From 7e20dce0699e9dcc9efae3e84fbfc34129e0b31e Mon Sep 17 00:00:00 2001
From: wp_xxyyzz <wp_xxyyzz@8e941d3f-bd1b-0410-a28a-d453659cc2b4>
Date: Thu, 24 Oct 2019 10:02:19 +0000
Subject: [PATCH] lazmapviewer: Fix crash when painting outside the buffer.

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@7168 8e941d3f-bd1b-0410-a28a-d453659cc2b4
---
 components/lazmapviewer/source/mvde_intfgraphics.pas | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/components/lazmapviewer/source/mvde_intfgraphics.pas b/components/lazmapviewer/source/mvde_intfgraphics.pas
index 165652374..2a27115ad 100644
--- a/components/lazmapviewer/source/mvde_intfgraphics.pas
+++ b/components/lazmapviewer/source/mvde_intfgraphics.pas
@@ -60,6 +60,11 @@ uses
   LCLType,
   FPImgCanv, GraphType;
 
+function InRange(x, min, max: Integer): Boolean;
+begin
+  Result := (x >= min) and (x <= max);
+end;
+
 {$IF Laz_FullVersion < 1090000}
 // Workaround for http://mantis.freepascal.org/view.php?id=27144
 procedure CopyPixels(ASource, ADest: TLazIntfImage;
@@ -164,6 +169,10 @@ begin
         for i := 0 to intfImg.Width - 1 do begin
           cimg := intfImg.Colors[i, j];
           alpha := cimg.Alpha / word($FFFF);
+          if not InRange(i + X, 0, FBuffer.Width-1) then
+            Continue;
+          if not InRange(j + Y, 0, FBuffer.Height-1) then
+            Continue;
           cbuf := FBuffer.Colors[i + X, j + Y];
           cbuf.Red := Round(alpha * cimg.Red + (1 - alpha) * cbuf.Red);
           cbuf.Green := Round(alpha * cimg.Green + (1 - alpha) * cbuf.Green);
@@ -173,7 +182,8 @@ begin
     end else
       for j := 0 to intfImg.Height - 1 do
         for i := 0 to intfImg.Width - 1 do
-          FBuffer.Colors[i + X, j + Y] := intfImg.Colors[i, j];
+          if InRange(i + x, 0, FBuffer.Width-1) and InRange(j + Y, 0, FBuffer.Height-1) then
+            FBuffer.Colors[i + X, j + Y] := intfImg.Colors[i, j];
   finally
     intfimg.Free;
   end;