From 97b25425735a85cea29e9f4ca2334ae47a882ca1 Mon Sep 17 00:00:00 2001
From: Pietro Gagliardi <pietro10@mac.com>
Date: Sat, 12 Apr 2014 15:26:27 -0400
Subject: [PATCH] Fixed ARGB rendering on Windows. Now to make it
flicker-free...
---
area_windows.go | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/area_windows.go b/area_windows.go
index 7cf1fb6..432b231 100644
--- a/area_windows.go
+++ b/area_windows.go
@@ -120,8 +120,11 @@ func paintArea(s *sysData) {
panic(fmt.Errorf("error creating off-screen rendering DC: %v", err))
}
rdc := _HANDLE(r1)
+ // the bitmap has to be compatible with the window
+ // if we create a bitmap compatible with the DC we just created, it'll be monochrome
+ // thanks to David Heffernan in http://stackoverflow.com/questions/23033636/winapi-gdi-fillrectcolor-btnface-fills-with-strange-grid-like-brush-on-window
r1, _, err = _createCompatibleBitmap.Call(
- uintptr(rdc),
+ uintptr(hdc),
uintptr(xrect.Right - xrect.Left),
uintptr(xrect.Bottom - xrect.Top))
if r1 == 0 { // failure
@@ -181,7 +184,8 @@ func paintArea(s *sysData) {
// first, we need to load the bitmap memory, because Windows makes it for us
// the pixels are arranged in RGBA order, but GDI+ requires BGRA
// this turns out to be just ARGB in little endian; let's convert into this memory
- toARGB(i, ppvBits)
+ // the bitmap Windows gives us has a stride == width
+ toARGB(i, ppvBits, i.Rect.Dx() * 4)
// the second thing is... make a device context for the bitmap :|
// Ninjifox just makes another compatible DC; we'll do the same
@@ -199,7 +203,7 @@ func paintArea(s *sysData) {
previbitmap := _HANDLE(r1)
// AND FINALLY WE CAN DO THE ALPHA BLENDING!!!!!!111
-/* blendfunc := _BLENDFUNCTION{
+ blendfunc := _BLENDFUNCTION{
BlendOp: _AC_SRC_OVER,
BlendFlags: 0,
SourceConstantAlpha: 255, // only use per-pixel alphas
@@ -220,7 +224,7 @@ func paintArea(s *sysData) {
if r1 == _FALSE { // failure
panic(fmt.Errorf("error alpha-blending image returned by AreaHandler.Paint() onto background: %v", err))
}
-*/
+
// and finally we can just blit that into the window
r1, _, err = _bitBlt.Call(
uintptr(hdc),