Image zooming

[xandaz]

  Hi. I dont suppose that someone could show me how to do zooming for a graphics app? Thanks ...
  I aint got the slightest idea on how to. I dont think it's with stretch.

[jj2007]

  Hi. I dont suppose that someone could show me how to do zooming for a graphics app? Thanks ...
  I aint got the slightest idea on how to. I dont think it's with stretch.

StretchBlit is the way to go for raster graphics. For vector stuff, check the ViewPortXX family.

ClientToScreen
CombineTransform
DPtoLP
GetCurrentPositionEx
GetGraphicsMode
GetMapMode
GetViewportExtEx
GetViewportOrgEx
GetWindowExtEx
GetWindowOrgEx
GetWorldTransform
LPtoDP
MapWindowPoints
ModifyWorldTransform
OffsetViewportOrgEx
OffsetWindowOrgEx
ScaleViewportExtEx
ScaleWindowExtEx
ScreenToClient
SetGraphicsMode
SetMapMode
SetViewportExtEx
SetViewportOrgEx
SetWindowExtEx
SetWindowOrgEx
SetWorldTransform

[xandaz]

   i've been trying that also.... I don't see how SetWorldTransform works. I've tried in a rotation operation but it didn't work. I know i must set graphis to GM_ADVANCED but still i don't know what i'm doing wrong. Thanks jj

[qWord]

Probably StretchBlit() is the better choose for you. However, in the attachment a example using SetWorldTransform().

[dedndave]

very nice qWord   :U
i can use that for schematics and other technical drawings   :bg

[jj2007]

Nice indeed, but limited to scaling raster graphics. For better quality, you need vector graphics, i.e.

      invoke LineTo,ebx,0,100*scalefactor

and similar. Instead of scalefactor, you can use ViewPortxx.
Another option is to stick to raster graphics and work with a huge compatible bitmap from which you can downscale to the required size.
If it's for anything that goes on printed matter, the editor will explain to you what "300 DPI minimum resolution" means :bg

[ToutEnMasm]

The griddemo (masm32\\examples\bcraven\griddemo)  show a method to do this.

[xandaz]

   How does one make a Screen dc smalled than the client area? I was trying the SetWindow/Viewport and the OffsetView/Window fuctions but nothing changed. can someone show me how? Showld i process the mouse messages so i draw only to a confined space? Thanks in advanced