我在这里解决了我以前的问题：
无法以编程方式使用 setGravity 垂直设置重力。这是一个Android错误或功能吗？
基本上我有一个自定义按钮，里面有一个 AutoResizeTextView。我想为按钮设置动画并将文本视图垂直居中。我通过测量和使用 layout 和 onLayout 方法解决了这个问题。它在大多数设备上都能正常工作。
但在某些设备上，AutoResizeTextView 内的文本上方有一个额外的填充，无论如何我都无法删除。表现不佳的设备是 Kindle Fire 和三星 Galaxy Tab2 7。Nook Color、摩托罗拉 Xoom 和我的摩托罗拉 Defy (CyanogenMod 10) 上的布局还可以。
我创建了一个示例项目来演示该问题。它包括 3 个类和一个布局文件：
活动主.xml：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<herrbert74.artvsample.MyButton
android:id="@+id/textView1"
android:layout_width="240dp"
android:layout_height="60dp"
android:background="@android:color/black"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:text="@string/hello_world" />
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="@+id/textView1"
android:layout_alignRight="@+id/textView1"
android:layout_marginBottom="46dp"
android:layout_marginRight="54dp"
android:text="Button" />
</RelativeLayout>
修改 AutoResizeTextView.java：
package herrbert74.artvsample;
import android.content.Context;
import android.graphics.Canvas;
import android.text.Layout.Alignment;
import android.text.StaticLayout;
import android.text.TextPaint;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.widget.TextView;
/**
* Text view that auto adjusts text size to fit within the view. If the text
* size equals the minimum text size and still does not fit, append with an
* ellipsis.
*
* @author Chase Colburn
* @since Apr 4, 2011
*/
public class AutoResizeTextView extends TextView {
// Minimum text size for this text view
public static final float MIN_TEXT_SIZE = 10;
// Interface for resize notifications
public interface OnTextResizeListener {
public void onTextResize(TextView textView, float oldSize, float newSize);
}
// Off screen canvas for text size rendering
private static final Canvas sTextResizeCanvas = new Canvas();
// Our ellipse string
private static final String mEllipsis = "...";
// Registered resize listener
private OnTextResizeListener mTextResizeListener;
// Flag for text and/or size changes to force a resize
private boolean mNeedsResize = false;
// Text size that is set from code. This acts as a starting point for
// resizing
private float mTextSize;
// Temporary upper bounds on the starting text size
private float mMaxTextSize = 0;
// Lower bounds for text size
private float mMinTextSize = MIN_TEXT_SIZE;
// Text view line spacing multiplier
private float mSpacingMult = 1.0f;
// Text view additional line spacing
private float mSpacingAdd = 0.0f;
// Add ellipsis to text that overflows at the smallest text size
private boolean mAddEllipsis = true;
// Default constructor override
public AutoResizeTextView(Context context) {
this(context, null);
}
// Default constructor when inflating from XML file
public AutoResizeTextView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
// Default constructor override
public AutoResizeTextView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
mTextSize = getTextSize();
}
/**
* When text changes, set the force resize flag to true and reset the text
* size.
*/
@Override
protected void onTextChanged(final CharSequence text, final int start,
final int before, final int after) {
mNeedsResize = true;
// Since this view may be reused, it is good to reset the text size
resetTextSize();
}
/**
* If the text view size changed, set the force resize flag to true
*/
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
if (w != oldw || h != oldh) {
mNeedsResize = true;
}
}
/**
* Register listener to receive resize notifications
*
* @param listener
*/
public void setOnResizeListener(OnTextResizeListener listener) {
mTextResizeListener = listener;
}
/**
* Override the set text size to update our internal reference values
*/
@Override
public void setTextSize(float size) {
super.setTextSize(size);
mTextSize = getTextSize();
}
/**
* Override the set text size to update our internal reference values
*/
@Override
public void setTextSize(int unit, float size) {
super.setTextSize(unit, size);
mTextSize = getTextSize();
}
/**
* Override the set line spacing to update our internal reference values
*/
@Override
public void setLineSpacing(float add, float mult) {
super.setLineSpacing(add, mult);
mSpacingMult = mult;
mSpacingAdd = add;
}
/**
* Set the upper text size limit and invalidate the view
*
* @param maxTextSize
