解决方法
在我们的项目中,我们使用名为TextDrawable的自定义类.这个类扩展了Drawable,在它的方法draw(Canvas)中,它简单地在画布上绘制文本.这个类适合我们的特定需求,但我认为,这个想法(主要是在draw()方法中会帮助你：
public class TextDrawable extends Drawable {
protected final Paint textPaint;
protected ColorStateList color;
protected String text;
protected int iHeight;
protected int iWidth;
protected int measuredWidth,measuredHeight;
private float ascent;
/**
* A flag whether the drawable is stateful - whether to redraw if the state of view has changed
*/
protected boolean stateful;
/**
* Vertical alignment of text
*/
private VerticalAlignment verticalAlignment;
.... some constructors...
public TextDrawable(Context ctx,String text,ColorStateList color,float textSize,VerticalAlignment verticalAlignment) {
textPaint = new Paint();
this.text = text;
initPaint();
this.textPaint.setTextSize(textSize);
measureSize();
setBounds(0,iWidth,iHeight);
this.color = color;
textPaint.setColor(color.getDefaultColor());
this.verticalAlignment = verticalAlignment;
}
/**
* Set bounds of drawable to start on coordinate [0,0] and end on coordinate[measuredWidth,* measuredHeight]
*/
public final void setBoundsByMeasuredSize() {
setBounds(0,measuredWidth,measuredHeight);
invalidateSelf();
}
@Override
public boolean isstateful() {
return stateful;
}
public void setStateful(boolean stateful) {
this.stateful = stateful;
}
private void initPaint() {
textPaint.setAntiAlias(true);
textPaint.setTextAlign(Paint.Align.CENTER);
}
/**
* Vertical alignment of text within the drawable (Horizontally it is always aligned to center
*/
public VerticalAlignment getVerticalAlignment() {
return verticalAlignment;
}
/**
* Vertical alignment of text within the drawable (Horizontally it is always aligned to center
*/
public void setVerticalAlignment(VerticalAlignment verticalAlignment) {
if (this.verticalAlignment != verticalAlignment) {
this.verticalAlignment = verticalAlignment;
invalidateSelf();
}
}
/**
* displayed text
*/
public String getText() {
return text;
}
/**
* displayed text
*/
public void setText(String text) {
if (this.text == null || !this.text.equals(text)) {
this.text = text;
invalidateSelf();
}
}
/**
* The color of text
*/
public ColorStateList getColor() {
return color;
}
/**
* The color of text
*/
public void setColor(ColorStateList colorStateList) {
if (this.color == null || !this.color.equals(colorStateList)) {
this.color = colorStateList;
invalidateSelf();
}
}
/**
* The color of text
*/
public void setColor(int color) {
setColor(ColorStateList.valueOf(color));
}
/**
* Text size
*/
public void setTextSize(float size) {
if (this.textPaint.getTextSize() != size) {
this.textPaint.setTextSize(size);
measureSize();
invalidateSelf();
}
}
/**
* Text size
*/
public void setTextSize(int unit,float size,Context context) {
setTextSize(TypedValue.applyDimension(unit,size,context.getResources().getdisplayMetrics()));
}
/**
* This method is called by default when any property that may have some influence on the size
* of drawable This method should use measuredWidth and measuredHeight properties to store the
* measured walues By default the measuredWIdth and measuredHeight are set to iWidth and iHeight
* (size of text) by this method.
*/
protected void measureSize() {
ascent = -textPaint.ascent();
iWidth = (int) (0.5f + textPaint.measureText(text));
iHeight = (int) (0.5f + textPaint.descent() + ascent);
measuredWidth = iWidth;
measuredHeight = iHeight;
}
public float getTextSize() {
return textPaint.getTextSize();
}
@Override
protected boolean onStateChange(int[] state) {
int clr = color != null ? color.getColorForState(state,0) : 0;
if (textPaint.getColor() != clr) {
textPaint.setColor(clr);
return true;
} else {
return false;
}
}
public Typeface getTypeface() {
return textPaint.getTypeface();
}
public void setTypeface(Typeface typeface) {
if (!textPaint.getTypeface().equals(typeface)) {
textPaint.setTypeface(typeface);
invalidateSelf();
}
}
/**
* The method is called before the text is drawn. This method can be overridden to draw some background (by default this method does nothing).
* @param canvas The canvas where to draw.
* @param bounds The bounds of the drawable.
*/
protected void drawBefore(Canvas canvas,Rect bounds) {
}
/**
* The method is called after the text is drawn. This method can be overriden to draw some more graphics over the text (by default this method does nothing).
* @param canvas The canvas where to draw.
* @param bounds The bound of the drawable.
*/
protected void drawAfter(Canvas canvas,Rect bounds) {
}
@Override
public void draw(Canvas canvas) {
if (text == null || text.isEmpty()) {
return;
}
final Rect bounds = getBounds();
int stack = canvas.save();
canvas.translate(bounds.left,bounds.top);
drawBefore(canvas,bounds);
if (text != null && !text.isEmpty()) {
final float x = bounds.width() >= iWidth ? bounds.centerX() : iWidth * 0.5f;
float y = 0;
switch (verticalAlignment) {
case BASELINE:
y = (bounds.height() - iHeight) * 0.5f + ascent;
break;
case TOP:
y = bounds.height();
break;
case BottOM:
y = bounds.height();
break;
}
canvas.drawText(text,x,y,textPaint);
}
drawAfter(canvas,bounds);
canvas.restoretoCount(stack);
}
@Override
public void setAlpha(int alpha) {
if (textPaint.getAlpha() != alpha) {
textPaint.setAlpha(alpha);
invalidateSelf();
}
}
@Override
public void setColorFilter(ColorFilter cf) {
if (textPaint.getColorFilter() == null || !textPaint.getColorFilter().equals(cf)) {
textPaint.setColorFilter(cf);
invalidateSelf();
}
}
@Override
public int getopacity() {
return PixelFormat.TRANSLUCENT;
}
public enum VerticalAlignment {
TOP,BottOM,BASELINE
}
以及如何使用它：
fab.setimageDrawable(new TextDrawable(fab.getContext(),"FAB",ColorStateList.valueOf(Color.BLACK),32.f,VerticalAlignment.BASELINE));
(fab是FloatingActionButton)
