Re: GDI+ Image sizing

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I'm not familiar with memDC but the process of double buffering in GDI+ is
similar to GDI where you use CreateCompatibleDC/CreateCompatibleBitmap.

In GDI+ you create an offscreen (compatible) bitmap using a graphics object
created based on your view. Example:
Graphics graphics(GetSafeHwnd())
Bitmap* pbmp = new Bitmap(cx, cy, &graphics)

You can then create your offscreen graphics object as follows:
Graphics* pg = Graphics::FromImage(pbmp);


"Mark F." <replytogroup@xxxxxxxx> wrote in message
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"Bogdan" <nobody@xxxxxxxxxx> wrote in message
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Few things that you might take into account:

1) Use double buffering to avoid ugly flashing. I.e. create an
offscreen
bitmap, create an offscreen graphics using the offscreen bitmap, load
the
image to another bitmap, use the offscreen graphics to draw the loaded
bitmap to the offscreen bitmap, and then draw to the offscreen bitmap
to
screen (i.e. in your OnDraw()). You should also take into account
clipping
region to avoid drawing of the whole image.


Like a MemDC that you manipulate then draw. ?

2) No need to release HDC (at least not in your example). When
graphics
object goes out of scope it'll cleanup after itself.


Ok.

3) And finally, answer to your question...
In order to scale the image you need to use DrawImage that takes both
source
and destination rectangles. In order to avoid cropping make sure that
the
source rectangle matches image's size.
The code should look something like the following:
graphics.DrawImage(&image, destRect, x, y, cx, cy, UnitPixel)
(x = 0, y = 0, cx = image width, cy = image height)


One of the overloaded functions for DrawImage.

Thanks!





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