Add methods to SkLayerDrawLooper to allow adding layers on top

src/effects/SkLayerDrawLooper.cpp

 
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "SkCanvas.h"
 #include "SkColor.h"
 #include "SkFlattenableBuffers.h"
 #include "SkLayerDrawLooper.h"
 #include "SkString.h"
 #include "SkStringUtils.h"
 #include "SkUnPreMultiply.h"
 
 SK_DEFINE_INST_COUNT(SkLayerDrawLooper)
 
 SkLayerDrawLooper::LayerInfo::LayerInfo() {
     fFlagsMask = 0;                     // ignore our paint flags
     fPaintBits = 0;                     // ignore our paint fields
     fColorMode = SkXfermode::kDst_Mode; // ignore our color
     fOffset.set(0, 0);
     fPostTranslate = false;
 }
 
 SkLayerDrawLooper::SkLayerDrawLooper()
         : fRecs(NULL),
+          fTopRec(NULL),
           fCount(0),
           fCurrRec(NULL) {
 }
 
 SkLayerDrawLooper::~SkLayerDrawLooper() {
     Rec* rec = fRecs;
     while (rec) {
         Rec* next = rec->fNext;
         SkDELETE(rec);
         rec = next;
     }
 }
 
 SkPaint* SkLayerDrawLooper::addLayer(const LayerInfo& info) {
     fCount += 1;
 
     Rec* rec = SkNEW(Rec);
     rec->fNext = fRecs;
     rec->fInfo = info;
     fRecs = rec;
+    if (NULL == fTopRec) {
+        fTopRec = rec;
+    }
 
     return &rec->fPaint;
 }
 
 void SkLayerDrawLooper::addLayer(SkScalar dx, SkScalar dy) {
     LayerInfo info;
 
     info.fOffset.set(dx, dy);
     (void)this->addLayer(info);
 }
 
+SkPaint* SkLayerDrawLooper::addLayerOnTop(const LayerInfo& info) {
+    fCount += 1;
+
+    Rec* rec = SkNEW(Rec);
+    rec->fNext = NULL;
+    rec->fInfo = info;
+    if (NULL == fRecs) {
+        fRecs = rec;
+    } else {
+        SkASSERT(NULL != fTopRec);
+        fTopRec->fNext = rec;
+    }
+    fTopRec = rec;
+
+    return &rec->fPaint;
+}
+
 void SkLayerDrawLooper::init(SkCanvas* canvas) {
     fCurrRec = fRecs;
     canvas->save(SkCanvas::kMatrix_SaveFlag);
 }
 
 static SkColor xferColor(SkColor src, SkColor dst, SkXfermode::Mode mode) {
     switch (mode) {
         case SkXfermode::kSrc_Mode:
             return src;
         case SkXfermode::kDst_Mode:
@@ skipping 94 matching lines @@
         postTranslate(canvas, fCurrRec->fInfo.fOffset.fX,
                       fCurrRec->fInfo.fOffset.fY);
     } else {
         canvas->translate(fCurrRec->fInfo.fOffset.fX, fCurrRec->fInfo.fOffset.fY);
     }
     fCurrRec = fCurrRec->fNext;
 
     return true;
 }
 
-SkLayerDrawLooper::Rec* SkLayerDrawLooper::Rec::Reverse(Rec* head) {

[Tom Hudson, 2013/05/22 09:46:04]

Getting rid of this looks like a win to me!

-    Rec* rec = head;
-    Rec* prev = NULL;
-    while (rec) {
-        Rec* next = rec->fNext;
-        rec->fNext = prev;
-        prev = rec;
-        rec = next;
-    }
-    return prev;
-}
-
 ///////////////////////////////////////////////////////////////////////////////
 
 void SkLayerDrawLooper::flatten(SkFlattenableWriteBuffer& buffer) const {
     this->INHERITED::flatten(buffer);
 
 #ifdef SK_DEBUG
     {
         Rec* rec = fRecs;
         int count = 0;
         while (rec) {
@@ skipping 14 matching lines @@
         buffer.writePoint(rec->fInfo.fOffset);
         buffer.writeBool(rec->fInfo.fPostTranslate);
         buffer.writePaint(rec->fPaint);
         rec = rec->fNext;
     }
 }
 
 SkLayerDrawLooper::SkLayerDrawLooper(SkFlattenableReadBuffer& buffer)
         : INHERITED(buffer),
           fRecs(NULL),
+          fTopRec(NULL),
           fCount(0),
           fCurrRec(NULL) {
     int count = buffer.readInt();
 
     for (int i = 0; i < count; i++) {
         LayerInfo info;
         info.fFlagsMask = buffer.readInt();
         info.fPaintBits = buffer.readInt();
         info.fColorMode = (SkXfermode::Mode)buffer.readInt();
         buffer.readPoint(&info.fOffset);
         info.fPostTranslate = buffer.readBool();
-        buffer.readPaint(this->addLayer(info));
+        buffer.readPaint(this->addLayerOnTop(info));
     }
     SkASSERT(count == fCount);
 
-    // we're in reverse order, so fix it now
-    fRecs = Rec::Reverse(fRecs);
-
 #ifdef SK_DEBUG
     {
         Rec* rec = fRecs;
         int n = 0;
         while (rec) {
             rec = rec->fNext;
             n += 1;
         }
         SkASSERT(count == n);
     }
@@ skipping 88 matching lines @@
             str->append("true ");
         } else {
             str->append("false ");
         }
 
         rec->fPaint.toString(str);
         rec = rec->fNext;
     }
 }
 #endif