ways of displaying a .png-file

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Hi all!

I have the following question:

I have some .png files, which i want to Display in a CWnd in a given Rect.

I found some code, which reads the BGRA values of one .png-File into an array and then creates a CBitmap out of this array and then displays the CBitmap.

Is there any disadvantage of doing this? Is there a better way of doing it?

Is there a ShowPng function somewhere?:-)

thanks for your help!

Posted 18-Feb-15 4:00am

Member 10781325

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3 solutions

Solution 1

Try examining the code on the following CodeProject articles (the first one in particular is very popular). Compare and contrast.

CxImage[^]

A user draw button that supports PNG files with transparency, for Visual C++ 6.0 and VS2005[^]

Loading JPG & PNG resources using GDI+[^]

Posted 18-Feb-15 4:13am

CHill60

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Member 10781325 18-Feb-15 11:35am

thx for you anwser!

Solution 3

With GDI+ is simple matter, see "Loading and Displaying Bitmaps"[^] at MSDN.
That's together with GdiplusStartup/GdiplusShutdown (sample usage here: "Drawing a Line"[^] at MSDN) is all you need.

Posted 18-Feb-15 5:07am

CPallini

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Member 10781325 18-Feb-15 11:35am

thx for hint!

Sergey Alexandrovich Kryukov 18-Feb-15 11:58am

5ed.
—SA

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This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

nv3 · Accepted Answer · 2015-02-18T04:28:00

Solution 2

No, there is no such function in pure C++ and MFC. What you are doing is absolutely correct. First convert the PNG into a memory representation and then form a bitmap out of it. Even if there was a library function in MFC, it had to do it in the same way.

If you are using that image often, you should think about caching the memory representation so that you don't have to read the file from disk multiple times.

Posted 18-Feb-15 4:28am

nv3

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Member 10781325 18-Feb-15 11:34am

thank's very much! That's exactly what i wanted to know!:-)

btw: by caching the memory you mean allocating memory with e.g. new or malloc?
or is there even a better place to hold it?

thx alot!

nv3 18-Feb-15 11:51am

Exactly. I would allocate space by new for those images that are used frequently in you program and delete those at the end of the program run. You might want to write a little helper class for that purpose that not only takes care of the automated delete, put also of the conversion from png-format to bitmap. It might even take usage counts of your images and for instance keep an image in memory if it is used three times or more.

CHill60 18-Feb-15 12:34pm

Good point on the caching. 5

nv3 18-Feb-15 12:53pm

Thanks!

Member 10781325 19-Feb-15 2:25am

Ok, thanks alot for your help! I will solve the Problem with a helper class:-)

ways of displaying a .png-file

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ways of displaying a .png-file

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