protected override void OnDispose()
{
if (_cache != null)
{
_cache.Count--;
_cache = null;
TryRemoveSourceCache(Source);
}
base.OnDispose();
}
private async void UpdateSource(string oldValue, string newValue)
{
// 重置字段
if (_cache != null)
{
_cache.Count--;
_cache = null;
_current = 0;
// 尝试清理之前的缓存
TryRemoveSourceCache(oldValue);
}
// 更新字段
GIFCache cache = null;
try
{
await _slim.WaitAsync();
if (!string.IsNullOrWhiteSpace(newValue) && !_caches.TryGetValue(newValue, out cache))
{
var name = newValue.TrimEnd(".gif", StringComparison.OrdinalIgnoreCase);
// 获取资源
using (var stream = await Storage.GetResourceStreamAsync(name, "gif"))
{
if (stream != null)
{
// 异步解码 GIF，防止卡 UI 线程
await Task.Run(() =>
{
using (var codec = SKCodec.Create(stream))
{
// 获取图片帧数并分配
var count = codec.FrameCount;
//codec.RepetitionCount
var images = new SKBitmap[count];
var accumulations = new int[count];
var total = 0;
// 循环图片帧
for (int i = 0; i < count; i++)
{
// 获取每帧的时长
var duration = codec.FrameInfo[i].Duration;
// 计算总时长
total += duration;
// 计算累加时长
var former = i == 0 ? 0 : accumulations[i - 1];
accumulations[i] = duration + former;
// 创建图片
var info = new SKImageInfo(codec.Info.Width, codec.Info.Height);
images[i] = new SKBitmap(info);
// 获取像素地址
var address = images[i].GetPixels();
// 创建 SKCodecOptions 描述图片帧
var options = new SKCodecOptions(i);
// 将像素复制到图片中
codec.GetPixels(info, address, options);
}
cache = new GIFCache(images, accumulations, total);
}
});
}
}
// 加入缓存
_caches.Add(newValue, cache);
}
}
finally
{
_slim.Release();
}
// 重绘界面
if (_isAnimating)
{
if (cache == null)
{
StopGIF();
}
else
{
_cache = cache;
_cache.Count++;
InvalidateSurface();
}
}
else
{
if (cache == null)
{
return;
}
switch (State)
{
case ViewState.Unloaded:
{
_cache = cache;
_cache.Count++;
}
break;
case ViewState.Loaded:
{
_cache = cache;
_cache.Count++;
PlayGIF();
}
break;
case ViewState.Disposed:
{
TryRemoveSourceCache(newValue);
break;
}
}
}
}
