fpspreadsheet: More efficient clipping in drawing of images on WorksheetGrid

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@5802 8e941d3f-bd1b-0410-a28a-d453659cc2b4

components/fpspreadsheet/source/visual/fpspreadsheetgrid.pas

@@ -2191,6 +2191,12 @@ begin
   ColRowToOffset(true, false, HeaderCount, clipArea.Left, tmp);
   ColRowToOffset(false, false, HeaderCount, clipArea.Top, tmp);
 
+  // Draw bitmap over grid. Take care of clipping.
+  Canvas.SaveHandleState;
+  try
+    InterSectClipRect(Canvas.Handle,
+      clipArea.Left, clipArea.Top, clipArea.Right, clipArea.Bottom);
+
     for i := 0 to Worksheet.GetImageCount-1 do begin
       img := Worksheet.GetPointerToImage(i);
       obj := Workbook.GetEmbeddedObj(img^.Index);
@@ -2203,11 +2209,12 @@ begin
       imgRect.Bottom := imgRect.Top + h;
       OffsetRect(imgRect, ToPixels(img^.OffsetX), ToPixels(img^.OffsetY));
 
+      // Nothing to do if image is outside the visible grid area
       if not IntersectRect(R, clipArea, imgRect) then
         continue;
 
+      // If not yet done load image stream into bitmap and scale to required size
       if img^.Bitmap = nil then begin
-      // Load image into bitmap and scale to required size
         img^.Bitmap := TBitmap.Create;
         TBitmap(img^.Bitmap).SetSize(w, h);
         TBitmap(img^.Bitmap).PixelFormat := pf32Bit;
@@ -2225,15 +2232,12 @@ begin
         end;
       end;
 
-    // Draw bitmap over grid. Take care of clipping.
-    Canvas.SaveHandleState;
-    try
-      InterSectClipRect(Canvas.Handle, R.Left, R.Top, R.Right, R.Bottom);
+      // Draw the bitmap
       Canvas.Draw(imgRect.Left, imgRect.Top, TBitmap(img^.Bitmap));
-    finally
-      Canvas.RestoreHandleState;
     end;
 
+  finally
+    Canvas.RestoreHandleState;
   end;
 end;