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Home » U++ Library support » Draw, Display, Images, Bitmaps, Icons » image drawn in Paint(Draw &w) does not stay when refereshed

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Re: image drawn in Paint(Draw &w) does not stay when refereshed [message #12952 is a reply to message #12943]

Fri, 30 November 2007 10:33

mrjt is currently offline

mrjt
Messages: 705
Registered: March 2007
Location: London

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You are correct in that it is a performance feature. ImageBuffers are only designed to be used for image processing, then converted to Images for storage. When you do Image = ImageBuffer, instead of using memcpy to duplicate the pixel data the ownership of the memory is just transfered.

The problem occurred in this case because the parameters for Draw::DrawImage are all something like:

void DrawImage(const Rect& r, const Image& img);

so that if you pass in an ImageBuffer it is implicitly converted to a temporary Image (because it has operator Image), loosing ownership of the pixel data. The Image is passed to DrawImage and then destroyed, deleting the pixel data. Viola! The Image no longer exists Smile

Smile

Glad I could help.

[Updated on: Fri, 30 November 2007 10:36]

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[Message index]

		image drawn in Paint(Draw &w) does not stay when refereshed By: amit on Wed, 28 November 2007 13:10
		Re: image drawn in Paint(Draw &w) does not stay when refereshed By: nixnixnix on Wed, 28 November 2007 23:43
		Re: image drawn in Paint(Draw &w) does not stay when refereshed By: mrjt on Thu, 29 November 2007 14:16
		Re: image drawn in Paint(Draw &w) does not stay when refereshed By: amit on Fri, 30 November 2007 00:28
		Re: image drawn in Paint(Draw &w) does not stay when refereshed By: mrjt on Fri, 30 November 2007 10:33
		Re: image drawn in Paint(Draw &w) does not stay when refereshed By: amit on Fri, 30 November 2007 15:31
		Re: image drawn in Paint(Draw &w) does not stay when refereshed By: amit on Fri, 30 November 2007 00:19

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