*/
public void setMaxTextSize(float maxTextSize) {
mMaxTextSize = maxTextSize;
requestLayout();
invalidate();
}
/**
* Return upper text size limit
*
* @return
*/
public float getMaxTextSize() {
return mMaxTextSize;
}
/**
* Set the lower text size limit and invalidate the view
*
* @param minTextSize
*/
public void setMinTextSize(float minTextSize) {
mMinTextSize = minTextSize;
requestLayout();
invalidate();
}
/**
* Return lower text size limit
*
* @return
*/
public float getMinTextSize() {
return mMinTextSize;
}
/**
* Set flag to add ellipsis to text that overflows at the smallest text size
*
* @param addEllipsis
*/
public void setAddEllipsis(boolean addEllipsis) {
mAddEllipsis = addEllipsis;
}
/**
* Return flag to add ellipsis to text that overflows at the smallest text
* size
*
* @return
*/
public boolean getAddEllipsis() {
return mAddEllipsis;
}
/**
* Reset the text to the original size
*/
public void resetTextSize() {
//ZBertalan:changed to mMaxTextSize
super.setTextSize(TypedValue.COMPLEX_UNIT_PX, mMaxTextSize);
//ZBertalan:swapped them
//mMaxTextSize = mTextSize;
mTextSize = mMaxTextSize;
}
/**
* Resize text after measuring ZBertalan: I commented this out because I
* need to resize the text in onMeasure, to layout the textview based on
* it's size
*/
/*
* @Override protected void onLayout(boolean changed, int left, int top, int
* right, int bottom) { if(changed || mNeedsResize) { int widthLimit =
* (right - left) - getCompoundPaddingLeft() - getCompoundPaddingRight();
* int heightLimit = (bottom - top) - getCompoundPaddingBottom() -
* getCompoundPaddingTop(); //og.d("AnswerView", "inside ARTV.onLayout() " +
* ); resizeText(widthLimit, heightLimit); } super.onLayout(changed, left,
* top, right, bottom); }
*/
/**
* @author zsbertalan Moved some code here to resize the textview here and
* position it based on it's new size
*/
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int newWidth = MeasureSpec.getSize(widthMeasureSpec);
int newHeight = MeasureSpec.getSize(heightMeasureSpec);
resizeText(newWidth, newHeight);
TextPaint p = getPaint();
newHeight = getTextHeight(getText(), p, newWidth, getTextSize());
this.setMeasuredDimension(newWidth, newHeight);
}
/**
* Resize the text size with default width and height
*/
public void resizeText() {
int heightLimit = getHeight() - getPaddingBottom() - getPaddingTop();
int widthLimit = getWidth() - getPaddingLeft() - getPaddingRight();
resizeText(widthLimit, heightLimit);
}
/**
* Resize the text size with specified width and height
*
* @param width
* @param height
*/
public void resizeText(int width, int height) {
CharSequence text = getText();
// Do not resize if the view does not have dimensions or there is no
// text
if (text == null || text.length() == 0 || height <= 0 || width <= 0
|| mTextSize == 0) {
return;
}
// Get the text view's paint object
TextPaint textPaint = getPaint();
// Store the current text size
float oldTextSize = textPaint.getTextSize();
// If there is a max text size set, use the lesser of that and the
// default text size
//ZBertalan: Bollocks. I changed to use mMaxTextSize all the time
//float targetTextSize = mMaxTextSize > 0 ? Math.min(mTextSize, mMaxTextSize) : mTextSize;
float targetTextSize = mMaxTextSize;
// Get the required text height
int textHeight = getTextHeight(text, textPaint, width, targetTextSize);
// Until we either fit within our text view or we had reached our min
// text size, incrementally try smaller sizes
while (textHeight > height && targetTextSize > mMinTextSize) {
targetTextSize = Math.max(targetTextSize - 2, mMinTextSize);
textHeight = getTextHeight(text, textPaint, width, targetTextSize);
}
// If we had reached our minimum text size and still don't fit, append
// an ellipsis
if (mAddEllipsis && targetTextSize == mMinTextSize
&& textHeight > height) {
// Draw using a static layout
TextPaint paint = new TextPaint(textPaint);
StaticLayout layout = new StaticLayout(text, paint, width,
Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, false);
layout.draw(sTextResizeCanvas);
int lastLine = layout.getLineForVertical(height) - 1;
int start = layout.getLineStart(lastLine);
int end = layout.getLineEnd(lastLine);
float lineWidth = layout.getLineWidth(lastLine);
float ellipseWidth = paint.measureText(mEllipsis);
