From 0fd65273d4726cf746d6cc40e1fae53abb1a24d0 Mon Sep 17 00:00:00 2001
From: wp_xxyyzz <wp_xxyyzz@8e941d3f-bd1b-0410-a28a-d453659cc2b4>
Date: Thu, 15 Aug 2019 09:48:55 +0000
Subject: [PATCH] mbColorLib: Eliminate effect of ScreenWin on result of
 TmbDeskPickerButton (based on code by forum user "d-_-b",
 https://forum.lazarus.freepascal.org/index.php/topic,46415.0.html)

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@7130 8e941d3f-bd1b-0410-a28a-d453659cc2b4
---
 components/mbColorLib/ScreenWin.pas | 45 +++++++++++++++++++----------
 1 file changed, 30 insertions(+), 15 deletions(-)

diff --git a/components/mbColorLib/ScreenWin.pas b/components/mbColorLib/ScreenWin.pas
index a6f421a05..09858c19b 100644
--- a/components/mbColorLib/ScreenWin.pas
+++ b/components/mbColorLib/ScreenWin.pas
@@ -29,6 +29,8 @@ type
   private
     FOnSelColorChange: TNotifyEvent;
     FOnKeyDown: TKeyEvent;
+    function GetDesktopColor(const X, Y: Integer): TColor;
+    function ReadScreenColor(const X, Y: Integer): TColor;
 
   protected
     procedure CMHintShow(var Message: TCMHintShow); message CM_HINTSHOW;
@@ -51,21 +53,6 @@ implementation
 uses
   HTMLColors;
 
-function GetDesktopColor(const X, Y: Integer): TColor;
-var
-  c: TCanvas;
-  screenDC: HDC;
-begin
-  c := TCanvas.Create;
-  try
-    screenDC := GetDC(0);
-    c.Handle := screenDC;
-    Result := c.Pixels[X, Y];
-  finally
-    c.Free;
-  end;
-end;
-
 
 { TScreenForm }
 
@@ -139,4 +126,32 @@ begin
   Top := 0;
 end;
 
+function TScreenForm.GetDesktopColor(const X, Y: Integer): TColor;
+var
+  savedAlphaBlendValue: Integer;
+begin
+  savedAlphaBlendValue := AlphablendValue;
+  try
+    AlphaBlendValue := 0;
+    Result := ReadScreenColor(X, Y);
+  finally
+    AlphaBlendValue := savedAlphaBlendValue;
+  end;
+end;
+
+function TScreenForm.ReadScreenColor(const X, Y: Integer): TColor;
+var
+  c: TCanvas;
+  screenDC: HDC;
+begin
+  c := TCanvas.Create;
+  try
+    screenDC := GetDC(0);
+    c.Handle := screenDC;
+    Result := c.Pixels[X, Y];
+  finally
+    c.Free;
+  end;
+end;
+
 end.