I am beginner in android studio and having headache with this if someone could help me am i missing something?.... I have problem with Constraint layout, the problem is i put some element(ImageView, Button it does not mater) in layout and constraint it to parent but when I run it in emulator it just is not showing. also it is not showing me those buttons under elements connect BaseLine and remove Constrains for that element.
"screenShot":
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<ImageView
android:id="#+id/imageView"
android:layout_width="343dp"
android:layout_height="118dp"
android:layout_marginTop="10dp"
android:scaleType="centerCrop"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_c`enter code here`onstraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
tools:srcCompat="#tools:sample/backgrounds/scenic[7]" />
</android.support.constraint.ConstraintLayout>
when i run it in emulator it just is not showing
The problem is here :
tools:srcCompat="#tools:sample/backgrounds/scenic[7]"
You need to understand what tools is, so I recommend to you to read a little bit the documentation.
Just a note of it :
It's a namespace that enable design-time features (such as which layout to show in a fragment) or compile-time behaviors (such as which shrinking mode to apply to your XML resources). When you build your app, the build tools remove these attributes so there is no effect on your APK size or runtime behavior.
Instead you have to use to show it on the emulator.
app:srcCompat="#drawable/your_drawable"
Note: remember to add : xmlns:app="http://schemas.android.com/apk/res-auto"
I found the solution.it's difrent in new Android Studio 3.4, You have to Right click on element and option Show Base Line is there now.
My problem
My card views defined through XML are not showing their proper rounded corners (they are being covered by its subviews) in Android studio preview.
Although it shows up fine after rendering in the simulator, I fear that this "glitch" may be a symptom of me doing something wrong or forgetting some critical attribute. And even if it wasn't a symptom of a deeper problem, could anyone offer any insight on how to fix this aesthetic error?
Could anyone weigh in on this?
<android.support.v7.widget.CardView
android:layout_marginTop="16dp"
android:layout_marginStart="16dp"
android:layout_marginEnd="16dp"
android:layout_marginBottom="16dp"
app:cardCornerRadius="10dp"
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v7.widget.AppCompatImageView
android:src="#color/red"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</android.support.v7.widget.CardView>
Android studio screenshot
Android emulator screenshot
The problem in the generated preview is that the content inside the CardView is not clipped to the bounds of the CardView, so the corner's you see are corners of the ImageView, which is actually clipped when you run on emulator/device.
If you really want to generate the real-like preview, you can try this workaround.
Add a stub drawable with the corner radius you want.
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<corners android:radius="20dp" />
<solid android:color="#android:color/holo_green_light" />
</shape>
Then set it as the background of the ImageView under the tools: namespace.
<ImageView android:layout_width="match_parent"
android:layout_height="match_parent"
android:src="#android:color/holo_blue_bright"
tools:src="#drawable/test" />
Android Studio supports a variety of XML attributes in the tools: namespace that enable design-time features (such as src of the ImageView to display when in preview mode).
here rounded corners show normally with your code. My test phone is Android 7.1. so I think you should clear the cache of your phone and install this app again. or maybe you should increase the value of
app:cardCornerRadius
then test it again.
Heyho mates,
currently I am learning the new layout editor of Android Studio with the new ConstraintLayout.
By the way, I hate it.
But I got the issue, that if I want to specify a layout_height with #dimen, it gets replaced with a dp value instead.
Someone else got this issue?
Android Studio version 2.2.2 & 2.2.3 same issue.
Newest gradle version.
Thanks in advance guys!
Edit :
Code example :
<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<android.support.constraint.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<ImageView
android:layout_width="wrap_content"
android:layout_height="#dimen/imageViewHeight"
app:srcCompat="#drawable/accept"
android:id="#+id/imageView"
android:layout_marginStart="16dp"
app:layout_constraintLeft_toLeftOf="parent"
android:layout_marginLeft="16dp"
android:layout_marginTop="16dp"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
</ScrollView>
Also happens outside scrollview.
Turns out this is a bug and will be fixed in Android Studio 2.3.
I think the reason behind this is, that ConstraintLayout as a WYSIWYG layout is inevitably meant to be edited/manipulated in the visual editor only.
Therefore keeping references to dimens in your dimens.xml would mean that as soon as you change something, move some elements around, these would not be relevant anymore and are hence replaced with "actual current values".
Also as mentioned in the docs:
All margins offered by the tool are factors of 8dp to help your views align to Material Design's 8dp square grid recommendations.
Following code works perfectly on Kitkat, but shadows are not visible in Lollipop.
Actually I can see shadow in Android Studio Preview, but not while running on a device/emulator. I'm using CardView for adapter of ViewPager (android.support.v4.view.ViewPager)
<android.support.v7.widget.CardView
xmlns:card_view="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
card_view:cardUseCompatPadding="true"
card_view:cardCornerRadius="4dp"
card_view:cardElevation="6dp">
Actually it also shows shadow in L version, but it is based on elevation so you can't see the shadow if card height is match parent
try adding margin to card if you want to see shadow
Found the solution. I'm able to get the shadow effect using following code.
android:background="#android:drawable/dialog_holo_dark_frame"
I am trying to make use of the elevation property in the latest Android Lollipop preview release. I set the targetSdk to 21 and the theme to Material. Next i added a background shape to a TextView and set the elevation to 8dp but the TextView is not showing any signs of a shadow. That is on a Nexus7 running the Lollipop preview. Is there anything else i have to consider?
