I am drawing a custom view in my application which basically takes arguments(XML) as the text to display and then keeps on rotating it infinitely.
While I was making this control I had a few doubts which I want to ask:
I have made 2 of my stylable attributes which I have declared in the attrs.xml file. These attributes are to set the width and the width of the circle used in my control. These values I would use in the ondraw method and the onmeasure method. I ran my program by declaring just these but there was an error which asked me to put android:width and android:height attributes. My question is why would I need those if I am already using my custom attributes to define the height and the width of my view
I am coding on a mac. Now when I was making my attrs.xml file, to get the autocomplete list which we usually get by ctrl+space was not showing up. Why is that. For e.g., i wanted to know what values can I give the format attribute of my custom attribute that like I am demostrating in the following:
<attr name ="somename" format="value I wanted to find out through autocomplete"> . Why is the autocomplete not popping up? It does pop up when I am making a.java file.
In my ondraw() method I wanted to draw a circle. Now for this I would require the co-ordinates of the center of the circle. So what I do is put 0, 0. But this is not correct. I want the circle to be at the center of the parent view it is in. So if my view is in a hierarchy I want it to respect that. I want to give the co-ordinates relative to the parent view. What is happeining right now is that it is being drawn at the top left corner of my screen. This is what I don't want. What do I do to achieve this?
why would I need those if I am already using my custom attributes to define the height and the width of my view?
This is because Android needs to know how and where to put your view in the layout. You can implement your view to make use of your custom height/width requirements by overriding View.onMeasure() to return your own size parameters. You can then just set android:layout_width="wrap_content" android:layout_height="wrap_content" in your layout file.
Why is the autocomplete not popping up? It does pop up when I am making a.java file.
Autocomplete and autodoc implementation for Android xml files is shaky at best, so it's not really surprising that it doesn't work. I'm not aware of a fix and AFAIK it's an IDE bug.
In my ondraw() method I wanted to draw
a circle. Now for this I would require
the co-ordinates of the center of the
circle. So what I do is put 0, 0. But
this is not correct. I want the circle
to be at the center of the parent view
it is in. So if my view is in a
hierarchy I want it to respect that. I
want to give the co-ordinates relative
to the parent view. What is happeining
right now is that it is being drawn at
the top left corner of my screen. This
is what I don't want. What do I do to
achieve this?
If you implemented onMeasure() correctly, the coordinates relative to parent should be taken care of already. To get the center of your view use the following code:
void onDraw(Canvas canvas)
{
int centerX = this.getWidth() / 2;
int centerY = this.getHeight()) / 2;
//..draw code here
}
Edit
Here's an example with source code that should help: http://mindtherobot.com/blog/272/android-custom-ui-making-a-vintage-thermometer/
Related
Within Android, I'm trying to move a TextView from outside the parents bounds into view, but the contents never shows up, or remains clipped if it was partially within the bounds already.
Initial situation at start
Situation after animation
(Below this is another view, that was completely out of bounds and isn't drawn either)
I have 4 TextViews below each other in a custom Object extending RelativeLayout. Based on a percentage the top 2 should move outside it's bounds and the bottom 2 should move in (from the bottom).
I use the following code to update the properties of each TextView. In this class each variable **positionY* is filled with their initial position from the layout-xml. effect is percentage between 0 & 1. The animation works, but the views aren't drawn again.
public class ActionBarTitleView extends RelativeLayout {
public void updateTransition(float effect) {
float height = getHeight();
titleView1.setY(title1positionY - height*effect);
detailView1.setY(detail1positionY - height*effect);
titleView2.setY(title2positionY - height*effect);
detailView2.setY(detail2positionY - height*effect);
invalidate();
}
}
What I tried
After some researching I found a few hints what the issue might be, but so far none of the tried options had any effect. Below is a list of things I've found on SO and tried.
Calling invalidate() on the RelativeLayout - No effect.
Invalditing the TextViews - No effect.
clipChildren = false for the RelativeLayout - No effect.
setWillNotDraw = false for the RelativeLayout - No effect. (onDraw is being called)
I haven't tried to solve this with a ScrollView, but I don't want to really, cause that adds another layer in the hierachy for something pretty small.
I thought I understood the drawing logic, but perhaps I'm missing something, so I hope someone might be able to point me in the right direction.
What I ended up doing (September 3rd)
Since no real solution was offered, I tried again and came to the following "fix". I set both second labels to Visibility.GONE, but within the original bounds of the container view. Then when I start the animation, I set their correct values, then move them outside the bounds and finally setting Visiblity.VISIBLE. When the animation progresses the labels roll into view as supposed to. So a fix to the issue, but no real explanation why the TextViews aren't drawn again...
I'm trying to place a small image on the top of a big one in a custom dialog.
I want the small one to be placed in a different place depending on a variable, which I called "pos". It contains a int value from 0 to 100, meaning percentage of the dialog width.
If pos = 0, I want to place the image in the left margin of the big one, if pos = 30 it should be placed in the 30% of the screen, starting from the left.
If pos = 50 I want it to able placed right in the middle, being 100 the maximum value for it and placing it in the right margin.
I include a draft to explain myself a bit better.
I tried with RelativeLayout.LayoutParams but I never get expected output.
Perhaps a simpler strategy is to extend ImageView, then create a custom image using Canvas commands in the onDraw method that draw the bitmap appropriately on the x axis with a background set to match your layout.
