From 479d1226faaa937ef6820b14f36099ef3f575883 Mon Sep 17 00:00:00 2001
From: Jonas Kümmerlin <jonas@kuemmerlin.eu>
Date: Sat, 18 Apr 2020 17:34:55 +0200
Subject: implement background color

reduce flickering by keeping pixels if we know the background didn't change

panel text is now gone, it would require us to redraw every transparent
widget on top, which is a bad tradeoff since that panel text isn't very
useful anyway.
---
 alf/alflayout.cpp | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

(limited to 'alf/alflayout.cpp')

diff --git a/alf/alflayout.cpp b/alf/alflayout.cpp
index c05d355..73b05a8 100644
--- a/alf/alflayout.cpp
+++ b/alf/alflayout.cpp
@@ -102,6 +102,18 @@ ALF_Layout_ForwardFont(ALFLayout *layout, HWND window, HFONT font, LPARAM redraw
     }
 }
 
+static void
+ALF_Layout_ForwardBgColor(ALFLayout *layout, HWND window, WPARAM wparam, LPARAM lparam)
+{
+    (void)window;
+
+    ALF_FOR_LIST(ALFWidgetPriv, list, &layout->widgets, i) {
+        if (i->flags & ALF_LAYOUT_INHERITBGCOLOR) {
+            SendMessage(i->hwnd, ALF_WM_SETBGCOLOR, wparam, lparam);
+        }
+    }
+}
+
 void
 ALF_Layout_EnsureRowExists(ALFLayout *layout, int rowno)
 {
@@ -305,6 +317,8 @@ ALF_Layout_Apply(ALFLayout* layout, HWND window)
     // now apply positions to widgets
     HDWP hdwp = BeginDeferWindowPos(layout->nColumns * layout->nRows);
 
+    ALFColor bgcolor = (ALFColor)SendMessage(window, ALF_WM_GETBGCOLOR, 0, 0);
+
     ALF_FOR_LIST(ALFWidgetPriv, list, &layout->widgets, c) {
         int col = c->x;
         int row = c->y;
@@ -320,10 +334,15 @@ ALF_Layout_Apply(ALFLayout* layout, HWND window)
         if (c->flags & ALF_LAYOUT_CUSTOMPOS) {
             hdwp = (HDWP)SendMessage(c->hwnd, ALF_WM_APPLYSIZE, (WPARAM)hdwp, (LPARAM)&r);
         } else {
+            UINT flags = SWP_NOACTIVATE | SWP_NOZORDER | SWP_NOOWNERZORDER;
+
+            if (bgcolor == ALF_COLOR_TRANSPARENT)
+                flags |= SWP_NOCOPYBITS;
+
             hdwp = DeferWindowPos(hdwp,
                                 c->hwnd, 0,
                                 r.left, r.top, r.right - r.left, r.bottom - r.top,
-                                SWP_NOACTIVATE | SWP_NOZORDER | SWP_NOCOPYBITS);
+                                flags);
         }
     }
 
@@ -349,6 +368,9 @@ ALF_Layout_AddWidget(ALFLayout* layout, HWND window, const ALFAddWidgetParams* p
     if (w->flags & ALF_LAYOUT_INHERITFONT) {
         SendMessage(w->hwnd, WM_SETFONT, (WPARAM)SendMessage(window, WM_GETFONT, 0, 0), 0);
     }
+    if (w->flags & ALF_LAYOUT_INHERITBGCOLOR) {
+        SendMessage(w->hwnd, ALF_WM_SETBGCOLOR, (WPARAM)SendMessage(window, ALF_WM_GETBGCOLOR, 0, 0), 0);
+    }
 
     ALF_ListInsert(layout->widgets.prev, &w->list);
 
@@ -502,6 +524,8 @@ ALF_Layout_SetWidgetFlags(ALFLayout *layout, HWND window, HWND needle, DWORD fla
 
             if (flags & ALF_LAYOUT_INHERITFONT)
                 SendMessage(w->hwnd, WM_SETFONT, (WPARAM)SendMessage(window, WM_GETFONT, 0, 0), 0);
+            if (flags & ALF_LAYOUT_INHERITBGCOLOR)
+                SendMessage(w->hwnd, ALF_WM_SETBGCOLOR, (WPARAM)SendMessage(window, ALF_WM_GETBGCOLOR, 0, 0), 0);
 
             ALF_InvalidateLayout(window);
 
@@ -681,6 +705,11 @@ ALF_Layout_HandleMessage(ALFLayout *layout, HWND hwnd, UINT msg, WPARAM wparam,
         return TRUE;
     }
 
+    if (msg == ALF_WM_SETBGCOLOR) {
+        ALF_Layout_ForwardBgColor(layout, hwnd, wparam, lparam);
+        return TRUE;
+    }
+
     if (msg == ALF_WM_INVALIDATELAYOUT) {
         ALF_Layout_Invalidate(layout, hwnd);
         return TRUE;
-- 
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