陆续写了十几篇关于《GDI+在Delphi程序的应用》的文章后,应几个小友来信要求,将我所使用的GDI+ for VCL,包括Delphi和C++Builder版发布在了csdn的资源下载区。
GDI+ C语言版本同时GDI+ for VCL版本2010.7.10修改版下载地址:http://download.csdn.net/source/2737743(因疏忽,导致个别克隆方法错误,修改过的主单元文件Gdiplus.pas的下载地址:http://download.csdn.net/source/3395894,可覆盖原Gdiplus.pas文件)。
其中的Delphi版与目前网上流通的版本不完全兼容;而C++Builder本来自带有C++版的Gdiplus,但由于与VCL有些冲突,使用起来较麻烦,所以本人参照Delphi版完全重新写了一个供C++Builder使用的VCL版(开源的),本BLOG中的有关GDI+的Delphi例子很容易就移植到C++Builder。
下面就GDI+ for VCL的一些特点作简单介绍:
GDI+是伴随Windows XP系统出现的增强性图形设备接口子系统,除了一整套API外,还提供了几十个C++类和大量的数据类型,同传统的Win32 GDI相比,GDI+不仅优化和扩展了GDI,而且使得使用C/C++开发Windows程序图形界面更容易操作。但是,对于Delphi和C++Builder所共用的VCL来说,由于VCL通过TCanvas、TBitmap和TImage等及其相关的类,把传统的GDI封装的几乎无可挑剔,类似C++的GDI+类,在易操作上就没什么优势可言了。但是,要想把GDI+封装成完全的VCL风格也存在几个问题: 1、正是由于VCL对GDI良好的封装,VCL所有与界面和图形有关的类对GDI存在严重的依赖性,即使GDI+封装成完全的VCL风格,也无法“插足”已有的界面和图形类,充其量只能起到“敲敲边鼓”的辅助作用,所以把GDI+封装成完全的VCL风格意义不大,除非GDI+为主,完全重构原有的界面和图形类; 2、现有大量的C++、.NET有关GDI+的代码移植到Delphi(C++Builser)时,结构修改量太大,而且对于已经熟悉C++或者.NET GDI+的人来说,重新掌握新的VCL风格无疑是痛苦的; 3、GDI+的坐标计量类型有整数和实数2套,如果按VCL风格写,势必要舍弃一套,保留整数型当然是最好的,但这2套类型又都不那么完整,整数型更是个半吊子系统。 鉴于以上原因,无论是目前网上流通的GDI+ for Delphi版本,还是本人改写的GDI+ for VCL,都基本采用了原C++类风格,甚至于.net的GDI+版本也与.net其它类风格不一样,更多的保留了原C++风格(就我个人的看法,不知什么原因,GDI+ for C++版本无论是架构设计,还是代码水平,其实都很差,同C++的STL没法比)。 当然,同网上流通的GDI+ for Delphi版本比,我改写的GDI+ for VCL版本并没有完全照搬原C++代码,兼顾了部分VCL和.NET风格,比如加入了VCL异常、布尔类型和绝大部分枚举和集合类型都采用了VCL风格、增加了.NET风格的Pens和Brushs等全局变量(C++Builder)或者全局函数(Delphi)。 GDI+ for VCL的所有类(不包括TPens和TBrushs)都派生于TGdiplusBase: TCloneAPI = function(Native: GpNative; var clone: GpNative): TStatus; stdcall;TGdiplusBase = class(TObject)
private
FNative: GpNative;
protected
constructor CreateClone(SrcNative: GpNative; clonefunc: TCloneAPI = nil);
property Native: GpNative read FNative write FNative;
public
constructor Create;
class function NewInstance: TObject; override;
procedure FreeInstance; override;
end;
原C++的GdiplusBase只是重载了new和delete操作符,分别以GDI+的GdipAlloc和GdipFree替换了原系统默认的内存分配和释放方法,而TGdiplusBase也相应的重载了TObject的NewInstance方法和FreeInstance方法(其实在不重载也能正常运行);
在TGdiplusBase中有个保护的GpNative(指针)类型的成员Native(Delphi中说明为属性,C++builder直接说明为数据成员),供所用派生类使用(原C++类将这个成员分散说明在各个类中),这个数据成员就是Gdiplus.dll内部使用的类指针,GDI+类都是通过对应的内部类指针对Dll Exports函数的调用实现的(假如你讨厌GDI+的类,你完全可以抛开它们而直接使用指针操作原始的Dll Exports函数);
至于TGdiplusBase构造方法CreateClone则是我为了简化派生类的Clone方法所提供的基类保护方法。
