如何使用ImageList修改GMMarker图标？代码调用失效求助

Got it, let's break down why your imagelist.GetBitmap(1, GMMarker1.Items[markers].Icon); line isn't working, then fix it step by step:

• The Icon property of GMMarker.Items likely expects either a file path string (which is why assigning 'C:\Test\icon01.png' works flawlessly) or a TIcon object instance.
• TImageList.GetBitmap pulls out a TBitmap object, which is a completely different type than TIcon—you can't directly assign a bitmap to an icon property, hence the failure.

Here are three reliable solutions tailored to different scenarios:

Solution 1: Convert Bitmap to TIcon and Assign Directly #

If your GMMarker accepts TIcon instances for its Icon property, convert the bitmap from your ImageList first:

var
  TempBitmap: TBitmap;
  TempIcon: TIcon;
begin
  TempBitmap := TBitmap.Create;
  TempIcon := TIcon.Create;
  try
    // Extract the target bitmap from the ImageList
    ImageList1.GetBitmap(1, TempBitmap);
    // Convert the bitmap to a usable icon
    TempIcon.Assign(TempBitmap);
    // Assign the icon to your GMMarker item
    GMMarker1.Items[markers].Icon := TempIcon;
  finally
    // Clean up resources to avoid memory leaks
    TempBitmap.Free;
    TempIcon.Free;
  end;
end;

Solution 2: Extract Icon Directly from ImageList (Most Efficient) #

Skip the bitmap conversion entirely by using TImageList.GetIcon to pull a TIcon directly from your ImageList:

var
  TempIcon: TIcon;
begin
  TempIcon := TIcon.Create;
  try
    // Grab the icon directly from the ImageList
    ImageList1.GetIcon(1, TempIcon);
    // Assign it to your GMMarker item
    GMMarker1.Items[markers].Icon := TempIcon;
  finally
    TempIcon.Free;
  end;
end;

Solution 3: Save Icon to Temporary File (If GMMarker Only Accepts File Paths) #

If your GMMarker only supports file paths for the Icon property, save the extracted icon to a temporary file and assign that path:

uses
  System.IOUtils;

var
  TempIcon: TIcon;
  TempIconPath: string;
begin
  TempIcon := TIcon.Create;
  try
    ImageList1.GetIcon(1, TempIcon);
    // Generate a temporary .ico file path
    TempIconPath := TPath.Combine(TPath.GetTempPath, 'temp_marker_icon.ico');
    // Save the icon to the temporary file
    TempIcon.SaveToFile(TempIconPath);
    // Assign the file path to your GMMarker item
    GMMarker1.Items[markers].Icon := TempIconPath;
    // Optional: Delete the temporary file later if you don't need it anymore
    // DeleteFile(TempIconPath);
  finally
    TempIcon.Free;
  end;
end;

A quick check of your GMMarker component's documentation will confirm which approach fits best—most modern map marker components accept TIcon instances directly, so Solution 2 is probably your fastest fix.

内容的提问来源于stack exchange，提问作者Marcelo Pomarolli