Montag, 15. Februar 2016

AppInventor Tutorial: How to Develop a Wallpaper App?

Where can I find images for a wallpaper app?

Important is, that you will use free images without copyright. There are two sources, which we can really recommend:

These websites contain thousands of free images. Even attribution is not necessary, but of course, if you want you can give some credits or you donate a coffee on pixabay for a photographer. Never use images from the simple Google(TM) image search. They are mostly copyright protected.

But in the Google(TM) image search you customize the settings in this way, that you are only searching for free images for commercial use. Please have a look on all the possibilities. You also can change the image in an image manipulation program like Gimp, but not all the images. This is a special setting in Google(TM) image search.

In most Wallpaper Apps I only can select a part of the image, is it the same with your code?

Unfortunately, yes. We tried a lot of possibilities how to choose the whole image for a wallpaper app, but also in our code you only can select a part of the wallpaper image. We did not find a solution. But it is possible. If you will find a solution to select the whole in image in landscape and portrait please let us know. Thanks!

My photographies from the websites you recommended have a low contrast, how I can change it?

There is the free image manipulation program Gimp, which you can download on 

With this program you can a lot of image manipulation do like in Photoshop(TM). You have to use curves function for to change the brightness and the contrast. If your image is blurry you can change this in the filter menu. There are lots of filter for to make your image much better. Try them out. We have a German version of Gimp and so I do not know the correct names of the filters and functions in Gimp in English.

You can also use the HDR plugin from the Gimp plugin library. You find this plugins on the Gimp website (see above). The HDR plugin is useful for a lot of images, but not every image will look good with this effect. Try it out and make your experiences.

How to save an image on the SD card?

In this tutorial you can also see how to save an image on the SD card. You do this with a canvas and the canvas background image. The canvas blocks have also a save function. You will see it in the video.

Let's watch the wallpaper video tutorial!

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