如何获取字符串的TextWidth（无Canvas）？ [英] How to get TextWidth of string (without Canvas)?

问题描述

我想在应用程序启动之前获取字符串的文本宽度。一切正常，直到Application.MainForm画布呈现。问题是，当我尝试在应用程序的OnCreate事件中动态创建TOrdinarium。主窗体Canvas不允许绘图出现错误。 （Application.MainForm是nil ....）。我尝试了几种方式动态创建Canvas（其中一个如下所示），但是它不能测量文本大小，而不附加到父级控件。

I would like to get text width of a string before an application starts. Everything works fine until Application.MainForm canvas present. The problem is, when I try dynamically create TOrdinarium in the OnCreate event of the app. main form, "Canvas does not allow drawing" error occurs. (Application.MainForm is nil....). I tried several ways to create Canvas dynamically (one of them is written below), but it can not measure text sizes without being attached to parented control.

有没有办法让它的工作不正常？

Is there way how to make it work somehow?

Thanx

我尝试过：

  TOrdinarium = class (TCustomControl)
    private 
       function GetVirtualWidth:integer;
    end;

constructor TOrdinarium.Create(AOwner:TComponent);
begin
 inherited;
 Width:=GetVirtualWidth;
end; 

function TOrdinarium.GetVirtualWidth:integer;
var  ACanvas : TControlCanvas;
  begin
  ACanvas := TControlCanvas.Create;
  TControlCanvas(ACanvas).Control := Application.MainForm; 
  ACanvas.Font.Assign(Font);

  result:=ACanvas.TextWidth('0');

  ACanvas.Free;
  end;

推荐答案

这样做：

procedure TForm1.FormCreate(Sender: TObject);
var
  c: TBitmap;
begin
  c := TBitmap.Create;
  try
    c.Canvas.Font.Assign(self.Font);
    Caption := IntToStr(c.Canvas.TextWidth('My String'));
  finally
    c.Free;
  end;
end;

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