Antony’s Mobile Blog

Some of you may have seen this problem when trying to uninstall Screenshot for Symbian OS (S60 3rd). You cannot uninstall the application at all. The installer always says “Unable to delete file”.

What is going on here? It seems there is a bug on some of S60 3rd devices. For some unknown reasons, the installer cannot remove backup information file. It happens when Screenshot for Symbian OS (S60 3rd) is installed on the memory card. If it is installed on the phone memory, it won’t happen.

How to solve the problem?

• Connect your device to the PC in “Mass storage” mode.
• Browse to the memory card to \private\20000555 folder.
• Delete a file called backup_registration.xml.
• Now you should be able to uninstall Screenshot for Symbian OS (S60 3rd).

I am working to solve this bug on the latest version, i.e. 2.80. Please stay tune.

The beta version of Screenshot for Symbian OS (S60 3rd) is now available on SourceForge.net. Please feel free to download and test it.

Note that this new version is available for S60 3rd Edition only. Furthermore, the binary is unsigned. You need to sign it yourself using developer’s certificate. You cannot use self-signed certificate as this application requires accessing sensitive API. If you don’t know how to sign using developer’s certificate, please see my blog posting, Signing S60 3rd Applications with Your Certificate. Sorry for the inconvenience. I cannot do anything better because of the limitation of Symbian Signed.

What’s new in this version? New shortcuts!!! Yes, finally I have added two new shortcuts in this version:

• Camera key
• C (Backspace) key

You can use your Camera key to capture screenshot. I haven’t tested this feature on all phones that have Camera key. However, I have tested it on Nokia N73 and it works fine.

Why do I introduce new shortcuts? The answer is simple. Nokia has removed Edit key, which is used on Screenshot for Symbian OS to capture screenshot. Since some newer phones do not have Edit key any more, we definitely need another key.

Recently I had a strange problem with my Nokia E61 device. The device needs to be charged every day. I was quite sure that the battery was still okay. The device was relatively new, about 1 month old. Before it happened, I could use my device for 3 - 4 days without charging.

I thought it must be from one of the applications that I have installed recently. I suspected one of the applications that I have just installed. Then, I decided to uninstall it (I am not going to disclose the name of the application). What happened after that? The problem with my battery was solved. I can use my device normally.

Why did it happen? Apparently, the application installed a server that runs in the background. I am not sure what the server is doing, but it empties the battery very fast.

As a mobile developer, how can we avoid this? Forum Nokia has a good paper, S60 Platform Effective Power and Resource Management. I won’t repeat everything here; just highlight some of the important points:

• Continuous timers, ticking too frequently (for example, more than once every five seconds), can adversely affect power consumption.
• If an application is moved to the background, it should, where appropriate, be paused and timers should be stopped.
• The backlight shall not be kept on without a good reason. It is turned off after a short period of inactivity is to conserve power; therefore overriding the system defaults should only be done if there is a compelling reason.
• Communication technologies, such as Bluetooth and WiFi, should be used carefully, as there is always some drain on the battery when any network interface is active.
• The camera has to be powered off when it is no longer used. Even if the camera is not being actively used, it is still consuming power if it is not powered off.

Please, always remember that mobile device has limited battery power. It is not the same as desktop world where the power is “unlimited”.