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
参考ScalableTextView.java这里自动适合Android的TextView。我已经添加了代码来根据文本长度收缩和扩展TextView
其他回答
我发现下面的方法对我很有用。它不循环，同时考虑高度和宽度。注意，在视图上调用setTextSize时指定PX单位是很重要的。
Paint paint = adjustTextSize(getPaint(), numChars, maxWidth, maxHeight);
setTextSize(TypedValue.COMPLEX_UNIT_PX,paint.getTextSize());
下面是我使用的例程，从视图中传入getPaint()。带有'wide'字符的10个字符的字符串用于估计独立于实际字符串的宽度。
private static final String text10="OOOOOOOOOO";
public static Paint adjustTextSize(Paint paint, int numCharacters, int widthPixels, int heightPixels) {
float width = paint.measureText(text10)*numCharacters/text10.length();
float newSize = (int)((widthPixels/width)*paint.getTextSize());
paint.setTextSize(newSize);
// remeasure with font size near our desired result
width = paint.measureText(text10)*numCharacters/text10.length();
newSize = (int)((widthPixels/width)*paint.getTextSize());
paint.setTextSize(newSize);
// Check height constraints
FontMetricsInt metrics = paint.getFontMetricsInt();
float textHeight = metrics.descent-metrics.ascent;
if (textHeight > heightPixels) {
newSize = (int)(newSize * (heightPixels/textHeight));
paint.setTextSize(newSize);
}
return paint;
}
我刚刚创建了以下方法(基于Chase的想法)，如果你想在任何画布上绘制文本，它可能会帮助你:
private static void drawText(Canvas canvas, int xStart, int yStart,
int xWidth, int yHeigth, String textToDisplay,
TextPaint paintToUse, float startTextSizeInPixels,
float stepSizeForTextSizeSteps) {
// Text view line spacing multiplier
float mSpacingMult = 1.0f;
// Text view additional line spacing
float mSpacingAdd = 0.0f;
StaticLayout l = null;
do {
paintToUse.setTextSize(startTextSizeInPixels);
startTextSizeInPixels -= stepSizeForTextSizeSteps;
l = new StaticLayout(textToDisplay, paintToUse, xWidth,
Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true);
} while (l.getHeight() > yHeigth);
int textCenterX = xStart + (xWidth / 2);
int textCenterY = (yHeigth - l.getHeight()) / 2;
canvas.save();
canvas.translate(textCenterX, textCenterY);
l.draw(canvas);
canvas.restore();
}
这可以在任何自定义视图的任何onDraw()方法中使用。
实际上解决方案是在谷歌的DialogTitle类…虽然它不如公认的方法有效，但它更简单，也更容易适应。
public class SingleLineTextView extends TextView {
public SingleLineTextView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
setSingleLine();
setEllipsize(TruncateAt.END);
}
public SingleLineTextView(Context context, AttributeSet attrs) {
super(context, attrs);
setSingleLine();
setEllipsize(TruncateAt.END);
}
public SingleLineTextView(Context context) {
super(context);
setSingleLine();
setEllipsize(TruncateAt.END);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
final Layout layout = getLayout();
if (layout != null) {
final int lineCount = layout.getLineCount();
if (lineCount > 0) {
final int ellipsisCount = layout.getEllipsisCount(lineCount - 1);
if (ellipsisCount > 0) {
final float textSize = getTextSize();
// textSize is already expressed in pixels
setTextSize(TypedValue.COMPLEX_UNIT_PX, (textSize - 1));
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}
}
}
}
}
这是一个简单的解决方案，使用TextView本身和textchangedlistens添加到它:
expressionView = (TextView) findViewById(R.id.expressionView);
expressionView.addTextChangedListener(textAutoResizeWatcher(expressionView, 25, 55));
private TextWatcher textAutoResizeWatcher(final TextView view, final int MIN_SP, final int MAX_SP) {
return new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {}
@Override
public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {}
@Override
public void afterTextChanged(Editable editable) {
final int widthLimitPixels = view.getWidth() - view.getPaddingRight() - view.getPaddingLeft();
Paint paint = new Paint();
float fontSizeSP = pixelsToSp(view.getTextSize());
paint.setTextSize(spToPixels(fontSizeSP));
String viewText = view.getText().toString();
float widthPixels = paint.measureText(viewText);
// Increase font size if necessary.
