Delphi 与 DirectX 之 DelphiX(89): TDIB.DrawAlphaMask();

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, DIB, StdCtrls, ExtCtrls;

type
  TForm1 = class(TForm)
    DXPaintBox1: TDXPaintBox;
    Button1: TButton;
    Button2: TButton;
    ColorBox1: TColorBox;
    ColorBox2: TColorBox;
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

const str = '春';

var
  dib,dib1,dib2: TDIB;

procedure TForm1.FormCreate(Sender: TObject);
const
  ImgPath1 = 'C:\Temp\DX.jpg';
begin
  dib := TDIB.Create;
  dib1 := TDIB.Create;
  dib2 := TDIB.Create;

  dib.LoadFromFile(ImgPath1);

  DXPaintBox1.ClientWidth := dib.Width;
  DXPaintBox1.ClientHeight := dib.Height;
  DXPaintBox1.DIB.Assign(dib);

  dib1.Assign(dib);

  dib2.SetSize(dib.Width, dib.Height, 24);
  dib2.Canvas.Brush.Style := bsClear;
  dib2.Canvas.Font.Name := '黑体';
  dib2.Canvas.Font.Size := 90;
  dib2.Canvas.Font.Style := [fsBold];

  ColorBox1.Selected := clBlack;
  ColorBox2.Selected := clYellow;
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  dib.Free;
  dib1.Free;
  dib2.Free;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  dib1.Assign(dib);
  dib2.Fill(ColorBox1.Selected);
  dib2.Canvas.Font.Color := ColorBox2.Selected;
  dib2.Canvas.TextOut(0, 0, str);

  dib1.DrawAlphaMask(dib2, dib1, 0, 0, dib.Width, dib.Height, 0, 0);

  DXPaintBox1.DIB.Assign(dib1);
  DXPaintBox1.Repaint;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  dib1.Assign(dib);
  dib2.Fill(ColorBox2.Selected);
  dib2.Canvas.Font.Color := ColorBox1.Selected;
  dib2.Canvas.TextOut(0, 0, str);

  dib1.DrawAlphaMask(dib2, dib1, 0, 0, dib.Width, dib.Height, 0, 0);

  DXPaintBox1.DIB.Assign(dib1);
  DXPaintBox1.Repaint;
end;

end.

窗体文件:

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object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 142
  ClientWidth = 226
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  OnCreate = FormCreate
  OnDestroy = FormDestroy
  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 = 143
    Top = 78
    Width = 75
    Height = 25
    Caption = 'Button1'
    TabOrder = 0
    OnClick = Button1Click
  end
  object Button2: TButton
    Left = 143
    Top = 109
    Width = 75
    Height = 25
    Caption = 'Button2'
    TabOrder = 1
    OnClick = Button2Click
  end
  object ColorBox1: TColorBox
    Left = 143
    Top = 8
    Width = 81
    Height = 22
    ItemHeight = 16
    TabOrder = 2
  end
  object ColorBox2: TColorBox
    Left = 143
    Top = 36
    Width = 81
    Height = 22
    ItemHeight = 16
    TabOrder = 3
  end
end