Code archives/Graphics/Draw with 2D pan and zoom

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Draw with 2D pan and zoom by Warpy
(Posted 18 years ago)
I've wrapped the DrawLine, DrawRect, etc. functions with ones called DrawZoomLine, DrawZoomRect, etc., to take into account zooming and panning.
Setting the global variables panx# and pany# makes (panx,pany) be the centre of the screen, and setting the global var zoom# defines the scaling factor. 
Global gwidth#,gheight#

Global panx#=0,pany#=0,zoom#=1,tzoom#=zoom





Function transformpoly#[](poly#[] , px# , py# , an# , scale# = 1) 

	'px, py: translate

	'an: rotate

	'scale: duhhh thicko

	

	Local opoly#[Len(poly)]

	

	can# = Cos(an)

	san#=Sin(an)

	For n=0 To Len(poly)-1 Step 2

		x#=poly[n]*scale

		y#=poly[n+1]*scale

		opoly[n]=x*Can-y*San+px

		opoly[n+1]=x*San+y*Can+py

	Next

	Return opoly

End Function



Function zoompoly#[](poly#[])

	Local opoly#[Len(poly)]

	For n=0 To Len(poly)-1 Step 2

		opoly[n]=zoomx(poly[n])

		opoly[n+1]=zoomy(poly[n+1])

	Next

	Return opoly

End Function



Function drawrotatedline#(x1# , y1# , x2# , y2# , px# , py# , an# , scale# = 1)

	'px,py: translate

	'an: rotate

	'scale: duhhh thicko

	

	can# = Cos(an)

	san# = Sin(an)

	

	nx1#=(x1*can-y1*san)*scale+px

	ny1#=(x1*san+y1*can)*scale+py

	nx2#=(x2*can-y2*san)*scale+px

	ny2#=(x2*san+y2*can)*scale+py

	DrawLine nx1,ny1,nx2,ny2

End Function



Function drawoutline(poly#[],thickness=1)

	'DrawPoly poly

	SetLineWidth thickness

	l = Len(poly)

	For n=0 To l-3 Step 2

		x1#=poly[n]

		y1#=poly[n+1]

		x2#=poly[(n+2) Mod l]

		y2#=poly[(n+3) Mod l]

		DrawZoomLine x1,y1,x2,y2

	Next

	SetLineWidth 1

End Function





Function ZoomX#(x#)

	Return (x - panx) * zoom + gwidth / 2

End Function

Function ZoomY#(y#)

	Return (y - pany) * zoom + gheight / 2

End Function



Function UnzoomX#(x#)

	Return (x - gwidth / 2) / zoom + panx

End Function

Function UnzoomY#(y#)

	Return (y - gheight / 2) / zoom + pany

End Function



Function DrawZoomPoly(poly#[],outline=False)

	poly=poly[..]

	While i < Len(poly)

		poly[i] = zoomx(poly[i])

		poly[i + 1] = zoomy(poly[i + 1]) 

		i:+ 2

	Wend

	If outline

		ox# = poly[0]

		oy# = poly[1]

		i = 2

		While i < Len(poly)

			DrawLine ox , oy , poly[i] , poly[i + 1]

			ox = poly[i]

			oy=poly[i+1]

			i:+ 2

			DrawLine poly[0],poly[1],ox,oy

		Wend

	Else

		DrawPoly poly

	EndIf

End Function



Function DrawZoomLine(ax# , ay# , bx# , by#)

	ax = zoomx(ax)

	ay = zoomy(ay)

	bx = zoomx(bx)

	by = zoomy(by)

	DrawLine ax,ay,bx,by

End Function



Function DrawZoomRect(x# , y# , width# , height#,zoomdimensions=1,filled=1)

	x = zoomx(x)

	y = zoomy(y)

	If zoomdimensions

		width:* zoom

		height:* zoom

	EndIf

	If filled

		DrawRect x , y , width , height

	Else

		DrawLine x , y , x + width , y

		DrawLine x + width , y , x + width , y + height

		DrawLine x , y , x , y + height

		DrawLine x , y + height , x + width , y + height

	EndIf

End Function



Function DrawZoomCircle(x# , y# , radius#)

	x = zoomx(x) 

	y = zoomy(y)

	radius:* zoom

	DrawOval x - radius , y - radius , 2 * radius , 2 * radius

End Function



Function DrawZoomText(txt$ , x# , y#)

	x = ZoomX(x)

	y = ZoomY(y)

	DrawText txt , x , y

End Function



Function DrawZoomImage(image:TImage , x# , y#,width#,heighto=0)

	If heighto

		w# = width / ImageHeight(image)

	Else

		w# = width / ImageWidth(image)

	EndIf

	SetScale w*zoom , w*zoom

	DrawImage image , zoomx(x) , zoomy(y)

	SetScale 1,1

End Function





'graphics init

Function initgfx()

	Graphics gwidth , gheight

End Function