Fix skshaper in component builds

It was building a shared library, but had no exports (on Windows).
We think the correct model for modules in the future is for each one
to be a separate DLL linked against the public API/exports of Skia.
This serves as the model for that. Doing this with other modules will
probably require exporting more symbols from Skia.

Change-Id: I116b1635533d755ae71e8df5aa234270b7f77a31
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/267477
Reviewed-by: Mike Klein <[email protected]>
Commit-Queue: Brian Osman <[email protected]>

Author: brianosman

modules/skshaper/BUILD.gn

@@ -26,6 +26,7 @@ if (skia_enable_skshaper) {
     deps = [
       "../..:skia",
     ]
+    defines = [ "SKSHAPER_IMPLEMENTATION=1" ]
     sources = skia_shaper_primitive_sources
     if (skia_use_icu && skia_use_harfbuzz) {
       sources += skia_shaper_harfbuzz_sources

modules/skshaper/include/SkShaper.h

@@ -17,6 +17,26 @@
 
 #include <memory>
 
+#if !defined(SKSHAPER_IMPLEMENTATION)
+    #define SKSHAPER_IMPLEMENTATION 0
+#endif
+
+#if !defined(SKSHAPER_API)
+    #if defined(SKIA_DLL)
+        #if defined(_MSC_VER)
+            #if SKSHAPER_IMPLEMENTATION
+                #define SKSHAPER_API __declspec(dllexport)
+            #else
+                #define SKSHAPER_API __declspec(dllimport)
+            #endif
+        #else
+            #define SKSHAPER_API __attribute__((visibility("default")))
+        #endif
+    #else
+        #define SKSHAPER_API
+    #endif
+#endif
+
 class SkFont;
 class SkFontMgr;
 
@@ -26,7 +46,7 @@ class SkFontMgr;
 
    If compiled without HarfBuzz, fall back on SkPaint::textToGlyphs.
  */
-class SkShaper {
+class SKSHAPER_API SkShaper {
 public:
     static std::unique_ptr<SkShaper> MakePrimitive();
     #ifdef SK_SHAPER_HARFBUZZ_AVAILABLE
@@ -232,7 +252,7 @@ class SkShaper {
 /**
  * Helper for shaping text directly into a SkTextBlob.
  */
-class SkTextBlobBuilderRunHandler final : public SkShaper::RunHandler {
+class SKSHAPER_API SkTextBlobBuilderRunHandler final : public SkShaper::RunHandler {
 public:
     SkTextBlobBuilderRunHandler(const char* utf8Text, SkPoint offset)
         : fUtf8Text(utf8Text)