/// <summary>Creates a thumbnail</summary>
/// <param name="info">Media information to use for header text</param>
/// <param name="pFormatContext">The format context to use</param>
/// <param name="vidStream">The video stream to use</param>
/// <param name="options">Options setting the appearence of the sheet</param>
/// <param name="onProgress">Is called after each taken frame and passes (int currentIndex, int positions.Count) - if true is returned, the loop is canceled</param>
private unsafe static Bitmap ExtractVideoThumbnailSheet(FFmpegMediaInfo info, AVFormatContext* pFormatContext, AVStream* vidStream, VideoThumbSheetOptions options, Func<int, int, bool> onProgress)
{
#region Structure diagram
/* m := Margin, p := Padding, tw := ThumbWidth, th := ThumbHeight, hh := HeaderHeight, ### := Thumbnail image
m ###tw### p ###tw### p ###tw### p ###tw### p ###tw### m
+--------------------------------------------------------+
| | m } Margin
| +----------------------------------------------------+ |
| |Filename: xxxxxxxxxxxxxxxxxxxxxx.avi | | xx \
| |Length: 0:00:00 Resolution: 640x480 @25FPS | | hh } Header height
| |Streams: Video[div5/xvid], Audio[mp3a/MP3/eng] | | xx /
| +----------------------------------------------------+ |
| | 2*p } 2 * Padding
| +----------------------------------------------------+ |
| |########| |########| |########| |########| |########| | ## \
| |########| |########| |########| |########| |########| | th } Thumbnail height
| |########| |########| |########| |########| |########| | ## /
| +----------------------------------------------------+ |
| | p } 1* Padding
| +----------------------------------------------------+ |
| |########| |########| |########| |########| |########| |
... ... ...
... ... ...
| |########| |########| |########| |########| |########| |
+ +----------------------------------------------------+ +
| | m } Margin
+--------------------------------------------------------+
*/
#endregion
#region Header and image preperations
// Get video info from codec
int width = vidStream->codec->width;
int height = vidStream->codec->height;
AVRational framerate = vidStream->codec->framerate;
long duration = pFormatContext->duration;
// Create header text and calculate its height (using current video stream)
string header = String.Format("Filename: {0}\r\nLength: {1} Resolution: {2}x{3} @{4}FPS\r\nStreams: {5}",
Path.GetFileName(info.Filename),
ToFormattedString(info.Duration),
width, height, ToDescString(framerate),
String.Join(", ", info.Streams.Select(s => s.ToString()).ToArray())
);
int headerHight = Convert.ToInt32(MeassureString(header, options.HeaderFont).Height);
// Calculate image sizes and create image
int thumbHeight = height * options.ThumbWidth / width;
int imgWidth = 2 * options.Margin + options.ThumbColumns * (options.ThumbWidth + options.Padding) - options.Padding;
int imgHeight = 2 * options.Margin + headerHight + options.ThumbRows * (thumbHeight + options.Padding) + options.Padding;
int thumbTop = options.Margin + headerHight + 2 * options.Padding;
Bitmap bmp = new Bitmap(imgWidth, imgHeight);
int count = options.ThumbColumns * options.ThumbRows;
List<long> positions = CreateRegularTimePositionList(duration, count);
#endregion
using (Graphics g = Graphics.FromImage(bmp))
using (Brush headerBrush = new SolidBrush(options.HeaderColor))
using (Pen borderPen = new Pen(options.ThumbBorderColor, 1f))
using (Brush indexShadowBrush = new SolidBrush(options.IndexShadowColor))
using (Brush indexBrush = new SolidBrush(options.IndexColor))
{
// Set background color
g.Clear(options.BackgroundColor);
// Draw header text
float marginF = Convert.ToSingle(options.Margin);
g.DrawString(header, options.HeaderFont, headerBrush, new PointF(marginF, marginF));
// Loop through images as they are extracted
int c, r, x, y;
string tsText;
SizeF tsSize;
float ix, iy;
ExtractFrames(pFormatContext, vidStream, positions, options.ForceExactTimePosition, (i, ts, img) =>
{
// Calculate positions and sizes
c = i % options.ThumbColumns; // column
r = i / options.ThumbColumns; // row
x = options.Margin + c * (options.ThumbWidth + options.Padding); // thumb left
y = thumbTop + r * (thumbHeight + options.Padding); // thumb top
tsText = String.Format("{0:00}:{1:00}:{2:00}", ts.Hours, ts.Minutes, ts.Seconds); // timestamp text
tsSize = g.MeasureString(tsText, options.IndexFont); // timestamp text size
ix = Convert.ToSingle(x + options.ThumbWidth) - tsSize.Width - 3f; // timestamp text left
iy = Convert.ToSingle(y + thumbHeight) - tsSize.Height - 3f; // timestamp text top
// Insert thumbnail image resized
g.DrawImage(img, x, y, options.ThumbWidth, thumbHeight);
// Overdraw edges with border
if (options.DrawThumbnailBorder)
g.DrawRectangle(borderPen, x, y, options.ThumbWidth, thumbHeight);
// Draw timestamp shadow
g.DrawString(tsText, options.IndexFont, indexShadowBrush, ix - 1f, iy - 1f);
g.DrawString(tsText, options.IndexFont, indexShadowBrush, ix + 1f, iy + 1f);
// Draw timestamp
g.DrawString(tsText, options.IndexFont, indexBrush, ix, iy);
// Dispose the thumbnail image because it's not needed anymore
img.Dispose();
// Publish progress
if (onProgress != null)
return onProgress(i, count);
else
return false;
});
}
return bmp;
}
/// <summary>Creates a thumbnail sheet</summary>
/// <param name="streamIndex">The index of the video stream to extract the frames from (-1 selects the first video stream)</param>
/// <param name="options">Options setting the thumbnail sheet's appearence</param>
/// <param name="onProgress">Is called after each taken frame and passes (int currentIndex, int positions.Count) - if true is returned, the loop is canceled</param>
public Bitmap GetThumbnailSheet(int streamIndex, VideoThumbSheetOptions options, Func<int, int, bool> onProgress)
{
FFmpegStreamInfo stream;
if (streamIndex == -1)
stream = this.Streams.FirstOrDefault(s => s.StreamType == FFmpegStreamType.Video);
else
stream = this.Streams[streamIndex];
if (stream == null || stream.StreamType != FFmpegStreamType.Video)
throw new Exception("No video stream selected!");
return ExtractVideoThumbnailSheet(this, this.AVFormatContext, stream.AVStream, options, onProgress);
}