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實現圖文混排
如上圖需求,要實現上述圖文混排有如下幾種方法
1-用SpannableString
SpannableString ss = new SpannableString("這是一間營業時間從午夜十二點到早上七點的特殊食堂");
int len = ss.length();
//獲取Drawable資源
Drawable d = getResources().getDrawable(R.drawable.icon);
d.setBounds(0, 0, d.getIntrinsicWidth(), d.getIntrinsicHeight());
//創建ImageSpan
ImageSpan span = new ImageSpan(d, ImageSpan.ALIGN_BASELINE);
//用ImageSpan替換文本
ss.setSpan(span, len - 1, len, Spannable.SPAN_INCLUSIVE_EXCLUSIVE);
txtInfo.setText(ss);
然而要實現行數限制且超過限制時省略的話,SpannableString就比較複雜了。
2-Html實現富文本
用html實現富文本也是比較常用的了,如果要插入圖片的話還需要ImageGetter來通過html中的資源ID拿到Drawable。
首先需要根據圖片類型來自定義ImageGetter,分爲網絡圖片、sd卡圖片、本地drawable圖片。這裏只分析本地drawable圖片的ImageGetter。注意這裏是圖片在drawable路徑下情形,mipmap需要將“drawable”改爲“mipmap”
public class LocalImageGetter implements Html.ImageGetter {
Context c;
public LocalImageGetter(Context c) {
this.c = c;
}
@Override
public Drawable getDrawable(String source) {
int id = c.getResources().getIdentifier(source, "drawable", c.getPackageName());
if (id == 0) {
id = c.getResources().getIdentifier(source, "drawable", "android");
}
if (id == 0) {
return null;
} else {
Drawable d = c.getResources().getDrawable(id);
d.setBounds(0, 0, d.getIntrinsicWidth(), d.getIntrinsicHeight());
return d;
}
}
}
然後自定義TagHandler來解析html的標籤,詳情見源碼中的HtmlTagHandler。最後實現代碼:
Html.ImageGetter imgGetter = new LocalImageGetter(getContext());
String html = "<img src='img01'/> + "深夜食堂" + "<img src='img02'/>
text.setText(Html.fromHtml(html, imgGetter, new HtmlTagHandler()));
- 圖文混排對齊
step1
自定義ImageSpanpublic class AlignTextSpan extends ImageSpan {
public AlignTextSpan(Drawable b, int verticalAlignment) {
super(b, verticalAlignment);
}
@Override
public void draw(Canvas canvas, CharSequence text,
int start, int end, float x,
int top, int y, int bottom, Paint paint) {
Drawable b = getDrawable();
Paint.FontMetricsInt fm = paint.getFontMetricsInt();
int transY = (y + fm.descent + y + fm.ascent) / 2 - b.getBounds().bottom / 2;//計算y方向的位移
canvas.save();
canvas.translate(x, transY);//繪製圖片位移一段距離
b.draw(canvas);
canvas.restore();
}
}
step2
setText時Html轉SpannedSpanned spanned = Html.fromHtml(html, imgGetter, null);
if(spanned instanceof SpannableStringBuilder){
ImageSpan[] imageSpans = spanned.getSpans(0, spanned.length(), ImageSpan.class);
for(ImageSpan imageSpan : imageSpans){
int start = spanned.getSpanStart(imageSpan);
int end = spanned.getSpanEnd(imageSpan);
Drawable d = imageSpan.getDrawable();
AlignTextSpan newImageSpan = new AlignTextSpan(d, ImageSpan.ALIGN_BASELINE);
((SpannableStringBuilder) spanned).setSpan(newImageSpan, start, end, Spanned.SPAN_EXCLUSIVE_INCLUSIVE);
((SpannableStringBuilder) spanned).removeSpan(imageSpan);
}
}
setText(spanned, BufferType.SPANNABLE);
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實現行數限制及末尾省略
實現原理:
參照TextView的末尾省略原理,對於沒有達到maxline的文本直接html包裝插入圖片;而對於需要省略顯示的情形,我們只需要重寫TextView對文本的截取及添加省略號的過程。根據圖片大小及個數(實例中圖片較小,按一個字符佔位)佔位去掉末尾多餘字符,並將末尾字符替換爲“...”(或者自定義省略),最後html包裝插入圖片。重寫TextView的onTextChanged()及onDraw()方法,setText("深夜食堂深夜食堂")後的過程
step1:TextView繪製文本時,內容從“”到"深夜食堂深夜食堂"會觸發onTextChange(),拿到原始文本fullText=“深夜食堂深夜食堂”
@Override
protected void onTextChanged(CharSequence text, int start, int before, int after) {
super.onTextChanged(text, start, before, after);
if (!programmaticChange) {
fullText = text.toString();//拿到原始文本
isStale = true;
}
}
@Override
protected void onDraw(Canvas canvas) {
if (isStale) {
super.setEllipsize(null);//避免重複省略
resetText();//自定義處理原始文本
}
super.onDraw(canvas);
}
Layout layout = new StaticLayout(fullText, getPaint(), getWidth() - getPaddingLeft() - getPaddingRight(),
Layout.Alignment.ALIGN_NORMAL, lineSpacingMultiplier, lineAdditionalVerticalPadding, false);
if (layout.getLineCount() > maxLines) {
workingText = fullText.substring(0, layout.getLineEnd(maxLines - 1)).trim();
workingText = workingText.substring(0, workingText.length() - placeholderCount) + ELLIPSIS;
ellipsized = true;
}
step4:用html處理截斷後的文本,
String html = "<img src='img01'/>
+ "深夜食堂深夜食堂" + "<img src='img02'/>
public void setHtmlFromString(String html) {
Html.ImageGetter imgGetter;
imgGetter = new LocalImageGetter(getContext());
setText(Html.fromHtml(html, imgGetter, new HtmlTagHandler()));
setMovementMethod(LinkMovementMethod.getInstance());
}
最終效果圖