Delphi 与 DirectX 之 DelphiX(3): 初识 TDXDraw

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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 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.


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.


本例效果图:

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:
--------------------------------------------------------------------------------

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

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