[svg] Add svg_tool

A simple svg -> png converter, to demonstrate basic API usage.

TBR=
Change-Id: I34417c437b91e97811f5db512a9e79aa5cc099b8
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/325336
Reviewed-by: Florin Malita <fmalita@google.com>
Commit-Queue: Florin Malita <fmalita@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>

BUILD.gn

@@ -1901,6 +1901,7 @@ if (skia_enable_tools) {
     ]
   }
 
+  # TODO(fmalita): componentize & relocate
   test_lib("experimental_svg_model") {
     if (skia_use_expat) {
       sources = [
@@ -1936,6 +1937,16 @@ if (skia_enable_tools) {
     }
   }
 
+  test_app("svg_tool") {
+    if (skia_use_expat) {
+      sources = [ "experimental/svg/utils/SvgTool.cpp" ]
+      deps = [
+        ":experimental_svg_model",
+        ":flags",
+      ]
+    }
+  }
+
   test_lib("experimental_xform") {
     sources = [
       "experimental/xform/SkShape.cpp",

experimental/svg/utils/SvgTool.cpp

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2020 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include <iostream>
+
+#include "experimental/svg/model/SkSVGDOM.h"
+#include "include/core/SkMatrix.h"
+#include "include/core/SkStream.h"
+#include "include/core/SkSurface.h"
+#include "include/encode/SkPngEncoder.h"
+#include "tools/flags/CommandLineFlags.h"
+
+static DEFINE_string2(input , i, nullptr, "Input SVG file.");
+static DEFINE_string2(output, o, nullptr, "Output PNG file.");
+
+static DEFINE_int(width , 1024, "Output width.");
+static DEFINE_int(height, 1024, "Output height.");
+
+int main(int argc, char** argv) {
+    CommandLineFlags::Parse(argc, argv);
+
+    if (FLAGS_input.isEmpty() || FLAGS_output.isEmpty()) {
+        std::cerr << "Missing required 'input' and 'output' args.\n";
+        return 1;
+    }
+
+    if (FLAGS_width <= 0 || FLAGS_height <= 0) {
+        std::cerr << "Invalid width/height.\n";
+        return 1;
+    }
+
+    SkFILEStream in(FLAGS_input[0]);
+    if (!in.isValid()) {
+        std::cerr << "Could not open " << FLAGS_input[0] << "\n";
+        return 1;
+    }
+
+    auto svg_dom = SkSVGDOM::MakeFromStream(in);
+    if (!svg_dom) {
+        std::cerr << "Could not parse " << FLAGS_input[0] << "\n";
+        return 1;
+    }
+
+    auto surface = SkSurface::MakeRasterN32Premul(FLAGS_width, FLAGS_height);
+
+    svg_dom->setContainerSize(SkSize::Make(FLAGS_width, FLAGS_height));
+    svg_dom->render(surface->getCanvas());
+
+    SkPixmap pixmap;
+    surface->peekPixels(&pixmap);
+
+    SkFILEWStream out(FLAGS_output[0]);
+    if (!out.isValid()) {
+        std::cerr << "Could not open " << FLAGS_output[0] << " for writing.\n";
+        return 1;
+    }
+
+    // Use default encoding options.
+    SkPngEncoder::Options png_options;
+
+    if (!SkPngEncoder::Encode(&out, pixmap, png_options)) {
+        std::cerr << "PNG encoding failed.\n";
+        return 1;
+    }
+
+    return 0;
+}