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Win32: Disable fb transparency when it is broken

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On Windows 7, when GLFW framebuffer transparency and the DWM are enabled
but DWM transparency is disabled (i.e. when the Transparency setting is
disabled under Personalization > Color), the contents of the framebuffer
is combined with the last frame using additive blending instead of
replacing the previous contents.

This commit limits GLFW framebuffer transparency on Windows 7 to when
DWM transparency is enabled, removing the previous workaround of setting
a layered window color key that led to rendering artifacts.

Fixes #1512.

(cherry picked from commit 05dd2fa298)
This commit is contained in:
Camilla Löwy
2020-07-28 00:12:45 +02:00
parent b8a6254a26
commit 8363179eee
6 changed files with 49 additions and 38 deletions
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src/win32_window.c
+32 -31
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@@ -377,12 +377,17 @@ static void updateWindowStyles(const _GLFWwindow* window)
//
static void updateFramebufferTransparency(const _GLFWwindow* window)
{
BOOL enabled;
BOOL composition, opaque;
DWORD color;
if (!IsWindowsVistaOrGreater())
return;
if (SUCCEEDED(DwmIsCompositionEnabled(&enabled)) && enabled)
if (FAILED(DwmIsCompositionEnabled(&composition)) || !composition)
return;
if (IsWindows8OrGreater() ||
(SUCCEEDED(DwmGetColorizationColor(&color, &opaque)) && !opaque))
{
HRGN region = CreateRectRgn(0, 0, -1, -1);
DWM_BLURBEHIND bb = {0};
@@ -390,37 +395,18 @@ static void updateFramebufferTransparency(const _GLFWwindow* window)
bb.hRgnBlur = region;
bb.fEnable = TRUE;
if (SUCCEEDED(DwmEnableBlurBehindWindow(window->win32.handle, &bb)))
{
// Decorated windows don't repaint the transparent background
// leaving a trail behind animations
// HACK: Making the window layered with a transparency color key
// seems to fix this. Normally, when specifying
// a transparency color key to be used when composing the
// layered window, all pixels painted by the window in this
// color will be transparent. That doesn't seem to be the
// case anymore, at least when used with blur behind window
// plus negative region.
LONG exStyle = GetWindowLongW(window->win32.handle, GWL_EXSTYLE);
exStyle |= WS_EX_LAYERED;
SetWindowLongW(window->win32.handle, GWL_EXSTYLE, exStyle);
// Using a color key not equal to black to fix the trailing
// issue. When set to black, something is making the hit test
// not resize with the window frame.
SetLayeredWindowAttributes(window->win32.handle,
RGB(255, 0, 255), 255, LWA_COLORKEY);
}
DwmEnableBlurBehindWindow(window->win32.handle, &bb);
DeleteObject(region);
}
else
{
LONG exStyle = GetWindowLongW(window->win32.handle, GWL_EXSTYLE);
exStyle &= ~WS_EX_LAYERED;
SetWindowLongW(window->win32.handle, GWL_EXSTYLE, exStyle);
RedrawWindow(window->win32.handle, NULL, NULL,
RDW_ERASE | RDW_INVALIDATE | RDW_FRAME);
// HACK: Disable framebuffer transparency on Windows 7 when the
// colorization color is opaque, because otherwise the window
// contents is blended additively with the previous frame instead
// of replacing it
DWM_BLURBEHIND bb = {0};
bb.dwFlags = DWM_BB_ENABLE;
DwmEnableBlurBehindWindow(window->win32.handle, &bb);
}
}
@@ -1097,6 +1083,7 @@ static LRESULT CALLBACK windowProc(HWND hWnd, UINT uMsg,
}
case WM_DWMCOMPOSITIONCHANGED:
case WM_DWMCOLORIZATIONCOLORCHANGED:
{
if (window->win32.transparent)
updateFramebufferTransparency(window);
@@ -1821,7 +1808,8 @@ int _glfwPlatformWindowHovered(_GLFWwindow* window)
int _glfwPlatformFramebufferTransparent(_GLFWwindow* window)
{
BOOL enabled;
BOOL composition, opaque;
DWORD color;
if (!window->win32.transparent)
return GLFW_FALSE;
@@ -1829,7 +1817,20 @@ int _glfwPlatformFramebufferTransparent(_GLFWwindow* window)
if (!IsWindowsVistaOrGreater())
return GLFW_FALSE;
return SUCCEEDED(DwmIsCompositionEnabled(&enabled)) && enabled;
if (FAILED(DwmIsCompositionEnabled(&composition)) || !composition)
return GLFW_FALSE;
if (!IsWindows8OrGreater())
{
// HACK: Disable framebuffer transparency on Windows 7 when the
// colorization color is opaque, because otherwise the window
// contents is blended additively with the previous frame instead
// of replacing it
if (FAILED(DwmGetColorizationColor(&color, &opaque)) || opaque)
return GLFW_FALSE;
}
return GLFW_TRUE;
}
void _glfwPlatformSetWindowResizable(_GLFWwindow* window, GLFWbool enabled)