我正在寻找一种最佳的方法来调整包装文本在一个TextView，使它将适合它的getHeight和getWidth界限。我不是简单地寻找一种方法来包装文本-我想确保它既包装，又足够小，完全适合在屏幕上。
我在StackOverflow上看到了一些需要自动调整大小的情况，但它们要么是非常特殊的情况下的hack解决方案，没有解决方案，或涉及重新绘制TextView递归直到它足够小(这是内存紧张，迫使用户观看文本收缩一步一步与每次递归)。
但我相信有人已经找到了一个很好的解决方案，它不涉及我正在做的事情:编写几个繁重的例程来解析和测量文本，调整文本的大小，然后重复，直到找到一个合适的小尺寸。
TextView使用什么例程来包装文本?难道这些不能用来预测文本是否足够小吗?
是否有一个最佳实践的方法来自动调整TextView的大小，以适应，包装，在它的getHeight和getWidth边界?
当前回答
如果有人需要它，这里是相同的代码片段，但Xamarin.Android。
/**
* DO WHAT YOU WANT TO PUBLIC LICENSE
* Version 1, December 2017
*
* Copyright (C) 2017 Nathan Westfall
*
* Everyone is permitted to copy and distribute verbatim or modified
* copies of this license document, and changing it is allowed as long
* as the name is changed.
*
* DO WHAT YOU WANT TO PUBLIC LICENSE
* TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
*
* 0. You just DO WHAT YOU WANT TO.
*/
using Android.Content;
using Android.Runtime;
using Android.Widget;
using Android.Util;
using Android.Text;
using Java.Lang;
namespace My.Text
{
public class AutoResizeTextView : TextView
{
public const float MIN_TEXT_SIZE = 20;
public interface OnTextResizeListener
{
void OnTextResize(TextView textView, float oldSize, float newSize);
}
private const string mEllipsis = "...";
private OnTextResizeListener mTextResizeListener;
private bool mNeedsResize = false;
private float mTextSize;
private float mMaxTextSize = 0;
private float mMinTextSize = MIN_TEXT_SIZE;
private float mSpacingMult = 1.0f;
private float mSpacingAdd = 0.0f;
public bool AddEllipsis { get; set; } = true;
public AutoResizeTextView(Context context) : this(context, null) { }
public AutoResizeTextView(Context context, IAttributeSet attrs) : this(context, attrs, 0) { }
public AutoResizeTextView(Context context, IAttributeSet attrs, int defStyle): base(context, attrs, defStyle)
{
mTextSize = TextSize;
}
protected override void OnTextChanged(ICharSequence text, int start, int lengthBefore, int lengthAfter)
{
base.OnTextChanged(text, start, lengthBefore, lengthAfter);
mNeedsResize = true;
ResetTextSize();
}
protected override void OnSizeChanged(int w, int h, int oldw, int oldh)
{
base.OnSizeChanged(w, h, oldw, oldh);
if (w != oldw || h != oldh)
mNeedsResize = true;
}
public void SetOnResizeListener(OnTextResizeListener listener)
{
mTextResizeListener = listener;
}
public override void SetTextSize([GeneratedEnum] ComplexUnitType unit, float size)
{
base.SetTextSize(unit, size);
mTextSize = TextSize;
}
public override void SetLineSpacing(float add, float mult)
{
base.SetLineSpacing(add, mult);
mSpacingMult = mult;
mSpacingAdd = add;
}
public void SetMaxTextSize(float maxTextSize)
{
mMaxTextSize = maxTextSize;
RequestLayout();
Invalidate();
}
public float GetMaxTextSize()
{
return mMaxTextSize;
}
public void SetMinTextSize(float minTextSize)
{
mMinTextSize = minTextSize;
RequestLayout();
Invalidate();
}
public float GetMinTextSize()
{
return mMinTextSize;
}
public void ResetTextSize()
{
if(mTextSize > 0)
{
base.SetTextSize(ComplexUnitType.Px, mTextSize);
mMaxTextSize = mTextSize;
}
}
protected override void OnLayout(bool changed, int left, int top, int right, int bottom)
{
if(changed || mNeedsResize)
{
int widthLimit = (right - left) - CompoundPaddingLeft - CompoundPaddingRight;
int heightLimit = (bottom - top) - CompoundPaddingBottom - CompoundPaddingTop;
ResizeText(widthLimit, heightLimit);
}
base.OnLayout(changed, left, top, right, bottom);
base.OnLayout(changed, left, top, right, bottom);
}
public void ResizeText()
{
int heightLimit = Height - PaddingBottom - PaddingTop;
int widthLimit = Width - PaddingLeft - PaddingRight;
ResizeText(widthLimit, heightLimit);
}
public void ResizeText(int width, int height)
{
var text = TextFormatted;
if (text == null || text.Length() == 0 || height <= 0 || width <= 0 || mTextSize == 0)
return;
if (TransformationMethod != null)
text = TransformationMethod.GetTransformationFormatted(TextFormatted, this);
TextPaint textPaint = Paint;
float oldTextSize = textPaint.TextSize;
float targetTextSize = mMaxTextSize > 0 ? System.Math.Min(mTextSize, mMaxTextSize) : mTextSize;
