Fixed QOI test, added QOI write

Framework/Images/Enums/ImageWriteFormat.cs

@@ -0,0 +1,7 @@
+namespace Foster.Framework;
+
+internal enum ImageWriteFormat
+{
+	Png,
+	Qoi
+}

Framework/Images/Image.cs

@@ -160,6 +160,28 @@ public void WritePng(string path)
 	/// Write the image to PNG
 	/// </summary>
 	public void WritePng(Stream stream)
+	{
+		Write(stream, ImageWriteFormat.Png);
+	}
+
+	/// <summary>
+	/// Writes the image to a PNG file
+	/// </summary>
+	public void WriteQoi(string path)
+	{
+		using var stream = File.Create(path);
+		WritePng(stream);
+	}
+
+	/// <summary>
+	/// Write the image to QOI
+	/// </summary>
+	public void WriteQoi(Stream stream)
+	{
+		Write(stream, ImageWriteFormat.Qoi);
+	}
+
+	private void Write(Stream stream, ImageWriteFormat format)
 	{
 		static unsafe void Write(IntPtr context, IntPtr data, int size)
 		{
@@ -169,7 +191,7 @@ static unsafe void Write(IntPtr context, IntPtr data, int size)
 		}
 
 		GCHandle handle = GCHandle.Alloc(stream);
-		Platform.FosterImageWrite(Write, GCHandle.ToIntPtr(handle), Width, Height, ptr);
+		Platform.FosterImageWrite(Write, GCHandle.ToIntPtr(handle), format, Width, Height, ptr);
 		handle.Free();
 	}
 

Framework/Platform.cs

@@ -204,7 +204,7 @@ public static void FreeUTF8(IntPtr ptr)
 	[DllImport(DLL)]
 	public static extern void FosterImageFree(IntPtr data);
 	[DllImport(DLL)]
-	public static extern bool FosterImageWrite(FosterWriteFn func, IntPtr context, int w, int h, IntPtr data);
+	public static extern bool FosterImageWrite(FosterWriteFn func, IntPtr context, ImageWriteFormat format, int w, int h, IntPtr data);
 	[DllImport(DLL)]
 	public static extern IntPtr FosterFontInit(IntPtr data, int length);
 	[DllImport(DLL)]

Platform/include/foster_platform.h

@@ -392,6 +392,12 @@ typedef enum FosterLogging
 	FOSTER_LOGGING_NONE
 } FosterLogging;
 
+typedef enum FosterImageWriteFormat
+{
+	FOSTER_IMAGE_WRITE_FORMAT_PNG,
+	FOSTER_IMAGE_WRITE_FORMAT_QOI,
+} FosterImageWriteFormat;
+
 typedef void (FOSTER_CALL * FosterLogFn)(const char *msg);
 typedef void (FOSTER_CALL * FosterExitRequestFn)();
 typedef void (FOSTER_CALL * FosterOnTextFn)(const char* txt);
@@ -558,7 +564,7 @@ FOSTER_API unsigned char* FosterImageLoad(const unsigned char* memory, int lengt
 
 FOSTER_API void FosterImageFree(unsigned char* data);
 
-FOSTER_API bool FosterImageWrite(FosterWriteFn* func, void* context, int w, int h, const void* data);
+FOSTER_API bool FosterImageWrite(FosterWriteFn* func, void* context, FosterImageWriteFormat format, int w, int h, const void* data);
 
 FOSTER_API FosterFont* FosterFontInit(unsigned char* data, int length);
 

Platform/src/foster_image.c

@@ -16,6 +16,7 @@
 
 bool FosterImage_TestQOI(const unsigned char* data, int length);
 unsigned char* FosterImage_LoadQOI(const unsigned char* data, int length, int* w, int * h);
+bool FosterImage_WriteQOI(FosterWriteFn* func, void* context, int w, int h, const void* data);
 
 unsigned char* FosterImageLoad(const unsigned char* data, int length, int* w, int* h)
 {
@@ -37,20 +38,28 @@ void FosterImageFree(unsigned char* data)
 	stbi_image_free(data);
 }
 
-bool FosterImageWrite(FosterWriteFn* func, void* context, int w, int h, const void* data)
+bool FosterImageWrite(FosterWriteFn* func, void* context, FosterImageWriteFormat format, int w, int h, const void* data)
 {
 	// note: 'FosterWriteFn' and 'stbi_write_func' must be the same
-	return stbi_write_png_to_func((stbi_write_func*)func, context, w, h, 4, data, w * 4) != 0;
+	switch (format)
+	{
+	case FOSTER_IMAGE_WRITE_FORMAT_PNG:
+		return stbi_write_png_to_func((stbi_write_func*)func, context, w, h, 4, data, w * 4) != 0;
+	case FOSTER_IMAGE_WRITE_FORMAT_QOI:
+		return FosterImage_WriteQOI(func, context, w, h, data);
+	}
+	return false;
 }
 
 bool FosterImage_TestQOI(const unsigned char* data, int length)
 {
-	if (length < 4)
+	if (length < QOI_HEADER_SIZE)
 		return false;
 
-	for (int i = 0; i < SDL_max(4, length); i ++)
-		if (data[i] != "qoif"[i])
-			return false;
+	int p = 0;
+	unsigned int magic = qoi_read_32(data, &p);
+	if (magic != QOI_MAGIC)
+		return false;
 
 	return true;
 }
@@ -72,4 +81,20 @@ unsigned char* FosterImage_LoadQOI(const unsigned char* data, int length, int* w
 		*h = 0;
 		return NULL;
 	}
-}
+}
+
+bool FosterImage_WriteQOI(FosterWriteFn* func, void* context, int w, int h, const void* data)
+{
+	qoi_desc desc = { w, h, 4, 1 };
+	int length;
+	void* encoded = qoi_encode(data, &desc, &length);
+
+	if (encoded != NULL)
+	{
+		((stbi_write_func*)func)(context, encoded, length);
+		QOI_FREE(encoded);
+		return true;
+	}
+
+	return false;
+}