Rework progressive render loop.

core/src/fpdfapi/fpdf_render/fpdf_render.cpp

Index: core/src/fpdfapi/fpdf_render/fpdf_render.cpp
diff --git a/core/src/fpdfapi/fpdf_render/fpdf_render.cpp b/core/src/fpdfapi/fpdf_render/fpdf_render.cpp
index 35d62ce0b3d6eebba3d396d47972a20c3e41e133..9412fe38dd81c2a454e6697b89d1b05be0477e1b 100644
--- a/core/src/fpdfapi/fpdf_render/fpdf_render.cpp
+++ b/core/src/fpdfapi/fpdf_render/fpdf_render.cpp
@@ -4,7 +4,7 @@
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
-#include "render_int.h"
+#include "core/src/fpdfapi/fpdf_render/render_int.h"
 
 #include "core/include/fpdfapi/fpdf_module.h"
 #include "core/include/fpdfapi/fpdf_render.h"
@@ -1039,9 +1039,8 @@ CPDF_ProgressiveRenderer::CPDF_ProgressiveRenderer(
       m_pOptions(pOptions),
       m_LayerIndex(0),
       m_ObjectIndex(0),
-      m_ObjectPos(nullptr),
-      m_PrevLastPos(nullptr) {
-}
+      m_pCurrentLayer(nullptr),
+      m_ObjectPos(nullptr) {}
 
 CPDF_ProgressiveRenderer::~CPDF_ProgressiveRenderer() {
   if (m_pRenderStatus)
@@ -1058,41 +1057,22 @@ void CPDF_ProgressiveRenderer::Start(IFX_Pause* pPause) {
 }
 
 void CPDF_ProgressiveRenderer::Continue(IFX_Pause* pPause) {
-  if (m_Status != ToBeContinued) {
-    return;
-  }
-  FX_DWORD nLayers = m_pContext->CountLayers();
-  for (; m_LayerIndex < nLayers; m_LayerIndex++) {
-    CPDF_RenderContext::Layer* pLayer = m_pContext->GetLayer(m_LayerIndex);
-    FX_POSITION LastPos = pLayer->m_pObjectList->GetLastObjectPosition();
-    if (!m_ObjectPos) {
-      if (LastPos == m_PrevLastPos) {

[Tom Sepez, 2016/02/12 20:19:20]

We now use the notion of a "current layer" rather than prev last pos to tell if
we had a current layer.  This is the main fix.

-        if (!pLayer->m_pObjectList->IsParsed()) {
-          pLayer->m_pObjectList->ContinueParse(pPause);
-          if (!pLayer->m_pObjectList->IsParsed()) {
-            return;
-          }
-          LastPos = pLayer->m_pObjectList->GetLastObjectPosition();
-        }
-      }
-      if (LastPos == m_PrevLastPos) {

[Tom Sepez, 2016/02/12 20:19:20]

This cleanup falls down to below and merges with block at old 1150.

-        if (m_pRenderStatus) {
-          m_pRenderStatus.reset();
-          m_pDevice->RestoreState();
-          m_ObjectPos = NULL;
-          m_PrevLastPos = NULL;
-        }
-        continue;
+  int step_limit =
+      CPDF_ModuleMgr::Get()->GetRenderModule()->GetConfig()->m_RenderStepLimit;
+  int objs_to_go = step_limit;

[Tom Sepez, 2016/02/12 20:19:20]

Change in behaviour here, we check for limit every N objs, not every N objs
within a single layer, reseting at layer boundaries ...