int textHeight = GetTextHeight(text, textPaint, width, targetTextSize);
while(textHeight > height && targetTextSize > mMinTextSize)
{
targetTextSize = System.Math.Max(targetTextSize - 2, mMinTextSize);
textHeight = GetTextHeight(text, textPaint, width, targetTextSize);
}
if(AddEllipsis && targetTextSize == mMinTextSize && textHeight > height)
{
TextPaint paint = new TextPaint(textPaint);
StaticLayout layout = new StaticLayout(text, paint, width, Layout.Alignment.AlignNormal, mSpacingMult, mSpacingAdd, false);
if(layout.LineCount > 0)
{
int lastLine = layout.GetLineForVertical(height) - 1;
if (lastLine < 0)
SetText("", BufferType.Normal);
else
{
int start = layout.GetLineStart(lastLine);
int end = layout.GetLineEnd(lastLine);
float lineWidth = layout.GetLineWidth(lastLine);
float ellipseWidth = textPaint.MeasureText(mEllipsis);
while (width < lineWidth + ellipseWidth)
lineWidth = textPaint.MeasureText(text.SubSequence(start, --end + 1).ToString());
SetText(text.SubSequence(0, end) + mEllipsis, BufferType.Normal);
}
}
}
SetTextSize(ComplexUnitType.Px, targetTextSize);
SetLineSpacing(mSpacingAdd, mSpacingMult);
mTextResizeListener?.OnTextResize(this, oldTextSize, targetTextSize);
mNeedsResize = false;
}
private int GetTextHeight(ICharSequence source, TextPaint paint, int width, float textSize)
{
TextPaint paintCopy = new TextPaint(paint);
paintCopy.TextSize = textSize;
StaticLayout layout = new StaticLayout(source, paintCopy, width, Layout.Alignment.AlignNormal, mSpacingMult, mSpacingAdd, false);
return layout.Height;
}
}
}
其他回答
这个解决方案适合我们:
public class CustomFontButtonTextFit extends CustomFontButton
{
private final float DECREMENT_FACTOR = .1f;
public CustomFontButtonTextFit(Context context) {
super(context);
}
public CustomFontButtonTextFit(Context context, AttributeSet attrs) {
super(context, attrs);
}
public CustomFontButtonTextFit(Context context, AttributeSet attrs,
int defStyle) {
super(context, attrs, defStyle);
}
private synchronized void refitText(String text, int textWidth) {
if (textWidth > 0)
{
float availableWidth = textWidth - this.getPaddingLeft()
- this.getPaddingRight();
TextPaint tp = getPaint();
Rect rect = new Rect();
tp.getTextBounds(text, 0, text.length(), rect);
float size = rect.width();
while(size > availableWidth)
{
setTextSize( getTextSize() - DECREMENT_FACTOR );
tp = getPaint();
tp.getTextBounds(text, 0, text.length(), rect);
size = rect.width();
}
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec)
{
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int parentWidth = MeasureSpec.getSize(widthMeasureSpec);
int parentHeight = MeasureSpec.getSize(heightMeasureSpec);
refitText(this.getText().toString(), parentWidth);
if(parentWidth < getSuggestedMinimumWidth())
parentWidth = getSuggestedMinimumWidth();
if(parentHeight < getSuggestedMinimumHeight())
parentHeight = getSuggestedMinimumHeight();
this.setMeasuredDimension(parentWidth, parentHeight);
}
@Override
protected void onTextChanged(final CharSequence text, final int start,
final int before, final int after)
{
super.onTextChanged(text, start, before, after);
refitText(text.toString(), this.getWidth());
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh)
{
super.onSizeChanged(w, h, oldw, oldh);
if (w != oldw)
refitText(this.getText().toString(), w);
}
}
以下是我采取的方法。这很简单。它使用连续逼近来集中于字体大小，通常可以在不到10次迭代中计算出来。只需将“activityWidth”替换为你用来显示文本的视图的宽度。在我的示例中，它被设置为与屏幕宽度相同的私有字段。初始fontsize 198只在该方法产生异常的情况下设置(这真的不应该发生):
private float GetFontSizeForScreenWidth(String text)
{
float fontsize = 198;
try
{
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setColor(Color.RED);
Typeface typeface = Typeface.create("Helvetica", Typeface.BOLD);
paint.setTypeface(typeface);
paint.setTextAlign(Align.CENTER);
int lowVal = 0;
int highVal = 2000;
int currentVal = highVal;
/*
* Successively approximate the screen size until it is
* within 2 pixels of the maximum screen width. Generally
* this will get you to the closest font size within about 10
* iterations.
