Improve filters preview performance (fix #1400)

Now several filter steps are applied in a background thread and a UI
timer refresh several rows in screen at the same time (instead of one
row per time). (This is something in my personal to-do list from long
time ago too.)

src/app/commands/filters/filter_manager_impl.cpp

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2016  David Capello
+// Copyright (C) 2001-2017  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -110,7 +110,7 @@ void FilterManagerImpl::beginForPreview()
     m_previewMask->replace(m_site.sprite()->bounds());
   }
 
-  m_row = 0;
+  m_row = m_nextRowToFlush = 0;
   m_mask = m_previewMask;
 
   {
@@ -257,17 +257,24 @@ void FilterManagerImpl::applyToTarget()
 
 void FilterManagerImpl::flush()
 {
-  if (m_row >= 0) {
+  int h = m_row - m_nextRowToFlush;
+
+  if (m_row >= 0 && h > 0) {
     Editor* editor = current_editor;
+
+    // We expand the region one pixel at the top and bottom of the
+    // region [m_row,m_nextRowToFlush) to be updated on the screen to
+    // avoid screen artifacts when we apply filters like convolution
+    // matrices.
     gfx::Rect rect(
       editor->editorToScreen(
         gfx::Point(
           m_bounds.x,
-          m_bounds.y+m_row-1)),
+          m_bounds.y+m_nextRowToFlush-1)),
       gfx::Size(
         editor->projection().applyX(m_bounds.w),
-        (editor->projection().scaleY() >= 1 ? editor->projection().applyY(1):
-                                              editor->projection().removeY(1))));
+        (editor->projection().scaleY() >= 1 ? editor->projection().applyY(h+2):
+                                              editor->projection().removeY(h+2))));
 
     gfx::Region reg1(rect);
     gfx::Region reg2;
@@ -275,6 +282,7 @@ void FilterManagerImpl::flush()
     reg1.createIntersection(reg1, reg2);
 
     editor->invalidateRegion(reg1);
+    m_nextRowToFlush = m_row+1;
   }
 }
 

src/app/commands/filters/filter_manager_impl.h

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2016  David Capello
+// Copyright (C) 2001-2017  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -120,6 +120,7 @@ namespace app {
     doc::ImageRef m_src;
     doc::ImageRef m_dst;
     int m_row;
+    int m_nextRowToFlush;
     gfx::Rect m_bounds;
     doc::Mask* m_mask;
     base::UniquePtr<doc::Mask> m_previewMask;

src/app/commands/filters/filter_preview.cpp

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2016  David Capello
+// Copyright (C) 2001-2017  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -13,6 +13,8 @@
 #include "app/commands/filters/filter_manager_impl.h"
 #include "app/modules/editors.h"
 #include "app/ui/editor/editor.h"
+#include "base/bind.h"
+#include "base/scoped_lock.h"
 #include "doc/layer.h"
 #include "doc/sprite.h"
 #include "ui/manager.h"
@@ -28,6 +30,7 @@ FilterPreview::FilterPreview(FilterManagerImpl* filterMgr)
   : Widget(kGenericWidget)
   , m_filterMgr(filterMgr)
   , m_timer(1, this)
+  , m_filterThread(nullptr)
 {
   setVisible(false);
 }
@@ -39,25 +42,32 @@ FilterPreview::~FilterPreview()
 
 void FilterPreview::stop()
 {
-  if (m_timer.isRunning()) {
-    ASSERT(m_filterMgr != NULL);
-
-    m_filterMgr->end();
+  {
+    base::scoped_lock lock(m_filterMgrMutex);
+    if (m_timer.isRunning()) {
+      ASSERT(m_filterMgr);
+      m_filterMgr->end();
+    }
   }
 
-  m_filterMgr = NULL;
   m_timer.stop();
+
+  if (m_filterThread) {
+    m_filterThread->join();
+    m_filterThread.reset();
+  }
 }
 
 void FilterPreview::restartPreview()
 {
-  m_filterMgr->beginForPreview();
-  m_timer.start();
-}
+  base::scoped_lock lock(m_filterMgrMutex);
 
