public Bitmap GetResizedBitmap(string path, out int originalWidth, out int originalHeight)
{
if (!FilenameUtils.LooksLikeImage(path) || !File.Exists(path))
{
originalWidth = 0;
originalHeight = 0;
return(new Bitmap(1, 1, PixelFormat.Format32bppPArgb));
}
Bitmap bitmapFull = GetBitmap(path, _shouldRotateThisImage, out bool bitmapWillLockFile);
// resize and preserve ratio
originalWidth = bitmapFull.Width;
originalHeight = bitmapFull.Height;
if (bitmapFull.Width > MaxWidth || bitmapFull.Height > MaxHeight)
{
using (bitmapFull)
{
var ratio = Math.Min((double)MaxWidth / bitmapFull.Width,
(double)MaxHeight / bitmapFull.Height);
int newWidth = (int)(bitmapFull.Width * ratio);
int newHeight = (int)(bitmapFull.Height * ratio);
return(ClassImageOps.ResizeImage(bitmapFull, newWidth, newHeight, this.ResizeToFit, path));
}
}
else if (bitmapWillLockFile)
{
// make a copy of the bitmap, otherwise the file remains locked
using (bitmapFull)
{
return(new Bitmap(bitmapFull));
}
}
else
{
return(bitmapFull);
}
}
// add paths to cache, and then checks for images to remove.
public void Add(string[] paths)
{
bool checkIfTooManyInCache = false;
foreach (var path in paths)
{
if (path == null)
{
continue;
}
lock (_lock)
{
// skip if it's already in the cache
if (_list.SearchForUpToDateCacheEntry(path) != -1)
{
continue;
}
// reading and resizing the bitmap can be done outside the lock,
// but this might do redundant work.
var bitmap = GetResizedBitmap(path, out int originalWidth, out int originalHeight);
DateTime lastmod = DateTime.MinValue;
long filesize = 0;
if (File.Exists(path))
{
var fileInfo = new FileInfo(path);
lastmod = fileInfo.LastWriteTimeUtc;
filesize = fileInfo.Length;
}
bitmap = ClassImageOps.ResizeImageByFactor(bitmap, ResizeFactor, VerticalScrollFactor);
bitmap = ClassImageOps.TileImage(bitmap, _tileImages, MaxWidth, MaxHeight);
_list.Add(new CacheEntry(
path, bitmap, originalWidth, originalHeight, lastmod, filesize));
checkIfTooManyInCache = _list.Count > _cacheSize;
}
}
if (checkIfTooManyInCache)
{
// ask form before we call Dispose() in case form is currently using this image.
_callbackOnUiThread.Invoke(new Action(() =>
{
lock (_lock)
{
// it's possible there is no work left to do, due to another thread.
// iterate backwards, since RemoveAt repositions subsequent elements
var howManyToRemove = _list.Count - _cacheSize;
for (int i = howManyToRemove - 1; i >= 0; i--)
{
if (i <= _list.Count - 1 && _canDisposeBitmap(_list[i].Image))
{
_list.RemoveAt(i);
}
}
}
}));
}
}
