1// Copyright 2009 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package png
6
7import (
8	"bytes"
9	"compress/zlib"
10	"encoding/binary"
11	"fmt"
12	"image"
13	"image/color"
14	"image/draw"
15	"io"
16	"testing"
17)
18
19func diff(m0, m1 image.Image) error {
20	b0, b1 := m0.Bounds(), m1.Bounds()
21	if !b0.Size().Eq(b1.Size()) {
22		return fmt.Errorf("dimensions differ: %v vs %v", b0, b1)
23	}
24	dx := b1.Min.X - b0.Min.X
25	dy := b1.Min.Y - b0.Min.Y
26	for y := b0.Min.Y; y < b0.Max.Y; y++ {
27		for x := b0.Min.X; x < b0.Max.X; x++ {
28			c0 := m0.At(x, y)
29			c1 := m1.At(x+dx, y+dy)
30			r0, g0, b0, a0 := c0.RGBA()
31			r1, g1, b1, a1 := c1.RGBA()
32			if r0 != r1 || g0 != g1 || b0 != b1 || a0 != a1 {
33				return fmt.Errorf("colors differ at (%d, %d): %T%v vs %T%v", x, y, c0, c0, c1, c1)
34			}
35		}
36	}
37	return nil
38}
39
40func encodeDecode(m image.Image) (image.Image, error) {
41	var b bytes.Buffer
42	err := Encode(&b, m)
43	if err != nil {
44		return nil, err
45	}
46	return Decode(&b)
47}
48
49func convertToNRGBA(m image.Image) *image.NRGBA {
50	b := m.Bounds()
51	ret := image.NewNRGBA(b)
52	draw.Draw(ret, b, m, b.Min, draw.Src)
53	return ret
54}
55
56func TestWriter(t *testing.T) {
57	// The filenames variable is declared in reader_test.go.
58	names := filenames
59	if testing.Short() {
60		names = filenamesShort
61	}
62	for _, fn := range names {
63		qfn := "testdata/pngsuite/" + fn + ".png"
64		// Read the image.
65		m0, err := readPNG(qfn)
66		if err != nil {
67			t.Error(fn, err)
68			continue
69		}
70		// Read the image again, encode it, and decode it.
71		m1, err := readPNG(qfn)
72		if err != nil {
73			t.Error(fn, err)
74			continue
75		}
76		m2, err := encodeDecode(m1)
77		if err != nil {
78			t.Error(fn, err)
79			continue
80		}
81		// Compare the two.
82		err = diff(m0, m2)
83		if err != nil {
84			t.Error(fn, err)
85			continue
86		}
87	}
88}
89
90func TestWriterPaletted(t *testing.T) {
91	const width, height = 32, 16
92
93	testCases := []struct {
94		plen     int
95		bitdepth uint8
96		datalen  int
97	}{
98
99		{
100			plen:     256,
101			bitdepth: 8,
102			datalen:  (1 + width) * height,
103		},
104
105		{
106			plen:     128,
107			bitdepth: 8,
108			datalen:  (1 + width) * height,
109		},
110
111		{
112			plen:     16,
113			bitdepth: 4,
114			datalen:  (1 + width/2) * height,
115		},
116
117		{
118			plen:     4,
119			bitdepth: 2,
120			datalen:  (1 + width/4) * height,
121		},
122
123		{
124			plen:     2,
125			bitdepth: 1,
126			datalen:  (1 + width/8) * height,
127		},
128	}
129
130	for _, tc := range testCases {
131		t.Run(fmt.Sprintf("plen-%d", tc.plen), func(t *testing.T) {
132			// Create a paletted image with the correct palette length
133			palette := make(color.Palette, tc.plen)
134			for i := range palette {
135				palette[i] = color.NRGBA{
136					R: uint8(i),
137					G: uint8(i),
138					B: uint8(i),
139					A: 255,
140				}
141			}
142			m0 := image.NewPaletted(image.Rect(0, 0, width, height), palette)
143
144			i := 0
145			for y := 0; y < height; y++ {
146				for x := 0; x < width; x++ {
147					m0.SetColorIndex(x, y, uint8(i%tc.plen))
148					i++
149				}
150			}
151
152			// Encode the image
153			var b bytes.Buffer
154			if err := Encode(&b, m0); err != nil {
155				t.Error(err)
156				return
157			}
158			const chunkFieldsLength = 12 // 4 bytes for length, name and crc
159			data := b.Bytes()
160			i = len(pngHeader)
161
162			for i < len(data)-chunkFieldsLength {
163				length := binary.BigEndian.Uint32(data[i : i+4])
164				name := string(data[i+4 : i+8])
165
166				switch name {
167				case "IHDR":
168					bitdepth := data[i+8+8]
169					if bitdepth != tc.bitdepth {
170						t.Errorf("got bitdepth %d, want %d", bitdepth, tc.bitdepth)
171					}
172				case "IDAT":
173					// Uncompress the image data