GDI+ for VCL定义了一个异常类EGdiplusException:
EGdiplusException = class(Exception)private
FGdipError: TStatus;
function GetGdipErrorString: string;
public
constructor CreateStatus(Status: TStatus);
property GdipError: TStatus read FGdipError;
property GdipErrorString: string read GetGdipErrorString;
end;
除各类的析构方法外,其它类方法都使用了异常检查,这使得GDI+ for VCL代码同原C++代码和目前流通的GDI+ for Delphi比,更加方便和健壮,通过使用EGdiplusException.GdipError或者EGdiplusException.GdipErrorString,可以得到GDI+最后一次异常代码或信息。
GDI+ for VCL重新定义了绝大多数数据类型,如将C++风格的常量和枚举类型改为了VCL风格的枚举和集合类型,重构某些数据结构,以提供对VCL数据类型的支持或转换。以Color类为例,改写后的TGpColor:
// Known Color#define KnownColorCount 141static const ARGB kcAliceBlue = 0xfff0f8ff;
static const ARGB kcAntiqueWhite = 0xfffaebd7;(略)
class Color
{
private:
union
{
ARGB FARGB;
struct
{
BYTE FBlue;
BYTE FGreen;
BYTE FRed;
BYTE FAlpha;
};
};
static TIdentMapEntry KnownColors[];
void MakeARGB(BYTE a, BYTE r, BYTE g, BYTE b);
void MakeARGB(BYTE a, Graphics::TColor color);
COLORREF GetCOLORREF();
AnsiString GetKnownName(void);
public:
Color();
Color(Color &color);
Color(ARGB argb);
Color(BYTE alpha, ARGB argb);
Color(BYTE r, BYTE g, BYTE b);
Color(BYTE a, BYTE r, BYTE g, BYTE b);
Color(BYTE alpha, Graphics::TColor color);
Color(Graphics::TColor color);
Color(AnsiString Name, BYTE Alpha = 255);
static Color FromTColor(BYTE alpha, Graphics::TColor color);
static Color FromTColor(Graphics::TColor color);
static Color FromArgb(ARGB argb);
static Color FromArgb(BYTE alpha, ARGB argb);
static Color FromArgb(BYTE r, BYTE g, BYTE b);
static Color FromArgb(BYTE a, BYTE r, BYTE g, BYTE b);
static Color FromName(AnsiString Name, BYTE Alpha = 255);
static Color FromCOLORREF(BYTE alpha, COLORREF rgb);
static Color FromCOLORREF(COLORREF rgb);
bool IsEmpty();
Color& operator = (Color c);
Color& operator = (ARGB c);
bool operator == (Color& c);
bool operator != (Color& c);
static ARGB StringToARGB(AnsiString Name, BYTE Alpha = 255);
static AnsiString ARGBToString(ARGB argb);
__property ARGB Argb = { read = FARGB };
__property BYTE Alpha = { read = FAlpha };
__property BYTE A = { read = FAlpha };
__property BYTE Red = { read = FRed };
__property BYTE R = { read = FRed };
__property BYTE Green = { read = FGreen };
__property BYTE G = { read = FGreen };
__property BYTE Blue = { read = FBlue };
__property BYTE B = { read = FBlue };
__property COLORREF Rgb = { read = GetCOLORREF };
__property AnsiString Name = { read = GetKnownName };
};
