/// <summary>
/// Updates the rendered state of the specified <see cref="IComponent"/>.
/// </summary>
/// <param name="componentId">The identifier of the <see cref="IComponent"/> to render.</param>
protected internal void RenderNewBatch(int componentId)
{
// It's very important that components' rendering logic has no side-effects, and in particular
// components must *not* trigger Render from inside their render logic, otherwise you could
// easily get hard-to-debug infinite loops.
// Since rendering is currently synchronous and single-threaded, we can enforce the above by
// checking here that no other rendering process is already underway. This also means we only
// need a single _renderBatchBuilder instance that can be reused throughout the lifetime of
// the Renderer instance, which also means we're not allocating on a typical render cycle.
// In the future, if rendering becomes async, we'll need a more sophisticated system of
// capturing successive diffs from each component and probably serializing them for the
// interop calls instead of using shared memory.
// Note that Monitor.TryEnter is not yet supported in Mono WASM, so using the following instead
var renderAlreadyRunning = Interlocked.CompareExchange(ref _renderBatchLock, 1, 0) == 1;
if (renderAlreadyRunning)
{
throw new InvalidOperationException("Cannot render while a render is already in progress. " +
"Render logic must not have side-effects such as manually triggering other rendering.");
}
try
{
RenderInExistingBatch(_sharedRenderBatchBuilder, componentId);
UpdateDisplay(_sharedRenderBatchBuilder.ToBatch());
}
finally
{
_sharedRenderBatchBuilder.Clear();
Interlocked.Exchange(ref _renderBatchLock, 0);
}
}
private void ProcessRenderQueue()
{
_isBatchInProgress = true;
try
{
// Process render queue until empty
while (_batchBuilder.ComponentRenderQueue.Count > 0)
{
var nextToRender = _batchBuilder.ComponentRenderQueue.Dequeue();
RenderInExistingBatch(nextToRender);
}
UpdateDisplay(_batchBuilder.ToBatch());
}
finally
{
RemoveEventHandlerIds(_batchBuilder.DisposedEventHandlerIds.ToRange());
_batchBuilder.Clear();
_isBatchInProgress = false;
}
}
