add /img/n/m endpoint to skiaserve

tools/debugger/SkDebugCanvas.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkCanvasPriv.h"
 #include "SkClipStack.h"
 #include "SkDebugCanvas.h"
@@ skipping 178 matching lines @@
             fActiveLayers.pop();
         }
     }
 
     for (int i = 0; i < fActiveLayers.count(); ++i) {
         fActiveLayers[i]->setActive(true);
     }
 
 }
 
-void SkDebugCanvas::drawTo(SkCanvas* canvas, int index) {
+void SkDebugCanvas::drawTo(SkCanvas* canvas, int index, int m) {
     SkASSERT(!fCommandVector.isEmpty());
     SkASSERT(index < fCommandVector.count());
 
     int saveCount = canvas->save();
 
     SkRect windowRect = SkRect::MakeWH(SkIntToScalar(canvas->getBaseLayerSize().width()),
                                        SkIntToScalar(canvas->getBaseLayerSize().height()));
 
     bool pathOpsMode = getAllowSimplifyClip();
     canvas->setAllowSimplifyClip(pathOpsMode);
@@ skipping 11 matching lines @@
     }
 
     if (fMegaVizMode) {
         this->markActiveCommands(index);
     }
    
     // If we have a GPU backend we can also visualize the batching information
 #if SK_SUPPORT_GPU
     GrAuditTrail* at = nullptr;
     GrRenderTarget* rt = canvas->internal_private_accessTopLayerRenderTarget();
-    if (rt && fDrawGpuBatchBounds) {
+    if (rt && (fDrawGpuBatchBounds || m != -1)) {
         GrContext* ctx = rt->getContext();
         if (ctx) {
             at = ctx->getAuditTrail();
         }
     }
 #endif
 
     for (int i = 0; i <= index; i++) {
         if (i == index && fFilter) {
             canvas->clear(0xAAFFFFFF);
@@ skipping 90 matching lines @@
     // draw any batches if required and issue a full reset onto GrAuditTrail
     if (at) {
         // get the render target of the top device so we can ignore batches drawn offscreen
         SkBaseDevice* bd = canvas->getDevice_just_for_deprecated_compatibility_testing();
         SkGpuDevice* gbd = reinterpret_cast<SkGpuDevice*>(bd);
         uint32_t rtID = gbd->accessRenderTarget()->getUniqueID();
 
         // get the bounding boxes to draw
         GrAuditTrail::AutoEnable ae(at);
         SkTArray<GrAuditTrail::BatchInfo> childrenBounds;
-        at->getBoundsByClientID(&childrenBounds, index);
+        if (m == -1) {
+            at->getBoundsByClientID(&childrenBounds, index);
+        } else {
+            // the client wants us to draw the mth batch
+            at->getBoundsByBatchListID(&childrenBounds.push_back(), m);
+        }
         SkPaint paint;
         paint.setStyle(SkPaint::kStroke_Style);
         paint.setStrokeWidth(1);
         for (int i = 0; i < childrenBounds.count(); i++) {
             if (childrenBounds[i].fRenderTargetUniqueID != rtID) {
                 // offscreen draw, ignore for now
                 continue;
             }
             paint.setColor(SK_ColorBLACK);
             canvas->drawRect(childrenBounds[i].fBounds, paint);
@@ skipping 363 matching lines @@
 }
 
 bool SkDebugCanvas::lastClipStackData(const SkPath& devPath) {
     if (fCalledAddStackData) {
         fClipStackData.appendf("<br>");
         addPathData(devPath, "pathOut");
         return true;
     }
     return false;
 }