typedef Color TGpColor, *PGpColor;
typedef ARGB TARGB, *PARGB;
不仅提供了对VCL的TColor类型的支持(定义为TGpColor类型的参数可直接传递TColor类型),也提供了对GDI+标准颜色的支持与转换(按标准颜色名称得到标准颜色或者按标准颜色取得名称)。在Delphi中,对应TGpColor的地方一律采用TARGB类型,同时提供了与TGpColor函数成员类似的转换方法:
function ARGBToString(Argb: TARGB): string;function StringToARGB(const S: string; Alpha: BYTE = 255): TARGB;
procedure GetARGBValues(Proc: TGetStrProc);
function ARGBToIdent(Argb: Longint; var Ident: string): Boolean;
function IdentToARGB(const Ident: string; var Argb: Longint): Boolean;
function ARGB(r, g, b: BYTE): TARGB; overload;
function ARGB(a, r, g, b: BYTE): TARGB; overload;
function ARGB(a: Byte; Argb: TARGB): TARGB; overload;
function ARGBToCOLORREF(Argb: TARGB): Longint;
function ARGBToColor(Argb: TARGB): Graphics.TColor;
function ARGBFromCOLORREF(Rgb: Longint): TARGB; overload;
function ARGBFromCOLORREF(Alpha: Byte; Rgb: Longint): TARGB; overload;
function ARGBFromTColor(Color: Graphics.TColor): TARGB; overload;
function ARGBFromTColor(Alpha: Byte; Color: Graphics.TColor): TARGB; overload;
GDI+ for VCL还增加了.NET风格的Pens和Brushs等全局变量(C++Builder)或者全局函数(Delphi),不仅提供了141种标准颜色的画笔和画刷,也可使用自定义颜色调用Pens和Brushs的缺省数组(Delphi)或者重载的操作符(C++Builder)形成新的画笔和画刷,大大简化了一般的GDI+编程代码,C++Builder的定义为:
static TGpPens Pens;
static TGpBrushs Brushs;
而Delphi则定义为:
function Pens: TPens;
function Brushs: TBrushs;
你可能注意到上面的类型说明中Delphi和C++Builder类的名称不一样,前者为TGpPens和TGpBrushs,而后者直接写为TPens和TBrushs,这是本人写代码时的一点疏忽,不过对写代码没任何影响。
有关GDI+与VCL的话题就说到这里,下面用Delphi和C++Builder以一个简单相同的例子程序作为本文的结尾。
Delphi代码:
unit main;interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, Buttons, ExtCtrls;
type
TMainForm = class(TForm)
BitBtn1: TBitBtn;
CbColor: TComboBox;
procedure FormPaint(Sender: TObject);
procedure CbColorDrawItem(Control: TWinControl; Index: Integer;
Rect: TRect; State: TOwnerDrawState);
procedure FormCreate(Sender: TObject);
procedure CbColorChange(Sender: TObject);
private
{ Private declarations }
procedure GetKnownColorStr(const s: string);
public
{ Public declarations }
end;
var
MainForm: TMainForm;
implementation
uses Gdiplus;
{$R *.dfm}
procedure TMainForm.CbColorChange(Sender: TObject);
begin
