在Delphi Seattle中更改运行时DPI后如何处理菜单缩放

这是一种目前有效的解决方案。使用Delphi Detours库，将此单元添加到dpr使用列表中（我必须将其放在其他表单之前的列表顶部附近），从而根据包含以下内容的表单将正确的字体大小应用于菜单画布任何弹出菜单中的菜单项。该解决方案特意忽略了顶层菜单（主菜单栏），因为VCL不能正确处理那里的所有者测量的项目。

unit slMenuDPIFix;

// add this unit to the main application dpr file BEFORE ANY FORMS in the uses list.

interface

implementation

uses
  Winapi.Windows, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Menus, slScaleUtils, Math,
  DDetours;

type
  TMenuClass = class(TMenu);
  TMenuItemClass = class(TMenuItem);

var
  TrampolineMenuCreate: procedure(const Self: TMenuClass; AOwner: TComponent) = nil;
  TrampolineMenuItemAdvancedDrawItem: procedure(const Self: TMenuItemClass; ACanvas: TCanvas; ARect: TRect; State: TOwnerDrawState; TopLevel: Boolean) = nil;
  TrampolineMenuItemMeasureItem: procedure(const Self: TMenuItemClass; ACanvas: TCanvas; var Width, Height: Integer) = nil;

function GetPopupDPI(const MenuItem: TMenuItemClass): Integer;
var
  pm: TMenu;
  pcf: TCustomForm;
begin
  Result := Screen.PixelsPerInch;
  pm := MenuItem.GetParentMenu;
  if Assigned(pm) and (pm.Owner is TControl) then
    pcf := GetParentForm(TControl(pm.Owner))
  else
    pcf := nil;
  if Assigned(pcf) and (pcf is TForm) then
    Result := TForm(pcf).PixelsPerInch;
end;

procedure MenuCreateHooked(const Self: TMenuClass; AOwner: TComponent);
begin
  TrampolineMenuCreate(Self, AOwner);
  Self.OwnerDraw := True;     // force always ownerdraw.
end;

procedure MenuItemAdvancedDrawItemHooked(const Self: TMenuItemClass; ACanvas: TCanvas; ARect: TRect; State: TOwnerDrawState; TopLevel: Boolean);
begin
  if (not TopLevel) then
  begin
    ACanvas.Font.Height := MulDiv(ACanvas.Font.Height, GetPopupDPI(Self), Screen.PixelsPerInch);
  end;
  TrampolineMenuItemAdvancedDrawItem(Self, ACanvas, ARect, State, TopLevel);
end;

procedure MenuItemMeasureItemHooked(const Self: TMenuItemClass; ACanvas: TCanvas; var Width, Height: Integer);
var
  lHeight: Integer;
  pdpi: Integer;
begin
  pdpi := GetPopupDPI(Self);
  if (Self.Caption <> cLineCaption) and (pdpi <> Screen.PixelsPerInch) then
  begin
    ACanvas.Font.Height := MulDiv(ACanvas.Font.Height, pdpi, Screen.PixelsPerInch);
    lHeight := ACanvas.TextHeight('|') + MulDiv(6, pdpi, Screen.PixelsPerInch);
  end else
    lHeight := 0;

  TrampolineMenuItemMeasureItem(Self, ACanvas, Width, Height);

  if lHeight > 0 then
    Height := Max(Height, lHeight);
end;

initialization

  TrampolineMenuCreate := InterceptCreate(@TMenuClass.Create, @MenuCreateHooked);
  TrampolineMenuItemAdvancedDrawItem := InterceptCreate(@TMenuItemClass.AdvancedDrawItem, @MenuItemAdvancedDrawItemHooked);
  TrampolineMenuItemMeasureItem := InterceptCreate(@TMenuItemClass.MeasureItem, @MenuItemMeasureItemHooked);

finalization

  InterceptRemove(@TrampolineMenuCreate);
  InterceptRemove(@TrampolineMenuItemAdvancedDrawItem);
  InterceptRemove(@TrampolineMenuItemMeasureItem);

end.

一个人可以同样轻松地修补Vcl.Menus，但我不想这样做。