utility/graphics/paint_manager.cc

// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "ppapi/utility/graphics/paint_manager.h"

#include "ppapi/c/pp_errors.h"
#include "ppapi/cpp/instance.h"
#include "ppapi/cpp/logging.h"
#include "ppapi/cpp/module.h"

namespace pp {

PaintManager::PaintManager()
    : instance_(NULL),
      client_(NULL),
      is_always_opaque_(false),
      callback_factory_(NULL),
      manual_callback_pending_(false),
      flush_pending_(false),
      has_pending_resize_(false) {
  // Set the callback object outside of the initializer list to avoid a
  // compiler warning about using "this" in an initializer list.
  callback_factory_.Initialize(this);
}

PaintManager::PaintManager(Instance* instance,
                           Client* client,
                           bool is_always_opaque)
    : instance_(instance),
      client_(client),
      is_always_opaque_(is_always_opaque),
      callback_factory_(NULL),
      manual_callback_pending_(false),
      flush_pending_(false),
      has_pending_resize_(false) {
  // Set the callback object outside of the initializer list to avoid a
  // compiler warning about using "this" in an initializer list.
  callback_factory_.Initialize(this);

  // You can not use a NULL client pointer.
  PP_DCHECK(client);
}

PaintManager::~PaintManager() {
}

void PaintManager::Initialize(Instance* instance,
                              Client* client,
                              bool is_always_opaque) {
  PP_DCHECK(!instance_ && !client_);  // Can't initialize twice.
  instance_ = instance;
  client_ = client;
  is_always_opaque_ = is_always_opaque;
}

void PaintManager::SetSize(const Size& new_size) {
  if (GetEffectiveSize() == new_size)
    return;

  has_pending_resize_ = true;
  pending_size_ = new_size;

  Invalidate();
}

void PaintManager::Invalidate() {
  // You must call SetSize before using.
  PP_DCHECK(!graphics_.is_null() || has_pending_resize_);

  EnsureCallbackPending();
  aggregator_.InvalidateRect(Rect(GetEffectiveSize()));
}

void PaintManager::InvalidateRect(const Rect& rect) {
  // You must call SetSize before using.
  PP_DCHECK(!graphics_.is_null() || has_pending_resize_);

  // Clip the rect to the device area.
  Rect clipped_rect = rect.Intersect(Rect(GetEffectiveSize()));
  if (clipped_rect.IsEmpty())
    return;  // Nothing to do.

  EnsureCallbackPending();
  aggregator_.InvalidateRect(clipped_rect);
}

void PaintManager::ScrollRect(const Rect& clip_rect, const Point& amount) {
  // You must call SetSize before using.
  PP_DCHECK(!graphics_.is_null() || has_pending_resize_);

  EnsureCallbackPending();
  aggregator_.ScrollRect(clip_rect, amount);
}

Size PaintManager::GetEffectiveSize() const {
  return has_pending_resize_ ? pending_size_ : graphics_.size();
}

void PaintManager::EnsureCallbackPending() {
  // The best way for us to do the next update is to get a notification that
  // a previous one has completed. So if we're already waiting for one, we
  // don't have to do anything differently now.
  if (flush_pending_)
    return;

  // If no flush is pending, we need to do a manual call to get back to the
  // main thread. We may have one already pending, or we may need to schedule.
  if (manual_callback_pending_)
    return;

  Module::Get()->core()->CallOnMainThread(
      0,
      callback_factory_.NewCallback(&PaintManager::OnManualCallbackComplete),
      0);
  manual_callback_pending_ = true;
}

void PaintManager::DoPaint() {
  PP_DCHECK(aggregator_.HasPendingUpdate());

  // Make a copy of the pending update and clear the pending update flag before
  // actually painting. A plugin might cause invalidates in its Paint code, and
  // we want those to go to the *next* paint.
  PaintAggregator::PaintUpdate update = aggregator_.GetPendingUpdate();
  aggregator_.ClearPendingUpdate();

  // Apply any pending resize. Setting the graphics to this class must happen
  // before asking the plugin to paint in case it requests the Graphics2D during
  // painting. However, the bind must not happen until afterward since we don't
  // want to have an unpainted device bound. The needs_binding flag tells us
  // whether to do this later.
  bool needs_binding = false;
  if (has_pending_resize_) {
    graphics_ = Graphics2D(instance_, pending_size_, is_always_opaque_);
    needs_binding = true;

    // Since we're binding a new one, all of the callbacks have been canceled.
    manual_callback_pending_ = false;
    flush_pending_ = false;
    callback_factory_.CancelAll();

    // This must be cleared before calling into the plugin since it may do
    // additional invalidation or sizing operations.
    has_pending_resize_ = false;
    pending_size_ = Size();
  }

  // Apply any scroll before asking the client to paint.
  if (update.has_scroll)
    graphics_.Scroll(update.scroll_rect, update.scroll_delta);

  if (client_->OnPaint(graphics_, update.paint_rects, update.paint_bounds)) {
    // Something was painted, schedule a flush.
    int32_t result = graphics_.Flush(
        callback_factory_.NewOptionalCallback(&PaintManager::OnFlushComplete));

    // If you trigger this assertion, then your plugin has called Flush()
    // manually. When using the PaintManager, you should not call Flush, it
    // will handle that for you because it needs to know when it can do the
    // next paint by implementing the flush callback.
    //
    // Another possible cause of this assertion is re-using devices. If you
    // use one device, swap it with another, then swap it back, we won't know
    // that we've already scheduled a Flush on the first device. It's best to
    // not re-use devices in this way.
    PP_DCHECK(result != PP_ERROR_INPROGRESS);

    if (result == PP_OK_COMPLETIONPENDING) {
      flush_pending_ = true;
    } else {
      PP_DCHECK(result == PP_OK);  // Catch all other errors in debug mode.
    }
  }

  if (needs_binding)
    instance_->BindGraphics(graphics_);
}

void PaintManager::OnFlushComplete(int32_t result) {
  PP_DCHECK(flush_pending_);
  flush_pending_ = false;

  // Theoretically this shouldn't fail unless we've made an error, but don't
  // want to call into the client code to do more painting if something bad
  // did happen.
  if (result != PP_OK)
    return;

  // If more paints were enqueued while we were waiting for the flush to
  // complete, execute them now.
  if (aggregator_.HasPendingUpdate())
    DoPaint();
}

void PaintManager::OnManualCallbackComplete(int32_t) {
  PP_DCHECK(manual_callback_pending_);
  manual_callback_pending_ = false;

  // Just because we have a manual callback doesn't mean there are actually any
  // invalid regions. Even though we only schedule this callback when something
  // is pending, a Flush callback could have come in before this callback was
  // executed and that could have cleared the queue.
  if (aggregator_.HasPendingUpdate() && !flush_pending_)
    DoPaint();
}


}  // namespace pp