Android imageview set image from bitmap


  1. Working with ImageViews and Bitmaps in Android Application Development
  2. Examining ImageView
  3. How to work with Bitmap in Android |

We can achieve this using an extended ResizableImageView class as described in the post. An ImageView can display an image differently based on the scaleType provided. Above we discussed the fitXY type along with adjustViewBounds to match the aspect ratio of the drawable.

Working with ImageViews and Bitmaps in Android Application Development

The following is a list of all the most common types:. The fitXY scale type allows you to set the exact size of the image in your layout. However, be mindful of potential distortions of the image due to scaling.

Android Development Tutorial - Transfer Bitmap between Activities

Refer to this ImageView ScaleType visual guide for additional reference. Since Android has so many different screen sizes, resolutions and densities, there is a powerful system for selecting the correct image asset for the correct device. There are specific drawable folders for each device density category including: Notice that every app has folders for image drawables such as drawable-mdpi which is for "medium dots per inch". To create alternative bitmap drawables for different densities, you should follow the 3: Refer to the chart below:.

This means that if you generate a x for mdpi 1x baseline , then you should generate the same resource in x for hdpi 1. See these density guidelines for additional details. This handy utility allows us to select a resources directory, choose an extra high density image and the tool will automatically generate the corresponding lower size images for us and place the subfolders inside the generated res-drawable directory within the actual res folder in your project as the example shows below in "Project" view left and the default "Android" view right:. Refer to the screens support reference for a more detailed look at supporting a wide range of devices.

Also check out the iconography guide for more details. Starting with Android 4. Mipmaps are most commonly used for application icons such as the launcher icon. To learn more about the benefits of mipmaps be sure to check out the mipmapping for drawables post.

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For example, an xxxhdpi app icon might be used on the launcher for an xxhdpi device. Review this post about preparing for the Nexus 6 which explains in more detail. If we need to resize a Bitmap, we can call the [createScaledBitmap] http: Bitmap , int, int, boolean ] method to resize any bitmap to our desired width and height:.

You often want to resize a bitmap but preserve the aspect ratio using a BitmapScaler utility class with code like this:. In other cases, you may want to determine the device height or width in order to resize the image accordingly. Copy this DeviceDimensionsHelper.

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  • Android: How to load an image from a file and set on an ImageView |
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Check out this source for more information on how to scale a bitmap based instead on relative device width and height. While there are workarounds to transfer this data after the image has been copied, there are current limitations. If you need this info or wish to upload it to some site, you should send the original file and not the downsampled version. Android has now vector drawables support, which allows SVG files to be imported to a specific format.

Jump to Section. Edit Page Page History. Overview Typically, images are displayed using the built-in image view. Otherwise, you will consume extra memory, experience sluggish scrolling, or encounter out of memory issues if you render a lot of pictures. In addition to placeholder and error , there is also other configuration options such as noFade and noPlaceholder. Placeholder Note: Placeholders and error images are not resized and must be fairly small images.

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Open up your static placeholder or error images in your drawable folders and make sure that the dimensions of the images are relatively small i. If not, resize those static images first and save them back to the project. We can resize an image with respect to the aspect ratio using resize and specifying 0 for the other dimension as outlined here:. We can combine resizing with certain transforms to make the image appear differently.

Examining ImageView

For example, we can do a center cropping with:. Transform options include centerCrop Crops an image inside of the bounds , centerInside Centers an image inside of the bounds , fit Attempt to resize the image to fit exactly into the target. See this post for more details.

If an image or set of images aren't loading, make sure to check the Android monitor log in Android Studio. There's a good chance you might see an java. OutOfMemoryError "Failed to allocate a [ This is quite common and means that you are loading one or more large images that have not been properly resized.

How to work with Bitmap in Android |

First, you have to find which image s being loaded are likely causing this error. For any given Picasso call, we can fix this by one or more of the following approaches:. Applying these tips to all of your Picasso image loads should resolve any out of memory issues. As a fallback, you might want to open up your AndroidManifest. Note that this is not generally a good idea, but can be used temporarily to trigger less out of memory errors.

If you experience errors loading images, you can attach a listener to the Builder object to print the stack trace. If we wish to readjust the ImageView size after the image has been retrieved, we first define a Target object that governs how the Bitmap is handled:. The Target object must be stored as a member field or method and cannot be an anonymous class otherwise this won't work as expected. The reason is that Picasso accepts this parameter as a weak memory reference.

Because anonymous classes are eligible for garbage collection when there are no more references, the network request to fetch the image may finish after this anonymous class has already been reclaimed. See this Stack Overflow discussion for more details.