Invalidate;
end;
procedure TMainForm.CbColorDrawItem(Control: TWinControl; Index: Integer;
Rect: TRect; State: TOwnerDrawState);
var
g: TGpGraphics;
r: TGpRect;
begin
g := TGpGraphics.Create(CbColor.Canvas.Handle);
try
CbColor.Canvas.FillRect(Windows.TRect(Rect));
r := GpRect(Rect.Left, Rect.Top, CbColor.ItemHeight, CbColor.ItemHeight - 4);
OffSet(r, 2, 2);
g.FillRectangle(Brushs[StringToARGB(CbColor.Items[Index])], r);
g.DrawRectangle(Pens.Black, r);
CbColor.Canvas.TextOut(r.X + r.Width + 5, r.Y, CbColor.Items[Index]);
finally
g.Free;
end;
end;
procedure TMainForm.FormCreate(Sender: TObject);
begin
GetARGBValues(GetKnownColorStr);
CbColor.ItemIndex := 0;
end;
procedure TMainForm.FormPaint(Sender: TObject);
const
QualityStr: array[0..4] of string =
('Default', 'HighSpeed', 'HighQuality', 'GammaCorrected', 'AssumeLinear');
Alphas: array[0..3] of Byte = (255, 128, 64, 32);
var
g : TGpGraphics;
font: TGpFont;
kc, bc: TARGB;
i, j: Integer;
begin
// 建立与窗口关联的Graphics对象,使用Handle建立在D7中效果很好,可2007不停闪烁
// g := TGpGraphics.Create(Handle, False);
g := TGpGraphics.Create(Canvas.Handle);
// 建立与本窗口字体关联的Gdiplus字体对象,以下3句都可建立,
// 但是第三句显示有点不一样,可能没包括字符集的信息
font := TGpFont.Create(Canvas.Handle);
// font := TGpFont.Create(Canvas.Handle, Self.Font.Handle);
// font := TGpFont.Create(Self.Font.Name, Self.Font.Size, Self.Font.Style);
kc := StringToARGB(CbColor.Items[CbColor.ItemIndex]);
if (kc and $808080) = $808080 then bc := kcBlack
else bc := kcAliceBlue;
// 以下使用内建的Pens和Brushs作图,也可分别使用TGpPen和TGpBrush建立
g.DrawLine(Pens.Brown, 120, 30, 659, 30);
g.FillRectangle(Brushs[bc], 120, 38, 540, 200);
// 显示纵标题
for i := 0 to 4 do
g.DrawString(QualityStr[i], font, Brushs.Black, 4.0, i * 40 + 48);
// 显示横标题
for i := 0 to 3 do
g.DrawString('Alpha: ' + IntToStr(Alphas[i]), font, Brushs.Black, 130.0 + i * 140, 8);
g.DrawString('选择显示颜色', font, Brushs.Black, 4.0, 260.0);
// 根据所选颜色和Alpha,用不同的合成品质画色块
for i := 0 to 3 do
begin
for j := Integer(Low(TCompositingQuality)) to Integer(High(TCompositingQuality)) do
begin
g.CompositingQuality := TCompositingQuality(j);
g.DrawLine(Pens[ARGB(Alphas[i], kc), 20],
130 + i * 140, j * 40 + 58, 230 + i * 140, j * 40 + 58);
end;
end;
font.Free;
g.Free;
end;
procedure TMainForm.GetKnownColorStr(const s: string);
begin
CbColor.Items.Add(s);
end;
end.