Here is the layout:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:background="#drawable/rect"
android:text="hallo world"
android:padding="8dp"
android:elevation="8dp" />
</LinearLayout>
This is the background drawable:
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<solid android:color="#7d0073ff" />
<corners android:radius="16dp" />
</shape>
Here is the TextView:
For some reason if you set a solid color with a transparency, the elevation shadow does not show up.
In your example, I changed #7d0073ff to #0073ff and I got a shadow.
This is probably a bug, as in their documentation it gives a similar example using a translucent background color.
After going through the docs again, I finally found the solution.
Just add card_view:cardUseCompatPadding="true" to your CardView and shadows will appear on Lollipop devices.
What happens is, the content area in a CardView take different sizes on pre-lollipop and lollipop devices. So in lollipop devices the shadow is actually covered by the card so its not visible. By adding this attribute the content area remains the same across all devices and the shadow becomes visible.
My xml code is like :
<android.support.v7.widget.CardView
android:id="#+id/media_card_view"
android:layout_width="match_parent"
android:layout_height="130dp"
card_view:cardBackgroundColor="#android:color/white"
card_view:cardElevation="2sp"
card_view:cardUseCompatPadding="true"
>
...
</android.support.v7.widget.CardView>
ADDING android:elevation shadow to an ImageView:
android:clipToPadding="false"
+
android:outlineProvider="bounds"
+
android:elevation="2dp"
I was also having this problem, and as it turns out, you need to turn hardware acceleration on in the android manifest
<application
...
android:hardwareAccelerated="true">
be aware, if you have the following line in the manifest then shadows wont show:
android:hardwareAccelerated="false"
TL;DR
Check your card: (or whatever word you use) namespace declaration and make sure it matches this: xmlns:card="http://schemas.android.com/apk/res-auto"
I know there are a few answers here already, but I wanted to add mine as it wasn't included in these current suggestions. In order to get the shadows working on both KitKat and Marshmallow, (only emulators I tried, I'm sure it works in between) I added the following xml attributes to my card:
card:cardElevation="25dp"
card:cardUseCompatPadding="true"
After banging my head against my desk for why that wasn't working, trying to set the background color of the card to something completely opaque, enabling hardware acceleration in the manifest, and even praying, I checked the namespace declarations in my file. To my horror, I saw that the card xml namespace had been assigned to the following:
xmlns:card="http://schemas.android.com/tools"
After fixing that namespace declaration, I ran my dummy app again and let out a sigh of relief as shadows were finally being shown as expected.
Here is proof in case you're a doubter like me. And please Google, Android, whoever: Make shadows great again. They shouldn't be this difficult.
Here is the entire file that created the layout pictured below:
<?xml version="1.0" encoding="utf-8"?>
<!--MAKE SURE YOU HAVE THE RIGHT XML NAMESPACE ASSIGNED-->
<!--TO WHATEVER WORD YOU PUT IN FRONT OF THE CARD-->
<!--XML ATTRIBUTES. IN THIS CASE, MINE IS card-->
<android.support.percent.PercentRelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:card="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#607D8B"
android:fitsSystemWindows="true"
tools:context="com.mlustig.playground.MainActivity">
<android.support.v7.widget.CardView
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_centerInParent="true"
app:layout_aspectRatio="66%"
app:layout_heightPercent="75%"
card:cardElevation="25dp"
card:cardUseCompatPadding="true" />
</android.support.percent.PercentRelativeLayout>
Yes, I know. It's annoying that you can't simply copy and paste this layout and run it because it has PercentRelativeLayout in it, but I left it there on purpose. You should definitely check it out. Super powerful, very useful. Nice nice nice. Hope this helped.
As noted earlier, this is an open bug in Android : if the background drawable uses a solid color with transparency, then the shadow won't be shown.
To work around the issue, display the background in its own separate view and set the alpha on that view. Wrap the background view and the TextView in a RelativeLayout to place the background directly under the TextView and use android:layout_alignLeft, android:layout_alignBottom etc to make it the same size. They need to be at the same elevation, and the background must appear before the TextView in the xml so it is drawn under it.
<RelativeLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingLeft="40dp"
android:paddingRight="40dp"
android:paddingTop="20dp"
android:paddingBottom="20dp"
android:clipToPadding="false"
android:background="#ffffff">
<View
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="#+id/text_view"
android:layout_alignRight="#id/text_view"
android:layout_alignBottom="#id/text_view"
android:layout_alignTop="#id/text_view"
android:background="#drawable/rect"
android:alpha="0.5"
android:elevation="8dp"/>
<TextView
android:id="#id/text_view"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="hallo world"
android:textColor="#ffffff"
android:padding="8dp"
android:elevation="8dp" />
</RelativeLayout>
The drawable is the same as yours but without transparency:
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle">
<solid android:color="#0073ff" />
<corners android:radius="16dp" />
</shape>
Result:
A few notable points:
You must ensure that the enclosing RelativeLayout is large enough to display the shadow. If you just set its dimensions to wrap_content without padding, the shadow will be clipped to the layout's bounds. As explained in this question, you can use padding and set android:cipToPadding="false" to make it large enough for the shadow. You might not need as much padding in this case, I haven't experimented with that.
In this case we need to use a separate view for the background because if we had set the alpha directly on the TextView then the text would have been affected as well. Depending on your use case you might not need a separate view and enclosing layout and could just just have one view, with alpha set on the view and no transparency in the drawable.
Try using : app:cardElevation="4dp"
Try adding margin to the CardView.