More Area planning and TODOs.

areaplan.md

@@ -61,12 +61,83 @@ func repaint(s *sysData) HRESULT {
 	if hdc == 0 {		// failure
 		panic(fmt.Errorf("error beginning Area repaint: %v", err))
 	}
+
+	cliprect := image.Rect(int(xrect.Left), int(xrect.Top), int(xrect.Right), int(xrect.Bottom))
+	imgret := make(chan *image.NRGBA)
+	defer close(imgret)
+	s.paint <- PaintRequest{
+		Rect:		cliprect,
+		Out:		imgret,
+	}
+	i := <-imgret
 	// TODO DRAW
+
 	EndPaint(s.hwnd, &ps)
 	return 0
 }
 ```
 
+We can use GDI+ (gdiplus.dll) and its flat API for drawing...
+```c
+GpStatus WINGDIPAPI GdipCreateBitmapFromScan0(INT width, INT height, INT stride, PixelFormat format, BYTE* scan0, GpBitmap** bitmap);
+GpStatus WINGDIPAPI GdipCreateFromHDC(HDC hdc, GpGraphics **graphics)
+GpStatus WINGDIPAPI GdipDrawImageI(GpGraphics *graphics, GpImage *image, INT x, INT y)
+GpStatus WINGDIPAPI GdipDeleteGraphics(GpGraphics *graphics)
+GpStatus WINGDIPAPI GdipDisposeImage(GpImage *image)
+```
+(`GpBitmap` extends `GpImage`.) The only problem is the pixel format: the most appropriate one is `PixelFormat32bppARGB`, which is not premultiplied, but the components are in the wrong order... (there is no RGBA pixel format in any bit width) (TODO `GdipDisposeImage` seems wrong since it bypasses `~Bitmap()` and goes right for `~Image()` but I don't see an explicit `~Bitmap`...)
+
+Disregarding the RGBA issue, the draw code would be
+```go
+	var bitmap, graphics uintptr
+
+	status := GdipCreateBitmapFromScan0(
+		i.Rect.Dx(),
+		i.Rect.Dy(),
+		i.Stride,
+		PixelFormat32bppARGB,
+		(*byte)(unsafe.Pointer(&i.Pix[0])),
+		&bitmap)
+	if status != 0 {		// failure
+		panic(fmt.Errorf("error creating GDI+ bitmap to blit (GDI+ error code %d)", status))
+	}
+	status = GdipCreateFromHDC(hdc, &graphics)
+	if status != 0 {		// failure
+		panic(fmt.Errorf("error creating GDI+ graphics context to blit to (GDI+ error code %d)", status))
+	}
+	status = GdipDrawImageI(graphics, bitmap, cliprect.Min.X, cliprect.Min.Y)
+	if status != 0 {		// failure
+		panic(fmt.Errorf("error blitting GDI+ bitmap (GDI+ error code %d)", status))
+	}
+	status = GdipDeleteGraphics(graphics)
+	if status != 0 {		// failure
+		panic(fmt.Errorf("error freeing GDI+ graphics context to blit to (GDI+ error code %d)", status))
+	}
+	status = GdipDisposeImage(bitmap)
+	if status != 0 {		// failure
+		panic(fmt.Errorf("error freeing GDI+ bitmap to blit (GDI+ error code %d)", status))
+	}
+```
+
+We must also initialize and shut down GDI+ in uitask:
+```go
+	var gdiplustoken uintptr
+
+	// init
+	startupinfo := &GdiplusStartupInput{
+		GdiplusVersion:	1,
+	}
+	status := GdiplusStartup(&token, startupinfo, nil)
+	if status != 0 {		// failure
+		return fmt.Errorf("error initializing GDI+ (GDI+ error code %d)", status)
+	}
+
+	// shutdown
+	GdiplusShutdown(gdiplustoken)
+```
+
+TODO is there a function to turn a `GpStatus` into a string?
+
 TODO note http://msdn.microsoft.com/en-us/library/windows/desktop/bb775501%28v=vs.85%29.aspx#win_class for information on handling some key presses, tab switch, etc. (need to do this for the ones below too)
 
 TODO figure out scrolling
@@ -165,7 +236,7 @@ func our_drawRect(self C.id, rect C.struct_xrect) {
 		bitmapFormat:NSAlphaNonpremultipliedBitmapFormat		// this is where the flag for placing alpha first would go if alpha came first; the default is alpha last, which is how we're doing things
 		bytesPerRow:i.Stride
 		bitsPerPixel:32]
-	[bitmap drawAtPoint:NSMakePoint(cliprect.x, cliprect.y)]
+	[bitmap drawAtPoint:NSMakePoint(cliprect.Min.X, cliprect.Min.Y)]
 	[bitmap release]
 }
 ```

todo.md

@@ -77,6 +77,7 @@ important things:
 	- do this for type signatures in exported functions: (err error) or just error?
 	- do this for the names of GTK+ helper functions (gtkXXX or gXXX)
 - on windows 7, progress bars seem to animate from 0 -> pos when you turn off marquee mode and set pos; see if that's documented or if I'm doing something wrong
+- clean up windows struct field names (holdover from when the intent was to make a wrapper lib first and then use it rather than using the windows API directly)
 
 far off:
 - localization