Question

我正在玩FireMonkey只是为了测试一些东西。其中一个是在画布上实现“非常简单”的绘图。例如Line，Rectangle等......

第一个问题是，是否有相当于为VCL for FireMonkey提供的graphex演示？

否则，出于练习的目的，我正在尝试在FireMonkey中复制该演示，而刚才是线条图。我可以让线条图像工作，就像我在线条周围移动鼠标时所预期的那样。不幸的是，我不能让它自动擦除在鼠标所在的前一点绘制的旧行。这似乎是由TPen属性的TPenMode属性处理的 - 我可以告诉它 - 在FireMonkey中的TStroke属性。即在绘制（移动鼠标）时将属性设置为pmXor，然后在完成时将其设置为pmCopy。

我如何使用FireMonkey做类似的事情？

这是在TImage的MouseMove事件期间调用的例程：

  FDrawSurface.Bitmap.Canvas.BeginScene;
  try
    case FShapeToDraw of
      doLine:
      begin
        FDrawSurface.Bitmap.Canvas.DrawLine(PointF(TopLeft.X, TopLeft.Y), PointF(BottomRight.X, BottomRight.Y), 100);
      end;

    end;
  finally
    FDrawSurface.Bitmap.Canvas.EndScene;
    FDrawSurface.Bitmap.BitmapChanged;
  end;

FDrawSurface是一个TImage。 TopLeft是一个TPoint，它包含鼠标在TImaeg的OnMouseDown事件中捕获的位置的X和Y，而BottomRight是来自OnMouseMove事件的当前X和Y坐标。

因此每次移动鼠标时，我的图像上都会出现“附加”行。

由于

Answer 1

AFAIK，FMX没有这样的模式...... 此外，您在画布上绘制的内容并未真正保存（如果您知道如何直接保存它，请在评论中解释我）：如果您将表单移到桌面之外，然后将其恢复，则清理画布...

因此，要实现graphex演示，您必须使用其他技术进行编码..

例如，使用TBitmap存储您的真实“图像”，并仅使用画布进行“预览”......

unit main;

interface

uses
  System.SysUtils, System.Types, System.UITypes, System.Classes, System.Variants,
  FMX.Types, FMX.Controls, FMX.Forms, FMX.Dialogs, FMX.Objects;

type
  TfrmMain = class(TForm)
    recBoard: TRectangle;
    btnCopy: TButton;
    Image1: TImage;
    procedure recBoardMouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Single);
    procedure recBoardMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Single);
    procedure recBoardMouseUp(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Single);
    procedure recBoardMouseInOut(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure btnCopyClick(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
  private
    { Private declarations }
    bmp: TBitmap;
    pFrom, pTo: TPointF;
  public
    { Public declarations }
  end;

var
  frmMain: TfrmMain;

implementation

{$R *.fmx}

procedure TfrmMain.btnCopyClick(Sender: TObject);
begin
  Image1.Bitmap.Assign(bmp);
end;

procedure TfrmMain.FormCreate(Sender: TObject);
begin
  pFrom := PointF(-1, -1);
  bmp := TBitmap.Create(Round(recBoard.Width), Round(recBoard.Height));
end;

procedure TfrmMain.FormDestroy(Sender: TObject);
begin
  bmp.Free;
end;

procedure TfrmMain.recBoardMouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Single);
begin
  if Button = TMouseButton.mbLeft then
  begin
    pFrom := PointF(X, Y);
    pTo   := PointF(X, Y);
  end;
end;

procedure TfrmMain.recBoardMouseInOut(Sender: TObject);
begin
  pFrom := PointF(-1, -1);
end;

procedure TfrmMain.recBoardMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Single);
begin
  if ((pFrom.X <> -1) and (pFrom.X <> -1)) then
  with recBoard.Canvas do
  begin
    BeginScene;
    if ssLeft in Shift then
    begin
      FillRect(RectF(0, 0, bmp.Width, bmp.Height), 0, 0, [], 255);
      DrawBitmap(bmp, RectF(0, 0, bmp.Width, bmp.Height), RectF(0, 0, bmp.Width, bmp.Height), 255);
      Stroke.Color := claBlue;
      pTo := PointF(X, Y);
      DrawEllipse(RectF(pFrom.X, pFrom.Y, pTo.X, pTo.Y), 255);
    end;
    EndScene;
  end;
  Self.Caption := Format('(%0.0f;%0.0f)', [X, Y]);
end;

procedure TfrmMain.recBoardMouseUp(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Single);
begin
  with bmp.Canvas do
  begin
    BeginScene;
    DrawEllipse(RectF(pFrom.X, pFrom.Y, pTo.X, pTo.Y), 255);
    EndScene;
  end;
  pFrom := PointF(-1, -1);
end;


















end.

Answer 2

我最终做的 - 基于上面的Whiler的洞察力，是在“绘制例程”（即鼠标按下）开始时存储位图的状态，然后在MouseMove上存储，然后我渲染新线（在此例如），我恢复状态，然后绘制新线......

procedure TFMXDrawSurface.DrawSurfaceMouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Single);
begin
  FOrigin := PointF(X, Y);
  FMovePt := PointF(X, Y);
  FPrevPt := PointF(X, Y);
  FDrawing := True;
  FTempDrawbitmap.Assign(FDrawSurface.Bitmap);
end;

procedure TFMXDrawSurface.DrawSurfaceMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Single);
begin
  if FDrawing then
  begin
    DrawShape(FOrigin, FMovePt);
    FMovePt := PointF(X, Y);
    DrawShape(FOrigin, FMovePt);
    FPrevPt := PointF(X, Y);
  end;
end;

procedure TFMXDrawSurface.DrawShape(TopLeft, BottomRight: TPointF);
var
  R: TRectF;
begin
  FDrawSurface.Bitmap.Canvas.BeginScene;
  try

    case FShapeToDraw of
      doLine:
      begin
        // restore canvas to initial state so we don't keep old movement data around
        R.TopLeft := PointF(0.0, 0.0);
        R.BottomRight := PointF(FDrawSurface.Width, FDrawSurface.Height);
        FDrawSurface.Bitmap.Canvas.DrawBitmap(FTempDrawBitmap, R, R, 100);
        FDrawSurface.Bitmap.Canvas.RestoreState(FDrawState);
        FDrawSurface.Bitmap.Canvas.DrawLine(PointF(TopLeft.X, TopLeft.Y), PointF(BottomRight.X, BottomRight.Y), 100);
      end;
    end;
  finally
    FDrawSurface.Bitmap.Canvas.EndScene;
    FDrawSurface.Bitmap.BitmapChanged;
  end;

end;

它有效，但我不知道它是否是“正确”的方式......

FireMonkey PenMode等效 - DrawLine

2 个答案: