I have to complete a task in which I have to create a 5x5 box matrix. When user click any of the box, highlight that box a number inside. Can someone guide me how to do this?
I have to use Table Layout or some thing else.
Following is the box.
Square Board
I created this board using onMeasure event.
So you can create custom view which extends old one and override this event for creating square view or layout.
And then you can easily add this view to TableRow inside TableLayout.
If you need I can put all needed code or if you have another question let me know.
#Override
public void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int h = this.getMeasuredHeight();
int w = this.getMeasuredWidth();
int curSquareDim = Math.min(w, h);
// Inside a viewholder or other grid element,
// with dynamically added content that is not in the XML,
// height may be 0.
// In that case, use the other dimension.
if (curSquareDim == 0)
curSquareDim = Math.max(w, h);
if(curSquareDim < squareDim)
{
squareDim = curSquareDim;
}
Log.d("MyApp", "h "+h+"w "+w+"squareDim "+squareDim);
setMeasuredDimension(squareDim, squareDim);
}
Related
I've created a custom view which creates a bitmap and then in the onDraw() method I display an objects data.
Also in the XML file I have made the view horizontally scrollable.
My question is after I've drawn all the data on the canvas from the onDraw() method, how can I increase the view's size to show all the data.
i.e I want the view to scroll just enough until the data has finished and not any more.
I do have the y-coordinate for the last item displayed.
Currently I'm setting the width of the view to 800dp in the XML file, but for some object's it cut's off some of the data.
Thanks
You can override the onMeasure() method to adjust the size of your View:
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int parentViewWidth = MeasureSpec.getSize(widthMeasureSpec);
int parentViewHeight = MeasureSpec.getSize(heightMeasureSpec);
// ... take into account the parent's size as needed ...
super.onMeasure(
MeasureSpec.makeMeasureSpec(newWidth, MeasureSpec.EXACTLY),
MeasureSpec.makeMeasureSpec(newHeight, MeasureSpec.EXACTLY));
}
What's the correct way of overriding onMeasure()? I've seen various approaches. For example, Professional Android Development uses MeasureSpec to calculate the dimensions, then ends with a call to setMeasuredDimension(). For example:
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
int parentWidth = MeasureSpec.getSize(widthMeasureSpec);
int parentHeight = MeasureSpec.getSize(heightMeasureSpec);
this.setMeasuredDimension(parentWidth/2, parentHeight);
}
On the other hand, as per this post, the "correct" way is to use MeasureSpec, call setMeasuredDimensions(), followed by a call to setLayoutParams(), and ending with a call to super.onMeasure(). For example:
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
int parentWidth = MeasureSpec.getSize(widthMeasureSpec);
int parentHeight = MeasureSpec.getSize(heightMeasureSpec);
this.setMeasuredDimension(parentWidth/2, parentHeight);
this.setLayoutParams(new *ParentLayoutType*.LayoutParams(parentWidth/2,parentHeight));
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
So which is the right way? Neither approach has worked 100% for me.
I guess really what I'm asking is does anyone know of a tutorial that explains onMeasure(), layout, dimensions of child views etc.?
The other solutions are not comprehensive. They may work in some cases, and are a good place to start, but they may are not guaranteed to work.
When onMeasure gets called you may or may not have the rights to change the size. The values that are passed to your onMeasure (widthMeasureSpec, heightMeasureSpec) contain information about what your child view is allowed to do. Currently there are three values:
MeasureSpec.UNSPECIFIED - You can be as big as you'd like
MeasureSpec.AT_MOST - As big as you want (up to the spec size), This is parentWidth in your example.
MeasureSpec.EXACTLY - No choice. Parent has chosen.
This is done so that Android can make multiple passes to find the right size for each item, see here for more details.
If you do not follow these rules, your approach is not guaranteed to work.
For example if you want to check if you're allowed to change the size at all you can do the following:
final int widthSpecMode = MeasureSpec.getMode(widthMeasureSpec);
final int heightSpecMode = MeasureSpec.getMode(heightMeasureSpec);
boolean resizeWidth = widthSpecMode != MeasureSpec.EXACTLY;
boolean resizeHeight = heightSpecMode != MeasureSpec.EXACTLY;
Using this information you will know whether you can modify the values as in your code. Or if you are required to do something different. A quick and easy way to resolve your desired size is to use one of the following methods:
int resolveSizeAndState (int size, int measureSpec, int childMeasuredState)
int resolveSize (int size, int measureSpec)
While the first is only available on Honeycomb, the second is available on all versions.
Note: You may find that resizeWidth or resizeHeight are always false. I found this to be the case if I was requesting MATCH_PARENT. I was able to fix this by requesting WRAP_CONTENT on my parent layout and then during the UNSPECIFIED phase requesting a size of Integer.MAX_VALUE. Doing so gives you the max size your parent allows on the next pass through onMeasure.
The documentation is the authority on this matter: http://developer.android.com/guide/topics/ui/how-android-draws.html and http://developer.android.com/guide/topics/ui/custom-components.html
To summarize: at the end of your overridden onMeasure method you should call setMeasuredDimension.
You should not call super.onMeasure after calling setMeasuredDimension, that will just erase whatever you set. In some situations you might want to call the super.onMeasure first and then modify the results by calling setMeasuredDimension.
Don't call setLayoutParams in onMeasure. Layout happens in a second pass after measuring.
I think it depends on the parent which you are overriding.
For example, if you are extending a ViewGroup (like FrameLayout), when you have measured the size, you should call like below
super.onMeasure(MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY),
MeasureSpec.makeMeasureSpec(height, MeasureSpec.EXACTLY));
because you may want to ViewGroup to do rest work (do some stuffs on child view)
If you are extending a View (like ImageView), you can just call this.setMeasuredDimension(width, height);, because the parent class will just do something like you have done usually.
In a word, if you want some features your parent class offers free you should call super.onMeasure() (pass MeasureSpec.EXACTLY mode measure spec usually), otherwise call this.setMeasuredDimension(width, height); is enough.
If changing the views size inside of onMeasure all you need is the setMeasuredDimension call. If you are changing the size outside of onMeasure you need to call setLayoutParams. For instance changing the size of a text view when the text is changed.
Depends on the control you are using. The instructions in the documentation work for some controls (TextView, Button, ...), but not for others (LinearLayout, ...). The way that worked very well for me was to call the super once I am done. Based on the article in the below link.
http://humptydevelopers.blogspot.in/2013/05/android-view-overriding-onmeasure.html
here is how I solved the problem:
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
....
setMeasuredDimension( measuredWidth, measuredHeight );
widthMeasureSpec = MeasureSpec.makeMeasureSpec( measuredWidth, MeasureSpec.EXACTLY );
heightMeasureSpec = MeasureSpec.makeMeasureSpec( measuredHeight, MeasureSpec.EXACTLY);
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
Moreover it was necessary for the ViewPager component
I guess, setLayoutParams and recalculating the measurements is a workaround to resize the child views correctly, as this is usually done in the derived class's onMeasure.
However, this rarely works correct (for whatever reason...), better invoke measureChildren (when deriving a ViewGroup) or try something similar when necessary.
you can take this piece of code as an example of onMeasure()::
public class MyLayerLayout extends RelativeLayout {
public MyLayerLayout(Context context) {
super(context);
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int parentWidth = MeasureSpec.getSize(widthMeasureSpec);
int parentHeight = MeasureSpec.getSize(heightMeasureSpec);
int currentChildCount = getChildCount();
for (int i = 0; i < currentChildCount; i++) {
View currentChild = getChildAt(i);
//code to find information
int widthPercent = currentChildInfo.getWidth();
int heightPercent = currentChildInfo.getHeight();
//considering we will pass height & width as percentage
int myWidth = (int) Math.round(parentWidth * (widthPercent / 100.0));
int myHeight = (int) Math.round(parentHeight * (heightPercent / 100.0));
//Considering we need to set horizontal & vertical position of the view in parent
AlignmentTraitValue vAlign = currentChildInfo.getVerticalLocation() != null ? currentChildlayerInfo.getVerticalLocation() : currentChildAlignmentTraitValue.TOP;
AlignmentTraitValue hAlign = currentChildInfo.getHorizontalLocation() != null ? currentChildlayerInfo.getHorizontalLocation() : currentChildAlignmentTraitValue.LEFT;
int topPadding = 0;
int leftPadding = 0;
if (vAlign.equals(currentChildAlignmentTraitValue.CENTER)) {
topPadding = (parentHeight - myHeight) / 2;
} else if (vAlign.equals(currentChildAlignmentTraitValue.BOTTOM)) {
topPadding = parentHeight - myHeight;
}
if (hAlign.equals(currentChildAlignmentTraitValue.CENTER)) {
leftPadding = (parentWidth - myWidth) / 2;
} else if (hAlign.equals(currentChildAlignmentTraitValue.RIGHT)) {
leftPadding = parentWidth - myWidth;
}
LayoutParams myLayoutParams = new LayoutParams(myWidth, myHeight);
currentChildLayoutParams.setMargins(leftPadding, topPadding, 0, 0);
currentChild.setLayoutParams(myLayoutParams);
}
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
}
I wanted to create a custom LinearLayout (and later a custom ImageButton) that could take percentage values for both dimensions of size based on its parent's size regardless of the parent type (Relative or Linear). I was following this post: How to size an Android view based on its parent's dimensions, and it was very helpful, but I have a problem that those answers don't address.
When I place my Custom LinearLayout inside another LinearLayout, everything works as expected. My Custom LinearLayout covers the expected space (80% of the parent's width in the example below).
However if I place it inside a RelativeLayout, my screen always shows empty, I am not sure why this happens.
Here is my class:
public class ButtonPanel extends LinearLayout {
public ButtonPanel(Context context, AttributeSet attrs) {
super(context, attrs);
}
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int parentWidth = MeasureSpec.getSize(widthMeasureSpec);
int parentHeight = MeasureSpec.getSize(heightMeasureSpec);
int widthMode = MeasureSpec.getMode(widthMeasureSpec);
int heightMode = MeasureSpec.getMode(heightMeasureSpec);
int newWidth = (int) Math.ceil(parentWidth * 0.8);
this.setMeasuredDimension(newWidth, parentHeight);
this.setLayoutParams(new RelativeLayout.LayoutParams(newWidth,parentHeight));
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
}
And here is my testing layout for the activity.
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<com.android.tests.views.ButtonPanel
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#drawable/inner_panel"
android:gravity="center_horizontal"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true">
</com.android.tests.views.ButtonPanel>
</RelativeLayout>
In my activity all I do is set the Content View to the above layout.
(Incidentally, does anybody now how I could get the type of the parent dynamically for setting the new LayoutParameters? Above you'll see the parent type (RelativeLayout) hard-coded into the Custom View onMeasure function)
Thanks in advance for any help!
Is this exposed to be a problem?
this.setLayoutParams(new RelativeLayout.LayoutParams(newWidth,parentHeight)); // <-- a RelativeLayout params?
In the onMeasure function you could use something like this to know what class is the parent of the view.
this.getParent().getClass().getName()
This should also work
a instanceof B
or
B.class.isAssignableFrom(a.getClass())
When using "instanceof", you need to know the class of "B" at compile time. When using "isAssignableFrom" it can be dynamic and change during runtime.
If you are not compfortable with string comparison, you could also use enums.
Turns out my two inquiries in this post were more related than expected.
I realized that by setting my view's LayoutParams to a completely new instance, I was overwriting the layout positioning information needed by the Relative Layout to position my view.
By 'zeroing out' that information, my view has the right dimensions, but the layout doesn't know where to place it, so it simply doesn't.
The following code for the new onMeasure shows how just directly modifying the height and width of the LayoutParams already attached to my view I avoid both overwriting the layout position information and having to create new LayoutParams based on the parent's type.
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int specWidth = MeasureSpec.getSize(widthMeasureSpec);
int specHeight = MeasureSpec.getSize(heightMeasureSpec);
int newWidth = (int) Math.ceil(parentWidth * 0.8);
int newHeight = (int) Math.ceil(parentHeight * 0.8);
this.setMeasuredDimension(newWidth, newHeight);
this.getLayoutParams().height = newHeight;
this.getLayoutParams().width = newWidth;
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
Now, I'll be honest and say that this code is still not bug-free. Bringing the activity to the foreground and background multiple times constantly reduces the size of this custom view. The 0.8 reduction factor gets applied over and over each time the activity is brought up (I suspect the setting of the LayoutParams has to do with it, it might actually be unnecessary, but I haven't has time to test).
BUT, this still answered the question concerning this post, namely, why was my view not appearing at all despite having the right dimensions.
I have an array of Buttons (different sizes etc) which are configured from and xml file (written by me). I want to add those buttons on the bottom of the screen and when the row of buttons ends, just start a new row and add buttons until the array ends. I want to mention that I do not set the size of the buttons in the xml file so I don't know the size from the beginning. Another problem is that after or before I add the button to the layout programatically with layout.addView(button) the method button.getWidth() returns 0 because the UI elements are not drawn in the UI yet. I also overrided the onLayout() method but still wasn't able to redraw the buttons.
If you have any ideas, please help.
Thanks
Well you could make the button take the same size using weight property. In that case, decide how many buttons you need in a row and use a for loop to do it accordingly. If you need the width you could use something like
Add this to your onCreate
ViewTreeObserver vto = layout.getViewTreeObserver();
vto.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
You should be able to get the width and height
over here.
layout.getViewTreeObserver().removeGlobalOnLayoutListener(this);
}
});
This is how I did it. I overrided the onMeasure() method of the layout containing the buttons.
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int specSize = MeasureSpec.getSize(widthMeasureSpec);
this.width = specSize;
specSize = MeasureSpec.getSize(heightMeasureSpec);
this.height = specSize;
//now you can use the sizes before the layout is drawn
this.webview.setLayoutParams(new FrameLayout.LayoutParams(LayoutParams.FILL_PARENT,this.height - this.menuBarHeight) );
//don't forget for the parent method!
//but at the end, after the measures are done
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
I've written a custom view which I'd like to ensure is viewable on any screen size.
I've overridden the onMeasure:
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int parentWidth = MeasureSpec.getSize(widthMeasureSpec);
int parentHeight = MeasureSpec.getSize(heightMeasureSpec);
this.setMeasuredDimension(parentWidth, parentHeight);
}
and this seems to work fine when the view is smaller than the screen. Sometimes, though, the custom view is larger than the screen, and I'm planning for smaller screen sizes, so I wrapped the custom view in a ScrollView but now the parentHeight in the onMeasure comes out as 0.
I've changed the superclass of the custom view from View to ScrollView, hoping for an easy win of inheriting the scrolling functionality, but this hasn't happened so I'm left with trying to find a way of getting the ScrollView functionality to work with my custom view, or writing my own scrolling functionality.
Has anyone any advice? I've seen this post on Large Image Scrolling Using Low Level Touch Events and was going to copy some of that functionality if I'm forced to write my own, but would appreciate a nudge in the right direction either way.
Turns out the answer was simple. I left the ScrollView in and changed my onMeasure. The thing to note about it is that although Android would supply the width, it wouldn't supply me with a height, which was initially confusing. To just get the view to fill the available space I grabbed the visible rect of the parent view. Code in full (hopefully it'll help someone else who is having the same problem):
#Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int parentWidth = MeasureSpec.getSize(widthMeasureSpec);
int parentHeight;
if(isLandscape()) {
Rect r = new Rect();
((ScrollView)getParent()).getGlobalVisibleRect(r);
parentHeight = r.bottom - r.top;
} else {
parentHeight = (int) Util.getViewHeight();
}
this.setMeasuredDimension(parentWidth, parentHeight);
}