From 6c11f048d17747a59bb947d9cdbe73b7523fc034 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C3=ABl=20Van=20Canneyt?= <michael@freepascal.org>
Date: Thu, 7 Mar 2024 22:22:57 +0100
Subject: [PATCH] * Fix from Werner Pamler to implement missing method. Fixes
 issue #40685

---
 packages/fcl-image/src/fpreadbmp.pp | 31 +++++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/packages/fcl-image/src/fpreadbmp.pp b/packages/fcl-image/src/fpreadbmp.pp
index 49ec462ff7..e948103228 100644
--- a/packages/fcl-image/src/fpreadbmp.pp
+++ b/packages/fcl-image/src/fpreadbmp.pp
@@ -33,9 +33,9 @@ unit FPReadBMP;
 interface
 
 {$IFDEF FPC_DOTTEDUNITS}
-uses FpImage, System.Classes, System.SysUtils, FpImage.Common.Bitmap;
+uses FpImage, System.Types, System.Classes, System.SysUtils, FpImage.Common.Bitmap;
 {$ELSE FPC_DOTTEDUNITS}
-uses FpImage, classes, sysutils, BMPcomn;
+uses FpImage, types, classes, sysutils, BMPcomn;
 {$ENDIF FPC_DOTTEDUNITS}
 
 type
@@ -68,6 +68,7 @@ type
       // required by TFPCustomImageReader
       procedure InternalRead  (Stream:TStream; Img:TFPCustomImage); override;
       function  InternalCheck (Stream:TStream) : boolean; override;
+      class function  InternalSize  (Stream:TStream) : TPoint; override;
     public
       constructor Create; override;
       destructor Destroy; override;
@@ -516,6 +517,32 @@ begin
     end;
 end;
 
+class function TFPReaderBMP.InternalSize (Stream: TStream): TPoint;
+var
+  fileHdr: TBitmapFileHeader;
+  infoHdr: TBitmapInfoHeader;
+  n: Int64;
+  StartPos: Int64;
+begin
+  Result := Point(0, 0);
+
+  StartPos := Stream.Position;
+  try
+    n := Stream.Read(fileHdr, SizeOf(fileHdr));
+    if n <> SizeOf(fileHdr) then exit;
+    if {$IFDEF ENDIAN_BIG}swap(fileHdr.bfType){$ELSE}fileHdr.bfType{$ENDIF} <> BMmagic then exit;
+    n := Stream.Read(infoHdr, SizeOf(infoHdr));
+    if n <> SizeOf(infoHdr) then exit;
+    {$IFDEF ENDIAN_BIG}
+    Result := Point(swap(infoHdr.Width), swap(infoHdr.Height));
+    {$ELSE}
+    Result := Point(infoHdr.Width, infoHdr.Height);
+    {$ENDIF}
+  finally
+    Stream.Position := StartPos;
+  end;
+end;
+
 initialization
   ImageHandlers.RegisterImageReader ('BMP Format', 'bmp', TFPReaderBMP);
 end.