Develop Reference

ImageView android:cropToPadding, what it actually does?

I went through the documentation for the tag android:cropToPadding here, it only says:
If true, the image will be cropped to fit within its padding.
May be a boolean value, such as "true" or "false".
which is quite confusing for me to understand.
I have an ImageView inside my app, (which was developed by someone else):
<ImageView
android:layout_width="125dp"
android:layout_height="125dp"
android:layout_gravity="center"
android:maxWidth="100dp"
android:padding="20dp" />
This ImageView had cropToPadding tag inside it, there were like 20 ImageView on main screen, which all had this tag inside them, and the app was obviously taking time to load as there were more Images, but then removing images was not an option, so I was finding stuff that was useless and trying to optimize the layout when I came across this tag.
Removing this tag did no change to the images that were shown inside the ImageView, but there must be some reason that every image contained this tag. So I started finding what this tag did, and documentation wasn't much clear as to why this tag should be used.
Can someone please explain what this tag does to the Image? I found out not many resources, all that I found was "This crops the Image to padding", what does that mean! I know what padding is, I know what cropping is, but what does "Sets whether this ImageView will crop to padding" mean?

This is a complex question to answer, because we have to drill into some nitty-gritty details of how ImageView actually draws the image to the screen.
The first thing to establish is that there are two rectangles that affect ImageView drawing behavior. The first is the rectangle defined by the ImageView's dimensions ignoring padding. The second is the rectangle defined by the ImageView's dimensions considering padding. (Obviously, if padding is 0, then these will be the same.)
The next thing to establish is that ImageViews all have a scale type that defines how the image is stretched and/or cropped when the image's intrinsic size doesn't match the size of the rectangle that it is being drawn into.
The default scale type is FIT_CENTER, which scales the image down to fit within the view bounds + padding (that is, the image will be drawn inside the rectangle that considers padding). Since the image is being drawn inside the padding rectangle, android:cropToPadding has no effect.
However, other scale types work differently. The scale type CENTER simply positions the image in the middle of the view, but performs no scaling (so the image will be clipped if it is bigger than the view). In this case, android:cropToPadding defines whether the image will be clipped by only the view's bounds or also clipped by the view's padding.
A picture is worth a thousand words:
This picture shows the same 72x72 image inside a 72x72 view with 16dp padding and CENTER scale type. The left ImageView has android:cropToPadding="false" and the right ImageView has android:cropToPadding="true".

Android ImageView ScaleType and item height

Things looked quite simple first but in the end the result is not good.
I have an image which has a width larger than screen's width. So I need to scale it down in my imageview. I looked over the ScaleType options and tried them all but none is ok. First "center" only displays the image centered on the layout, no scaling done. "fitCenter" scales the image to fit in my layout but has a major drawback: the height of the item remains as it would have the large image in it. Take a look at the second screen in the attached image. How can I force the list item, to reduce its height to wrap both the text and the image ?

Use the scaletype which seems best to you ( I guess you like what you see with fitCenter). The additional thing that you must do is
android:adjustViewBounds="true"
in your ImageView.
or you could go with FitXY but sometimes the result is not exactly what you want.

use android:scaleType="fitXY"

Could you use FitXY?
This would work if you knew the size of the area you were putting the image into.
CentreInside may also work, I've used this to scale down images, but I think it depends if you've control of the size of the bounding layout element.

You either need to set android:height = "wrap_content" on your outer container, or set static height of TextBox and give ImageView android:weight = "1" so that the ImageView takes remaining space in container.

android ImageView/ RelativeLayout increase size by Dragging the corner of ImageView/ RelativeLayout

i want to increase the size of ImageView/ RelativeLayout by Dragging the corner of ImageView/ RelativeLayout. But no difference in width and set it bottom. I set it by using android:layout_alignParentBottom="true" and also set image in imageview. but how to drag i don't know. Is there is any option available in Android? can any one suggest some solution for this? pls help me

you can use onTouch() for the ImageView.
Once it is touched show a small image at the edge of the imageview. And on touching that image and moving(onTouch() gives the pixel positions until you touch it) you will be getting the pixel positions. Based on that you can set the height and width of the imageview.

Android: Actual position of an ImageView

Is there a way to tell precisely where an image is placed on the parent?
ImageView layout returns some frame around the actual image.
One can see the difference when working with images that are very different from the screen proportions. For example a square image on a long screen.
Worse: devices like Edge have their bottom bar that consumes parts of the screen and affect the layouting calculations. In that case it's hard to do reverse calculations.

I can't test this now, but try something like the following, I believe this should do what you need:
ImageView iv = (ImageView)findViewById(R.id.image_view);
Rect rect = iv.getDrawable().getRect();
int xOffset = rect.left;
int yOffset = rect.top;
That should give you the exact pixel location of the top left corner. I'm pretty sure that the top-left is considered the origin...test this and see if it gives you the expected results, though.

What is android:layout_gravity="clip_vertical" exactly

The property android:layout_gravity="clip_vertical|horizontal" does the following as mentioned in the SDK documentation:
Additional option that can be set to
have the top and/or bottom edges of
the child clipped to its container's
bounds. The clip will be based on the
vertical gravity: a top gravity will
clip the bottom edge, a bottom gravity
will clip the top edge, and neither
will clip both edges.
But I can't see anything of this in my applications,
so what is the purpose of this property exactly ?
thanks

Short version:
clip_horizontal and clip_vertical apply to the measurements of the view itself, before any contents (such as the image in a BitmapDrawable) are rendered.
Long version:
I've run into some similar confusion over clip_horizontal and clip_vertical. (In my case, it was related to android:gravity for a BitmapDrawable, but it's similar enough to be applicable.)
From the documentation I thought that something like android:gravity="top|left|clip_vertical" on a bitmap would cause the image's top left corner to be positioned at the view's top left corner, and that, if the bitmap was taller than the view, it would be "clipped" at the bottom edge of the view. In other words, show only as much of the bitmap that the view is tall enough to reveal; do not stretch the bitmap, but instead only show whatever will fit, letting the rest extend below the bottom edge.
However, the opposite happened: when I set clip_vertical, a large bitmap was squished vertically to fit within the height of the view.
After examining the applyDisplay() method in platform/frameworks/core/java/android/view/Gravity.java, I realized my mistake:
It isn't the bitmap image that was going to be clipped, but the view -- the actual size of the container the image is ultimately rendered into.
Setting clip_vertical in my case didn't mean "clip the image at the bottom edge," it meant "clip the BitmapDrawable's view itself so its height matches the height of its parent container"...which then caused the image to be "squished" as it filled that shorter height.
So, the important thing to remember with android:gravity and android:layout_gravity is that clip_horizontal and clip_vertical apply to the measurements of the view itself, before any contents (such as my BitmapDrawable) are rendered.

Maybe there is no effect because horizontal is not defined in the android:layout_gravity. clip_vertical is just an additional property that is used in addition to a base property.

Flag to clip the edges of the object to its container along the horizontal axis.
check this