C++ Builder代码:
//---------------------------------------------------------------------------#ifndef mainH
#define mainH
//---------------------------------------------------------------------------
#include <Classes.hpp>
#include <Controls.hpp>
#include <StdCtrls.hpp>
#include <Forms.hpp>
#include <Buttons.hpp>
//---------------------------------------------------------------------------
class TMainForm : public TForm
{
__published: // IDE-managed Components
TBitBtn *BitBtn1;
TComboBox *CbColor;
void __fastcall CbColorDrawItem(TWinControl *Control, int Index, TRect &Rect,
TOwnerDrawState State);
void __fastcall CbColorChange(TObject *Sender);
void __fastcall FormPaint(TObject *Sender);
private: // User declarations
void __fastcall GetKnownColorStr(const String s);
public: // User declarations
__fastcall TMainForm(TComponent* Owner);
};
//---------------------------------------------------------------------------
extern PACKAGE TMainForm *MainForm;
//---------------------------------------------------------------------------
#endif
//---------------------------------------------------------------------------
#include <vcl.h>
#pragma hdrstop
#include "main.h"
#include "Gdiplus.hpp"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TMainForm *MainForm;
//---------------------------------------------------------------------------
__fastcall TMainForm::TMainForm(TComponent* Owner)
: TForm(Owner)
{
GetARGBValues(GetKnownColorStr);
CbColor->ItemIndex = 0;
}
//---------------------------------------------------------------------------
void __fastcall TMainForm::GetKnownColorStr(const String s)
{
CbColor->Items->Add(s);
}
//---------------------------------------------------------------------------
void __fastcall TMainForm::CbColorDrawItem(TWinControl *Control, int Index,
TRect &Rect, TOwnerDrawState State)
{
TGpGraphics *g = new TGpGraphics(CbColor->Canvas->Handle);
try
{
CbColor->Canvas->FillRect(Rect);
TGpRect r(Rect.Left, Rect.Top, CbColor->ItemHeight, CbColor->ItemHeight - 4);
r.Offset(2, 2);
TGpColor c = TGpColor::StringToARGB(CbColor->Items->Strings[Index]);
TGpBrush *b = Brushs[c];
g->FillRectangle(b, r);
g->DrawRectangle(Pens.Black, r);
CbColor->Canvas->TextOutA(r.X + r.Width + 5, r.Y, CbColor->Items->Strings[Index]);
}
__finally
{
delete g;
}
}
//---------------------------------------------------------------------------
void __fastcall TMainForm::CbColorChange(TObject *Sender)
{
Invalidate();
}
//---------------------------------------------------------------------------
void __fastcall TMainForm::FormPaint(TObject *Sender)
{
const static String QualityStr[5] =
{"Default", "HighSpeed", "HighQuality", "GammaCorrected", "AssumeLinear"};
const static Byte Alphas[4] = {255, 128, 64, 32};
// TGpGraphics *g = new TGpGraphics(Handle, false);
TGpGraphics *g = new TGpGraphics(Canvas->Handle);
// 建立与本窗口字体关联的Gdiplus字体对象,以下3句都可建立,
// 但是第三句显示有点不一样,可能没包括字符集的信息
TGpFont *font = new TGpFont(Canvas->Handle);
// TGpFont *font = new TGpFont(Canvas->Handle, Font->Handle);
// TGpFont *font = new TGpFont(Font->Name, Font->Size, Font->Style);
try
{
TARGB kc = TGpColor::StringToARGB(CbColor->Items->Strings[CbColor->ItemIndex]);
TARGB bc = (kc & 0x808080) == 0x808080? kcBlack : kcAliceBlue;
g->DrawLine(Pens.Brown, 120, 30, 659, 30);
g->FillRectangle(Brushs[bc], 120, 38, 540, 200);
for (int i = 0; i < 5; i ++)
g->DrawString(QualityStr[i], font, Brushs.Black, 4.0, i * 40 + 48);
for (int i = 0; i < 4; i ++)
g->DrawString("Alpha: " + IntToStr(Alphas[i]),
font, Brushs.Black, 130.0 + i * 140, 8.0);
g->DrawString("选择显示颜色", font, Brushs.Black, 4.0, 260.0);
for (int i = 0; i < 4; i ++)
{
for (int j = 0; j < 5; j ++)
{
g->CompositingQuality = (TCompositingQuality)j;
g->DrawLine(Pens(TGpColor(Alphas[i], kc), 20),
130 + i * 140, j * 40 + 58, 230 + i * 140, j * 40 + 58);
}
}
}
__finally
{
delete font;
delete g;
}
}
//---------------------------------------------------------------------------
运行结果:
通过这个例子,可以进一步了解前面介绍的颜色转换函数的应用、Pens和Brushs的应用;同时也增加对GDI+颜色类型TARGB不同于TColor的感性认识,即对Alpha的了解以及不同的Alphi值在不同的合成品质下的差异;还可掌握TCanvas与GDI+混合使用自绘TComboBox选项的技巧。