*/
do
{
paint.setTextSize(currentVal);
float textWidth = paint.measureText(text);
float diff = activityWidth - textWidth;
if ((diff >= 0) && (diff <= 2))
{
fontsize = paint.getTextSize();
return fontsize;
}
if (textWidth > activityWidth)
highVal = currentVal;
else if (textWidth < activityWidth)
lowVal = currentVal;
else
{
fontsize = paint.getTextSize();
return fontsize;
}
currentVal = (highVal - lowVal) / 2 + lowVal;
} while (true);
}
catch (Exception ex)
{
return fontsize;
}
}
扩展TextView和覆盖onDraw与下面的代码。它将保持文本纵横比，但将其大小填充空间。如果需要，您可以轻松地修改代码以进行拉伸。
@Override
protected void onDraw(@NonNull Canvas canvas) {
TextPaint textPaint = getPaint();
textPaint.setColor(getCurrentTextColor());
textPaint.setTextAlign(Paint.Align.CENTER);
textPaint.drawableState = getDrawableState();
String text = getText().toString();
float desiredWidth = getMeasuredWidth() - getPaddingLeft() - getPaddingRight() - 2;
float desiredHeight = getMeasuredHeight() - getPaddingTop() - getPaddingBottom() - 2;
float textSize = textPaint.getTextSize();
for (int i = 0; i < 10; i++) {
textPaint.getTextBounds(text, 0, text.length(), rect);
float width = rect.width();
float height = rect.height();
float deltaWidth = width - desiredWidth;
float deltaHeight = height - desiredHeight;
boolean fitsWidth = deltaWidth <= 0;
boolean fitsHeight = deltaHeight <= 0;
if ((fitsWidth && Math.abs(deltaHeight) < 1.0)
|| (fitsHeight && Math.abs(deltaWidth) < 1.0)) {
// close enough
break;
}
float adjustX = desiredWidth / width;
float adjustY = desiredHeight / height;
textSize = textSize * (adjustY < adjustX ? adjustY : adjustX);
// adjust text size
textPaint.setTextSize(textSize);
}
float x = desiredWidth / 2f;
float y = desiredHeight / 2f - rect.top - rect.height() / 2f;
canvas.drawText(text, x, y, textPaint);
}
我结合了上面的一些建议，用二分法制作了一个上下伸缩的图。它还在宽度范围内缩放。
/**
* DO WHAT YOU WANT TO PUBLIC LICENSE
* Version 2, December 2004
*
* Copyright (C) 2004 Sam Hocevar <sam@hocevar.net>
*
* Everyone is permitted to copy and distribute verbatim or modified
* copies of this license document, and changing it is allowed as long
* as the name is changed.
*
* DO WHAT YOU WANT TO PUBLIC LICENSE
* TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
*
* 0. You just DO WHAT YOU WANT TO.