-FilterManagerImpl* FilterPreview::getFilterManager() const
-{
-  return m_filterMgr;
+  m_filterMgr->beginForPreview();
+  m_filterIsDone = false;
+  m_filterThread.reset(new base::thread(
+    base::Bind<void>(&FilterPreview::onFilterThread, this)));
+
+  m_timer.start();
 }
 
 bool FilterPreview::onProcessMessage(Message* msg)
@@ -80,17 +90,30 @@ bool FilterPreview::onProcessMessage(Message* msg)
       m_timer.stop();
       break;
 
-    case kTimerMessage:
+    case kTimerMessage: {
+      base::scoped_lock lock(m_filterMgrMutex);
       if (m_filterMgr) {
-        if (m_filterMgr->applyStep())
-          m_filterMgr->flush();
-        else
+        m_filterMgr->flush();
+        if (m_filterIsDone)
           m_timer.stop();
       }
       break;
+    }
   }
 
   return Widget::onProcessMessage(msg);
 }
 
+// This is executed in other thread.
+void FilterPreview::onFilterThread()
+{
+  while (!m_filterIsDone && m_timer.isRunning()) {
+    {
+      base::scoped_lock lock(m_filterMgrMutex);
+      m_filterIsDone = !m_filterMgr->applyStep();
+    }
+    base::this_thread::yield();
+  }
+}
+
 } // namespace app

src/app/commands/filters/filter_preview.h

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2015  David Capello
+// Copyright (C) 2001-2017  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -8,6 +8,9 @@
 #define APP_COMMANDS_FILTERS_FILTER_PREVIEW_H_INCLUDED
 #pragma once
 
+#include "base/mutex.h"
+#include "base/thread.h"
+#include "base/unique_ptr.h"
 #include "ui/timer.h"
 #include "ui/widget.h"
 
@@ -23,14 +26,18 @@ namespace app {
 
     void stop();
     void restartPreview();
-    FilterManagerImpl* getFilterManager() const;
 
   protected:
     bool onProcessMessage(ui::Message* msg) override;
 
   private:
+    void onFilterThread();
+
     FilterManagerImpl* m_filterMgr;
     ui::Timer m_timer;
+    base::mutex m_filterMgrMutex;
+    base::UniquePtr<base::thread> m_filterThread;
+    bool m_filterIsDone;
   };
 
 } // namespace app

src/app/commands/filters/filter_window.cpp

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2015  David Capello
+// Copyright (C) 2001-2017  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -121,6 +121,8 @@ void FilterWindow::restartPreview()
 
 void FilterWindow::setNewTarget(Target target)
 {
+  stopPreview();
+
   m_filterMgr->setTarget(target);
   m_targetButton.setTarget(target);
 }
@@ -143,6 +145,8 @@ void FilterWindow::onShowPreview(Event& ev)
 // Called when the user changes the target-buttons.
 void FilterWindow::onTargetButtonChange()
 {
+  stopPreview();
+
   // Change the targets in the filter manager and restart the filter preview.
   m_filterMgr->setTarget(m_targetButton.getTarget());
   restartPreview();
@@ -150,7 +154,8 @@ void FilterWindow::onTargetButtonChange()
 
 void FilterWindow::onTiledChange()
 {
-  ASSERT(m_tiledCheck != NULL);
+  ASSERT(m_tiledCheck);
+  stopPreview();
 
   // Call derived class implementation of setupTiledMode() so the
   // filter is modified.
@@ -162,4 +167,9 @@ void FilterWindow::onTiledChange()
   restartPreview();
 }
 
+void FilterWindow::stopPreview()
+{
+  m_preview.stop();
+}
+
 } // namespace app

src/app/commands/filters/filter_window.h

@@ -1,5 +1,5 @@
 // Aseprite
-// Copyright (C) 2001-2015  David Capello
+// Copyright (C) 2001-2017  David Capello
 //
 // This program is distributed under the terms of
 // the End-User License Agreement for Aseprite.
@@ -62,6 +62,8 @@ namespace app {
     virtual void setupTiledMode(TiledMode tiledMode) { }
 
   private:
+    void stopPreview();
+
     const char* m_cfgSection;
     FilterManagerImpl* m_filterMgr;
     ui::Box m_hbox;