如何将图片放大或缩小

Question

1.我想将一个图片放大或缩小。例如：一张100*100的图片缩小成一张32*32的图片或放大成一张200*200的图片。
2.窗口上有一个加载图片按钮。我想让用户点击此按钮后出现的对话框中至出现各类图片文件（例如：BMP,JPG,GIF等等）
3.如何判断IMAGE控件中图片文件的类型

Answer 1

选把Stretch:=True
控制Image的Width和Height不就OK

Answer 2

给你一段代码,自己研究    ProgressBar1->Position=0;
    TRect   AAA,ARect ;
    Graphics::TBitmap *Bitmap;    DBImage1->CopyToClipboard();
    DBImage1->PasteFromClipboard();
    if (Clipboard()->HasFormat(CF_BITMAP))
    {
        Bitmap = new Graphics::TBitmap();
        try{
            Bitmap->Assign(Clipboard());
            float xw,xh;//,s_h,n_h,s_w,n_w;            int x_h=200;
            int x_w=x_h*((float)Bitmap->Width/(float)Bitmap->Height);
            delete_Image();
            TImage *Imagex=new TImage(image_proc);
            Imagex->Parent=ScrollBox1;
            Imagex->AutoSize=false;
            Imagex->Left=3;
            Imagex->Top=4;
            Imagex->Visible=true;
            Imagex->Width=x_w;
            Imagex->Height=x_h;
            Imagex->Name="Image2";            xh=(float)Bitmap->Height/(float)Imagex->Height;
            xw=(float)Bitmap->Width/(float)Imagex->Width;
            ProgressBar1->Max=Imagex->Height;
            for(int i=0;i<=Imagex->Height;i++)
            {
                for(int j=0;j<=Imagex->Width;j++)
                {
                AAA = Rect(j,i,j+1,i+1);
                ARect = Rect(xw*j,xh*i,xw*j+1,xh*i+1);
                Imagex->Canvas->CopyRect(AAA, Bitmap->Canvas, ARect);
                
                }
                ProgressBar1->Position=i;
            }
            //Imagex->AutoSize=true;
            delete Bitmap;
            }
            catch(...){
            delete Bitmap;
        }
    }
    ProgressBar1->Position=0;
    ok_pictrue=true;