GSI example

Here's a simple GDI example that clears a window, and draws a line and text, with no flickering when the window is resized.

Strict

Extern "win32"
	Function ReleaseDC( hwnd:Int, hdc:Int )
	Function GetCurrentObject( hdc:Int, objectType:Int )
	Function MoveToEx( hdc:Int, x:Int, y:Int, point:Int )
	Function LineTo( hdc:Int, x:Int, y:Int )
	Function CreatePen:Int(fnPenStyle:Int,nWidth:Int,crColor:Int)
	Function FillRect(hdc:Int,rect:Byte Ptr,hbr:Int)
	Function GetDeviceCaps(hdc%,index%)
	Function DrawTextA(hdc%,txt$z,nCount%,tRECT:Byte Ptr,format%)
	Function MulDiv(nNumber%,nNumerator%,nDenominator%)
	Function SetBkMode(hdc%,mode%)
	Function SetTextColor(hdc%,color%)
	Function CreateFontA(nHeight%,nWidth%,nEscapement%,nOrientation%,fnWeight%,fdwItalic%,fdwUnderline%,fdwStrikeOut%,fdwCharSet%,fdwOutputPrecision%,fdwClipPrecision%,fdwQuality%,fdwPitchAndFamily%,lpszFace$z)
EndExtern

Global win:TGadget = CreateWindow("LineTest", 0,0, 400,400 )
Global canvas:TGadget = CreateCanvas( 0,0,400,400, win )
SetGadgetLayout canvas,1,1,1,1
SetGraphics CanvasGraphics(canvas)

Local g:TGadget=CreateComboBox(200,200,100,26,canvas)
SetGadgetLayout g,1,0,1,0
AddGadgetItem g,"Test"
SelectGadgetItem g,0

AddHook EmitEventHook,hook

While WaitEvent()
	Select EventID()
		Case EVENT_WINDOWCLOSE
			End
	EndSelect
Wend

Function Hook:Object(id:Int,data:Object,context:Object)
	Local event:TEvent=TEvent(data)
	If Not event Return data
	Select event.id
		Case EVENT_GADGETPAINT,EVENT_WINDOWSIZE
			SetGraphics CanvasGraphics(canvas)
			GDICls()
			gdiDrawLine(10,10,200,100)
			Return
	EndSelect
	Return data
EndFunction

Function gdiCls()
	Local pen:Int=CreatePen(0,10,$00FF0000)
	Local hwnd:Int=QueryGadget( canvas, QUERY_HWND )
	Local hdc:Int=GetDC( hwnd )
	SelectObject(hdc,pen)
	fillrect hdc,[0,0,GraphicsWidth(),GraphicsHeight()],pen
	ReleaseDC(hwnd, hdc)
	DeleteObject( pen )	
EndFunction

Function gdiDrawLine(x#,y#,x2#,y2#,draw_last_pixel=True)
	Local pen:Int=CreatePen(0,1,$0000FF00)
	Local hwnd:Int=QueryGadget( canvas, QUERY_HWND )
	Local hdc:Int=GetDC( hwnd )
	SelectObject(hdc,pen)
	
	MoveToEx(hdc,x,y,0)
	LineTo(hdc,x2,y2)
	gdiDrawText "Hello",0,0
	
	ReleaseDC(hwnd, hdc)
	DeleteObject( pen )	
EndFunction

Function gdiDrawText(text$,x,y)
	Local hwnd:Int=QueryGadget(canvas,QUERY_HWND)
	Local hdc:Int=GetDC( hwnd )
	Local size=12
	Const LOGPIXELSYS = 90
	Const DEFAULT_CHARSET = 1
	Const OUT_DEFAULT_PRECIS = 0
	Const CLIP_DEFAULT_PRECIS = 0
	Const PROOF_QUALITY = 2
	Const DEFAULT_PITCH = 0
	Local weight%=FW_NORMAL , italics%=False , underline%=False
	Local textformat=0
	Const DT_NOCLIP=$100
	Local width,height
	Local fontobject%=CreateFontA(-MulDiv(size,GetDeviceCaps(hdc,LOGPIXELSYS),72), 0, 0, 0, weight, italics, underline, False, DEFAULT_CHARSET, OUT_DEFAULT_PRECIS, CLIP_DEFAULT_PRECIS, PROOF_QUALITY, DEFAULT_PITCH, "Arial")
	SelectObject hdc,fontobject
	SetTextColor hdc, 255 | 0 Shl 8 | 0 Shl 16
	Local tf%=TextFormat|DT_NOCLIP
	If width>0 And height>0 tf=TextFormat
	SetBkMode hdc,$1
	DrawTextA hdc,text$,text.Length,[x,y,x+width,y+height],tf
EndFunction