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/ImageInfo_015.cpp b/docs/examples/ImageInfo_015.cpp
new file mode 100644
index 0000000..9048824
--- /dev/null
+++ b/docs/examples/ImageInfo_015.cpp
@@ -0,0 +1,34 @@
+// 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=befac1c29ed21507d367e4d824383a04
+REG_FIDDLE(ImageInfo_015, 256, 640, false, 0) {
+void draw(SkCanvas* canvas) {
+    const char* colors[] = { "Unknown", "Alpha_8", "RGB_565", "ARGB_4444", "RGBA_8888", "RGB_888x",
+                             "BGRA_8888", "RGBA_1010102", "RGB_101010x", "Gray_8", "RGBA_F16Norm",
+                             "RGBA_F16" };
+    const char* alphas[] = {"Unknown ", "Opaque  ", "Premul  ", "Unpremul"};
+    SkAlphaType alphaTypes[] = { kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType,
+    kUnpremul_SkAlphaType
+                               };
+    SkPaint paint;
+    SkFont font(SkTypeface::MakeFromName("monospace", SkFontStyle()), 10);
+    int y = 15;
+    canvas->drawString("   colorType   alphaType  canonical", 10, y, font, paint);
+    for (SkColorType colorType : {
+    kUnknown_SkColorType, kAlpha_8_SkColorType, kRGB_565_SkColorType,
+    kARGB_4444_SkColorType, kRGBA_8888_SkColorType, kRGB_888x_SkColorType,
+    kBGRA_8888_SkColorType, kRGBA_1010102_SkColorType, kRGB_101010x_SkColorType,
+    kGray_8_SkColorType, kRGBA_F16_SkColorType
+                                 } ) {
+        for (SkAlphaType alphaType : alphaTypes) {
+            SkAlphaType canonicalAlphaType  = kUnknown_SkAlphaType;
+            bool result = SkColorTypeValidateAlphaType(colorType, alphaType, &canonicalAlphaType);
+            SkString string;
+            string.printf("%13s %10s %10s", colors[(int) colorType], alphas[(int) alphaType],
+                     result ? alphas[(int) canonicalAlphaType] : "------  ");
+            canvas->drawString(string, 10, y += 14, font, paint);
+        }
+    }
+}
+}  // END FIDDLE