Delphi 与 DirectX 之 DelphiX(3): 初识 TDXDraw

在 DelphiX 中, 所能看到的一般都是画在 TDXDraw.

TDXDraw 默认两个绘图表面: TDXDraw.Surface 和 TDXDraw.Primary;
一般先在后台(Surface)绘图, 然后再用 TDXDraw.Flip 命令切换前后台, 从而看到绘制效果.

TDXDraw.Flip 会置换 Surface 和 Primary 两个对象, 所以我们尽可以只在 Surface 上绘图;
由于 DirectX 的工作机制, 让这个切换速度异常地快(只是切换一个指针), 从而可以完成非常流畅的动画、游戏.

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从 TDXDraw 的绘图表面也可以获取 Canvas 对象, 因而在 TDXDraw 中也可以使用 GDI/GDI+ 的绘图命令;
不过把 GDI/GDI+ 和 DirectX 一起使用应该会让 DirectX 的性能缩水, 但有这种可能总是好的, 起码比单独使用 GDI/GDI+ 要好.

下面例子中就使用了 DXDraw1.Surface.Canvas 对象;
使用完 DXDraw1.Surface.Canvas 后, 一定要释放(DXDraw1.Surface.Canvas.Release);

另外, 绘图前经常要先用指定的颜色填充表面, 譬如: DXDraw1.Surface.Fill(颜色值);
这里的颜色格式和 Delphi 的不一样, 和 HTML 使用的颜色值的顺序是一样的, 譬如: $FF0000 表示红色.

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本例效果图:

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代码文件:

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unit Unit1;



interface



uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, StdCtrls, DXDraws;



type

  TForm1 = class(TForm)

    DXDraw1: TDXDraw;

    Button1: TButton;

    Button2: TButton;

    procedure Button1Click(Sender: TObject);

    procedure Button2Click(Sender: TObject);

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



procedure TForm1.Button1Click(Sender: TObject);

var

  str: string;

begin

  str := FormatDateTime('h:n:s:zz', Time); {获取当前时间, 精确到毫秒}

  DXDraw1.Surface.Fill($FF0000); {填充为红色, 注意这个颜色格式是和 HTML 的颜色顺序一样的}

  DXDraw1.Surface.Canvas.Brush.Style := bsClear;

  DXDraw1.Surface.Canvas.Font.Color := clYellow;

  DXDraw1.Surface.Canvas.Font.Size := 16;

  DXDraw1.Surface.Canvas.TextOut(10, 10, str);

  DXDraw1.Surface.Canvas.Release; {释放 Canvas 对象}

  DXDraw1.Flip;

end;



{这和上面的功能一样, 只是简化了写法}

procedure TForm1.Button2Click(Sender: TObject);

var

  str: string;

begin

  str := FormatDateTime('h:n:s:zz', Time);

  DXDraw1.Surface.Fill(0); {填充黑色}

  with DXDraw1.Surface.Canvas do begin

    Brush.Style := bsClear;

    Font.Color := clLime;

    Font.Size := 16;

    TextOut(10, 10, str);

    Release; {释放 Canvas 对象}

  end;

  DXDraw1.Flip;

end;



end.


 
   

窗体文件:

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object Form1: TForm1

  Left = 0

  Top = 0

  Caption = 'Form1'

  ClientHeight = 127

  ClientWidth = 201

  Color = clBtnFace

  Font.Charset = DEFAULT_CHARSET

  Font.Color = clWindowText

  Font.Height = -11

  Font.Name = 'Tahoma'

  Font.Style = []

  OldCreateOrder = False

  PixelsPerInch = 96

  TextHeight = 13

  object DXDraw1: TDXDraw

    Left = 8

    Top = 8

    Width = 185

    Height = 81

    AutoInitialize = True

    AutoSize = True

    Color = clBlack

    Display.FixedBitCount = False

    Display.FixedRatio = True

    Display.FixedSize = True

    Options = [doAllowReboot, doWaitVBlank, doCenter, do3D, doDirectX7Mode, doHardware, doSelectDriver]

    SurfaceHeight = 81

    SurfaceWidth = 185

    TabOrder = 0

    Traces = <>

  end

  object Button1: TButton

    Left = 30

    Top = 95

    Width = 75

    Height = 25

    Caption = 'Button1'

    TabOrder = 1

    OnClick = Button1Click

  end

  object Button2: TButton

    Left = 118

    Top = 95

    Width = 75

    Height = 25

    Caption = 'Button2'

    TabOrder = 2

    OnClick = Button2Click

  end

end