使用WinApi功能在FMX画布上绘图

问题描述

这个问题看起来很简单，使用VCL可以很好地工作（图像是VCL上的TImage）：

This question looks very simple, with VCL this is works fine (Image is TImage on VCL):

procedure TFormMain.btnDrawBackgroundClick(Sender: TObject);
var
  theme: HTHEME;
begin
  theme := OpenThemeData(0, 'TASKDIALOG');
  if theme <> 0 then
  try
    DrawThemeBackground(theme,
                        Image.Canvas.Handle,
                        TDLG_SECONDARYPANEL,
                        0,
                        Image.ClientRect,
                        nil);
  finally
    CloseThemeData(theme);
  end;
end;

问题：为了在FMX上获得相同的效果（在Windows上），我应该改变什么

Question: what I should change to get the same effect with FMX (on Windows)

推荐答案

基于根本无法做到这一点。

Based on this answer you simply can't do that.

但是总有一些解决方法，您可以尝试这样。

But there is always some workaround and you can try something like this.

procedure TFormMain.btnDrawBackgroundClick(Sender: TObject);
var
  lTheme : HTHEME;
  lStream : TMemoryStream;
  lBitmap : Vcl.Graphics.TBitmap;
begin
  lTheme := OpenThemeData(0, 'TASKDIALOG');
  if lTheme <> 0 then
  try
    lBitmap := Vcl.Graphics.TBitmap.Create;
    try
      lBitmap.Width := Round(Image.Width);
      lBitmap.Height := Round(Image.Height);
      DrawThemeBackground(lTheme, lBitmap.Canvas.Handle, TDLG_SECONDARYPANEL, 0,
                          Rect(0, 0, lBitmap.Width, lBitmap.Height), nil);
      lStream := TMemoryStream.Create;
      try
        lBitmap.SaveToStream(lStream);
        Image.Bitmap.LoadFromStream(lStream);
      finally
        lStream.Free;
      end;
    finally
      lBitmap.Free;
    end;
  finally
    CloseThemeData(lTheme);
  end;
end;

这篇关于使用WinApi功能在FMX画布上绘图的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！