174					r, err := zlib.NewReader(bytes.NewReader(data[i+8 : i+8+int(length)]))
175					if err != nil {
176						t.Error(err)
177						return
178					}
179					n, err := io.Copy(io.Discard, r)
180					if err != nil {
181						t.Errorf("got error while reading image data: %v", err)
182					}
183					if n != int64(tc.datalen) {
184						t.Errorf("got uncompressed data length %d, want %d", n, tc.datalen)
185					}
186				}
187
188				i += chunkFieldsLength + int(length)
189			}
190		})
191
192	}
193}
194
195func TestWriterLevels(t *testing.T) {
196	m := image.NewNRGBA(image.Rect(0, 0, 100, 100))
197
198	var b1, b2 bytes.Buffer
199	if err := (&Encoder{}).Encode(&b1, m); err != nil {
200		t.Fatal(err)
201	}
202	noenc := &Encoder{CompressionLevel: NoCompression}
203	if err := noenc.Encode(&b2, m); err != nil {
204		t.Fatal(err)
205	}
206
207	if b2.Len() <= b1.Len() {
208		t.Error("DefaultCompression encoding was larger than NoCompression encoding")
209	}
210	if _, err := Decode(&b1); err != nil {
211		t.Error("cannot decode DefaultCompression")
212	}
213	if _, err := Decode(&b2); err != nil {
214		t.Error("cannot decode NoCompression")
215	}
216}
217
218func TestSubImage(t *testing.T) {
219	m0 := image.NewRGBA(image.Rect(0, 0, 256, 256))
220	for y := 0; y < 256; y++ {
221		for x := 0; x < 256; x++ {
222			m0.Set(x, y, color.RGBA{uint8(x), uint8(y), 0, 255})
223		}
224	}
225	m0 = m0.SubImage(image.Rect(50, 30, 250, 130)).(*image.RGBA)
226	m1, err := encodeDecode(m0)
227	if err != nil {
228		t.Error(err)
229		return
230	}
231	err = diff(m0, m1)
232	if err != nil {
233		t.Error(err)
234		return
235	}
236}
237
238func TestWriteRGBA(t *testing.T) {
239	const width, height = 640, 480
240	transparentImg := image.NewRGBA(image.Rect(0, 0, width, height))
241	opaqueImg := image.NewRGBA(image.Rect(0, 0, width, height))
242	mixedImg := image.NewRGBA(image.Rect(0, 0, width, height))
243	translucentImg := image.NewRGBA(image.Rect(0, 0, width, height))
244	for y := 0; y < height; y++ {
245		for x := 0; x < width; x++ {
246			opaqueColor := color.RGBA{uint8(x), uint8(y), uint8(y + x), 255}
247			translucentColor := color.RGBA{uint8(x) % 128, uint8(y) % 128, uint8(y+x) % 128, 128}
248			opaqueImg.Set(x, y, opaqueColor)
249			translucentImg.Set(x, y, translucentColor)
250			if y%2 == 0 {
251				mixedImg.Set(x, y, opaqueColor)
252			}
253		}
254	}
255
256	testCases := []struct {
257		name string
258		img  image.Image
259	}{
260		{"Transparent RGBA", transparentImg},
261		{"Opaque RGBA", opaqueImg},
262		{"50/50 Transparent/Opaque RGBA", mixedImg},
263		{"RGBA with variable alpha", translucentImg},
264	}
265
266	for _, tc := range testCases {
267		t.Run(tc.name, func(t *testing.T) {
268			m0 := tc.img
269			m1, err := encodeDecode(m0)
270			if err != nil {
271				t.Fatal(err)
272			}
273			err = diff(convertToNRGBA(m0), m1)
274			if err != nil {
275				t.Error(err)
276			}
277		})
278	}
279}
280
281func BenchmarkEncodeGray(b *testing.B) {
282	img := image.NewGray(image.Rect(0, 0, 640, 480))
283	b.SetBytes(640 * 480 * 1)
284	b.ReportAllocs()
285	b.ResetTimer()
286	for i := 0; i < b.N; i++ {
287		Encode(io.Discard, img)
288	}
289}
290
291type pool struct {
292	b *EncoderBuffer
293}
294
295func (p *pool) Get() *EncoderBuffer {
296	return p.b
297}
298
299func (p *pool) Put(b *EncoderBuffer) {
300	p.b = b
301}
302
303func BenchmarkEncodeGrayWithBufferPool(b *testing.B) {
304	img := image.NewGray(image.Rect(0, 0, 640, 480))
305	e := Encoder{
306		BufferPool: &pool{},
307	}
308	b.SetBytes(640 * 480 * 1)
309	b.ReportAllocs()
310	b.ResetTimer()
311	for i := 0; i < b.N; i++ {
312		e.Encode(io.Discard, img)
313	}
314}
315
316func BenchmarkEncodeNRGBOpaque(b *testing.B) {
317	img := image.NewNRGBA(image.Rect(0, 0, 640, 480))
318	// Set all pixels to 0xFF alpha to force opaque mode.
