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Increasing TextSize of TextView and then Decreasing It Doesn't return to normal height of view element

I'm fairly new to Android and would never have gotten as far as I am without this forum.
Here's my problem:
Am using a simple LinearLayout with an ImageView vertically positioned above a TextView. My goal is to display a series of screens with a images on the top and a short text caption on the bottom. The text is wrappable and the image should be scaled to fill the remaining available vertical space.
Everything works fine if I keep the text font size constant (I use .setTextSize(35) normally). The problem is that when I display an empty image, I choose to enlarge the text (.setTextSize(120)). That works OK..but then when I next display a subsequent image and revert to the text size to 35, there's a large unfilled gap between the bottom of the image and the top of the now smaller text area.
What appears to be happening is that using the larger text size once has somehow permanently increased the minimum height of the TextView. I've tried clearing the TextView (.setText("")..changing the size to very small (.setTextSize(12)...and endlessly fiddling with the LinearLayout parameters (weight, gravity)...to no avail. Any thoughts on how to fix this would be most welcome.
<ImageView android:id="#+id/img" android:layout_width="match_parent"
android:layout_height="0dp" android:layout_weight="1.0" android:layout_gravity="fill_vertical" android:contentDescription="#string/desc" />
<TextView android:id="#+id/caption" android:layout_width="match_parent"
android:layout_height="wrap_content" android:layout_weight="0" android:layout_gravity="bottom"
android:gravity="center"/>

***Solution discovered after posting: Turns out that this is a known bug since Android 3.1. See Android:TextView height doesn't change after shrinking the font size.
Of the recommended solutions/workarounds listed there, the one that I'm liking is that every time you set text do:
setText("I am a Text",TextView.BufferType.SPANNABLE);
Or after resizing your text just do: setText(getText(),TextView.BufferType.SPANNABLE);

Whether this answer helps much or not, I think android:layout_weight="0" is redundant. A weight statement (say android:layout_weight="1") is also more usually accompanied by a android:layout_height="0dp" or android:layout_width="0dp", depending on the orientation of the containing LinearLayout.

Is there a way to perfectly center text?

I wanted to know if it was possible to create a custom TextView that centers text perfectly, no matter what the font is. That's my major issue right now, but I'm also wondering if it's possible to set the specific height using pixels so that the height would also be consistent.
This picture shows how different fonts are sized and centered. The longest black line in the picture is the middle of the white space. Letters in the picture are the same in every way except for the fonts. The text size is the same (text.setTextSize(TypedValue.COMPLEX_UNIT_PX, 450);), and they're all centered. I hope someone knows the answer to these questions! If you need any code from my app, just ask. Thanks!
EDIT: I am aware of android:gravity="veritcal_center", but that only works to an extent. What you see above is that implemented in the textview, but each font has a different center of gravity, so android:gravity="veritcal_center" wouldn't really make all of these center perfectly along the screen. I'm looking for a way to create a custom textView that somehow measures the height of text and centers it with those parameters. A suggestion by #vmironov in the comments works, but only if the textview has one character. I have not been able to mess around with his code, but I will when I get a chance and I'll post here if I find anything. Thanks!

A simple way to achieve what you want is to use following code:
<LinearLayout
android:layout_width="100dp"
android:layout_height="20dp"
android:gravity="center">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="18sp"
android:text="#string/your_text" />
</LinearLayout>
set the height and width values of LinearLayout fixed if you want to set the text to be alligned in center within constant height and width

Set the gravity of the view to "center_vertical". Something like :
android:gravity="center_vertical"

You should be able to center your text by applying a gravity attribute to the containing TextView.
In XML you would assign an attribute to your TextView, which would look like this:
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:textSize="18sp"
android:textAppearance="?android:attr/textAppearanceMedium"
android:text="#string/some_text" />
If you do want to specify a particular size for your text, it is strongly suggested you use SP (Scaled Pixels) as your unit of measurement, and not Pixels. You could also set an Appearance Attribute for your TextView to control the size, which is also shown in the code example.

Why does the background of TextView change it's size?

