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/alfwindow.cpp | 46 +++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 45 insertions(+), 1 deletion(-)

(limited to 'alf/alfwindow.cpp')

diff --git a/alf/alfwindow.cpp b/alf/alfwindow.cpp
index 0b395b6..c3f8573 100644
--- a/alf/alfwindow.cpp
+++ b/alf/alfwindow.cpp
@@ -9,6 +9,7 @@ typedef struct {
     WORD                defid;
     HWND                hwndFocus;
     HFONT               font;
+    ALFColor            bgcolor;
 } ALFWindowPriv;
 
 static void
@@ -17,6 +18,7 @@ ALF_InitializeWindowPriv(HWND hwnd, ALFWindowPriv *priv, void *closure)
     priv->vtbl = (ALFWindowVTable*)GetClassLongPtr(hwnd, 0);
     priv->closure = closure;
     priv->defid = (WORD)-1;
+    priv->bgcolor = ALF_COLOR_SYS(COLOR_BTNFACE);
     ALF_Layout_Init(&priv->layout);
 }
 
@@ -148,6 +150,13 @@ ALF_WindowProc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam)
     }
 }
 
+static void
+ALF_Window_Paint(ALFWindowPriv *priv, HWND hwnd, HDC dc, RECT *r)
+{
+    (void)hwnd;
+    ALF_FillRect(dc, r, priv->bgcolor);
+}
+
 LRESULT
 ALF_DefWindowProc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam)
 {
@@ -184,6 +193,41 @@ ALF_DefWindowProc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam)
         // fallthrough to layout, will propagate font to children
     }
 
+    if (msg == ALF_WM_SETBGCOLOR) {
+        priv->bgcolor = (ALFColor)wparam;
+
+        InvalidateRect(hwnd, NULL, TRUE);
+
+        // fallthrough to layout, will propagate color to children
+    }
+
+    if (msg == ALF_WM_GETBGCOLOR) {
+        return (LRESULT)priv->bgcolor;
+    }
+
+    if (msg == WM_ERASEBKGND) {
+        return TRUE; // handled in WM_PAINT
+    }
+
+    if (msg == WM_PRINTCLIENT) {
+        RECT r = { 0, 0, 0, 0 };
+        GetClientRect(hwnd, &r);
+
+        ALF_Window_Paint(priv, hwnd, (HDC)wparam, &r);
+        return TRUE;
+    }
+
+    if (msg == WM_PAINT) {
+        PAINTSTRUCT ps;
+        HDC dc = BeginPaint(hwnd, &ps);
+
+        ALF_Window_Paint(priv, hwnd, dc, &ps.rcPaint);
+
+        EndPaint(hwnd, &ps);
+
+        return 0;
+    }
+
     if (msg == WM_GETFONT) {
         return (LRESULT)priv->font;
     }
@@ -390,7 +434,7 @@ ALF_RegisterWindowClass(HINSTANCE hInstance, const ALFWindowClassParams *params)
     cls.style = params->classStyle;
     cls.hInstance = hInstance;
     cls.hCursor = LoadCursor(NULL, (LPTSTR)IDC_ARROW);
-    cls.hbrBackground = (HBRUSH)(COLOR_BTNFACE+1);
+    cls.hbrBackground = NULL;
     cls.lpszClassName = classNamePtr;
     cls.cbWndExtra = sizeof(void*);
     cls.cbClsExtra = sizeof(void*);
-- 
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