Question

如何在FireMonkey中限制最小格式的宽度？在VCL中它曾经很容易 - 它只是在表单属性中有Max和Min限制。

Answer 1

未来读者注意事项：

这仅适用于XE3以下的版本，因为在XE3中删除了Fmx::Platform::TPlatform类。感谢@Alain Thiffault在评论中指出它。

原帖：

这是一个更复杂（但更优雅）的替代解决方案，定义了一个完全自定义的Form类，您可以从中继承自己的...

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，将其添加到表单的“使用”部分，并修改表单声明，而不是：

TForm1 = class(TForm)

它说：

TForm1 = class(TConstrainedForm)

由于缺乏自定义设计（此时无论如何，这是一个“快速解决方案”），您需要按如下方式挂钩表单的OnCreate事件：

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！

同样，如果不对FireMonkey平台本身进行一些改变，这是您现在最好的选择！

Answer 2

将其放在表单的“OnResize”事件中，根据需要替换值。当然，这不是世界上最好的解决方案，但它会让你度过难关，直到房产被重新引入！

procedure TForm1.FormResize(Sender: TObject);
begin
  if Width < 400 then
    Width := 400;
  if Height < 400 then
    Height := 400;
end;

以上代码很容易根据最大值或最小值的任意组合进行更改，所以玩得开心！

Answer 3

LaKraven，模拟mouseUp事件以摆脱闪烁。

if (Width > maxWidth) then
begin
  Width := maxWidth;
  Mouse_Event(MOUSEEVENTF_ABSOLUTE or MOUSEEVENTF_LEFTUP, 0, 0, 0, 0);
end;

Answer 4

此外，对于LaKraven关于基于FormResize的解决方案的回答，请使用ClientWidth和ClientHeight而不是Width和Height来阻止表单的拉伸。

procedure TForm1.FormResize(Sender: TObject);
begin
    if ClientWidth < 400 then
        ClientWidth := 400;
    if ClientHeight < 400 then
        ClientHeight := 400;
end;

Answer 5

下面是Sunec的答案的更新版本，以消除闪烁。

根据MSDN，Mouse_Event已被取代，应改为使用SendInput： https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-mouse_event

uses WinApi.Windows;

procedure TForm1.FormResize(Sender: TObject);
var
  LInput: TInput;
begin
  if ClientHeight < MIN_HEIGHT then
  begin
    ClientHeight := MIN_HEIGHT;
    FillMemory(@LInput, SizeOf(LInput), 0);
    LInput.Itype := INPUT_MOUSE;
    LInput.mi.dwFlags := MOUSEEVENTF_ABSOLUTE or MOUSEEVENTF_LEFTUP;
    SendInput(1, LInput, SizeOf(LInput));
  end;
  if ClientWidth < MIN_WIDTH then
  begin
    ClientWidth := MIN_WIDTH;
    FillMemory(@LInput, SizeOf(LInput), 0);
    LInput.Itype := INPUT_MOUSE;
    LInput.mi.dwFlags := MOUSEEVENTF_ABSOLUTE or MOUSEEVENTF_LEFTUP;
    SendInput(1, LInput, SizeOf(LInput));
  end;
end;

Answer 6

要使以上内容有用，请使用以下代码：

Uses Winapi.Windows;

Procedure TForm1.FormResize(Sender: TObject);
Begin
 If ClientWidth < 400 Then
    Begin
      ClientWidth := 400;
      Mouse_Event(MOUSEEVENTF_ABSOLUTE or MOUSEEVENTF_LEFTUP, 0, 0, 0, 0);
    End;

  If ClientHeight < 400 Then
    Begin
      ClientHeight := 400;
      Mouse_Event(MOUSEEVENTF_ABSOLUTE or MOUSEEVENTF_LEFTUP, 0, 0, 0, 0);
    End;
End;

如何在FireMonkey中限制最小格式的宽度？

6 个答案:

未来读者注意事项：

原帖：