I put a background to a TextView. I expect the background will adjust to my existing layout parameters and will not change the size of my TextView. So if I have width and height set to wrap_content, I would expect the background also wraps content (and scales down). But no, what I get is a bigger TextView
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="a"
android:textColor="#ffffff"
android:textSize="20sp"
android:background="#drawable/large_bg"
/>
I get
...
How do I make that the background also obeys wrap_content?
I mean, this looks like the background would be treated as content...

This is because when we set background than textView or any Widget adjusts itself according to that background.Until and Unless we have not mentioned the Fix Height and Width[Its Poor approach]

Custom typeface text size varies greatly between fonts

I have a few TextViews in my app where I use a custom typeface. I have given the view centered layout gravity to get the text centered in its parent layout. It looks fine in the previewer with the Sans font, but when I change the typeface, the result looks like the text is shifted down, like this:
Compared to this:
Here is the xml for that element:
<FrameLayout android:id="#+id/Turn_ScoreA_Frame" android:padding="5dp" android:background="#color/teamA_secondary" android:layout_margin="5dp" android:layout_gravity="center" android:layout_height="50dp" android:layout_width="110dp">
<android.view.View android:id="#+id/Turn_ScoreABG" android:background="#color/teamA_primary" android:layout_height="fill_parent" android:layout_width="fill_parent"></android.view.View>
<TextView android:id="#+id/Turn_ScoreA" android:includeFontPadding="false" android:text="5" android:layout_gravity="center" android:layout_height="wrap_content" android:layout_width="wrap_content" android:textSize="32dp"></TextView>
</FrameLayout>
This also occurs when I use fill_parent for layout_width and height of the text view, with text gravity center. I set the custom Typeface in the OnCreate of the view in which this layout is used, just by using TextView.SetTypeface.
Does anyone know what could be causing this? I'm having trouble tracking anything down on this.
As a note, I've worked around this on several views by setting the margin_bottom to -10dp or so, but I'd like to remove that, and I can't get that hack to work on confined views like this one, anyways.
The font is Anton, by the way.
EDIT: This is definitely the result of the text being too large for its container. The thing is, Sans fits just fine, and the new font would fit but its measured size is too large. What I'm hoping is to find a way to get the text to remain at its current visible size and fit in the center of the container, in such a way that doesn't feel too hacky =)

You need to add:
android:includeFontPadding="false"

You have 3 options
Decrease the text size
Increase the height of FrameLayout
Change the font which can fit correctly
you cannot change the property of the font, it is designed is such a way that it has empty space above it, which doesn't fit in your given android:layout_height="50dp" when android:textSize="32dp"

LinearLayout not wrapping image

I've got an ImageView that I've wrapped in a LinearLayout. The LinearLayout has a background drawable which is basically a border, so the effect is that my image has a border around it.
However no matter what I try, I get a big chunk of empty space underneath my image, which is pushing the lower border of my LinearLayout down. I want the LinearLayout to wrap tightly around the image with no padding (except for the 1sp that I specify)
This is how I've defined the two
<LinearLayout
a:orientation="vertical" a:layout_width="wrap_content"
a:layout_height="wrap_content"
a:gravity="top"
a:padding="1sp"
a:background="#drawable/heading_background">
<ImageView a:src="#drawable/photo"
a:layout_width="wrap_content"
a:layout_height="wrap_content"
a:scaleType="fitStart"/>
</LinearLayout>
Can anyone tell me what I'm doing wrong?
Thanks

I don't know how big your drawable is, but if it's really big* then your imageview tries to size itself to that format (wrap_content), but also is restricted by the actual space it's got. What happens exactly is a bit fuzzy for me, but with pictures that get resized (even when keeping aspect ratio like your fitStart does) I had to add the adjustviewbounds attribute: http://developer.android.com/reference/android/widget/ImageView.html#attr_android:adjustViewBounds
It resizes the ImageView back to the format I'd think it would allready have, but in my case it was needed to get it to actually "wrap" the content....
*And I don't mean enormous, just "big enough so it has to be scaled down a bit)

You will want to set a:adjustViewBounds as true in your ImageView. This ensures that the layout will wrap tightly around the image.

android:adjustViewBounds="true"