使用多线程将动画 GIF 图像放在 VCL 上

Question

I want to show a (animated) GIF in a TImage (GIF) while the main programming is running. Right now, either the main program waits for the GIF, or the GIF is waiting for the main program (thread) before showing.

My idea is that the GIF Image should be run in a separate thread. The GIF image is not used elsewhere in the main program. I have read a lot about multi-threading (new to me). Delphi allows me to build a new thread in a separate unit (a built-in feature), but many on-line examples and tutorials just put the TThread object on the main form. If I do that I get a compiler error that my mainform does not contain a member named 'Execute' See code).

What am I doing wrong? Should I go for the separate thread in the second unit? Any advise on how to access this GIF (TImage) via this separate thread? I do know that I have to take care of synchronization between the VCL and the separate thread. I also read that modern Delphi has a Queue possibility, claimed to be superior over synchronization.

(in the interface section):

type
  TThreadGIF = class(TThread)
  protected
    procedure Execute; override;
  end;

(in the implementation section, below the {$R *.dfm}):

procedure TThreadGIF.Execute;
begin
  NameThreadForDebugging('ThreadGIFname');
  { code should start here }
end;

If anybody knows a reference to a good tutorial, would also help.

How To Build Multithreaded Applications brings me in my current position.

Answer 1

You don't need a thread at all. The VCL's existing TGIFImage class, which can be used to display GIF images in a TImage component, already supports animated GIFs.

Look at the following TGIFImage properties:

Animate

Specifies whether the GIF should be animated.

The Animate property specifies whether the GIF stored in the TGIFImage instance should be animated when displayed.

AnimateLoop

Specifies whether the GIF animation should loop.

The AnimateLoop property specifies whether the animation of the GIF stored in the TGIFImage instance should loop.

Note: Changing the AnimateLoop property only has effect if the Animate property is set to True.

AnimationSpeed

Specifies the GIF animation speed.

The AnimationSpeed property specifies the GIF animation speed in percents of the normal speed.

The value of AnimationSpeed must be in the range from 0 through 1000.