Compile all fiddle examples locally

Motivation: it would be a good idea if the API documentation examples
were checked into the skia repository, so we could make sure they
compile as part of the commit queue.

Fiddle would make/update a named fiddle each time it gets a new
commit of Skia, extracted from the code in the examples/ directory.
The docs would point at those named fiddles.  Named fiddles have urls
in the form:

    https://fiddle.skia.org/c/@Bitmap_000

Then we would stick a link to the example into the header documentation
like this:

    /** Allocates the pixel memory for the bitmap, given its dimensions
        and SkColorType. Returns true on success, where success means
        either setPixels() or setPixelRef() was called.

        @param bitmap  SkBitmap containing SkImageInfo as input, and
                       SkPixelRef as output
        @return        true if SkPixelRef was allocated

        @example       https://fiddle.skia.org/c/@Bitmap_000
    */
    bool allocPixelRef(SkBitmap* bitmap) override;

There are still around 200 disabled examples that need to be fixed
(these result from API changes since the author left).

Change-Id: I14a31348a9ccaaa31f65424b91e3a3533d2583a7
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/198824
Commit-Queue: Hal Canary <halcanary@google.com>
Reviewed-by: Leon Scroggins <scroggo@google.com>
Reviewed-by: Joe Gregorio <jcgregorio@google.com>
diff --git a/docs/examples/Canvas_014.cpp b/docs/examples/Canvas_014.cpp
new file mode 100644
index 0000000..a0519e0
--- /dev/null
+++ b/docs/examples/Canvas_014.cpp
@@ -0,0 +1,40 @@
+// Copyright 2019 Google LLC.
+// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
+#include "fiddle/examples.h"
+// HASH=a7ac9c21bbabcdeeca00f72a61cd0f3e
+REG_FIDDLE(Canvas_014, 256, 256, false, 0) {
+void draw(SkCanvas* canvas) {
+  SkPaint paint;
+  SkFont font(nullptr, 100);
+  canvas->drawString("ABC", 20, 160, font, paint);
+  SkRect layerBounds = SkRect::MakeXYWH(32, 32, 192, 192);
+  canvas->saveLayerAlpha(&layerBounds, 128);
+  canvas->clear(SK_ColorWHITE);
+  canvas->drawString("DEF", 20, 160, font, paint);
+  SkImageInfo imageInfo;
+  size_t rowBytes;
+  SkIPoint origin;
+  uint32_t* access = (uint32_t*) canvas->accessTopLayerPixels(&imageInfo, &rowBytes, &origin);
+  if (access) {
+    int h = imageInfo.height();
+    int v = imageInfo.width();
+    int rowWords = rowBytes / sizeof(uint32_t);
+    for (int y = 0; y < h; ++y) {
+        int newY = (y - h / 2) * 2 + h / 2;
+        if (newY < 0 || newY >= h) {
+            continue;
+        }
+        for (int x = 0; x < v; ++x) {
+            int newX = (x - v / 2) * 2 + v / 2;
+            if (newX < 0 || newX >= v) {
+                continue;
+            }
+            if (access[y * rowWords + x] == SK_ColorBLACK) {
+                access[newY * rowWords + newX] = SK_ColorGRAY;
+            }
+        }
+    }
+  }
+  canvas->restore();
+}
+}  // END FIDDLE