319	bo := img.Bounds()
320	for y := bo.Min.Y; y < bo.Max.Y; y++ {
321		for x := bo.Min.X; x < bo.Max.X; x++ {
322			img.Set(x, y, color.NRGBA{0, 0, 0, 255})
323		}
324	}
325	if !img.Opaque() {
326		b.Fatal("expected image to be opaque")
327	}
328	b.SetBytes(640 * 480 * 4)
329	b.ReportAllocs()
330	b.ResetTimer()
331	for i := 0; i < b.N; i++ {
332		Encode(io.Discard, img)
333	}
334}
335
336func BenchmarkEncodeNRGBA(b *testing.B) {
337	img := image.NewNRGBA(image.Rect(0, 0, 640, 480))
338	if img.Opaque() {
339		b.Fatal("expected image not to be opaque")
340	}
341	b.SetBytes(640 * 480 * 4)
342	b.ReportAllocs()
343	b.ResetTimer()
344	for i := 0; i < b.N; i++ {
345		Encode(io.Discard, img)
346	}
347}
348
349func BenchmarkEncodePaletted(b *testing.B) {
350	img := image.NewPaletted(image.Rect(0, 0, 640, 480), color.Palette{
351		color.RGBA{0, 0, 0, 255},
352		color.RGBA{255, 255, 255, 255},
353	})
354	b.SetBytes(640 * 480 * 1)
355	b.ReportAllocs()
356	b.ResetTimer()
357	for i := 0; i < b.N; i++ {
358		Encode(io.Discard, img)
359	}
360}
361
362func BenchmarkEncodeRGBOpaque(b *testing.B) {
363	img := image.NewRGBA(image.Rect(0, 0, 640, 480))
364	// Set all pixels to 0xFF alpha to force opaque mode.
365	bo := img.Bounds()
366	for y := bo.Min.Y; y < bo.Max.Y; y++ {
367		for x := bo.Min.X; x < bo.Max.X; x++ {
368			img.Set(x, y, color.RGBA{0, 0, 0, 255})
369		}
370	}
371	if !img.Opaque() {
372		b.Fatal("expected image to be opaque")
373	}
374	b.SetBytes(640 * 480 * 4)
375	b.ReportAllocs()
376	b.ResetTimer()
377	for i := 0; i < b.N; i++ {
378		Encode(io.Discard, img)
379	}
380}
381
382func BenchmarkEncodeRGBA(b *testing.B) {
383	const width, height = 640, 480
384	img := image.NewRGBA(image.Rect(0, 0, width, height))
385	for y := 0; y < height; y++ {
386		for x := 0; x < width; x++ {
387			percent := (x + y) % 100
388			switch {
389			case percent < 10: // 10% of pixels are translucent (have alpha >0 and <255)
390				img.Set(x, y, color.NRGBA{uint8(x), uint8(y), uint8(x * y), uint8(percent)})
391			case percent < 40: // 30% of pixels are transparent (have alpha == 0)
392				img.Set(x, y, color.NRGBA{uint8(x), uint8(y), uint8(x * y), 0})
393			default: // 60% of pixels are opaque (have alpha == 255)
394				img.Set(x, y, color.NRGBA{uint8(x), uint8(y), uint8(x * y), 255})
395			}
396		}
397	}
398	if img.Opaque() {
399		b.Fatal("expected image not to be opaque")
400	}
401	b.SetBytes(width * height * 4)
402	b.ReportAllocs()
403	b.ResetTimer()
404	for i := 0; i < b.N; i++ {
405		Encode(io.Discard, img)
406	}
407}
408