*/
import android.content.Context;
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;
// Minimum text size for this text view
public static final float MAX_TEXT_SIZE = 128;
private static final int BISECTION_LOOP_WATCH_DOG = 30;
// Interface for resize notifications
public interface OnTextResizeListener {
public void onTextResize(TextView textView, float oldSize, float newSize);
}
// 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 = MAX_TEXT_SIZE;
// 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() {
if (mTextSize > 0) {
super.setTextSize(TypedValue.COMPLEX_UNIT_PX, mTextSize);
// mMaxTextSize = mTextSize;
}
}
/**
* Resize text after measuring
*/
@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();
resizeText(widthLimit, heightLimit);
}
super.onLayout(changed, left, top, right, bottom);
}
/**
* Resize the text size with default width and height
*/
public void resizeText() {
// Height and width with a padding as a percentage of height
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();
// Bisection method: fast & precise
float lower = mMinTextSize;
float upper = mMaxTextSize;
int loop_counter = 1;
float targetTextSize = (lower + upper) / 2;
int textHeight = getTextHeight(text, textPaint, width, targetTextSize);
int textWidth = getTextWidth(text, textPaint, width, targetTextSize);
while (loop_counter < BISECTION_LOOP_WATCH_DOG && upper - lower > 1) {
targetTextSize = (lower + upper) / 2;
textHeight = getTextHeight(text, textPaint, width, targetTextSize);
textWidth = getTextWidth(text, textPaint, width, targetTextSize);
if (textHeight > (height) || textWidth > (width))
upper = targetTextSize;
else
lower = targetTextSize;
loop_counter++;
}
targetTextSize = lower;
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
// modified: use a copy of TextPaint for measuring
TextPaint paintCopy = new TextPaint(textPaint);
paintCopy.setTextSize(targetTextSize);
StaticLayout layout = new StaticLayout(text, paintCopy, width,
Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, false);
// Check that we have a least one line of rendered text
if (layout.getLineCount() > 0) {
// Since the line at the specific vertical position would be cut
// off,
// we must trim up to the previous line
int lastLine = layout.getLineForVertical(height) - 1;
// If the text would not even fit on a single line, clear it
if (lastLine < 0) {
setText("");
}
// Otherwise, trim to the previous line and add an ellipsis
else {
int start = layout.getLineStart(lastLine);
int end = layout.getLineEnd(lastLine);
float lineWidth = layout.getLineWidth(lastLine);
float ellipseWidth = paintCopy.measureText(mEllipsis);
// Trim characters off until we have enough room to draw the
// ellipsis
while (width < lineWidth + ellipseWidth) {
lineWidth = paintCopy.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
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) {
// modified: make a copy of the original TextPaint object for measuring
// (apparently the object gets modified while measuring, see also the
// docs for TextView.getPaint() (which states to access it read-only)
TextPaint paint = new TextPaint(originalPaint);
// Update the text paint object
paint.setTextSize(textSize);
// Measure using a static layout
StaticLayout layout = new StaticLayout(source, paint, width,
Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true);
return layout.getHeight();
}
// Set the text size of the text paint object and use a static layout to
// render text off screen before measuring
private int getTextWidth(CharSequence source, TextPaint originalPaint,
int width, float textSize) {
// Update the text paint object
TextPaint paint = new TextPaint(originalPaint);
// Draw using a static layout
paint.setTextSize(textSize);
StaticLayout layout = new StaticLayout(source, paint, width,
Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true);
return (int) layout.getLineWidth(0);
}
}
这里还有另一个解决方案，只是为了好玩。它可能不是很有效，但它确实处理了文本的高度和宽度，以及有标记的文本。
@Override
protected void onMeasure(final int widthMeasureSpec, final int heightMeasureSpec)
{
if ((MeasureSpec.getMode(widthMeasureSpec) != MeasureSpec.UNSPECIFIED)
&& (MeasureSpec.getMode(heightMeasureSpec) != MeasureSpec.UNSPECIFIED)) {
final float desiredWidth = MeasureSpec.getSize(widthMeasureSpec);
final float desiredHeight = MeasureSpec.getSize(heightMeasureSpec);
float textSize = getTextSize();
float lastScale = Float.NEGATIVE_INFINITY;
while (textSize > MINIMUM_AUTO_TEXT_SIZE_PX) {
// Measure how big the textview would like to be with the current text size.
super.onMeasure(MeasureSpec.UNSPECIFIED, MeasureSpec.UNSPECIFIED);
// Calculate how much we'd need to scale it to fit the desired size, and
// apply that scaling to the text size as an estimate of what we need.
final float widthScale = desiredWidth / getMeasuredWidth();
final float heightScale = desiredHeight / getMeasuredHeight();
final float scale = Math.min(widthScale, heightScale);
// If we don't need to shrink the text, or we don't seem to be converging, we're done.
if ((scale >= 1f) || (scale <= lastScale)) {
break;
}
// Shrink the text size and keep trying.
textSize = Math.max((float) Math.floor(scale * textSize), MINIMUM_AUTO_TEXT_SIZE_PX);
setTextSize(TypedValue.COMPLEX_UNIT_PX, textSize);
lastScale = scale;
}
}
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
