rfac: Make Plot.drawGraph(Renderer) public, faster base64 encoding (#54)

* Make `Plot.drawGraph(renderer: Renderer)` public

* AGGRenderer: encode base-64 without intermediate copying of buffer

* AGG: Added a test for base-64 PNG output

* AGG tests: check data sizes

* Regenerate test manifests

Author: karwa

Sources/AGGRenderer/AGGRenderer/AGGRenderer.swift

@@ -249,8 +249,11 @@ public class AGGRenderer: Renderer{
     public func base64Png() -> String{
         let pngBufferPointer: UnsafePointer<UInt8> = get_png_buffer(agg_object)
         let bufferSize: Int = Int(get_png_buffer_size(agg_object))
-        return encodeBase64PNG(pngBufferPointer: pngBufferPointer,
-                               bufferSize: bufferSize)
+        return Data(
+            bytesNoCopy: UnsafeMutableRawPointer(mutating: pngBufferPointer),
+            count: bufferSize,
+            deallocator: .none
+        ).base64EncodedString(options: .lineLength64Characters)
     }
 
     deinit {

Sources/SwiftPlot/Base64Encoder.swift

@@ -13,7 +13,7 @@ public protocol Plot {
 extension Plot {
 
     /// Draws to the given renderer in-memory at a default size.
-    func drawGraph(renderer: Renderer) {
+    public func drawGraph(renderer: Renderer) {
         drawGraph(size: Size(width: 1000, height: 660),
                   renderer: renderer)
     }

Sources/SwiftPlot/Plot.swift

@@ -0,0 +1,43 @@
+#if canImport(AGGRenderer)
+import XCTest
+import SwiftPlot
+import AGGRenderer
+
+extension AGGRendererTests {
+    
+    func testBase64Encoding() {
+        let renderer = AGGRenderer()
+        let rect = Rect(origin: zeroPoint, size: Size(width: 200, height: 200))
+        
+        renderer.imageSize = rect.size
+        renderer.drawSolidRect(rect, fillColor: .white, hatchPattern: .none)
+        renderer.drawSolidCircle(center: Point(100,100), radius: 75, fillColor: .red)
+        
+        let png = renderer.base64Png()
+        XCTAssertEqual(png.count, 2315)
+        
+        // Check that we can decode it again.
+        guard let data = Data(base64Encoded: png, options: .ignoreUnknownCharacters) else {
+            XCTFail("Failed to decode base64-encoded PNG")
+            return
+        }
+        XCTAssertEqual(data.count, 1710)
+        // Check expected data.
+        // A reference file would be better, but this will have to do for now.
+        let pngPrefix = png.prefix(128)
+        let pngSuffix = png.suffix(128)
+        XCTAssertEqual(
+            String(pngPrefix),
+            #"iVBORw0KGgoAAAANSUhEUgAAAMgAAADICAMAAACahl6sAAABL1BMVEX/////6+v/"# + "\r\n" +
+            #"w8P/m5v/gYH/aWn/UVH/ODj/JCT/HBz/FBT/DAz/AwP//v7/39//pqb/bGz/PT3"#
+        )
+        XCTAssertEqual(
+            String(pngSuffix),
+            #"bOhf/ybcSl/8JBL307q16z"# + "\r\n" +
+            #"r65fM1xf2bV6P3+K7hZuvI3bu9L9w/VjOPx4/XBfurtteG886F0mk8lkMplMJpPJ"# + "\r\n" +
+            #"ZDKZTCaTSUH/ABlnILfhHFVMAAAAAElFTkSuQmCC"#
+        )
+    }
+}
+
+#endif // canImport(AGGRenderer)

Tests/SwiftPlotTests/AGGRenderer/agg-png-output.swift

@@ -0,0 +1,3 @@
+import XCTest
+
+final class AGGRendererTests: XCTestCase {}

Tests/SwiftPlotTests/AGGRenderer/aggTests.swift

@@ -1,6 +1,15 @@
 #if !canImport(ObjectiveC)
 import XCTest
 
+extension AGGRendererTests {
+    // DO NOT MODIFY: This is autogenerated, use:
+    //   `swift test --generate-linuxmain`
+    // to regenerate.
+    static let __allTests__AGGRendererTests = [
+        ("testBase64Encoding", testBase64Encoding),
+    ]
+}
+
 extension BarchartTests {
     // DO NOT MODIFY: This is autogenerated, use:
     //   `swift test --generate-linuxmain`
@@ -57,12 +66,23 @@ extension ScatterPlotTests {
     ]
 }
 
+extension SubPlotTests {
+    // DO NOT MODIFY: This is autogenerated, use:
+    //   `swift test --generate-linuxmain`
+    // to regenerate.
+    static let __allTests__SubPlotTests = [
+        ("testNestedSubplots", testNestedSubplots),
+    ]
+}
+
 public func __allTests() -> [XCTestCaseEntry] {
     return [
+        testCase(AGGRendererTests.__allTests__AGGRendererTests),
         testCase(BarchartTests.__allTests__BarchartTests),
         testCase(HistogramTests.__allTests__HistogramTests),
         testCase(LineChartTests.__allTests__LineChartTests),
         testCase(ScatterPlotTests.__allTests__ScatterPlotTests),
+        testCase(SubPlotTests.__allTests__SubPlotTests),
     ]
 }
 #endif