我想创建一个包含多个帧的gif文件。
我想使用微软支持的方法--Image.SaveAdd。
但我不知道如何设置EncoderParameters参数来组成gif文件。
我找不到相关文档参考。那么如何使用
Image.SaveAdd
创建gif文件呢?Image.SaveAdd
创建gif文件呢?也许对于原帖作者来说已经太晚了,但是我成功地使用System.Drawing创建了一个适当的gif。下面的代码基于jschroedl的答案,还设置了帧延迟和动画循环次数。
// Gdi+ constants absent from System.Drawing.
const int PropertyTagFrameDelay = 0x5100;
const int PropertyTagLoopCount = 0x5101;
const short PropertyTagTypeLong = 4;
const short PropertyTagTypeShort = 3;
const inr UintBytes = 4;
//...
var gifEncoder = GetEncoder(ImageFormat.Gif);
// Params of the first frame.
var encoderParams1 = new EncoderParameters(1);
encoderParams1.Param[0] = new EncoderParameter(Encoder.SaveFlag, (long)EncoderValue.MultiFrame);
// Params of other frames.
var encoderParamsN = new EncoderParameters(1);
encoderParamsN.Param[0] = new EncoderParameter(Encoder.SaveFlag, (long)EncoderValue.FrameDimensionTime);
// Params for the finalizing call.
var encoderParamsFlush = new EncoderParameters(1);
encoderParamsFlush.Param[0] = new EncoderParameter(Encoder.SaveFlag, (long)EncoderValue.Flush);
// PropertyItem for the frame delay (apparently, no other way to create a fresh instance).
var frameDelay = (PropertyItem)FormatterServices.GetUninitializedObject(typeof(PropertyItem));
frameDelay.Id = PropertyTagFrameDelay;
frameDelay.Type = PropertyTagTypeLong;
// Length of the value in bytes.
frameDelay.Len = Bitmaps.Count * UintBytes;
// The value is an array of 4-byte entries: one per frame.
// Every entry is the frame delay in 1/100-s of a second, in little endian.
frameDelay.Value = new byte[Bitmaps.Count * UintBytes];
// E.g., here, we're setting the delay of every frame to 1 second.
var frameDelayBytes = BitConverter.GetBytes((uint)100);
for (int j = 0; j < Bitmaps.Count; ++j)
Array.Copy(frameDelayBytes, 0, frameDelay.Value, j * UintBytes, UintBytes);
// PropertyItem for the number of animation loops.
var loopPropertyItem = (PropertyItem)FormatterServices.GetUninitializedObject(typeof(PropertyItem));
loopPropertyItem.Id = PropertyTagLoopCount;
loopPropertyItem.Type = PropertyTagTypeShort;
loopPropertyItem.Len = 1;
// 0 means to animate forever.
loopPropertyItem.Value = BitConverter.GetBytes((ushort)0);
using (var stream = new FileStream("animation.gif", FileMode.Create))
{
bool first = true;
Bitmap firstBitmap = null;
// Bitmaps is a collection of Bitmap instances that'll become gif frames.
foreach (var bitmap in Bitmaps)
{
if (first)
{
firstBitmap = bitmap;
firstBitmap.SetPropertyItem(frameDelay);
firstBitmap.SetPropertyItem(loopPropertyItem);
firstBitmap.Save(stream, gifEncoder, encoderParams1);
first = false;
}
else
{
firstBitmap.SaveAdd(bitmap, encoderParamsN);
}
}
firstBitmap.SaveAdd(encoderParamsFlush);
}
// ...
private ImageCodecInfo GetEncoder(ImageFormat format)
{
ImageCodecInfo[] codecs = ImageCodecInfo.GetImageDecoders();
foreach (ImageCodecInfo codec in codecs)
{
if (codec.FormatID == format.Guid)
{
return codec;
}
}
return null;
}
ULONG parameterValue;
EncoderParameters encoderParameters;
encoderParameters.Count = 1;
encoderParameters.Parameter[0].Guid = EncoderSaveFlag;
encoderParameters.Parameter[0].Type = EncoderParameterValueTypeLong;
encoderParameters.Parameter[0].NumberOfValues = 1;
encoderParameters.Parameter[0].Value = ¶meterValue;
// Save the first frame
parameterValue = EncoderValueMultiFrame;
rc = img1->Save(L"Output.gif", &encoderClsid, &encoderParameters);
assert(rc == Ok);
// Add the second frame
parameterValue = EncoderValueFrameDimensionTime;
rc = img1->SaveAdd(img2, &encoderParameters);
assert(rc == Ok);
// etc...adding frames img3,4,5...
// Done...
parameterValue = EncoderValueFlush;
rc = img1->SaveAdd(&encoderParameters);
assert(rc == Ok);
编辑:我刚意识到你要求C#,但我只有C ++代码。希望参数仍然适用。
如果您想使用多张图片创建gif图像,可以使用ngif。请参见this。
//you should replace filepath
String [] imageFilePaths = new String[]{"c:\\01.png","c:\\02.png","c:\\03.png"};
String outputFilePath = "c:\\test.gif";
AnimatedGifEncoder e = new AnimatedGifEncoder();
e.Start( outputFilePath );
e.SetDelay(500);
//-1:no repeat,0:always repeat
e.SetRepeat(0);
for (int i = 0, count = imageFilePaths.Length; i < count; i++ )
{
e.AddFrame( Image.FromFile( imageFilePaths[i] ) );
}
e.Finish();
/* extract Gif */
string outputPath = "c:\\";
GifDecoder gifDecoder = new GifDecoder();
gifDecoder.Read( "c:\\test.gif" );
for ( int i = 0, count = gifDecoder.GetFrameCount(); i < count; i++ )
{
Image frame = gifDecoder.GetFrame( i ); // frame i
frame.Save( outputPath + Guid.NewGuid().ToString()
+ ".png", ImageFormat.Png );
}