U: Add TGIFHeader, To verify the legality of GIF images

cef/gifanim/animate.go

@@ -14,12 +14,13 @@ package gifanim
 
 import (
 	"bytes"
+	"encoding/binary"
 	"github.com/energye/energy/v2/pkgs/ext"
 	"github.com/energye/golcl/lcl"
 	"github.com/energye/golcl/lcl/types"
+	"image"
 	"image/gif"
-	"image/png"
-	"os"
+	"io/ioutil"
 )
 
 const (
@@ -76,7 +77,7 @@ func (m *TGIFAnimate) onTimer(sender lcl.IObject) {
 	} else {
 		m.index++
 	}
-	nextDelay := m.nextDelay()
+	nextDelay := m.frames[m.index].delay
 	if nextDelay != m.delay {
 		m.delay = nextDelay
 		m.task.SetEnabled(false)
@@ -134,13 +135,19 @@ func (m *TGIFAnimate) load() {
 	m.reset()
 	m.count = len(m.gif.Image)
 	m.frames = make([]*Frame, m.count)
-	for i, frame := range m.gif.Image {
-		bounds := frame.Bounds()
-		var pngBuf bytes.Buffer
-		err := png.Encode(&pngBuf, frame)
+	var frameToBytes = func(frame *image.Paletted) (result []byte) {
+		var buf bytes.Buffer
+		//err := png.Encode(&buf, frame)
+		err := gif.Encode(&buf, frame, nil)
 		if err != nil {
 			panic(err)
 		}
+		result = buf.Bytes()
+		buf.Reset()
+		return
+	}
+	for i, frame := range m.gif.Image {
+		bounds := frame.Bounds()
 		m.frames[i] = &Frame{
 			index:  i,
 			method: m.gif.Disposal[i],
@@ -149,9 +156,8 @@ func (m *TGIFAnimate) load() {
 			w:      int32(bounds.Dx()),
 			h:      int32(bounds.Dy()),
 			delay:  uint32(m.gif.Delay[i] * 10),
-			data:   pngBuf.Bytes(),
+			data:   frameToBytes(frame),
 		}
-		pngBuf.Reset()
 	}
 	m.initialed()
 	m.gif = nil
@@ -183,10 +189,6 @@ func (m *TGIFAnimate) reset() {
 	m.count = 0
 }
 
-func (m *TGIFAnimate) nextDelay() uint32 {
-	return m.frames[m.index].delay
-}
-
 func (m *TGIFAnimate) currentFrame() *Frame {
 	return m.frames[m.index]
 }
@@ -290,20 +292,18 @@ func (m *TGIFAnimate) LoadFromFile(filePath string) {
 	if m.filePath == filePath {
 		return
 	}
-	file, err := os.Open(filePath)
+	data, err := ioutil.ReadFile(filePath)
 	if err != nil {
 		panic(err)
 	}
-	defer file.Close()
-	g, err := gif.DecodeAll(file)
-	if err != nil {
-		panic(err)
-	}
-	m.gif = g
-	m.load()
+	m.LoadFromBytes(data)
 }
 
 func (m *TGIFAnimate) LoadFromBytes(data []byte) {
+	header := m.ReadHeader(data)
+	if header == nil || !header.IsGIF() || !header.Is89a() {
+		return
+	}
 	g, err := gif.DecodeAll(bytes.NewReader(data))
 	if err != nil {
 		panic(err)
@@ -312,6 +312,17 @@ func (m *TGIFAnimate) LoadFromBytes(data []byte) {
 	m.load()
 }
 
+func (m *TGIFAnimate) ReadHeader(data []byte) *TGIFHeader {
+	if data != nil && len(data) > 13 {
+		header := new(TGIFHeader)
+		var buf bytes.Buffer
+		buf.Write(data[:13])
+		binary.Read(&buf, binary.LittleEndian, header)
+		return header
+	}
+	return nil
+}
+
 func Rect(left, top, right, bottom int32) types.TRect {
 	return types.TRect{Left: left, Top: top, Right: right, Bottom: bottom}
 }

cef/gifanim/frame.go

@@ -22,8 +22,8 @@ type Frame struct {
 	delay  uint32
 	data   []byte
 	//background lcl.IBitmap
-	//image      *lcl.TGIFImage
-	image *lcl.TPngImage
+	image *lcl.TGIFImage
+	//image *lcl.TPngImage
 }
 
 func (m *Frame) Index() int {
@@ -70,8 +70,8 @@ func (m *Frame) SetData(data []byte) {
 
 func (m *Frame) scan() {
 	if m.image == nil {
-		//m.image = lcl.NewGIFImage()
-		m.image = lcl.NewPngImage()
+		m.image = lcl.NewGIFImage()
+		//m.image = lcl.NewPngImage()
 		m.image.SetSize(m.w, m.h)
 		m.image.LoadFromBytes(m.data)
 	}

cef/gifanim/header.go

@@ -0,0 +1,35 @@
+//----------------------------------------
+//
+// Copyright © yanghy. All Rights Reserved.
+//
+// Licensed under Apache License Version 2.0, January 2004
+//
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+//----------------------------------------
+
+package gifanim
+
+type TGIFHeader struct {
+	Signature       [3]byte // 页眉签名（始终为“GIF”）
+	Version         [3]byte // GIF格式版本（“89a”）
+	ScreenWidth     uint16  // 以像素为单位的显示屏宽度
+	ScreenHeight    uint16  // 以像素为单位的显示屏高度
+	Packedbit       byte    // 屏幕和彩色地图信息
+	BackgroundColor byte    // 背景色索引
+	AspectRatio     byte    // 像素纵横比
+}
+
+func (m *TGIFHeader) Is89a() bool {
+	if m == nil {
+		return false
+	}
+	return m.Version[0] == '8' && m.Version[1] == '9' && m.Version[2] == 'a'
+}
+
+func (m *TGIFHeader) IsGIF() bool {
+	if m == nil {
+		return false
+	}
+	return m.Signature[0] == 'G' && m.Signature[1] == 'I' && m.Signature[2] == 'F'
+}