我希望为文本中的错误添加红色波浪线,例如:
不幸的是,我找不到合适的*Span类来包装错误文本。
我应该如何在Android中实现这样的功能?
我希望为文本中的错误添加红色波浪线,例如:
不幸的是,我找不到合适的*Span类来包装错误文本。
我应该如何在Android中实现这样的功能?
以下是一种不需要操作资源的解决方案:
public class WavyUnderlineSpan implements LineBackgroundSpan {
private int color;
private int lineWidth;
private int waveSize;
public WavyUnderlineSpan() {
this(Color.RED, 1, 3);
}
public WavyUnderlineSpan(int color, int lineWidth, int waveSize) {
this.color = color;
this.lineWidth = lineWidth;
this.waveSize = waveSize;
}
@Override
public void drawBackground(Canvas canvas, Paint paint, int left, int right, int top, int baseline, int bottom,
CharSequence text, int start, int end, int lnum) {
Paint p = new Paint(paint);
p.setColor(color);
p.setStrokeWidth(lineWidth);
int width = (int) paint.measureText(text, start, end);
int doubleWaveSize = waveSize * 2;
for (int i = left; i < left + width; i += doubleWaveSize) {
canvas.drawLine(i, bottom, i + waveSize, bottom - waveSize, p);
canvas.drawLine(i + waveSize, bottom - waveSize, i + doubleWaveSize, bottom, p);
}
}
}
我通过实现自定义Span解决了这个问题:
将error_underline.png
添加到您的资源中: <-- 这里是微小的6x3像素
然后使用这个类创建spans:
static class ErrorSpan extends DynamicDrawableSpan {
private BitmapDrawable mRedWavy;
private int mWidth;
private int mBmpHeight;
ErrorSpan(Resources resources) {
super(DynamicDrawableSpan.ALIGN_BASELINE);
mRedWavy = new BitmapDrawable(resources, BitmapFactory.decodeResource(resources, R.drawable.error_underline));
mBmpHeight = mRedWavy.getIntrinsicHeight();
mRedWavy.setTileModeX(TileMode.REPEAT);
}
@Override
public Drawable getDrawable() {
return mRedWavy;
}
@Override
public int getSize(Paint paint, CharSequence text,
int start, int end,
Paint.FontMetricsInt fm) {
mWidth = (int) paint.measureText(text, start, end);
return mWidth;
}
@Override
public void draw(Canvas canvas, CharSequence text,
int start, int end, float x,
int top, int y, int bottom, Paint paint) {
mRedWavy.setBounds(0, 0, mWidth, mBmpHeight);
canvas.save();
canvas.translate(x, bottom-mBmpHeight);
mRedWavy.draw(canvas);
canvas.restore();
canvas.drawText(text.subSequence(start, end).toString(), x, y, paint);
}
}
public class ErrorSpan extends DynamicDrawableSpan {
private int width;
int lineWidth;
int waveSize;
int color;
public ErrorSpan(Resources resources) {
this(resources, Color.RED, 1, 3);
}
public ErrorSpan(Resources resources, int color, int lineWidth, int waveSize) {
super(DynamicDrawableSpan.ALIGN_BASELINE);
// Get the screen's density scale
final float scale = resources.getDisplayMetrics().density;
// Convert the dps to pixels, based on density scale
this.lineWidth = (int) (lineWidth * scale + 0.5f);
this.waveSize = (int) (waveSize * scale + 0.5f);
this.color = color;
}
@Override
public Drawable getDrawable() {
return null;
}
@Override
public int getSize(Paint paint, CharSequence text,
int start, int end,
Paint.FontMetricsInt fm) {
width = (int) paint.measureText(text, start, end);
return width;
}
@Override
public void draw(Canvas canvas, CharSequence text,
int start, int end, float x,
int top, int y, int bottom, Paint paint) {
Paint p = new Paint(paint);
p.setColor(color);
p.setStrokeWidth(lineWidth);
int doubleWaveSize = waveSize * 2;
for (int i = (int)x; i < x + width; i += doubleWaveSize) {
canvas.drawLine(i, bottom, i + waveSize, bottom - waveSize, p);
canvas.drawLine(i + waveSize, bottom - waveSize, i + doubleWaveSize, bottom, p);
}
canvas.drawText(text.subSequence(start, end).toString(), x, y, paint);
}
}