// Private methods.
/// <summary>
/// Creates an asynchronous state, and executes the method on the thread pool.
/// </summary>
/// <param name="method">The method to execute.</param>
/// <param name="userState">The user state.</param>
private void Execute(AsyncTaskCallback method, object userState)
{
// Create the asynchronous state for the current method.
AsyncState asyncState = new AsyncState(userState);
// Execute the method on the thread pool.
ThreadPool.QueueUserWorkItem((object state) =>
{
// Lock the task.
lock (this.syncTask)
{
// Lock the state.
lock (this.syncState)
{
// Change the task state.
this.taskState = AsyncTaskState.Running;
// Set the current asychronous state.
this.asyncState = asyncState;
}
// Execute the task method.
method(asyncState);
// If the method has been canceled.
if (asyncState.IsCanceled)
{
// Execute the cancel callback method.
asyncState.CancelCallback();
}
// Lock the state.
lock (this.syncState)
{
// Change the task state.
this.taskState = AsyncTaskState.Ready;
// Set the current asychronous state to null.
this.asyncState = null;
// Signal the completion of the asynchronous operation.
asyncState.Complete();
}
// Dispose of the asynchronous state.
asyncState.Dispose();
}
});
}
/// <summary>
/// Creates a new bitmap for the current map, scaled at the specified size. The scaled version of the map fits the largest dimension between width and height.
/// </summary>
/// <param name="asyncState">The asynchronous state.</param>
/// <returns>The map bitmap.</returns>
private Bitmap OnDrawMap(AsyncState asyncState)
{
// Save the map object in a local variable.
Map map = this.map;
// Acquire an exclusive access to the map.
lock (map)
{
// Create a new bitmap.
Bitmap bitmap = new Bitmap(bitmapSize.Width, bitmapSize.Height);
// Draw the bitmap.
using (Graphics graphics = Graphics.FromImage(bitmap))
{
// Set the smooting mode to default.
graphics.SmoothingMode = SmoothingMode.Default;
using (SolidBrush brush = new SolidBrush(this.colorBackground))
{
using (Pen pen = new Pen(this.colorRegionNormalBorder))
{
// Fill the background.
graphics.FillRectangle(brush, 0, 0, bitmapSize.Width, bitmapSize.Height);
// Set the smooting mode to high quality.
graphics.SmoothingMode = SmoothingMode.HighQuality;
// Change the brush color.
brush.Color = this.colorRegionNormalBackground;
// Get an exclusive reader lock to the regions list.
this.regions.Lock();
try
{
// Draw the map regions.
foreach (MapRegion region in this.regions)
{
// If the asynchronous operation has been canceled.
if (asyncState.IsCanceled)
{
// Dispose the bitmap.
bitmap.Dispose();
// Return null.
return null;
}
// Draw the region.
region.Draw(graphics, brush, this.showBorders ? pen : null);
}
}
finally
{
this.regions.Unlock();
}
}
}
}
// Return the bitmap.
return bitmap;
}
}