如何限制FireMonkey中的最小窗体宽度？ [英] How to restrict minimum form's width in FireMonkey?

问题描述

如何在FireMonkey中限制最小窗体的宽度？它在VCL中过去很容易 - 它在表单属性中只有Max和Min约束。

How do I restrict a minimum form's width in FireMonkey? It used to be so easy in VCL - it just had Max and Min constraints in forms properties.

推荐答案

这是一个更复杂但更优雅）替代解决方案，定义一个完全自定义的Form类，您可以从中继承自己的...

Here's a more complicated (but more elegant) alternative solution, defining an entirely custom Form class from which you can inherit your own...

unit FMX.ConstrainedForm;

interface

uses
  System.Classes, System.Types, System.UITypes, FMX.Forms, FMX.Platform, FMX.Types;

type
  TFormConstraints = class(TPersistent)
  private
    FMaxHeight: Integer;
    FMaxLeft: Integer;
    FMaxWidth: Integer;
    FMaxTop: Integer;
    FMinHeight: Integer;
    FMinLeft: Integer;
    FMinWidth: Integer;
    FMinTop: Integer;
  public
    constructor Create;
  published
    property MaxHeight: Integer read FMaxHeight write FMaxHeight default 0;
    property MaxLeft: Integer read FMaxLeft write FMaxLeft default 0;
    property MaxWidth: Integer read FMaxWidth write FMaxWidth default 0;
    property MaxTop: Integer read FMaxTop write FMaxTop default 0;
    property MinHeight: Integer read FMinHeight write FMinHeight default 0;
    property MinLeft: Integer read FMinLeft write FMinLeft default 0;
    property MinWidth: Integer read FMinWidth write FMinWidth default 0;
    property MinTop: Integer read FMinTop write FMinTop default 0;
  end;

  TConstrainedForm = class(TCustomForm)
  private
    FConstraints: TFormConstraints;
  protected
    procedure StartWindowResize; override;
    procedure StartWindowDrag; override;
  public
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;
    procedure SetBounds(ALeft, ATop, AWidth, AHeight: Integer); override;
  published
    property Constraints: TFormConstraints read FConstraints write FConstraints;
    property BiDiMode;
    property Caption;
    property Cursor default crDefault;
    property BorderStyle default TFmxFormBorderStyle.bsSizeable;
    property BorderIcons default [TBorderIcon.biSystemMenu, TBorderIcon.biMinimize, TBorderIcon.biMaximize];
    property ClientHeight;
    property ClientWidth;
    property Left;
    property Top;
    property Margins;
    property Position default TFormPosition.poDefaultPosOnly;
    property Width;
    property Height;
    property ShowActivated default True;
    property StaysOpen default True;
    property Transparency;
    property TopMost default False;
    property Visible;
    property WindowState default TWindowState.wsNormal;
    property OnCreate;
    property OnDestroy;
    property OnClose;
    property OnCloseQuery;
    property OnActivate;
    property OnDeactivate;
    property OnResize;
    property Fill;
    property StyleBook;
    property ActiveControl;
    property StyleLookup;
    property OnPaint;
  end;

procedure Register;

implementation

{ TFormConstraints }

constructor TFormConstraints.Create;
begin
  inherited;
  FMaxHeight := 0;
  FMaxLeft := 0;
  FMaxWidth := 0;
  FMaxTop := 0;
  FMinHeight := 0;
  FMinLeft := 0;
  FMinWidth := 0;
  FMinTop := 0;
end;

{ TConstrainedForm }

constructor TConstrainedForm.Create(AOwner: TComponent);
begin
  FConstraints := TFormConstraints.Create;
  inherited;
end;

destructor TConstrainedForm.Destroy;
begin
  FConstraints.Free;
  inherited;
end;

procedure TConstrainedForm.SetBounds(ALeft, ATop, AWidth, AHeight: Integer);
begin
  if (FConstraints.FMinWidth > 0) and (AWidth < FConstraints.FMinWidth) then
    AWidth := FConstraints.FMinWidth;

  if (FConstraints.FMaxWidth > 0) and (AWidth > FConstraints.FMaxWidth) then
    AWidth := FConstraints.FMaxWidth;

  if (FConstraints.FMinHeight > 0) and (AHeight < FConstraints.FMinHeight) then
    AHeight := FConstraints.FMinHeight;

  if (FConstraints.FMaxHeight > 0) and (AHeight > FConstraints.FMaxHeight) then
    AHeight := FConstraints.FMaxHeight;

  if (FConstraints.FMinLeft > 0) and (ALeft < FConstraints.FMinLeft) then
    ALeft := FConstraints.FMinLeft;

  if (FConstraints.FMaxLeft > 0) and (ALeft > FConstraints.FMaxLeft) then
    ALeft := FConstraints.FMaxLeft;

  if (FConstraints.FMinTop > 0) and (ATop < FConstraints.FMinTop) then
    ATop := FConstraints.FMinTop;

  if (FConstraints.FMaxTop > 0) and (ATop > FConstraints.FMaxTop) then
    ATop := FConstraints.FMaxTop;

  Platform.SetWindowRect(Self, RectF(ALeft, ATop, ALeft + AWidth, ATop + AHeight));
  inherited SetBounds(ALeft, ATop, AWidth, AHeight);
end;

procedure TConstrainedForm.StartWindowDrag;
begin
  inherited;

end;

procedure TConstrainedForm.StartWindowResize;
begin
  inherited;
end;

procedure Register;
begin
  RegisterClass(TConstrainedForm);
end;

end.

将此文件存储为FMX.ConstrainedForm.pas，将其添加到窗体的用途部分，修改表单的声明，以便代替：

Store this file as FMX.ConstrainedForm.pas, add it to your Form's "uses" section, and modify the declaration of your form so that instead of:

TForm1 = class(TForm)

它说：

TForm1 = class(TConstrainedForm)

由于缺乏定制设计（此时无论如何，这是一个快速解决方案），那么您需要如下挂钩表单的OnCreate事件：

Due to the lack of a custom designed (at this point anyway, this is a "quick solution"), you then need to hook your form's OnCreate event as follows:

procedure TForm1.FormCreate(Sender: TObject);
begin
  Constraints.MinWidth := 400;
  Constraints.MinHeight := 400;
end;

现在，此表单不允许用户将其宽度或高度设置为低于400！

Now this form will not allow the user to set its width or height below 400!

再次，没有对FireMonkey平台本身进行一些不必要的变化，这是现在最好的！

Again, without making some substancial changes to the FireMonkey Platform itself, this is the best you're going to get for now!

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