if (widthPixels < widthLimitPixels){
while (widthPixels < widthLimitPixels && fontSizeSP <= MAX_SP){
++fontSizeSP;
paint.setTextSize(spToPixels(fontSizeSP));
widthPixels = paint.measureText(viewText);
}
--fontSizeSP;
}
// Decrease font size if necessary.
else {
while (widthPixels > widthLimitPixels || fontSizeSP > MAX_SP) {
if (fontSizeSP < MIN_SP) {
fontSizeSP = MIN_SP;
break;
}
--fontSizeSP;
paint.setTextSize(spToPixels(fontSizeSP));
widthPixels = paint.measureText(viewText);
}
}
view.setTextSize(fontSizeSP);
}
};
}
private float pixelsToSp(float px) {
float scaledDensity = getResources().getDisplayMetrics().scaledDensity;
return px/scaledDensity;
}
private float spToPixels(float sp) {
float scaledDensity = getResources().getDisplayMetrics().scaledDensity;
return sp * scaledDensity;
}
这种方法将根据需要增加或减少字体大小以适应文本，尊重作为参数接收的MIN_SP和MAX_SP边界。
我只是借用了一些其他人的想法，并在下面写了一些代码，可能会有帮助。
import android.content.Context;
import android.graphics.Canvas;
import android.text.Layout.Alignment;
import android.text.StaticLayout;
import android.text.TextPaint;
import android.text.TextUtils;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.widget.TextView;
public class AutoResizeTextView extends TextView {
private static final int MAX_SIZE = 1000;
private static final int MIN_SIZE = 5;
private TextPaint mTextPaint;
private float mSpacingMult = 1.0f;
private float mSpacingAdd = 0.0f;
private boolean needAdapt = false;
private boolean adapting = false;
public AutoResizeTextView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}
public AutoResizeTextView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public AutoResizeTextView(Context context) {
super(context);
init();
}
private void init() {
mTextPaint = new TextPaint();
}
@Override
protected void onDraw(Canvas canvas) {
if (adapting) {
return;
}
if (needAdapt) {
adaptTextSize();
} else {
super.onDraw(canvas);
}
}
private void adaptTextSize() {
CharSequence text = getText();
int viewWidth = getMeasuredWidth();
int viewHeight = getMeasuredHeight();
if (viewWidth==0 || viewHeight==0
|| TextUtils.isEmpty(text)) {
return;
}
adapting = true;
/* binary search */
int bottom=MIN_SIZE, top=MAX_SIZE, mid = 0;
while (bottom <= top) {
mid = (bottom + top)/2;
mTextPaint.setTextSize(mid);
int textWidth = (int) mTextPaint.measureText(text, 0, text.length());
int textHeight = getTextHeight(text, viewWidth);
if (textWidth<viewWidth && textHeight<viewHeight) {
bottom = mid+1;
} else {
top = mid-1;
}
}
int newSize = mid-1;
setTextSize(TypedValue.COMPLEX_UNIT_PX, newSize);
adapting=false;
needAdapt = false;
invalidate();
}
private int getTextHeight(CharSequence text, int targetWidth) {
StaticLayout layout = new StaticLayout(text, mTextPaint, targetWidth,
Alignment.ALIGN_NORMAL, mSpacingMult, mSpacingAdd, true);
return layout.getHeight();
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
needAdapt = true;
}
@Override
protected void onTextChanged(CharSequence text, int start,
int lengthBefore, int lengthAfter) {
super.onTextChanged(text, start, lengthBefore, lengthAfter);
needAdapt = true;
}
@Override
public void setLineSpacing(float add, float mult) {
super.setLineSpacing(add, mult);
mSpacingMult = mult;
mSpacingAdd = add;
}
}