+  while (m_Status == ToBeContinued) {
+    if (!m_pCurrentLayer) {
+      if (m_LayerIndex >= m_pContext->CountLayers()) {
+        m_Status = Done;
+        return;
       }
-      if (m_PrevLastPos) {
-        m_ObjectPos = m_PrevLastPos;
-        pLayer->m_pObjectList->GetNextObject(m_ObjectPos);
-      } else {
-        m_ObjectPos = pLayer->m_pObjectList->GetFirstObjectPosition();
+      CPDF_RenderContext::Layer* pLayer = m_pContext->GetLayer(m_LayerIndex);
+      if (!pLayer->m_pObjectList->IsParsed()) {
+        pLayer->m_pObjectList->ContinueParse(pPause);
+        if (!pLayer->m_pObjectList->IsParsed())
+          return;
       }
-      m_PrevLastPos = LastPos;
-    }
-    if (!m_pRenderStatus) {
+      m_pCurrentLayer = pLayer;
       m_ObjectPos = pLayer->m_pObjectList->GetFirstObjectPosition();
       m_ObjectIndex = 0;
       m_pRenderStatus.reset(new CPDF_RenderStatus());
@@ -1105,19 +1085,15 @@ void CPDF_ProgressiveRenderer::Continue(IFX_Pause* pPause) {
       device2object.SetReverse(pLayer->m_Matrix);
       device2object.TransformRect(m_ClipRect);
     }
-    int objs_to_go = CPDF_ModuleMgr::Get()
-                         ->GetRenderModule()
-                         ->GetConfig()
-                         ->m_RenderStepLimit;
     while (m_ObjectPos) {
       CPDF_PageObject* pCurObj =
-          pLayer->m_pObjectList->GetObjectAt(m_ObjectPos);
+          m_pCurrentLayer->m_pObjectList->GetObjectAt(m_ObjectPos);
       if (pCurObj && pCurObj->m_Left <= m_ClipRect.right &&
           pCurObj->m_Right >= m_ClipRect.left &&
           pCurObj->m_Bottom <= m_ClipRect.top &&
           pCurObj->m_Top >= m_ClipRect.bottom) {
-        if (m_pRenderStatus->ContinueSingleObject(pCurObj, &pLayer->m_Matrix,
-                                                  pPause)) {
+        if (m_pRenderStatus->ContinueSingleObject(
+                pCurObj, &m_pCurrentLayer->m_Matrix, pPause)) {
           return;
         }
         if (pCurObj->m_Type == CPDF_PageObject::IMAGE &&
@@ -1125,39 +1101,25 @@ void CPDF_ProgressiveRenderer::Continue(IFX_Pause* pPause) {
           m_pContext->GetPageCache()->CacheOptimization(
               m_pRenderStatus->m_Options.m_dwLimitCacheSize);
         }
+        m_ObjectIndex++;
+        m_pCurrentLayer->m_pObjectList->GetNextObject(m_ObjectPos);
         if (pCurObj->m_Type == CPDF_PageObject::FORM ||
-            pCurObj->m_Type == CPDF_PageObject::SHADING) {
-          objs_to_go = 0;
-        } else {
-          objs_to_go--;
-        }
-      }
-      m_ObjectIndex++;
-      pLayer->m_pObjectList->GetNextObject(m_ObjectPos);
-      if (objs_to_go == 0) {
-        if (pPause && pPause->NeedToPauseNow()) {
-          return;
+            pCurObj->m_Type == CPDF_PageObject::SHADING || --objs_to_go == 0) {
+          if (pPause && pPause->NeedToPauseNow()) {
+            return;
+          }
+          objs_to_go = step_limit;
         }
-        objs_to_go = CPDF_ModuleMgr::Get()
-                         ->GetRenderModule()
-                         ->GetConfig()
-                         ->m_RenderStepLimit;
       }
     }
-    if (!pLayer->m_pObjectList->IsParsed()) {
-      return;
-    }
     m_pRenderStatus.reset();
     m_pDevice->RestoreState();
     m_ObjectPos = NULL;
-    m_PrevLastPos = NULL;
-    if (pPause && pPause->NeedToPauseNow()) {
-      m_LayerIndex++;
-      return;
-    }
+    m_pCurrentLayer = nullptr;
+    m_LayerIndex++;
   }
-  m_Status = Done;
 }
+
 int CPDF_ProgressiveRenderer::EstimateProgress() {
   if (!m_pContext) {
     return 0;