我画的图怎么不显示?

[16084279]

我在主窗体中new了一个位图,做如下操作,但是却没有我画的线,怎么回事呢?
必须要用Graphics::TBitmap来画,希望高手不吝指教.

Bitmap1=new Graphics::TBitmap;
Bitmap1->Width=300;
Bitmap1->Height=300;
Bitmap1->Canvas->Pen->Color=clRed;
Bitmap1->Canvas->MoveTo(100,100);
Bitmap1->Canvas->LineTo(200,200);
Invalidate();

[hdaq]

你的代码没有什么问题，Graphics::TBitmap本身并不会在窗体上显示，你得借助窗体的Canvas或TImage等控件来显示：

Graphics::TBitmap *Bitmap1=new Graphics::TBitmap();
Bitmap1->Width=300;
Bitmap1->Height=300;
Bitmap1->PixelFormat = pf24bit;
Bitmap1->Canvas->Pen->Color=clRed;
Bitmap1->Canvas->MoveTo(100,100);
Bitmap1->Canvas->LineTo(200,200);
Image1->Picture->Bitmap->Assign(Bitmap1);
delete Bitmap1;

[qibo999]

是啊，用
Image1->Picture->Bitmap->Assign(Bitmap1);

[16084279]

但是我是写在控件中的，如何用代码生成一个TImage的实例呢？
头文件中：
TImage *Bitmap1;
cpp中：
Bitmap1=new TImage;

但是不行。说找不到一个TImage::TImage()的匹配。
TImage(Classes::TComponent* AOwner);这个东西，参数我又不知道是什么？

[16084279]

Image1=new TImage(Form1);
Bitmap1=new Graphics::TBitmap;
Bitmap1->Width=300;
Bitmap1->Height=300;
Bitmap1->Canvas->Pen->Color=clRed;
Bitmap1->Canvas->MoveTo(100,100);
Bitmap1->Canvas->LineTo(200,200);
Image1->Picture->Bitmap->Assign(Bitmap1);
Invalidate();
这样试了，还是不行

[bluedodo]

必须用构造函数，试试
Bitmap1=new TImage(this);

[c2y]

直接使用TImage控件就行了。

[c2y]

Image1->Width=300;
Image1->Height=300;
Image1->Canvas->Pen->Color=clRed;
Image1->Canvas->MoveTo(100,100);
Image1->Canvas->LineTo(200,200);

[16084279]

void __fastcall TForm1::FormClick(TObject *Sender)
{
Image1=new TImage(Form1);

Image1->Width=300;
Image1->Height=300;
Image1->Canvas->Pen->Color=clRed;
Image1->Canvas->MoveTo(100,100);
Image1->Canvas->LineTo(200,200);
}
还是不行

[16084279]

Image1=new TImage(this);
TImage创建成功了，但是图还是显不出来

[qibo999]

正确做法：

TImage Image1=new TImage(Form1);
Image1->Parent=Form1;//*******************关键要加上！
Image1->Top = 1;
Image1->Left = 1;
Image1->Width=300;
Image1->Height=300;
Image1->Canvas->Pen->Color=clRed;
Image1->Canvas->MoveTo(100,100);
Image1->Canvas->LineTo(200,200);

记得 delete Image1啊！

[c2y]

先在Form上加上TImage控件，然后
void __fastcall TForm1::FormClick(TObject *Sender)
{
Image1->Width=300;
Image1->Height=300;
Image1->Canvas->Pen->Color=clRed;
Image1->Canvas->MoveTo(100,100);
Image1->Canvas->LineTo(200,200);
}

[c2y]

或者不加TImage控件，这样：
.h文件中加入
private: // User declarations
TImage *Image1;

void __fastcall TForm1::FormClick(TObject *Sender)
{
if(Image1==NULL) Image1=new TImage(Form1);
Image1->Parent=this;
Image1->Top = 10;
Image1->Left = 10;
Image1->Width=300;
Image1->Height=300;
Image1->Canvas->Pen->Color=clRed;
Image1->Canvas->MoveTo(100,100);
Image1->Canvas->LineTo(200,200);
}