Vector style support, tile server semantics, and marker tile performance

CTilePng.podspec

@@ -0,0 +1,20 @@
+Pod::Spec.new do |s|
+  s.name = "CTilePng"
+  s.version = "1.3.1"
+  s.summary = "The C shim MapConductorCore's Rust PNG encoder is reached through."
+  s.license = { :type => "Apache-2.0", :file => "LICENSE" }
+  s.author = "MapConductor"
+  s.homepage = "https://github.com/MapConductor/ios-sdk-core"
+  s.source = { :git => "https://github.com/MapConductor/ios-sdk-core.git", :tag => s.version.to_s }
+  s.platform = :ios, "15.1"
+  # Its own pod, not source files inside MapConductorCore.
+  #
+  # `TilePngEncoder.swift` says `import CTilePng`, which needs CTilePng to be
+  # a module. Compiled *into* MapConductorCore the C has no module of its own
+  # and that import does not resolve -- Swift Package Manager gives it one
+  # because it is a separate target there, and CocoaPods only does the same if
+  # it is a separate pod. Without this the pod builds everywhere except where
+  # it matters: React Native, which consumes the source pod.
+  s.source_files = "Sources/CTilePng/**/*.{c,h}"
+  s.public_header_files = "Sources/CTilePng/include/*.h"
+end

MapConductorCore.podspec

@@ -9,4 +9,11 @@ Pod::Spec.new do |s|
   s.platform = :ios, "15.1"
   s.swift_version = "5.9"
   s.source_files = "Sources/MapConductorCore/**/*.swift"
+  # The C shim is its own pod so that `import CTilePng` resolves. See
+  # CTilePng.podspec for why it cannot be source files in here.
+  s.dependency "CTilePng"
+  # The Rust PNG encoder. Marker tiles are rasterised in-process and the
+  # platform encoder is several times slower; MarkerTileRenderer falls back to
+  # it if this is missing, so the pod stays usable either way.
+  s.vendored_frameworks = "TilePng.xcframework"
 end

Package.swift

@@ -28,8 +28,18 @@ let package = Package(
     targets: [
         // Targets are the basic building blocks of a package, defining a module or a test suite.
         // Targets can depend on other targets in this package and products from dependencies.
+        // The Rust PNG encoder. Built and packaged by the
+        // mapconductor-vectortile repo (scripts/build-ios-core-png.sh) and
+        // copied here by its scripts/sync-sdk.sh.
+        // The Rust PNG encoder. The archive and its header travel separately:
+        // Xcode merges every linked XCFramework's Headers into one include
+        // directory, so two of them shipping a module.modulemap collide, which
+        // anything depending on both this and MvtRender would hit.
+        .binaryTarget(name: "TilePng", path: "TilePng.xcframework"),
+        .target(name: "CTilePng"),
         .target(
-            name: "MapConductorCore"
+            name: "MapConductorCore",
+            dependencies: ["CTilePng", "TilePng"]
         ),
         .testTarget(
             name: "MapConductorCoreTests",

Sources/CTilePng/include/tile_png.h

@@ -0,0 +1,40 @@
+// PNG encoding for the iOS SDK core. Mirrors crates/tile-png-ffi.
+//
+// Travels as a source header in ios-sdk-core rather than inside the
+// XCFramework: Xcode merges every linked framework's Headers into one include
+// directory, and two frameworks shipping a module.modulemap collide there.
+#ifndef TILE_PNG_H
+#define TILE_PNG_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// Swift's C importer keeps a bare 0 but drops macros whose body starts with a
+// minus, so the error codes are restated on the Swift side. Keep them in step.
+#define TILE_PNG_OK 0
+#define TILE_PNG_ERR_BAD_ARGUMENT (-1)
+#define TILE_PNG_ERR_ENCODE_FAILED (-2)
+#define TILE_PNG_ERR_PANIC (-3)
+
+/// Encodes an RGBA8 buffer as PNG. Release the result with
+/// tile_png_buffer_free. When `premultiplied` is non-zero the input buffer is
+/// un-premultiplied in place and must not be reused.
+int32_t tile_png_encode(uint8_t *rgba,
+                        uint32_t width,
+                        uint32_t height,
+                        int32_t premultiplied,
+                        uint8_t **out_ptr,
+                        size_t *out_len);
+
+/// Releases a buffer returned by tile_png_encode.
+void tile_png_buffer_free(uint8_t *ptr, size_t len);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* TILE_PNG_H */

Sources/CTilePng/shim.c

@@ -0,0 +1,3 @@
+// SwiftPM needs a target to have at least one source file. This one exists so
+// CTilePng can be a target whose only real content is its public header; the
+// implementation is linked from the TilePng XCFramework.