// Trim characters off until we have enough room to draw the
// ellipsis
while (width < lineWidth + ellipseWidth) {
lineWidth = textPaint.measureText(text.subSequence(start,
--end + 1).toString());
}
setText(text.subSequence(0, end) + mEllipsis);
}
// Some devices try to auto adjust line spacing, so force default line
// spacing
// and invalidate the layout as a side effect
// textPaint.setTextSize(targetTextSize);
setTextSize(TypedValue.COMPLEX_UNIT_PX, targetTextSize);
setLineSpacing(mSpacingAdd, mSpacingMult);
// Notify the listener if registered
if (mTextResizeListener != null) {
mTextResizeListener.onTextResize(this, oldTextSize, targetTextSize);
}
// Reset force resize flag
mNeedsResize = false;
}
// Set the text size of the text paint object and use a static layout to
// render text off screen before measuring
private int getTextHeight(CharSequence source, TextPaint originalPaint, int width,
float textSize) {
TextPaint paint = new TextPaint(originalPaint);
// Update the text paint object
paint.setTextSize(textSize);
// Draw using a static layout
StaticLayout layout = new StaticLayout(source, paint, width,
Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true);
layout.draw(sTextResizeCanvas);
return layout.getHeight();
}
}
MyButton.java：包herrbert74.artvsample；
import android.content.Context;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.view.WindowManager;
import android.widget.LinearLayout;
public class MyButton extends LinearLayout {
private AutoResizeTextView tv;
Context ctx;
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
AutoResizeTextView tv = (AutoResizeTextView) getChildAt(0);
int padding = getHeight() / 8;
int left = padding;
int top = (getHeight() - tv.getMeasuredHeight()) / 2;
int right = padding + tv.getMeasuredWidth();
int bottom = getHeight() / 2 + tv.getMeasuredHeight() / 2;
tv.layout(left, top, right, bottom);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int w = MeasureSpec.getSize(widthMeasureSpec);
int h = MeasureSpec.getSize(heightMeasureSpec);
if (w == 0) {
WindowManager wm = (WindowManager) ctx
.getSystemService(Context.WINDOW_SERVICE);
DisplayMetrics metrics = new DisplayMetrics();
wm.getDefaultDisplay().getMetrics(metrics);
w = metrics.widthPixels;
h = metrics.heightPixels;
}
tv.measure(MeasureSpec.makeMeasureSpec(w - 40, MeasureSpec.AT_MOST),
MeasureSpec.makeMeasureSpec(h - 20, MeasureSpec.AT_MOST));
setMeasuredDimension(MeasureSpec.getSize(widthMeasureSpec),
MeasureSpec.getSize(heightMeasureSpec));
}
public MyButton(Context context, AttributeSet attrs) {
this(context, attrs, 0);
tv = new AutoResizeTextView(context);
tv.setMaxTextSize(54);
tv.setTextColor(context.getResources().getColor(android.R.color.white));
tv.setClickable(true);
tv.setBackgroundResource(android.R.color.darker_gray);
addView(tv);
}
public MyButton(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs);
ctx = context;
}
protected MyButton(Context context) {
super(context, null);
}
public void setText(String text) {
tv.setText(text);
}
public String getText() {
return tv.getText().toString();
}
public void setTextSize(float f) {
tv.setTextSize(f);
}
}
MainActivity.java：包herrbert74.artvsample；
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
public class MainActivity extends Activity {
int x;
MyButton tv;
@Override
protected void onCreate(Bundle savedInstanceState) {
x = -1;
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final String[] texts = { "normal text", "a bit longer text", "even longer text by a word", "Long. Longest text ever. Long. Long." };
tv = (MyButton) findViewById(R.id.textView1);
Button b = (Button) findViewById(R.id.button1);
b.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (x < texts.length - 1)
x++;
else
x = 0;
tv.setText(texts[x]);
Log.d("AnswerView", "Text: " + texts[x]);
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}
在示例项目中，有一个用于更改文本的按钮。起初没有文字，然后文字越来越长。您可以在图片上看到差异。
按钮背景为黑色，textview 背景为灰色。
以下是带有正确按钮的 Defy 文本视图：
请注意，在 Kindle 上，textview 已经声明了一些没有文字的地方！Kindle Fire 布局错误：
在 myButton 构造函数中，我尝试了以下无济于事：
tv.setPadding(0, 0, 0, 0);
tv.setLineSpacing(0f, 1f);
tv.setCompoundDrawablePadding(0);
tv.setCompoundDrawablesWithIntrinsicBounds(null, null, null, null);
tv.setCompoundDrawablesWithIntrinsicBounds(0, 0, 0, 0);