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Hello, my name is ton_malaka. I'm newbie on Qt Designer. I use Qt Designer 3.3.8 on openSuSE 10.3.

I try to implement Canny Edge Detection with Qt Designer. First of all, I must try to load image from file location on Main Window Form. I've been tried to follow a example code (showimage.cpp) on Qt Assistant, but that's example just have been built with Qt (not Qt Designer).

I attach the code that I modified on attachments. The code still have error. The error message is :

QPaintDevice: Must construct a QApplication before a QPaintDevice

If you don't mind, can you help me to solve the problem ? I want modify the code like this :
1. The application just use a MainWindow with MenuBar.
2. Load the image file and show it on the "PixmapLabel". I gave the name with "PixmapLabelIn".
3. After load image successfull on "PixmapLabelIn", next process is detect the edge image on "PixmapLabelIn" with Canny Edge Detection method. The result is shown on "PixmapLabelOut".

I say thank you so much for your help.

ton_malaka