Delphi 与 DirectX 之 DelphiX(26): TDIB 的主要载体 TDXPaintBox

TDXPaintBox 和 TPaintBox 一样拥有重要的属性 Canvas;

现在要关心的是 TDXPaintBox 另一个主要属性: DIB(TDIB 对象);
在下面学习 TDIB 时, 应该会大量用到这个 TDXPaintBox.

虽然叫它 TDXPaintBox, 但我觉得它更像 TImage, 只是把 TImage.Picture 换做了 TDXPaintBox.DIB.

在设计时可以给 TDXPaintBox 的 DIB 对象添加图片, 不过本例是运行时添加的; 运行效果图:

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另外, 这是本例中的图片, 应右键另存到 C:\Temp\DX.jpg :

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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, DIB, StdCtrls;

type
  TForm1 = class(TForm)
    DXPaintBox1: TDXPaintBox;
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

var
  w,h: Integer;

procedure TForm1.Button1Click(Sender: TObject);
begin
  DXPaintBox1.Width := w div 2;
  DXPaintBox1.Height := w div 2;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  DXPaintBox1.Width := ClientWidth;
  DXPaintBox1.Height := ClientHeight;
end;

procedure TForm1.Button3Click(Sender: TObject);
begin
  DXPaintBox1.Width := w;
  DXPaintBox1.Height := h;
end;

procedure TForm1.FormCreate(Sender: TObject);
const
  ImgPath1 = 'C:\Temp\DX.jpg';
begin
  DXPaintBox1.Left := 0;
  DXPaintBox1.Top := 0;

  DXPaintBox1.DIB.LoadFromFile(ImgPath1); {!}

  w := DXPaintBox1.DIB.Width;
  h := DXPaintBox1.DIB.Height;

  DXPaintBox1.Width := w;
  DXPaintBox1.Height := h;

  DXPaintBox1.Stretch := True;
end;

end.

窗体文件:

---

object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 165
  ClientWidth = 225
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  OnCreate = FormCreate
  PixelsPerInch = 96
  TextHeight = 13
  object DXPaintBox1: TDXPaintBox
    Left = 8
    Top = 8
    Width = 81
    Height = 73
    AutoStretch = False
    Center = False
    KeepAspect = False
    Stretch = False
    ViewWidth = 0
    ViewHeight = 0
  end
  object Button1: TButton
    Left = 23
    Top = 132
    Width = 60
    Height = 25
    Caption = 'Button1'
    TabOrder = 0
    OnClick = Button1Click
  end
  object Button2: TButton
    Left = 89
    Top = 132
    Width = 60
    Height = 25
    Caption = 'Button2'
    TabOrder = 1
    OnClick = Button2Click
  end
  object Button3: TButton
    Left = 157
    Top = 132
    Width = 60
    Height = 25
    Caption = 'Button3'
    TabOrder = 2
    OnClick = Button3Click
  end
end