handle clipping large triangles

originally found by fuzzer.

Bug: skia:
Change-Id: I45007a619f13936153c0db8a60b3631a2c9db20c
Reviewed-on: https://skia-review.googlesource.com/101741
Reviewed-by: Cary Clark <caryclark@google.com>
Commit-Queue: Mike Reed <reed@google.com>

1 files changed, 61 insertions, 0 deletions

diff --git a/tools/sk_pixel_iter.h b/tools/sk_pixel_iter.h
new file mode 100644
index 0000000000..8bf5a55647
--- /dev/null
+++ b/tools/sk_pixel_iter.h
@@ -0,0 +1,61 @@
+/*
+ * Copyright 2018 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef sk_pixel_iter_DEFINED
+#define sk_pixel_iter_DEFINED
+
+#include "SkPixmap.h"
+#include "SkSurface.h"
+
+namespace sk_tool_utils {
+
+    class PixelIter {
+    public:
+        PixelIter();
+        PixelIter(SkSurface* surf) {
+            SkPixmap pm;
+            if (!surf->peekPixels(&pm)) {
+                pm.reset();
+            }
+            this->reset(pm);
+        }
+
+        void reset(const SkPixmap& pm) {
+            fPM = pm;
+            fLoc = { -1, 0 };
+        }
+
+        void* next(SkIPoint* loc = nullptr) {
+            if (!fPM.addr()) {
+                return nullptr;
+            }
+            fLoc.fX += 1;
+            if (fLoc.fX >= fPM.width()) {
+                fLoc.fX = 0;
+                if (++fLoc.fY >= fPM.height()) {
+                    this->setDone();
+                    return nullptr;
+                }
+            }
+            if (loc) {
+                *loc = fLoc;
+            }
+            return fPM.writable_addr(fLoc.fX, fLoc.fY);
+        }
+
+        void setDone() {
+            fPM.reset();
+        }
+
+    private:
+        SkPixmap    fPM;
+        SkIPoint    fLoc;
+    };
+
+}  // namespace sk_tool_utils
+
+#endif  // sk_tool_utils_DEFINED