1 files changed, 35 insertions, 0 deletions
diff --git a/prev/image_windows.c b/prev/image_windows.c
new file mode 100644
index 0000000..bcea3c4
--- /dev/null
+++ b/prev/image_windows.c
@@ -0,0 +1,35 @@
+// 16 august 2014
+
+#include "winapi_windows.h"
+#include "_cgo_export.h"
+
+// TODO rename to images_windows.c?
+
+HBITMAP toBitmap(void *i, intptr_t dx, intptr_t dy)
+{
+	BITMAPINFO bi;
+	VOID *ppvBits;
+	HBITMAP bitmap;
+
+	ZeroMemory(&bi, sizeof (BITMAPINFO));
+	bi.bmiHeader.biSize = sizeof (BITMAPINFOHEADER);
+	bi.bmiHeader.biWidth = (LONG) dx;
+	bi.bmiHeader.biHeight = -((LONG) dy);			// negative height to force top-down drawing;
+	bi.bmiHeader.biPlanes = 1;
+	bi.bmiHeader.biBitCount = 32;
+	bi.bmiHeader.biCompression = BI_RGB;
+	bi.bmiHeader.biSizeImage = (DWORD) (dx * dy * 4);
+	bitmap = CreateDIBSection(NULL, &bi, DIB_RGB_COLORS, &ppvBits, 0, 0);
+	if (bitmap == NULL)
+		xpanic("error creating HBITMAP in toBitmap()", GetLastError());
+	// image lists use non-premultiplied RGBA - see http://stackoverflow.com/a/25578789/3408572
+	// the TRUE here does the conversion
+	dotoARGB(i, (void *) ppvBits, TRUE);
+	return bitmap;
+}
+
+void freeBitmap(uintptr_t bitmap)
+{
+	if (DeleteObject((HBITMAP) bitmap) == 0)
+		xpanic("error deleting bitmap in freeBitmap()", GetLastError());
+}