I have some large images that I would like to display to the user. I want them to have the ability to zoom in. I am currently using TouchImageView, and it is working, however, the quality/resolution of the image does not change as I zoom in.
I noticed that some of the Gallery apps appear to be doing this. They load the entire image, at some sampling rate so that it can be displayed without an out of memory. Then as you zoom in, it appears that the quality of the image is getting increased.
Is there example code/library for functionality similar to this?
If you have 1 source image and are zooming in on it you aren't going to magically create resolution where there was none previously. The answer is to either create multiple r-sets or multiple images with different resolutions and load/zoom/scale dynamically, OR downsample the image yourself when displaying it zoomed out at a lower resolution.
For example, consider thumbnail images. They are created as a small sample of the original image. If you zoomed in on that thumbnail it would look horrible. You calculate the best r-set image based on the zoom level and coordinates of your client view.
I think my preference would be to preprocess the large images and create different levels of resolution as I mentioned in the first paragraph. Then as the user zooms in you load a different image. This is similar to how Google maps works for example.
I hope this helps.
I suggest that you use the view provided by Dave Morrissey:
Subsampling Scale Image View
An excerpt from the source:
A custom ImageView for Android with pinch to zoom and subsampled tiles
to support large images. While zooming in, the low resolution, full
size base layer is overlaid with smaller tiles in the best resolution
for the current scale, and tiles are loaded and discarded during
panning to avoid holding too much bitmap data in memory.
Related
I want to display set of images in horizontal viewpager.
I have used the "chrisbanes PhotoView" library.
Everything is working well but after zooming any image the quality of images getting lose even for high resolution images.
The Size of image is 1440*2560
Please let me know, if I am missing something
Thanks you in advanced
I'm taking whole screenshot of a WebView and display the bitmap on an ImageView. The bitmap can be 7 screen height. (E.g. 1440x14000 px)
I'm frequently face with
OutOfMemoryError.
I've seen this
This says that load a scaled down version into memory but I don't want to lose image quality. There are the same approaches on the web.
Is there any way to handle OutOfMemoryError without loading scaled down version?
The bitmap can be 7 screen height. (E.g. 1440x14000 px)
Note that this means that the user cannot see the whole image at once at full resolution.
I'm frequently face with OutOfMemoryError
On most devices, you will have a very difficult time loading an image that large, as you cannot get a single contiguous memory block that big.
This says that load a scaled down version into memory but I don't want to lose image quality
To some extent, you do not have much of a choice. If you want the user to see the full extent of the picture at once, the image has to be scaled to fit the screen.
Is there any way to handle OutOfMemoryError without loading scaled down version?
There are ImageView replacements that offer pan and zoom. Some of those, such as this one, handle loading in pieces of the image at a time, with whatever scaling is necessary for the current zoom level, to make it more likely that you will be able to show the user the entire image.
It is not a solution, of course, but I'm also not familiar with your exact needs, so maybe this may help you a little - you can try to play with bitmap options during decoding. Try to use Bitmap.Config.inPreferredConfig as RGB_565 - this will reduce size of your bitmap twice comparing to default ARGB_8888. But, of course, if you use complex images in your web page this may reduce their quality.
I have a image (resolution 8328x3987). And I want to load that image in my app with zoom controls for better viewing.
As we all know that Android will not load large images directly on device (like in my example). So Android system suggested us to scale down the image to load large images. I have tried this and scale my image upto four times as:
options.inSampleSize = 4;
Using this way my image will displayed on screen, but when I zoom-in the image then this image becomes unreadable (text becomes very blurry), this is because, maybe I scale down the image before showing?
But when I see that image in to device's default gallery app (Android Lollipop, Photos app), then this image looks like a mapview (only visible portion is readable and outside is blurry, and when I move the image then visible area becomes readable) when I zoomed in at max level. So my questions is:
Is Android lollipop added any new way to load large files that looks like mapview?
If not, then do you have an idea how that apps do this or any example?
Reducing the sample size of an image that big will not work at all.(very very bad resolution and memory consumption)
I suggest you to divide image to tiles and recycle the views just like map views do.
This library may help you. Or you can do it your way too.
I need to display a large image (3000x2000) with zoom and swipe gestures. Image is a map, so the key is performance and fluid motion.
Is there any control or library that does this well that I can use?
you can use
https://github.com/davemorrissey/subsampling-scale-image-view
which is able to load very large resolution images and also support scaling by gestures.
I am writing a Android app which need to display some high quality picture(took from professional DSLR). The problem is it can't be display from gallery.
I choose a photo in Gallery first. The target picture is 2464*1632 JPEG, roughly 4.5M;
Then I just need to compress it to 800*600 and display it in imageview:
image.setImageBitmap(this.bmp);
Thing is that I have tested other image I downloaded form internet(really low quality), and it works without any problem. Can anybody tell me why it can't be displayed? I will be really appericiated
Large images are tricky to handle due to limited memory. You have several choices:
Use a WebView (this allows you to have pinch and zoom functionality to make use of those extra pixels
Decode the image down to the size of the display and then put it in an ImageView using BitmapOpts http://developer.android.com/reference/android/graphics/BitmapFactory.Options.html and changing inSampleSize. It seems you may be having difficulty with that, so consider using createScaledBitmap which just needs the dest width and height.