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
Related
Using Android views, I've stumbled upon a recurring issue and thought it was about time to ask if anyone has a solution.
I have a parent ConstraintLayout, the blue one in the picture.
This layout contains two views: a green view constrained to the left of the parent, and the red view constrained to the center of the parent.
Both red view and green view are text views, and their actual size may vary depending on the language.
My wish is for the red view to always stay centered, so to grow symmetrically left and right until it reaches the green view. At its maximum width, the red view will touch the green view on the left, and there will be empty space on the right of the same width as the width of the green view.
Problem is that I can't find a way using regular XML layouts to do it. I can think of several hacks to do it, but thinking there should be a clean way.
Any idea?
Not sure but just an idea, maybe you can try to add two more barriers. One at the end of the green box at left. And one for it's symmetric. Because you said
and there will be empty space on the right of the same width as the
width of the green view
So with these two barriers you can mark the borders of the red one.
And you can set the constraints of the red to the barriers, and with 0dp width may work. Let us know :)
If you are certain that the width of the red view will not ever need to go to two lines because it runs out of space (maybe it is truncated, marque'd or ellipsised) then you would simply constrain the start and end of the red view to a guideline set in the center of the ConstraintLayout.
However, if you can't guarantee that the red view will never need two lines then you are stuck with a hack. The simplest hack would be to create an invisible view on the right that has the same width as the green view. (It could simply be another TextView with the same text and characteristics.) You would then constrain the start of the red view to the end of the green view and the end to the start of the invisible view.
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".
I am using a ConstraintLayout with two views inside. An ImageView that varies in size depending on the image loaded and a View which acts as a custom made dropshadow for the Image. What I've been doing so far is adding 8dp padding to the ImageView and then aligning all of the edges of the View to the ImageViews, thereby making the View stick out 8dp underneath the ImageView.
Now for several reasons I don't want to keep the padding on the ImageView but I still want to achieve the same effect. So basically I would like to align the Left of the View to 8dp left of the Left of the ImageView (and the same for every other edge, right, top, bottom).
Is there any way to achieve this?
Thanks in advance!
I´ve been having problems with this too, it seems ConstraintLayout does not support negative margins yet: https://code.google.com/p/android/issues/detail?id=235306.
In my case, I want a 20dp negative margin to a set of overlapping images on a header image. So far, I'm positioning an empty TextView below the guideline my header image is connected to, with a 20dp top margin and aligning my overlapping image views to that.
I Need to shift an ImageView, which is a direct child of a LinearLayout, a bit to the left.
What happens: The View is shifted (can see the "bounding box" is shifted, with android layout manager) but the drawable keeps in the same place.
Also the drawable is cut on the right side, if I set margin low enough.
Why is this? Any advice?
Clarification: I have to shift the Image to the left. That means a bit ouside of the bounds of the containing layout.
It seems elements are always clipped when they get outside of parent's bounds (also with clipChildren=false).
A solution is to create an additional container-layout for everything besides of the item to be shifted. And then shift the container-layout in the opposite direction.
For example, to shift -10dip:
<Original container ...>
<Item to be shifted/>
<New container with margin 10dip>
<Previous content of Original container ... />
</New container with margin 10dip>
</Original container>
If your container have enough padding you can set its clipToPadding to false and use negative margin!
Why are you using negative margin? use a positive a bit more to the opposite side of the ImageView to the direction you want to shift the image, i.e. if you want to shift the image to the left, use more positive margin to the right.
I have a RelativeLayout filling the screen and a couple of ImageView positioned on it using LayoutParams margins. These ImageView are animated in different ways, and in one case I want an image to "fly in" to the screen from the right.
Unfortunately, if I set leftMargin for that ImageView greater than the width of the screen, it does not appear (or appears cropped if it partially visible at the start of animation).
I tried setting width and height of RelativeLayout to be bigger than screen size - it works, but only partially: if the image is positioned completely off-screen, it does not work, and if the image is partially visible, it is not cropped, but that works only for right and bottom sides.
So, my question is this: how to position several ImageViews on and off the screen so that I can animate them using Animation?
In the end, I used a trick: I combined AnimationDrawable and view animation. I did the following (assuming that the animation has to run T milliseconds):
Position that ImageView on-screen.
Set as its background an AnimationDrawable with following frames:
empty Drawable: 1ms,
normal Drawable: Tms.
Change view's animation to this:
jump to off-screen position (translation with duration=1ms),
do normal animation.
This is probably a good place to start looking for those who would use Fixpoint's solution.
Android — How to position View off-screen?