5 files changed, 67 insertions, 2 deletions
diff --git a/include/cru/osx/graphics/quartz/Convert.h b/include/cru/osx/graphics/quartz/Convert.h
index 8d486069..be56b959 100644
--- a/include/cru/osx/graphics/quartz/Convert.h
+++ b/include/cru/osx/graphics/quartz/Convert.h
@@ -20,4 +20,5 @@ CGRect Convert(const Rect& rect);
 Rect Convert(const CGRect& rect);
 
 CGDataProviderRef ConvertStreamToCGDataProvider(io::Stream* stream);
+CGDataConsumerRef ConvertStreamToCGDataConsumer(io::Stream* stream);
 }  // namespace cru::platform::graphics::osx::quartz
diff --git a/include/cru/osx/graphics/quartz/ImageFactory.h b/include/cru/osx/graphics/quartz/ImageFactory.h
index 19e9c8c1..23d14332 100644
--- a/include/cru/osx/graphics/quartz/ImageFactory.h
+++ b/include/cru/osx/graphics/quartz/ImageFactory.h
@@ -15,6 +15,8 @@ class QuartzImageFactory : public OsxQuartzResource,
 
  public:
   std::unique_ptr<IImage> DecodeFromStream(io::Stream* stream) override;
+  void EncodeToStream(IImage* image, io::Stream* stream, ImageFormat format,
+                      float quality) override;
   std::unique_ptr<IImage> CreateBitmap(int width, int height) override;
 };
 }  // namespace cru::platform::graphics::osx::quartz
diff --git a/include/cru/platform/graphics/ImageFactory.h b/include/cru/platform/graphics/ImageFactory.h
index 2339a069..cd868087 100644
--- a/include/cru/platform/graphics/ImageFactory.h
+++ b/include/cru/platform/graphics/ImageFactory.h
@@ -3,7 +3,7 @@
 #include "cru/common/io/Stream.h"
 
 namespace cru::platform::graphics {
-enum class ImageFormat { Jpeg, Png };
+enum class ImageFormat { Jpeg, Png, Gif };
 
 struct CRU_PLATFORM_GRAPHICS_API IImageFactory
     : public virtual IGraphicsResource {
@@ -15,7 +15,7 @@ struct CRU_PLATFORM_GRAPHICS_API IImageFactory
    *  \param stream The stream to write to.
    *  \param format The format to encode to.
    *  \param quality The quality to encode to.
-   *  \todo Implement on macOS and Windows.
+   *  \todo Implement on Windows.
    */
   virtual void EncodeToStream(IImage* image, io::Stream* stream,
                               ImageFormat format, float quality) = 0;
diff --git a/src/osx/graphics/quartz/Convert.cpp b/src/osx/graphics/quartz/Convert.cpp
index 993b5b61..df62a206 100644
--- a/src/osx/graphics/quartz/Convert.cpp
+++ b/src/osx/graphics/quartz/Convert.cpp
@@ -49,4 +49,15 @@ CGDataProviderRef ConvertStreamToCGDataProvider(io::Stream* stream) {
                                         &kStreamToCGDataProviderCallbacks);
 }
 
+const CGDataConsumerCallbacks kStreamToCGDataConsumerCallbacks{
+    [](void* info, const void* buffer, size_t count) -> size_t {
+      return static_cast<io::Stream*>(info)->Write(
+          static_cast<const std::byte*>(buffer), count);
+    },
+    [](void* info) {}};
+
+CGDataConsumerRef ConvertStreamToCGDataConsumer(io::Stream* stream) {
+  return CGDataConsumerCreate(stream, &kStreamToCGDataConsumerCallbacks);
+}
+
 }  // namespace cru::platform::graphics::osx::quartz
diff --git a/src/osx/graphics/quartz/ImageFactory.cpp b/src/osx/graphics/quartz/ImageFactory.cpp
index a8c17719..2c6d4705 100644
--- a/src/osx/graphics/quartz/ImageFactory.cpp
+++ b/src/osx/graphics/quartz/ImageFactory.cpp
@@ -1,12 +1,16 @@
 #include "cru/osx/graphics/quartz/ImageFactory.h"
 #include "cru/common/Exception.h"
+#include "cru/common/platform/osx/Convert.h"
 #include "cru/osx/graphics/quartz/Convert.h"
 #include "cru/osx/graphics/quartz/Image.h"
+#include "cru/platform/Check.h"
 #include "cru/platform/graphics/Image.h"
 
 #include <ImageIO/ImageIO.h>
 
 namespace cru::platform::graphics::osx::quartz {
+using cru::platform::osx::Convert;
+
 QuartzImageFactory::QuartzImageFactory(IGraphicsFactory* graphics_factory)
     : OsxQuartzResource(graphics_factory) {}
 
@@ -28,6 +32,53 @@ std::unique_ptr<IImage> QuartzImageFactory::DecodeFromStream(
       new QuartzImage(GetGraphicsFactory(), this, cg_image, true));
 }
 
+static String GetImageFormatUniformTypeIdentifier(ImageFormat format) {
+  switch (format) {
+    case ImageFormat::Png:
+      return u"public.png";
+    case ImageFormat::Jpeg:
+      return u"public.jpeg";
+    case ImageFormat::Gif:
+      return u"com.compuserve.gif";
+    default:
+      throw Exception(u"Unknown image format.");
+  }
+}
+
+void QuartzImageFactory::EncodeToStream(IImage* image, io::Stream* stream,
+                                        ImageFormat format, float quality) {
+  if (quality <= 0 || quality > 1) {
+    throw Exception(u"Invalid quality value.");
+  }
+
+  auto quartz_image = CheckPlatform<QuartzImage>(image, GetPlatformId());
+  auto cg_image = quartz_image->GetCGImage();
+
+  CFStringRef uti = Convert(GetImageFormatUniformTypeIdentifier(format));
+  CGDataConsumerRef data_consumer = ConvertStreamToCGDataConsumer(stream);
+  CGImageDestinationRef destination =
+      CGImageDestinationCreateWithDataConsumer(data_consumer, uti, 1, nullptr);
+
+  CFMutableDictionaryRef properties =
+      CFDictionaryCreateMutable(nullptr, 0, nullptr, nullptr);
+  CFNumberRef quality_wrap =
+      CFNumberCreate(nullptr, kCFNumberFloatType, &quality);
+  CFDictionaryAddValue(properties, kCGImageDestinationLossyCompressionQuality,
+                       quality_wrap);
+
+  CGImageDestinationAddImage(destination, cg_image, properties);
+
+  if (!CGImageDestinationFinalize(destination)) {
+    throw Exception(u"Failed to finalize image destination.");
+  }
+
+  CFRelease(quality_wrap);
+  CFRelease(properties);
+  CFRelease(destination);
+  CFRelease(data_consumer);
+  CFRelease(uti);
+}
+
 std::unique_ptr<IImage> QuartzImageFactory::CreateBitmap(int width,
                                                          int height) {
   if (width <= 0) throw Exception(u"Image width should be greater than 0.");