Goal: ensure we always balance lock/unlock pixels calls.

A big caller of lockPixels is setContext in the bitmapshader.

This change replaces beginSession/endSession with adding endContext(), and
adds debugging code to ensure that
1. setContext calls are never nested
2. endContext is always called after each setContext call.
Review URL: https://codereview.appspot.com/6937046

git-svn-id: http://skia.googlecode.com/svn/trunk@6798 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 11 insertions, 9 deletions

diff --git a/src/core/SkDraw.cpp b/src/core/SkDraw.cpp
index 3035afe1ef..f71187e74a 100644
--- a/src/core/SkDraw.cpp
+++ b/src/core/SkDraw.cpp
@@ -1228,13 +1228,6 @@ void SkDraw::drawBitmap(const SkBitmap& bitmap, const SkMatrix& prematrix,
         }
     }
 
-    // only lock the pixels if we passed the clip and bounder tests
-    SkAutoLockPixels alp(bitmap);
-    // after the lock, check if we are valid
-    if (!bitmap.readyToDraw()) {
-        return;
-    }
-
     if (bitmap.getConfig() != SkBitmap::kA8_Config &&
             just_translate(matrix, bitmap)) {
         int ix = SkScalarRound(matrix.getTranslateX());
@@ -2279,7 +2272,7 @@ public:
 
     bool setup(const SkPoint pts[], const SkColor colors[], int, int, int);
 
-    virtual void shadeSpan(int x, int y, SkPMColor dstC[], int count);
+    virtual void shadeSpan(int x, int y, SkPMColor dstC[], int count) SK_OVERRIDE;
 
     SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkTriColorShader)
 
@@ -2406,7 +2399,7 @@ void SkDraw::drawVertices(SkCanvas::VertexMode vmode, int count,
     if (NULL != colors) {
         if (NULL == textures) {
             // just colors (no texture)
-            p.setShader(&triShader);
+            shader = p.setShader(&triShader);
         } else {
             // colors * texture
             SkASSERT(shader);
@@ -2421,6 +2414,7 @@ void SkDraw::drawVertices(SkCanvas::VertexMode vmode, int count,
             if (releaseMode) {
                 xmode->unref();
             }
+            shader = compose;
         }
     }
 
@@ -2436,10 +2430,17 @@ void SkDraw::drawVertices(SkCanvas::VertexMode vmode, int count,
             savedLocalM = shader->getLocalMatrix();
         }
 
+        // do we need this? triShader should have been installed in p, either
+        // directly or indirectly (using compose shader), so its setContext
+        // should have already been called.
         if (NULL != colors) {
+            SkASSERT(triShader.setContextHasBeenCalled());
+#if 0   
+            
             if (!triShader.setContext(*fBitmap, p, *fMatrix)) {
                 colors = NULL;
             }
+#endif
         }
 
         while (vertProc(&state)) {
@@ -2448,6 +2449,7 @@ void SkDraw::drawVertices(SkCanvas::VertexMode vmode, int count,
                     tempM.postConcat(savedLocalM);
                     shader->setLocalMatrix(tempM);
                     // need to recal setContext since we changed the local matrix
+                    shader->endContext();
                     if (!shader->setContext(*fBitmap, p, *fMatrix)) {
                         continue;
                     }