pdfviewer: more code comments + concat the pdf matrix with the existing matrix in canvas, instead o…

experimental/PdfViewer/SkTracker.h

Index: experimental/PdfViewer/SkTracker.h
===================================================================
--- experimental/PdfViewer/SkTracker.h	(revision 11730)
+++ experimental/PdfViewer/SkTracker.h	(working copy)
@@ -22,6 +22,18 @@
  *   A Tracker can be attached to a SkTrackDevice and it will store the track pixels.
  *   It can be used with SampleApp to investigate bugs (CL not checked in yet).
  *
+ *   The Tracker tracks 2 sets of points
+ *     A) one which is expected to issue breackpoints if the pixels are changes
+ *     B) one which if changes will disable the breackpoint
+ *   For point in A) there are two modes:
+ *     A.1) a breackpoint require that any of the points is changed
+ *     A.2) a breackpoint require that all of the points is changed
+ *   Points in B are allways in "any mode" - chaning the value of any pixel, will disable
+ *     the breackpoint
+ *
+ *   Point in A) are used to show what are the areas of interest, while poit in B are used to
+ *     disable breackpoints which would be issued in background change.
+ *
  */
 class SkTracker {
 public:
@@ -33,47 +45,60 @@
 
     virtual ~SkTracker() {}
 
+    // Clears all the points, but preserves the break mode.
     void clearPoints() {
         fCntExpectedTouched = 0;
         fCntExpectedUntouched = 0;
     }
 
+    // Enable the breackpoints.
     void enableTracking(bool b) {
         fEnabled = b;
     }
 
+    // Returns true if breackpoints are enabled.
     bool trackingEnabled() {
         return fEnabled;
     }
 
+    // Puts the tracker in Any mode.
     void any() {
         fBreakOnAny = true;
     }
 
+    // Puts the tracker in Any mode.
     void all() {
         fBreakOnAny = false;
     }
 
+    // returns true in in All mode. False for Any mode.
     bool requireAllExpectedTouched() {
         return !fBreakOnAny;
     }
 
+    // Returns the numbers of points in which if touched, would trigger a breackpoint.
     int cntExpectedTouched() {
         return fCntExpectedTouched;
     }
 
+    // Returns the points which if touched, would trigger a breackpoint.
+    // the Tracker owns the array
     const SkIPoint* expectedTouched() {
         return fExpectedTouched;
     }
 
+    // Returns the numbers of points in which if touched, would disable a breackpoint.
     int cntExpectedUntouched() {
         return fCntExpectedUntouched;
     }
 
+    // Returns the points which if touched, would disable a breackpoint.
+    // the Tracker owns the array
     const SkIPoint* expectedUntouched() {
         return fExpectedUntouched;
     }
 
+    // Adds a point which if changes in a drawFoo operation, would trigger a breakpoint.
     bool addExpectTouch(int x, int y) {
         if (fCntExpectedTouched >= MAX_TRACKING_POINTS) {
             return false;
@@ -86,6 +111,7 @@
         return true;
     }
 
+    // Adds a point which if changes in a drawFoo operation, would disable a breakpoint.
     bool addExpectUntouch(int x, int y) {
         if (fCntExpectedUntouched >= MAX_TRACKING_POINTS) {
             return false;
@@ -98,14 +124,17 @@
         return true;
     }
 
+    // Starts a new rendering session - reset the number of hits.
     void newFrame() {
         fHits = 0;
     }
 
+    // returns the number of breackpoints issues in this rendering session.
     int hits() {
         return fHits;
     }
 
+    // Called before drawFoo to store the state of the pixels
     void before(const SkBitmap& bitmap) {
         if (fCntExpectedTouched == 0) {
             return;
@@ -120,6 +149,7 @@
         }
     }
 
+    // Called after drawFoo to evaluate what pixels have changed, it could issue a breakpoint.
     // any/all of the expected touched has to be changed, and all expected untouched must be intact
     void after(const SkBitmap& bitmap) {
         if (fCntExpectedTouched == 0) {