.TypeAux:
		// Write only the data.
		op = op[1:]
		if !o.inAux {
			o.inAux = true
			o.auxOff = o.ops.pc().data
			o.auxLen = 0
			header := make([]byte, ops.TypeAuxLen)
			header[0] = byte(ops.TypeAux)
			o.ops.write(header)
		}
		o.auxLen += len(op)
	default:
		if o.inAux {
			o.inAux = false
			bo := binary.LittleEndian
			bo.PutUint32(o.ops.data[o.auxOff+1:], uint32(o.auxLen))
		}
	}
	o.ops.write(op, refs...)
}

func (d *opsData) pc() pc {
	return pc{data: len(d.data), refs: len(d.refs)}
}

func (b *BlockOp) decode(data []byte, refs []interface{}) {
	if ops.OpType(data[0]) != ops.TypeBlock {
		panic("invalid op")
	}
	bo := binary.LittleEndian
	dataIdx := int(bo.Uint32(data[1:]))
	refsIdx := int(bo.Uint32(data[5:]))
	version := int(bo.Uint32(data[9:]))
	*b = BlockOp{
		ops: refs[0].(*opsData),
		pc: pc{
			data: dataIdx,
			refs: refsIdx,
		},
		version: version,
	}
}

func (b BlockOp) Add(o *Ops) {
	if b.ops == nil {
		return
	}
	data := make([]byte, ops.TypeBlockLen)
	data[0] = byte(ops.TypeBlock)
	bo := binary.LittleEndian
	bo.PutUint32(data[1:], uint32(b.pc.data))
	bo.PutUint32(data[5:], uint32(b.pc.refs))
	bo.PutUint32(data[9:], uint32(b.version))
	o.Write(data, b.ops)
}

// Reset start reading from the op list.
func (r *OpsReader) Reset(ops *Ops) {
	if n := len(ops.stack); n > 0 {
		panic(fmt.Errorf("%d Begin(s) not matched with End", n))
	}
	r.ops = &ops.ops
	r.stack = r.stack[:0]
	r.pc = pc{}
}

func (r *OpsReader) Decode() (EncodedOp, bool) {
	for {
		if len(r.stack) > 0 {
			b := r.stack[len(r.stack)-1]
			if r.pc == b.endPC {
				r.ops = b.ops
				r.pc = b.retPC
				r.stack = r.stack[:len(r.stack)-1]
				continue
			}
		}
		if r.pc.data == len(r.ops.data) {
			return EncodedOp{}, false
		}
		key := OpKey{ops: r.ops, pc: r.pc.data, version: r.ops.version}
		t := ops.OpType(r.ops.data[r.pc.data])
		n := t.Size()
		nrefs := t.NumRefs()
		data := r.ops.data[r.pc.data : r.pc.data+n]
		refs := r.ops.refs[r.pc.refs : r.pc.refs+nrefs]
		switch t {
		case ops.TypeAux:
			var op opAux
			op.decode(data)
			n += op.len
			data = r.ops.data[r.pc.data : r.pc.data+n]
		case ops.TypeBlock:
			var op BlockOp
			op.decode(data, refs)
			blockOps := op.ops
			if ops.OpType(blockOps.data[op.pc.data]) != ops.TypeBlockDef {
				panic("invalid block reference")
			}
			if op.version != op.ops.version {
				panic("invalid BlockOp reference to reset Ops")
			}
			var opDef opBlockDef
			opDef.decode(blockOps.data[op.pc.data : op.pc.data+ops.TypeBlockDef.Size()])
			retPC := r.pc
			retPC.data += n
			retPC.refs += nrefs
			r.stack = append(r.stack, block{
				ops:   r.ops,
				retPC: retPC,
				endPC: opDef.endpc,
			})
			r.ops = blockOps
			r.pc = op.pc
			r.pc.data += ops.TypeBlockDef.Size()
			r.pc.refs += ops.TypeBlockDef.NumRefs()
			continue
		case ops.TypeBlockDef:
			var op opBlockDef
			op.decode(data)
			r.pc = op.endpc
			continue
		}
		r.pc.data += n
		r.pc.refs += nrefs
		return EncodedOp{Key: key, Data: data, Refs: refs}, true
	}
}