You can determine the width of the custom dialog in the the onMeasure method of your custom ImageView, so the returned bitmap (including empty background) can be the correct width, and the position of the smaller bitmap can be correctly apportioned.
Once you've created the class, which will take just a few minutes, you can add it to your XML layout with something like:
<com.domain.yourapp.YourCustomerImageView
android:id="#+id/bitmap_graph"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="3dp"/>
Background
To learn animations, I'm creating a Towers of Hanoi type of game. My main goal is to animate the movement of the block from one tower to another. I've got the following layout
|------RelativeLayout------|
|-Linear-|-Linear-|-Linear-|
|-Block1-|-----------------|
|-Block2-|-----------------|
|-Block3-|-----------------|
|--------------------------|
ID| Tower1 | Tower2 | Tower3 |
I've set the XML attribute android:clipChildren="false" on every ViewGroup.
For example, if I tried to animate the movement of Block1 from Tower1 to Tower2 using Block1.animate().setDuration(3000).translationX(1000). As the layout is right now, Block1 will animate within Tower1, but Block1 gets clipped the second it leaves Tower1.
I've played with changing the z-order by adding the blocks last in the XML file. It doesn't reliably work, though.
To ensure animations don't get clipped, I've decided to add a copy of the Block1 (named copyBlock) to the root RelativeLayout, position copyBlock on top of Block1, and animate it to the destination Tower2 (defined in coordinates)
To get the destination coordinates, I was planning on adding an invisible copyBlock to Tower2, then get the coordinates. This way, I can take advantage of the LinearLayout's layout functions to account for matters such as padding, gravity, etc. Otherwise, I'll have to get the position of Tower2, calculate the topmost block, adjust the coordinates of Block1 so that it'll be on top of the topmost block and centered.
But, I'm pretty sure this way is hacky, and there's a better way
Questions
How can I get the above destination coordinates without having to add an invisible view to the destination tower? Is there a way to ask for a "prelayout" without having to add View to the layout?
Do you have any explanations for why the animation gets clipped? Is there a better way to approach this rather than adding a new view to the root RelativeLayout ViewGroup?
Ok,
1- You can't overcome the clipping issue, because you are trying to move the child beyond the parent dimensions, unless you are moving within the same parent.
2- Use FrameLayout instead of RelativeLayout so you can control views margins correctly;
3- You can get the destination coordinates by knowing the height of the root layout and width, its seems the towers width are equal, so the (total width/3) will give the cell width then get the X coordinate, and the (total height - cell height ) will give the Y coordinate of the tower ( assuming you have the tower hight)
I am attempting to experiment in creating my own Views by subclassing "View." I want to simulate a new Button type class that will be drawn with the onDraw where I simply draw a rectangle from the canvas being passed in. I then add that custom View into the layout XML file, but I cannot control its size. For example, I set the width to "fill_parent" and the height to "wrap_content" but I don't know what the content of my View is. (BTW, the LinearLayout that my view is in is oriented to "vertical")
Can anyone give me some pointers in how to control the size of my View? For example, how does my custom view know what parameters were set in the XML file?
Android cannot detect the contents of your Canvas, so it assumes the contents are 0x0.
To do what you're looking for, you have to override onLayout or onMeasure (onLayout is specified by Android developers as a way to lay out children instead). You will also need a way to calculate the size of your contents.
First, start with a member variable called Point mSize = new Point(0, 0);. In a method other than onDraw, but called just as often, you will want to replace this with the size of your contents. If you draw a circle that has a radius of 25, do: mSize.x = 50; mSize.y = 50;.
Next, I'll introduce you to this answer (for onMeasure). It shows how to set the size of an item based on its parent's dimensions (divided by 2, in this case). Then, you can pull the size from mSize.x and mSize.y and apply those dimensions.
Finally, calling invalidate() after you measure your new mSize should force the View to lay itself out again, and adjust to your new parameters. This is the one part I'm unsure of in this regard.
NB: Also, you could call setLayoutParams using a fixed width and height once you calculate the size of your Canvas contents. Not sure of the performance implications for this, though.
Hi am developing android application with graph view. i got an open source graph application to show my values with graph lines. Here i am face problem while adding view. i am not able to add my custom view properly with relative layout.
Here i attached my custom view alignment .
In that image point 1. is my result while trying to add mt custom view.
But i need to add that as shown in 2. part.
my custom view is like shown in 3 .part
I am getting that line starting x,y and ending x,y values. I tried with that values but i got result as 2 part. Please provide me any suggestion
Or let me know is there any alignments required.
My code is like
View View v1=infalter.inflate(R.layout.bullet, null);
RelativeLayout.LayoutParams rl=new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
rl.setMargins(myX,myY, 0, 0);
mRelative.addView(v1,rl);
You are setting the margins for the x, y point that you got, so the view will start at x, y at the top left, which is what you got. You want to align the bottom center of the view, so you need to calculate this.
So:
top= y - viewHeight
left= x - viewWidht/2
I don't know what your values of myX and myY are, but it looks like you're trying to align the top right with your x and y margins applied to the right and top respectively. If this is indeed the case, you're probably better off with something like this:
rl.setMargins(0, 0, myX, myY);
rl.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);
The arguments to setMargins go in order as follows: left, top, right, bottom. If your myX value is the right margin and you want the object right aligned, the code above will specify these two preferences.
While playing with a relative layout to provide a help screen overlay I ran into weird things and had to set margins relative to the bottom right and not upper left. So I had a rule to align the view at the bottom and the right + the margins.
Maybe that will help.